doctoral thesis in materials science and engineering n the

Doctoral Thesis in Materials Science and Engineering

On the Origin and Distributions of the Inclusions in Production-scale ESR and PESR Remelted Ingots and Materials from Different Ingot Sizes and Solidification StructuresEVA SJOumlQVIST PERSSON

Stockholm Sweden 2021

kth royal institute of technology


Doctoral Thesis in Materials Science and EngineeringKTH Royal Institute of TechnologyStockholm Sweden 2021

Academic Dissertation which with due permission of the KTH Royal Institute of Technology is submitted for public defence for the Degree of Doctor of Philosophy on Friday the 28th May 2021 at 200 pm Digital and Green room Osquars backe 31 Soumldra tornet plan 4 Stockholm

copy Eva Sjoumlqvist Persson ISBN 978-91-7873-837-3TRITA-ITM-AVL 202114 Printed by Universitetsservice US-AB Sweden 2021

The good Lord made us all out of iron Then he turns up the heat to forge some of us into steel

- Marie Osmond

i

Abstract

The study was carried out with the aim to evaluate the origin morphology and distribution

of the non-metallic inclusions (NMI) in electro-slag remelted (ESR) steels and in electro-slag

remelted steels using a pressured controlled inert atmosphere (PESR) In addition to the NMI

studies the solidification structure in different ingot sizes were studied in order to define the

influence of the solidification on the NMI characteristics The steel grade chosen for the

studies was a common martensitic stainless steel The focus is on the origin and the

distribution of oxide inclusions with the assumption that sulfides and nitrides are secondary

inclusions in remelted material

In order to get a good statistical basis a large number of SEM samples from different axial

positions were taken from both an electrode and several ESR and PESR remelted ingots as well

as processed (rollingforging) materials The inclusions were investigated by using both two-

dimensional (2-D) and three-dimensional (3-D) methods Especially for steels with a higher

cleanliness as for example remelted steels a large analyzed area is important in order to get

a true picture of the inclusion morphology As an attempt to localize the origin of the

inclusions a pilot trial using a La2O3 as a tracer in the ESR process slag was performed To study

the influence of the solidification structure on the inclusions horizontal sliceslices were cut

from different positions from the electrode as well as from ESR and PESR remelted ingots of

different sizes Beside inclusions and chemical composition determinations across the

diameter of the slices also the second dendrite arm spacing (SDAS) and the angles of the

dendrites towards the axial plane were measured

The result gave rise to a new classification of the inclusions present in ESR or PESR remelted

steels i) Primary Inclusions They survive from the electrode because they were trapped inside

a steel drop or a fallen steel fragment without having contact with the ESRPESR process slag

The size depends on the size of the inclusions in the electrode and the size of the steel

droplets ii) Semi-Secondary Inclusions primary Al-Mg oxides covered by process slag Normal

size class is asymp lt 30 microm iii) Secondary Inclusions precipitated during solidification of the liquid

steel as a result of the reactions between alloying elements and the dissolved oxygen Normal

size class is lt 10 microm

The structure study showed that the transition from a columnar-dendritic to an equiaxial structure (CET) in the center of the ingot have a strong effect on the number and size of the inclusions As long as the center of the ingot solidifies in a columnar-dendritic manner the increase of the inclusion number and size is almost linear with an increasing ingot size However after the CET transition in the center the inclusion number and sizes are much larger For this steel grade the transition from a columnar-dendritic to an equiaxial is between the 800 mm in diameter (PESR-800) ingot and the 1050 mm in diameter (PESR-1050) ingot The primary arms growth rate needed for the CET transition is less than 4 x 10-7ms In order to undertake the transition the temperature gradient must be less than approximately 103 degCm On the whole the results illustrated that the overall cleanliness of the electrode (as well as the composition of the inclusions in the electrode) has an extremely large influence on the

ii

cleanliness in ESR and PESR remelted steels The majority of the failure critical inclusions originates direct or indirect from the inclusions in the electrode Moreover the solidification structure (ingot size) also has a direct bearing on the inclusion sizes and contents present in ESR and PESR ingots

iii

Sammanfattning

Detta arbete aumlr utfoumlrt med maringlet att faststaumllla kaumlllan morfologin och distributionen av icke-

metalliska inneslutningar (NMI) i elektroslaggomsmaumllta (ESR) staringl och i staringl elektroomsmaumllta

under en kontrollerad inert atmosfaumlr (PESR) Utoumlver inneslutningsstudierna har aumlven

stelningsstrukturen i olika goumltstorlekar undersoumlkts Detta i syfte att definiera strukturens

paringverkan paring de icke-metalliska inneslutningarna Den valda staringlsorten aumlr ett vanligt

martensitiskt rostfritt staringl Fokus av arbetet aumlr kaumlllan och distributionen av de oxidiska

inneslutningar med ett antagande att sulfider och nitrider aumlr sekundaumlra inneslutningar i

omsmaumllt material

I syfte att faring ett bra statistiskt underlag aumlr ett stort antal SEM-prover fraringn baringde olika vertikala

goumltpositioner uttagna fraringn en elektrod flera ESR- och PESR-goumlt samt fraringn bearbetat material

(smide valsning) Inneslutningarna aumlr studerade baringde med tvaring-dimensionella (2-D) och tre-

dimensionella (3-D) metoder Det aumlr extra viktigt foumlr staringl med en houmlgre renhet som till

exempel omsmaumllta staringl att analysera maringnga och stora ytor foumlr att faring en sann bild av

inneslutningsmorfologin I ett foumlrsoumlk att lokalisera kaumlllan foumlr de oxidiska inneslutningarna aumlr

pilot-foumlrsoumlk med ett sparingraumlmne i processlaggen genomfoumlrda I syfte att studera strukturens

inverkan paring inneslutningarna aumlr horisontella skivor kapade fraringn flera goumltstorlekar Foumlrutom

inneslutningarna och den kemiska analysen tvaumlrs skivorna studerades aumlven det sekundaumlra

dendritsarmsavstaringndet (SDAS) och dendriternas vinkel mot det horisontella planet

Resultatet aumlr en ny klassificering av inneslutningarna i ESR- och PESR-omsmaumllta staringl i) Primaumlra

Inneslutningar oumlverlever fraringn elektroden utan kontakt med ESRPESRs processlagg faringngade

i en fallande staringldroppe eller staringlfragment Deras storlek beror av storleken paring

inneslutningarna I elektroden samt de fallande staringldropparnas storlek ii) Semi-Sekundaumlra

Inneslutningar Fraumlmst Al-Mg oxider taumlckta med processlagg Normal storleksklass aumlr asymp lt 30

microm iii) Sekundaumlra Inneslutningar utskilda under stelningen av det flytande staringlet som ett

resultat av en reaktion mellan legeringselement och loumlst syre Normal storleksklass aumlr lt 10

microm

Strukturstudien visade att en oumlvergaringng fraringn riktad dendritisk struktur till enaxlig struktur har en stor paringverkan paring antalet och storleken av inneslutningarna Saring laumlnge som centrum I ett goumlt stelnar med en riktad dendritisk struktur aumlr oumlkningen av antalet inneslutningar linjaumlrt med oumlkad goumltstorlek Efter oumlvergaringngen till enaxlig struktur i centrum aumlr dock inneslutningarna baringde stoumlrre och fler Foumlr denna staringlsort intraumlffar oumlvergaringngen fraringn riktad dendritisk struktur till enaxlig struktur naringgonstans mellan en PESR-goumltdiameter paring 800 och 1050 mm Tillvaumlxthastigheten som behoumlvs av de primaumlra dendritarmarna foumlr att oumlvergaringngen skall ske aumlr under 4 x 10-7ms Dessutom kraumlvs en temperaturgradient som aumlr laumlgre aumln cirka 103 degCm Sammantaget visar resultatet att baringde maumlngden av inneslutningar I elektroden (tillika dess storlek och komposition) aumlr extremt viktig foumlr renheten i ESR-och PESR-omsmaumllta staringl Majoriteten av de i kritiska inneslutningarna haumlrstammar direkt eller indirekt fraringn inneslutningarna i elektroden Utoumlver det aumlr aumlven stelningsstrukturen (goumltstorleken) direkt avgoumlrande foumlr inneslutningarnas storlek och antal i ESR- och PESR-omsmaumllta material

iv

Acknowledgement

First I would like to express my sincere gratitude and appreciation to my supervisor Professor Paumlr Joumlnsson

I am also thankful for the support advices and not least help with creating some of the figures by my co-supervisor Andrey Karasev

However the thesis would never have been done without the outstanding help advice and encouragement by Professor emeritus Alec Mitchell UBC Canada and Professor emeritus Hassse Fredriksson KTH

I also would like to thank Dr Changji Xuan (and late Dr Mselly Nzotta) for the memorable discussions about inclusions The discussion lead to two articles by Dr Changji Xuan (with me and Dr Mselly Nzotta as co-authors) which both are very important for my work

I will also thank MSc Sofia Brorson with the structure determinations

I especially would like to thank Uddeholms AB for financing my trials and the writing of this thesis

Many thanks also goes to my colleagues at Uddeholms AB for helping me with trials inclusion and chemical analyzes and for not giving up on me

Eva Sjoumlqvist Persson

Hagfors 2021

v

Supplements

The following supplements have been the basis for the thesis

Supplement 1 ldquoThe behavior of Inclusions during ESR Remeltingrdquo Persson E Mitchell A Fredriksson H In Proceedings of the 2nd Ingot Casting Rolling Forging Conference ICRF 2014 Germany Stahleisen Milano Italy 7-9 May 2014

Supplement 2 ldquoDifferences in inclusion morphology between ESR remelted and ingot

casted common martensitic steelrdquo Persson ES Fredriksson H Mitchell A In Proceedings of the 5th International Conference on Process Development in Iron and Steelmaking Scanmet-V 2016 Lulearing Sweden 12ndash15 June 2016

Supplement 3 ldquoDifferences in inclusion morphology between ESR remelted steel with

and without tracer in the slagrdquo Persson ES Mitchell A In proceedings of the Liquid Metal Processing amp Casting Conference LMPC USA TMS Philadelphia PA USA 10ndash13 September 2017

Supplement 4 ldquoThe importance of Electrode Cleaness in the ESRPESR Processesrdquo Persson ES Mitchell A In Proceedings of the 3rd Ingot Casting Rolling Forging conference ICRF Germany Stahleisen Stockholm Sweden 16ndash19 October 2018

Supplement 5 ldquoStudies of three dimension inclusions from ESR remelted and

conventional cast steelrdquo Persson ES Karasev A Joumlnsson PG In Proceedings of the Liquid Metal Processing amp Casting Conference LMPC USA TMS Philadelphia PA USA 10ndash13 September 2017

Supplement 6 ldquoOrigin of the Inclusions in Production-Scale Electrodes ESR Ingots and

PESR Ingots in a Martensitic Stainless Steelrdquo E Sjoumlqvist Persson A Karasev A Mitchell and P G Joumlnsson Metals 2020 Vol20 Issue 12 pp1620 httpsdoiorg103390met10121620

Supplement 7 ldquoA novel evolution mechanism of Mg-Al-oxides in liquid steel Integration of chemical reaction and coalescence-collisionrdquo Xuan C Persson ES Jensen J Sevastopolev R Nzotta M J Alloys Comp 2019 812 httpsdoi101016jjallcom2019152149

Supplement 8 ldquoImpact of solidification on inclusion morphology in ESR and PESR remelted martensitic stainless steel ingotsrdquo E Sjoumlqvist Persson S Brorson A Mitchell and P G Joumlnsson Metals 2021 11 408 httpsdoiorg103390met11030408

vi

The contributions by the author of this thesis to the above supplement are the following

Supplement 1 Performed all of the literature survey the experimental work at the ESRPESR shop

observations and analyses of the SEM work major part of writing and presentation at the conference






observations and analyses of the SEM work major part of writing and presentation of the poster at

the conference




observations and analyses of the SEM work and major part of writing

Supplement 7 Main part of conceptualization Started the discussion about the surviving Al-Mg oxide

inclusions (spinels) that led to Dr Xuanrsquos calculations and the article analysis and investigation on the

inclusion morphology in conventional ingots electrodes and remelted ingots and material together

with the main author ongoing input during the writing of the article and edited the article together

with the main author before submission


observations and analyses of the SEM micro etching and chemical analyses work and major part of

writing

Other relevant publications not included in the thesis

Xuan C Persson ES Sevastopolev R Nzotta M Motion and Detachment Behaviors of Liquid Inclusion at Molten Steel-Slag Interfaces Metall Mater Trans B 2019 4 1957-1973 httpsdoiorg101007s11663-019-01568-2

E Sjoumlqvist Persson J Karlsson B Gustafsson K Steneholm ldquoProcess control of casting rate at Uddeholms ABrdquo In Proceedings of the Ist Ingot Casting Rolling Forging Conference ICRF 2012 Germany Stahleisen Achen Germany 2012

M Svensson E Sjoumlqvist Persson L Hallberg C-Aring Daumlcker Experience from plant trials with improved mould powder at Uddeholms AB In Proceedings of the 2nd

Ingot Casting Rolling Forging Conference ICRF 2014 Germany Stahleisen Milano Italy 7-9 May 2014

vii

List of Tables

Table 1 Previous studies on inclusions in electro-slag remelting (ESR) or electro-slag remelting under protective pressure-controlled atmosphere (PESR) remelted

Table 2 Overview of the eight supplements used in this thesis

Table 3 Chemical analysis of the process slags before the pilot trials where (1) is the reference ingot and (2) (two analysis) the trial ingot

Table 4 Parameters used in phase-field simulation

Table 5 Chemical composition of the top slags after remelting of the pilot trials with La2O3 as a tracer in the process slag (1) is from the reference ingot and (2) is from the trial ingot (2a) is taken from the darker slag and (2b) from the white parts se Figure 16b

Table 6 Melting points of inclusions occurring in electrode heats and ESRPESR ingots data from [57]

Table 7 Characterization and a general schematic of the three described inclusion types

Table 8 Secondary dendrite arm spacing (SDAS ℷ2) versus distance from the surface for the electrode 300 x 300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Table 9 Data and statistics for the secondary arm spacing (SDAS ℷ2) measurements Electrode 300 x 300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Table 10 Data and statistics for the angle between the dendrite arms and the axial plane Electrode 300 x 300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Table 11 Distance from ingot surface (mm) and growth rate ʋgrowth (ms) per electrode 300 x 300 mm (CE-300) electro-slag remelted ingot (ESR-400) and pressure electro-slag remelted ingots 500-1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Table 12 Temperature gradients (degCm) and distances from surface (mm) for electrode 300 x 300 mm (CE-300) electro-slag remelted ingot 400 x 400 mm (ESR-400) and pressure electro-slag remelted ingots 500-1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Table 13 Overview of the main topics results and application of the supplements

viii

List of Figures

Figure 1 Longest Solidification Time (LST) versus melt rate for ingots with different diameters

[45]

Figure 2 Schematic illustration of horizontal slices and sample positions on (a) the consumable electrode (CE-300) (b) ESR remelted ingots (ESR-400) and (c) PESR remelted ingots (PESR-500 PESR-800 PESR-1050)

Figure 3 (a) Schematic illustration of the positions of the macro samples for the electrode 300

x 300 mm and for the electro-slag remelted (ESR) ingot 400 x 400 mm (b) Schematic

illustration of the positions of the macro samples for the pressure electro-slag remelted (PESR)

ingots of 500-1050 mm in diameter

Figure 4 Schematic illustration of the longitudinal sections used for measuring the angle

between the dendrites and the axial plane

Figure 5 Measure principle example from position T2 (center) of the 500 mm in diameter

ingot (PESR-500) The primary arms and their connecting secondary arms are marked in red

The measurements were made in-between the red marked secondary arms

Figure 6 Phase-field simulation of Mg-Al-oxide solid inclusion attachment by liquid slag

Figure 7 Numbers of inclusions per mm2 and ingot size Material from electro-slag remelted

400 x 400 mm (ESR-400) electro-slag remelted 600 mm diameter (ESR-600) and pressure

electro ndashslag remelted 500-1050 mm diameter (PESR-500 PESR-800 PESR-1050 ingots) (b) is

an enlarged and zoomed version of (a)

Figure 8 Number of inclusions per mm2 before (HT2012) and after (HT2013) optimization of

the electrode quality (a) Material from an electro-slag remelted 400 x 400 mm ingot (ESR-

400) (b) Material from a pressure electro-slag remelted 500 mm diameter ingot (PESR-500)

Figure 9 Number of oxide inclusions per mm2 and ingot size Material from conventional

ingots with solidification lengths of approximately 600 and 700 mm (CON-600 CON-700)

electro-slag remelted 400 x 400 mm ingot (ESR-400) electro-slag remelted 600 mm diameter

ingot (ESR-600) and pressure electro-slag remelted 500-1050 mm ingots (PESR-500 PESR-

800 PESR-1050)

Figure 10 Example of inclusions compositions analyzed by using software Inca Feature

software and laid in the ternary diagram CaOMnOSiO2-MgO-Al2O3 for (a) a conventional

ingot and (b) a PESR remelted ingot

Figure 11 Average inclusion and slag (top and process) composition per process andor

furnace type

ix

Figure 12 Typical example of the largest inclusions found in material from the conventional

ingots (a) Inclusion with the look of a walnut containing Al-O Ca-Al-O and Ca-S (b) Elongated

string inclusion containing Al-Mg-O (spinel) and Ca-S

Figure 13 Typical example of the largest inclusions found in material from the ESR remelted

ingots (a) a round Ca-Al-O inclusion and (b) an elongated string inclusion containing Ca-Al-O

Ca-S and Ca-O

Figure 14 Typical example of the largest inclusions found in material from the PESR remelted

ingots (a) round Al-O and (b) elongated string inclusion Al-O and Ca-S

Figure 15 Ingot 1 (reference ingot) to the left and Ingot 2 (with La2O3as a tracer in the process

slag) to the right

Figure 16 Process slag taken from the top of the ingot after remelting from (a) Ingot 1

(reference ingot) and (b) Ingot 2 (with La2O3as a tracer in the process slag)

Figure 17 Number of oxide inclusions per mm2 and size class per ingot and position Ingot 1

(reference ingot) Ingot 2 (with La2O3as a tracer in the process slag) bottom position (B) and

top Position (T) Figure (b) is an enlarged and zoomed version of Figure (a)

Figure 18 Classification of inclusions in ingots Ingot 1 without a tracer (a) bottom (b) top

Ingot 2 with a La2O3 addition (c) bottom (d) top The field of view is 6620 mm2 each for the

bottom samples and 6190 mm2 each for the top samples

Figure 19 Differences in inclusions number per inclusion type between Ingot 1 reference and

Ingot 2 with a tracer in the process slag at (a) bottom and (b) top of ingot Field of view is

6620 mm2 each for the bottom samples and 6190 mm2 each for the top samples

Figure 20 The three largest inclusions per sample and their composition in Ingot 1 without

tracer in the process slag The given length corresponds to the scale line

Figure 21 The three largest inclusions per sample and their compositions in Ingot 2 where a

tracer was added to the process slag The given length corresponds to the scale line

Figure 22 Mapping of the largest inclusion in the top sample of Ingot 2 where La2O3as was

added as tracer to the process slag

Figure 23 The relation between Al oxide inclusion containing gt 3 Mg and the total amount

of oxide inclusions per measured inclusion size class and ingot type There were no inclusions

larger than size class 224-448 microm detected

Figure 24 Number of (a) oxide and (b) sulfide inclusions per unit area (NA) for the C-300 ESR-400 and PESR-500 samples The contents of sulfur in the steel [S] in the ESR-400 and in the PESR-500 are 32 respectively 24 of the amount of sulfur [S] in the CE-300

Figure 25 Number of different non-metallic inclusions (NMIs) per unit area (NA) observed by two-dimensional (2-D) investigations on different polished steel samples (a) CE-300 M (b) ESR-400 and (c) PESR-500

x

Figure 26 Compositions of the oxide inclusions in different samples observed by two-dimensional (2-D) investigations on polished sample surfaces (a) CE-300 M (b) ESR-400 and (c) PESR-500

Figure 27 Typical large-sized oxide inclusions in different samples observed by two-dimensional (2-D) investigations on polished sample surfaces (a) Types A and AM Al2O3 Al2O3-MgO (b) Type ACM Al2O3-MgO + CaO-Al2O3 + (CaS) (c) Type AC Al2O3-CaO + (CaS) (d) Type AC Al2O3-CaO + CaF2

Figure 28 Typical oxide inclusions in different samples observed by three-dimensional (3-D) investigations on surfaces of steel samples after electrolytic extraction (a) Type A Al2O3 (b) Type AM Al2O3-MgO (c) Type ACM Al2O3-MgO + CaO-Al2O3 + CaF2 (d) Type AC CaO-Al2O3 + (CaF2 + CaS)

Figure 29 Mapping of main elements in four different typical inclusions types observed by three-dimensional (3-D) investigations on the surfaces of steel samples after electrolytic extraction

Figure 30 Schematic illustrations of different oxide inclusions in the melted metal layer on the surface of electrode liquid slag melted metal bath and solidified ingot during the ESR process (a) Solid electrodemdashLiquid slag (b) Liquid slag (c) Liquid slagmdashMelted metal bath (d) Melted metal bathmdashSolidified ingot

Figure 31 Schematic presentation over the hypothetic life cycle of an oxide inclusion from the

ladle to an ESRPESR ingot

Figure 32 (a) Schematic illustration of the mechanisms of oxygen transfers and Al deoxidation in the ESR process (lsp-liquid steel pool) (b) Numbering of reactions in the figure is given according to [19]

Figure 33 Examples of macro structures in the electrode and the ingots (a) Electro-slag remelted 400 x 400 mm ingot (ESR-400) from surface to position T4 (in between corner and center) (b) Pressure electro-slag remelted 500 mm diameter ingot (PESR-500) with position T6 (inbetween corner and position T4) and position T4 marked The arrows point at the etching consentric bands (c) Pressure electro-slag remelted 1050 mm diameter ingot (PESR-1050) from surface to 155 mm The arrows point at the etching consentric bands (d) Electrode 300 x 300 mm (CE-300) from surface to 155 mm

Figure 34 Center of the cross sections from the electrode 300 x 300mm (CE-300) (a) Bottom

(B) (b) Middle (M) and (c) Top (T)

Figure 35 From position T4 (between center and corner) and position T2 (center) on the

cross sections from the electro-slag remelted ingot 400 x 400 mm (ESR-400) (a) Sample 1

(ESR-400 1) and (b) sample 2 (ESR-400 2)

Figure 36 Center of the cross sections from the pressure electro-slag remelted ingots (a) 500

mm diameter ingot (PESR-500) (b) 800 mm diameter ingot (PESR-800) and (c) 1050 mm

diameter ingot (PESR-1050)

xi

Figure 37 Secondary dendrite arm spacing (SDAS ℷ2) (microm) for electrode 300 x 300 mm (C-300) electro-slag remelted 400 x 400 mm (ESR-400) and electro-slag remelted under pressure controlled atmosphere pressure electro-slag remelted 500-1050 mm diameter (PESR-500-800-1050) ingots Cross section positions T6 - quarter radius T4 ndash half radius T2 ndash center

Figure 38 Secondary dendrite arm spacing (SDAS ℷ2) versus distance from the surface for different ingot types Electrode 300 x300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Figure 39 (a) The angle between the dendrite arms and the axial plane at position T2 on the pressure electro-slag remelted ingot with an 800 mm diameter (PESR-800) (b) The angle between the dendrite arms and the axial plane was not determined at position T2 on the pressure electro-slag remelted ingot with a 1050 mm diameter (PESR-1050)

Figure 40 Growth rate towards distance from ingot surface Equation (1) which is used to calculate the growth rate is just valid for columnar dendritic growth The bent curve for the pressure electro-slag remelted 1050 mm in diameter ingot (PESR-1050) indicates that it solidifies to form an equiaxial structure in the center

Figure 41 (a) Temperature gradient G (degCm) towards distance from ingot surface Equation (9) (which also is used to calculate the temperature gradient) is just valid for columnar dendritic growth The not linear connection for the pressure electro-slag remelted ingot of 1050 mm in diameter (PESR-1050) indicates that it solidifies as an equiaxial structure in the center (b) Growth rate Ʋgrowth (mms) as function of the temperature gradient G (degCm)

Figure 42 Growth rate Ʋgrowth (ms) (calculated on primary dendrite arm spacings) versus the

temperature gradient G (degCm) around the solidliquid tip The black line represets data from

Kurz solidification diagram [64] The area above the line solidifies in an equiaxial manner and

the area below in a columnar-dendritic manner [64] Data from Uddeholms martensitic

stainless steel are included the electrode 300x300 mm (CE-300) the electro-slag remelted

ingots 400x400 mm (ESR-400) and the pressure electro-slag remelted ingots 500-1050 mm

diameter (PESR-500 PESR-800 PESR-1050) All data have been taken from the center position

of the ingots The electrode and the PESR-1050 that both solidifies equiaxial dendritic in the

center are marked () This is due to that the equations used not are valid for the equaxial

solidification structure

Figure 43 (a) The deviations between the content of carbon (C) over the cross sections at

the bottom (B) and top (T) the electrode 300 x 300 mm (C-300) and the corresponding

electrode heat (b) The deviations between the contentnt of carbon (C) in the ingots and their

corresponding electrode heats Electro-slag remelted ingot 400 x 400 mm (ESR-400) and

pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-

1050)

xii

Figure 44 Number of oxide inclusions per mm2 and ingot size and from the electrode and the processed material from the ingots (after approximately a 75 reduction degree) at different axial positions Electro-slag remelted ingot 400 x 400 mm (ESR-400) and pressure electro-slag remelted ingots 500 ndash 1050 mm diameter (PESR-500 PESR-650 PESR-800 PESR-1050) at the bottom (B) middle (M) and top (T) positions No inclusions gt 448 microm were detected in the processed material

Figure 45 Inclusion measurement over the cross sections for (a) the pressure electro-slag remelted 800 mm diameter (PESR-800) and (b) 1050 mm diameter (PESR-1050) unprocessed ingots No inclusions gt 448 microm were detected

Figure 46 Figure 46 Number of oxide inclusions per mm2 in materials from different ingot types All positions are from the axial center with a field of view of approximately 6000 mm2 each The figure is enlarged and zoomed in Y-axis in order to focus on the large inclusions No inclusions gt 448 microm were detected

xiii

List of Abbreviations

ESR Electro-slag remelting

IESR Electro-slag remelting using an inert atmosphere

PESR Electro-slag remelting using a pressure controlled inert atmosphere

NMI Non-metallic inclusions

IMI Inter-metallic inclusions

LST Longest solidification time

CD Columnar dendritic solidification

EQ Equiaxial solidification

CET Columnarequiaxial transition

B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional

3-D Three-dimensional

SEM Scanning electron microscope

EDS Energy Dispersive X-ray Spectroscopy

EE Electrolytic extraction

SDAS Secondary dendrite arm spacing

LOM Light optical microscope

CE-300 Conventional cast electrode 300 x300 mm

ESR-400 ESR remelted ingot 400 x 400 mm

ESR-600 ESR remelted ingot 600 mm diameter

PESR-XXX PESR remelted ingot with XXX mm diameter

CONV-XXX Conventional cast ingot with XXX mm as the shortest solidification length

xiv

CONTENTS

Abstracthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipi

Sammanfattninghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipiii

Acknowledgementhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipiv

Supplementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipv

List of Tableshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipvii

List of Figureshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipviii

List of Abbreviationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipxiii

Contentshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipxiv

1 INTRODUCTIONhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip1

11 INDUSTRIAL MOTIVATION FOR WORKhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip1

12 LITERATURE STUDYhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip2

121 INCLUSIONShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip3

122 SOLIDIFICATIONhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip6

13 PRESENT WORKhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip9

2 EXPERIMENTAL METHODShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip11

21 MATERIALhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip11

22 SAMPLINGhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip12

221 SAMPLES FOR INCLUSION DETERMINATIONShelliphelliphelliphelliphelliphelliphelliphellip12

222 SAMPLES FOR STRUCTURE DETERMINATIONShelliphelliphelliphelliphelliphelliphellip13

23 INCLUSION DETERMINATIONhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip15

231 TWO-DIMENSIONAL (2-D) SEMhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip15

232 THREE-DIMENSIONAL (3-D) ELECTRIC EXTRACTION SEMhellip15

24 STRUCTURE DETERMINATIONShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip16

241 DENDRITE ARM SPACINGShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip16

242 SOLIDIFICATION ANGLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip16

25 CHEMICAL ANALYZEhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip17

26 DESCRIPTION OF THE STEEL PLANThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip17

3 THEORYhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip18

4 RESULTS AND DISCUSSIONhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip20

41 DIFFERENCE IN INCLUSION MORPHOLOGIEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip20

411 MATERIAL FROM DIFFERENT INGOT SIZEShelliphelliphelliphelliphelliphelliphelliphelliphellip20

412 MATERIAL FROM CONVENTIONAL AND REMELTED MATERIAL

helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip23

42 PILOT SCALE TRIALS USING A LA2O3 TRACER IN THE PROCESS SLAGhelliphelliphelliphelliphelliphelliphelliphellip27


431 COMPARISON BETWEEN ELECTRODE AND ESRPESR INGOT

FROM THE SAME ELECTRODE HEAT AND UPDATED

INCLUSION CLASSIFICATIONhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip36

4311 PRIMARY INCLUSIONShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip43

4312 SEMI-SECONDARY INCLUSIONShelliphelliphelliphelliphelliphellip44

xv

4313 SECONDARY INCLUSIONShelliphelliphelliphelliphelliphelliphelliphelliphellip44

4314 GENERAL SCEMATIC OF THE THREE TYPICAL

INCLUSION TYPEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip45

4315 HYPOTHETIC LIFE CYCLE OF AN OXIDE

INCLUSION FROM THE LADLE TO AN

ESRPESR

INGOThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip46

432 COMPARISON BETWEEN ESR AND PESR INGOTShelliphelliphelliphelliphelliphellip48

44 SOLIDIFICATION IN ELECTRODE AND ESRPESR REMELTED INGOTShelliphelliphelliphelliphelliphelliphellip49

441 MACRO COLUMNAR DENDRITIC (CD) AND EQIAXIAL (EQ)

STRUCTUREhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip49

442 GROWTH RATE AND TEMPERATURE GRADIENThelliphelliphelliphelliphelliphellip59

443 METAL COMPOSITION OVER THE CROSS SECTIONShelliphelliphelliphellip64

444 SIZE DISTRUBUTION OF INCLUSIONS IN VARIOUS

INVESTEGATED MATERIALS AND INGOTShelliphelliphelliphelliphelliphelliphelliphelliphelliphellip66

5 CONCLUDING DISCUSSIONShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip69

6 CONCLUSIONShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip74

7 SUSTAINIBILITY AND FUTURE WORKhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip76

71 SUSTAINABILITYhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip76

72 FUTURE WORKhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip76

8 REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip77

1

1 INTRODUCTION

11 INDUSTRIAL MOTIVATION FOR WORK

Due to increased requirements on the final properties of high-quality steels the limitations on the content of non-metallic inclusions (NMIs) and impurity elements in these steels are continually being more stringent The remelting techniques of electro-slag remelting (ESR) and electro-slag remelting under a protected pressure controlled atmosphere (PESR) produce clean steels with respect to non-metallic inclusion (NMI) content In order to optimize process routes for different steel grades it is important to define the advantages of using different processes For many applications (although not all) an ESR steel product is considered ldquocleanrdquo if the inclusion content gt20 microns is zero The content of inclusions lt20 micron is to be important for certain very demanding applications for example in bearing steels [12] and super clean plastic mould steels However numerous examinations have shown [3] that the gt20micron inclusion content is responsible for most service failures and is also primarily the result of slag or refractory reactions rather than de-oxidation reactions Various studies of the ESR process have indicated the importance of process parameters in

determining the ingot inclusion content [4-10] and have proposed a number of operating

mechanisms The determining factors have been indicated as slag composition melting rate

immersion depth fill-ratio and operating atmosphere However few studies account for the

role of the electrode inclusions Moreover none of these studies has shown the relative

importance of the factors in a quantitative manner leaving open the question of precisely

which factors should be the focus of attention in ensuring the cleanest ingot

2

12 LITERATURE STUDY

Previous studies on non-metallic inclusions and cleanliness in ESR or PESR remelted ingots are presented in Table 1 [3-8 11-24] It can be seen that the majority of them are executed in laboratory- or pilot-scale furnaces (from 08 to 50 kg experimental trials) and with a focus on steel grades other than martensitic stainless tool steels which is the focus of this investigation The inclusions found in laboratory-scale trials are usually in the size range of 1ndash5 microm but more often le2 microm However in industrial size ingots significantly larger inclusions can be found Therefore for reliable evaluations of the characteristics of NMI (especially larger size inclusions) in industrial-scale ingots investigations of NMIs carried out only in laboratory and pilot experiments are not sufficient In this study of inclusions in production-scale ingots the analyzed area is about 6000ndash6500 mm2 per sampling position (about 2000 mm2 for the ingots) On the forged or rolled areas approximately 1ndash3 inclusions between 20 and 30 microm per sample are detected The sample areas in laboratory-scale trials are usually about 100 mm2 According to Franceschini et al [25] an analyzed surface of 5000 mm2 is suitable for evaluating the cleanliness for remelting processed samples to compare with air samples where 1000 mm2 is sufficient


Year Author Steel Scale Diameterwidth Inclusions size Ref

1971 DAR Kay et al NA NA NA NA 11

1980 ZB Li et al NA NA NA NA 12

2012 C-B SHI et al NAK80 die steel NA NA NA 13

2012 C-B SHI et al Die steel Laboratory NA NA 14

2012 C-B SHI et al High-al steel NA NA lt 5microm 15

2012 XC Chen et al Inconel 718 NA NA CN 5-15 microm 16

1969 B CBurel steel iron Laboratory Mould 77 mm lt 15 microm 3

1974 A Mitchell et al oxygen containing iron iron-OFHC copper Laboratory Mould 762 mm 1-5 microm 17

1976 JCF Chan et al Stainless steel Laboratory Electrode 35 mm NA 18

2013 C-B SHI et al Die steel superallloys hellip Laboratory NA NA 19

2013 Y Dong et al Cold rolls steel MC5 Laboratory 800 gr NA NA 4

2014 Y-W Dong et al Die steel CR-5A Laboratory 800 gr NA NA 5

2013 C-B SHI et al H13 die steel Laboratory 50 kg Electrcode 90 mm abt 2 microm 20

2015 R Scheinder et al Hot work steel abt H11 Pilot Electrode 1015 mm NA 6

2016 C-B SHI et al High-Carbon 17 Cr Tool Steel Pilot PESR mould 170 mm abt 5 microm 21

2017 GDu et al H13 die steel Pilot ESR mould 300 mm 0-15 microm gt15 microm 7

2014 LZ Cang et al NA Pilot 15 kg Mould abt 105 mm 22

2019 C-B SHI et al Si-Mn killed steel asymp H13 Pilot PESR 95 mm 1-3 microm few gt 3microm 23

2013 G Reiter et al abt H11 H13 die steelmartensitic Cr-Ni steel Industrial NA ASTM E45 Heavy 8

2017 H Wang et al H13 die steel Laboratory Electrode 25 mm abt 1-2 microm 24

3

121 INCLUSIONS

The earlier and most generally accepted theories assume that the inclusions in the electrode will be rejected to the surface of the electrode tip to be incorporated into the liquid process slag [3918232627] The steel melt will then seek equilibrium with the process slag so that new different oxygen levels in the liquid steel pool will be obtained With respect to the inclusion solution during an ESR process Mitchell et al [28] showed in laboratory trials that the rate of solution of Al2O3 inclusions of 100 microm in a common ESR and PESR process slag (CaF2

+ 20ndash30 wt Al2O3) should be dissolved within the predicted exposure time to the liquid slag at the electrodeslag interface Also Li et al [29] investigated the dissolution rate of Al2O3 into a molten CaO-Al2O3-CaF2 flux In their study it was seen that when the Al2O3 rod was immersed into a molten flux an intermediate compound of CaO-2Al2O3 was initially formed before being dissolved in the flux The dissolution rate of Al2O3 increased with an increased CaOAl2O3 ratio in the flux a higher rotation speed of the rod in the flux and a higher temperature According to Wang et al [24] the original oxide inclusions in a Mg-free H13 consumable electrode are Al2O3 and the original oxide inclusions in a Mg-containing H13 steel consumable electrode are Mg spinels After an ESR remelting the oxide inclusions in the Mg-free ESR ingot are still Al2O3 while both Al2O3 and MgO-Al2O3 inclusions exist in the Mg-containing ESR ingot Related studies [30] on the removal of large inclusions from a cast steel electrode made with a deliberately-high content of inclusions larger than 500 microm have also indicated that not all large inclusions were removed by an ESR remelting by identifying that some large inclusions have survived into the ingot without change A similar study reported by Paton et al [31] indicates that approximately 20 of the large inclusions in the ESR ingot have the same composition as those compositions found in the electrode Mg spinel inclusions can be formed by reactions during the ESR process Shi et al [23] remelted vacuum-induction remelting (VIM)-produced electrodes (Si-Mn killed steel) containing only MnO-SiO2-Al2O3 inclusions in a pilot PESR using a process slag containing 3ndash4 MgO The inclusions found in the remelted ingot (Oslash95 mm) were only Mg spinel inclusions containing asymp 3 mass Mg readily formed in the liquid pool as a result of the reactions between the alloying elements and the dissolved oxygen that dissociated from the MnO-SiO2-Al2O3 inclusions in the liquid steel Laboratory results obtained by Dong et al [5] indicate that most non-metallic inclusions in an ESR remelted Cr-5A die steel using a multi-component process slag are MgO-Al2O3 inclusions Based on a laboratory study of H13 steel remelting Shi et al [6] also found that MgO-containing inclusions survive from the electrode Specifically they found that all the inclusions in the consumable electrode were Mg spinels occasionally surrounded by an outer (Ti V) N or MnS layer Their study showed that when only Al-based deoxidant additions or no deoxidants are used all the oxide inclusions remaining in the PESR ingots are Mg spinels After a PESR refining combined with a proper calcium treatment the ingot inclusion population was modified to mainly consist of CaO-MgO-Al2O3 inclusions but also including some CaO-Al2O3

inclusions The size range of the inclusions in the PESR ingots of this laboratory study was approximately lt2 microm suggesting that the inclusions were predominantly precipitates formed during solidification or cooling

4

Many research studies [3233] have reported on the physical removal of inclusions during steelmaking processes with a focus on the influence of buoyancy forces on the removal The ESR ingot pool presents a similar case but with significant differences in the liquid flow patterns and residence times The terminal velocity of a Mg spinel inclusion with a 50 microm diameter rising in a liquid steel is approximately 5 times 10-4 ms given the computed ingot pool pattern [34] This implies that any inclusion removal is determined by a balance between the probabilities of being exposed to the slagingot interface or being trapped in the solidifying metal as dictated by the bulk metal flow of the liquid ingot pool Inclusions (depending on their size and density) will be trapped in the flow pattern many never reaching the steelslag interface According to this model the contribution of inclusion refining though flotation is much smaller than what has previously been estimated The oxygen content in ESR and PESR remelted steels is discussed in several articles [715182335-40] The overall finding is that the system moves towards equilibrium directed by the slagmetal equilibria However the reported oxide inclusion contents contributes for only a very small fraction (lt1) of the total analyzed oxygen content Therefore the reduction in the oxygen level often reported between the electrode and ingot cannot be allocated to a removal of inclusions to the slag The oxygen level in the investigated high-chromium steel grade is usually between 5ndash10 ppm While oxygen reductions during ESR are indicative of a refining process they are not in themselves indicators of whether a inclusion removal or a formation of new inclusions have taken place Higher amounts of oxygen in the electrode (about 30ndash100 ppm) lead to a decreased oxygen content in a remelted steel [15353639] In contrast a lower amount of oxygen (about lt10ndash15 ppm) leads to an oxygen pick-up in the remelted ingot [222336ndash39] The majority of the inclusions containing sulfur will change their composition completely during the ESRPESR remelting processes In electrodes and conventional ingots MnS is the most common sulfur inclusion [1419] The MnS will dissolve on the electrode tip during the ESRPESR remelting The content of dissolved S in the droplets andor the liquid film on the electrode tip decreases drastically due to reaction with ESRPESR process slag As a result the overall amount of sulfur inclusions in ESRPESR remelted ingots is very low The reason is due to the following reaction in the slag bath

[S] + (CaO) =gt [O] + (CaS) (1) AlN inclusions will dissociate in the liquid metal film on the electrode tip during remelting of a die steel [19] However depending of the ratio between (Al) and (N) in the melt new AlN inclusions will precipitate in the molten pool (or in the solid material) during solidification of the ESRPESR ingots During melting of the process slag as well as during the start of the melting phase the Al content will increase in the ingot both due to electrochemical [41] and thermodynamic reactions according to equations (2) and (3) Even though the remelting is done by using AC the Faradaic reactions that take place on the slagmetal interfaces are not completely reversed with the 60Hz change in polarity Some Al3+ ldquoescapesrdquo the electrochemical reaction area probably due to the movement in the slag bath

5

Al3+ + 3e- =gt [Al] (2) At the beginning of the remelting the process slag also seek equilibrium with the molten steel Depending on the Si content in the steel equation (3) then can go in the leftwards direction However during the whole remelting process especially in ESR process using Al as continuous deoxidation the reaction will move towards the right-hand side The amount of Al2O3 in the slag will then increase during the process primarily due to equation (3) but also due to equations (4) and (5) below

3(SiO2) + 4[Al] = 3[Si] + 2(Al2O3) (3) In a study by Shin et al [42] laboratory trials were made in order to evaluate the reactions between different top slags and steels in second metallurgy The experimental result correlated well to the calculated results for Al and Si in the metal The results showed that the contents of Mg and Ca in molten steel gradually increase during the early stage of the reaction and that the degree of increase is higher with higher contents of SiO

2 in the top slag The cause

is the fact that the activity of CaO decrease with increasing contents of SiO2 in the slag This is due to the transportation of Mg and Ca from the slag to metal phase which is given by the equations below

3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)

3(CaO) + 2[Al] = 3[Ca] + (Al2O3) (5) According to Shin et al [42] the spinel inclusions will exist for longer times in the melt before modified to a CaO-Al2O3-SiO2-MgO system inclusion with increasing amounts of SiO2 in the slag According to the results above -the driving force for [Si] (equation 3) will go towards the left direction during startup of a remelting process This explains why you during the start have to undertake efforts to stabilize the amount of [Si] in the remelted steel - the driving force for Mg and Ca in the steel (equations 4 and 5) should lead to a higher amount of [Mg] in the conventional ingot and a higher amount of [Ca] in the ESRPESR ingot

6

122 SOLIDIFICATION

In order to optimize the properties (who are directly related to the microstructure) of a given steel grade it is important to understand the evolution of the microstructure during the solidification and subsequent cooling to room temperature [43] The main variables controlling the microstructure evolution include the interface velocity thermal gradient alloy composition and nucleation potential [43] These variables will change considerably during the columnarequiaxial transition (CET) Therefore it is important to know during which circumstances during remelting of an ingot this transition will take place

The critical point for growing and clustering of the newly nucleatedformed secondary inclusion as well as the growth and clustering of the primary and the semi-secondary inclusions is the local solidification time (LST) [2627] This in turn depends on the melting rate immersion depth of the electrode tip in the slag bath the electrodeingot ratio and time for heat transfer from the center to the surface of the ingot In reality it means that the larger the ESR ingot size the longer the LST At a critical LST value the solidification will turn from a columnar dendritic (CD) to an equiaxial (EQ) structure which is called the columnarequiaxial transition (CET) The parameters which cause the transition are the alloy segregation characteristics freezing rate undercooling and the presence or absence of nucleating sites for the equiaxial crystals [44] If the ingot structure changes from CD to EQ the consequent competing growth and possible movement of the EQ crystals leads to a random formation of pockets of segregated inter-dendritic liquid As a result the homogenization temperature normally used for the steel grade may lie above the critical temperature where the process starts to produce porosities due to the lower melting point in the last solidified material The result is that the ingot cannot be successfully homogenized [44] Due to the same reason the segregated liquid also leads to microstructure effects in many alloys that produce primary precipitates (NMI and inter-metallic inclusions (IMI)) which are not changed by subsequent mechanical or thermal processing [44] At this point (CET) the steel will be more segregated and the inclusions will have sufficient time to grow and agglomerate A calculation shows that an alloy with a LST value gt 3500 s is likely to solidify in the equiaxial mode [45] In Figure 1 results from laboratory trials by Mitchell are displayed [45] They indicate that the critical point could be reached at an ingot size of 1050 mm in diameter

7


[45]

As long as the ingot solidifies in a columnar-dendritic manner the angle between the columnar dendrites direction and the bottom of the liquid steel pool is 90deg at the center position of the ingot [262746] An investigation of the solidification of a 750 mm in diameter ESRPESR remelted ingot at different melt rates was made at Breitenfeldt Edelstahl AG in Austria [47] The results showed that the higher the melt rate the deeper liquid the steel pool However even at the highest used melt rate (standard melt rate +100 kgh) the solidification was columnar-dendritic from the surface to center At the same time the number and size of the inclusion increased with a higher melt ratedeeper pool depth Borodin et al [48] investigated the solidification of 400 mm in diameter ESR ingots remelted using different melt rates and on a 550 mm in diameter ingot remelted using one melt rate They found disoriented dendrites (equiaxial solidification) in the 400 mm in diameter ingot but not in the 500 mm in diameter ingot However the used melt rates were much higher (510 and 670 kgh for the 400 mm in diameter ingot and 700 kgh for the 500 mm in diameter ingot) than the ldquorule of thumbrdquo of an estimated melt rate (kgh) of plusmn80 of the ingot diameter (mm) The electrodes used were described to have a very convex shape (probably mostly due to the high melt rate and also depending on the use of a low electrodeingot ratio) which is not the case in the present high-quality ESR remelting processes According to Xuan et al [49] the most important factors for an inclusion to be captured in a process slag are its size and flotation speed in the steel According to this proposal in the case

8

of a vacuum-treated steel shop heat with different slag compositions and movements of the steel inclusions larger than approximately 20 microm in diameter should be captured in the process slag The critical size for flotation of an inclusion from the molten steel pool in the ESRPESR processes to the process slag along with the chemical composition of the slag and the size of the inclusion will also depend on the movements in the liquid steel pool The movements in the liquid steel pool depend on the size of the ingot and the depth of the steel pool The depth of the steel pool is dependent on the melt rate (kgh) the immersion depth of the electrode in the slag and the electrodeingot diameter relation The terminal velocity of a Mg spinel inclusion 50 microm in diameter rising in a liquid steel is approximately 5 times 10minus4 ms given the computed ingot pool pattern [50] This implies that any inclusion removal is determined by a balance between the probabilities of being exposed to the slagingot interface or being trapped in the solidifying metal as dictated by the bulk metal flow of the liquid ingot pool Inclusions (depending on their size and density) will be trapped in the flow pattern many never reaching the steelslag interface According to this model the contribution of inclusion refining though flotation is much smaller than what has previously been estimated Further studies are needed to better understand this mechanism during ESRPESR processes However it can be postulated due to the shorter LST ie shorter time for the steel pool to be liquid that the smaller the ingot size the less the overall possibility for flotation of inclusions In contrast this study shows that the larger the ESR or PESR ingot the more and larger inclusions could be found

According to Fredriksson et al [46] the surface of an as cast ingot solidifies in a different manner as compared to an ESR or PESR ingot In an as-cast ingot the melt close to the mould cools down rapidly to a temperature beneath the critical temperature for nucleation of crystals This results in many nuclei which form a surface zone consisting of equiaxial crystals The dendrites grow lt90deg up against the top center of the ingot controlled by the temperature gradient In ESR and PESR remelted ingots the surface zone of equiaxial crystals does not usually exist Instead the surface zone consists of long radially oriented crystals The long radial format of the dendrites is due to that the dendrites grow with the solidification front along the surface Therefore it can be stated that it in ESR and PESR processes no strongly undercooled surface zones exist that result in the formation of equiaxial crystals During solidification however due to the cooling effect from the mould there is a finer dendrite structure in the surface than in the center of the ingot The long crystals along the surface give the ESR and PESR ingots a smooth and good surface

9

13 PRESENT WORK

The focus of this study is on the origin and the distribution of oxide inclusions in production-

scale ingots and materials with the assumption that sulfides and nitrides are secondary


The objectives of the present study are

To determine the extent to which the electrode inclusion content is active in

controlling the ingot inclusion content

To investigate the impact of the ingot size (solidification structure) on the

inclusions morphology and distribution

To compare the results from production-scale ingots with previous

investigations mostly done in laboratory- or pilot-scales

This investigations are made on the inclusion morphologies and distribution in a common stainless martensitic steel grade remelted with a common process slag (except for one pilot trial) and with standard melt rates The samples are taken from processed materials (remelted and conventional) (rollingforging) from one electrode and from remelted ingots of different sizes Effect from using different process slags on production-scale ingots andor different melt rate on one ingot size are not taken into account However the principles presented would have been similar to the ones used in this investigation just maybe on different levels The same applies to different steel grades In order to get a good statistical basis a large field of view per sample was used In addition many samples were taken from different ingots of different sizes Electrode inclusions are modified by several mechanisms ie dissolution in the steel as the electrode melts dissolution in the slag at the electrodeslag interface dissolution in the slag during the droplet fall and flotation in the ingot pool followed by dissolution in the slag at the ingotslag interface This study does not define the role of each of these individual processes but presents the overall result of them as it pertains to the final inclusion content An overview over the eight supplements are displayed in Table 2

10


Study Objective Approach Parameters

1 Study on the inclusion distribution for processed materials from many ingots of different sizes remelted by ESR or PESR

Collect data on inclusion distribution for materials from different ingot sizes to get a better statistical basis

Samples taken from processed materials from 11 ingots of 5 sizes and at different radial positions SEM sample preparation

SEM data analyzed by the software Inca Feature

2 Study differences in inclusion morphologies between remelted and conventional material

Better understanding of the origin of the inclusions

Samples taken from material from 6 conventional ingots and 11 ESRPESR ingots at different radial positions


3 Study of the difference of the inclusions between an ingot with and an ingot without a tracer in the process slag

Define primary and secondary inclusions

Pilot trials using La2O3 as a tracer in the process slag One trial and one reference ingot of a 300 mm diameter

SEM data analyzed by the software Ina Feature slag analyzes

4 Deeper studies of the data from trial with La2O3

as a tracer in the process slag

Describe the importance of cleanliness the electrode used in remelting processes

Pilot trials using La2O3 as a tracer in the process slag one trial and one reference ingot 300 mm in diameter


5 3-D and 2-D studies of inclusions in an electrode an ESR ingot and a PESR ingot All from the same electrode heat

Deeper understanding of the morphologies of the inclusions

Samples taken from one electrode and two ingots at different radial positions 2-D SEM sample preparation 3-D Electrolytic extraction

SEM data 3-D SEM data 2-D analyzed by the software Inca Feature

6 Inclusions in electrode ESR and PESR ingots from the same electrode heat Link results to literature survey

Describe the origin of the oxide inclusions



7 Formation of Mg-Al oxides

Describe a novel mechanism to form Mg-Al oxides

Combining of thermodynamic and kinetic calculations

Thermodynamic kinetic industrial and SEM data

8 Inclusions in different ingot sizes and solidification structures

Describe the influence of the solidification structure on the inclusion morphology

Horizontal sliceslices were cut out from one electrode and four ingots Macro etching and SEM sample preparation

Structure data - SDAS solidification angles SEM data analyzed by the software Inca Feature Chemical analyzes

11

2 EXPERIMENTAL METHODS

21 MATERIAL

The material used for the studies is a common martensitic stainless steel A typical

composition of the steel is as follows C 038 Si 09 Mn 045 Cr 136 and V 028

The consumable electrode (300 mm x 300 mm) is produced in the steel shop at Uddeholms

AB in Hagfors The process route is EAF ladle furnace vacuum and ingot casting The ESR

ingots (400 mm x 400 mm and 600 mm in diameter) are produced in an open electro-slag

remelting furnace with using a moving mould electrode changes and using a continuous

aluminum de-oxidation Also multiple electrodes are used to make one ingot The PESR ingots

(500 800 and 1050 mm in diameter) are remelted in a pressure controlled electro-slag

remelting furnace using a static mould and an inert atmosphere One electrode gives one

ingot

For the trials with a tracer in the process slag already remelted and processed bars were used

as electrodes In the ESR and PESR trials (expect when a tracer in the process slags was used)

a common process slag was used which contained approximately one third each of CaO CaF2

and Al2O3 as well as asymp 3 MgO and asymp 15 SiO2 The composition of the process slag used for

the reference ingot (1) and the trial ingot (2) in the pilot-scale trials with La2O3 as a tracer in

the process slag are displayed in Table 3

Table 3 Chemical analysis of the process slags before the pilot trials where (1) is the reference ingot and (2) the trial ingot

Ingot Al2O3 CaO CaF2 La2O3 SiO2 MgO

1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12

22 SAMPLING 221 SAMPLES FOR INCLUSION DETERMINATIONS

The steel samples were taken from horizontal sliceslices of the electrode and ingots as follows i) top (T) middle (M) and bottom (B) for the electrode ii) one or two samples taken at positions in between the top and bottom (X) for the ESR ingots and iii) one middle sample for the PESR ingots as shown in Figure 2 For the processed materials all samples were taken at a radial center position The samples for the SEM investigations on ingots were taken from corner to corner on the electrode (3 positions times 5 samples) Furthermore the central sample as close to the center as possible due to the secondary pipedense area in the electrode In addition samples were taken from corner to corner from the ESR ingot (2 positions times 7 samples) and from side to side from the PESR ingots (1 position times 9-13 samples)

(a) (b) (c)

Figure 2 Schematic illustration of horizontal slices and sample positions on (a) the consumable electrode (CE-300) (b) ESR remelted ingots (ESR-400) and (c) PESR remelted ingots (PESR-500-1050)

13

222 SAMPLES FOR STRUCTURE DETERMINATION

The steel samples were taken from horizontal sliceslices of the electrode and ingots as follows top (T) middle (M) and bottom (B) for the electrode two samples taken at positions in between the top and bottom (X positions) for the ESR-400 and one middle sample (M) for the PESR ingots The cross sections have been cut in order to study the solidification structures and dendrite arm spacings The samples from the electrode and ingots cover the full distanceradius from the cornersurface to the center each sample having a dimension of asymp 150x100x15 mm A schematic presentation of the positions of the macro samples for both the square electrode ESR ingot and PESR ingots can be seen in Figures 3a and b

(a) (b)





Longitudinal sections were cut out from the cross sections from the 500 800 and 1050 mm

diameter PESR ingots They have been examined with respect to the angle between the

dendrite arms and axial planes as seen in Figure 4

14



15

23 INCLUSION DETERMINATION 231 TWO-DIMENSIONAL (2-D) SEM

The 2-D studies were performed on a larger area of a sample surface More specifically the field of view per sample position was about 6500 mm2 The samples were first studied using a scanning electron microscope (FEI Quanta 600 Mark II Thermo Fisher Scientific Waltham MA USA Also the number size and chemical composition of the inclusions larger than 8 microm were studied using the ldquoInca featuresrdquo software from Oxford Instruments (ETAS Group Stuttgart Germany) Afterwards the inclusions were divided into four size classes namely 8ndash112 microm 112ndash224 microm 224ndash448 microm and larger than 448 microm

232 THREE-DIMENSIONAL (3-D) SEM In the 3-D studies 01ndash03 g of steel samples were dissolved in a 10 AA electrolyte (10 wv acetylacetone ndash 1wv tetramethylammonium chloride ndash methanol) Thereafter the solution was filtrated and the inclusions were collected on a film filter After electrolytic extraction the NMIs were investigated using SEM in combination with EDS However due to the high amount of intermetallic inclusions (IMIs) in the martensitic stainless ingot the NMIs could not be investigated precisely on the film filter under a layer of extracted IMIs after the filtration of electrolytes Therefore the non-metallic inclusions which appeared completely on a surface of metal sample after electrolytic extraction were also investigated on the sample surfaces

16

24 STRUCTURE DETERMINATIONS 241 DENDRITE ARM SPACINGS (SDAS)

The secondary arm spacings (SDAS) at different positions were measured using a light optical

microscope (LOM) Leica MZ6 equipped with A Leica Qwin Runner V351 software The

investigations on the cross and longitudinal sections were made at former Exova AB in

Karlskoga

The SDAS were measured on the cross sections of the electrode and the ESR and PESR ingots

The measurement positions are shown in Table 2 Also the measurement principle is shown

in Figure 5 which shows the primary arms and their connecting secondary arms marked in

red The measurements were made in-between the red marked secondary arms Two to four

measurements on each position were used to determine an average SDAS value per position




242 SOLIDIFICATION ANGLES Both the SDAS at different positions and the angles between the dendrite arms and the axial

plane were measured using a light optical microscope (LOM) a Leica MZ6 equipped with a

Leica Qwin Runner V351 software The investigations on the cross and longitudinal sections

were made at former Exova AB in Karlskoga

17

25 CHEMICAL ANALYZE

Chemical compositions of the samples of the cross sections were made using a LECO CS600

instrument for the element carbon (C) and sulfur (S) and an X-ray Thermo 9800 instrument for

the other elements

26 DESCRIPTION OF THE STEEL PLANT

Uddeholms AB specializes in producing tool steels The steels are manufactured in the Hagfors steel mill The production is approximately 100000 tons per year in the steel melting shop The steel grades are mainly hot work steels cold work steels and plastic mould steels About 55 of the steel grades are electro-slag remelted (ESR) or electro-slag remelted under a protected pressure-controlled atmosphere (PESR) The reason to choose ESR or PESR remelting processes could either be to reach higher mechanical properties (more homogenous material) or a better polishability of the steel The production route for the electrodes starts with remelting of scraps and alloys in an EAF (electric arc furnace) ladle heating with further alloying ladle vacuum treatment followed by an up-hill protected casting After that the electrodes are heat treated grinded and welded to a shaft The electrodes are remelted into ingots using electro-slag remelting (ESR) inert electro-slag (IESR) or pressured controlled electro-slag remelting (PESR) At this moment Uddeholms AB have four ESR furnaces one IESR furnace and seven PESR furnaces The remelted ingots are heat treated before further processing (rollingforging) The remelted materials are then heat treated and machined

18

3 THEORY

INTEGRATION OF CHEMICAL REACTIONS AND COALESCENCE-COLLISIONS OF MG-AL OXIDES

IN REMELTED INGOTS

The calculations are made for this thesis by Dr Changji Xuan with input and remelting data from the author Corresponding calculations were first done regarding the inclusions in a steel ladle [51] The purpose in this study is to describe a possible way for an Al-Mg-oxide (spinel) on the electrode tip to react with the ESR or PESR process slag The process slag is here assumed to be an infinitive inclusion The temperature on the electrode tip is approximately 25deg above the liquidus of the steel [20234052] The reacting components of the process slag is assumed to be CaO and Al2O3 [29 40] which share in the slag is recounted up to 100 See supplement 7 [51] for derivation of the equations and explanations of the symbols beneath The attachment behavior among liquid inclusion solid inclusion and molten slag is simulated by using a phase-field method The reader it referred to Ref [51] for more details regarding the model description and derivation Here we only present the explicit formulation of the main equations The time-dependent phase-field empty is formulated by using the Ginzburg-Landau (TDGL) equation (6) (6)

partempty

partt=-L∙ 30empty2(1 minus empty)2 [

As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]

+ 2emptyW(1 minus empty)(1 minus 2empty)-Kemptynabla2empty

The evolution of liquid inclusion and slag concentration field xLI is described by using the time-dependent Cahn-Hilliard (TDCH) equation (7) (7)

partxLIpartt

=nabla∙ MnablaAL[1 minus empty3(6empty2-15empty+10)][21199091198711198683 minus 3(xeqLI + xeqLM)119909119871119868

2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868

∙ xeqLM(xeqLI + xeqLM)] + Asempty3(6empty2-15empty+10)(xLI-B) minus 119870119909119871119868nabla

2119909119871119868

The TDGL and TDCH equations are numerically solved through a semi-implicit Fourier-spectral method [53] The parameters used for the simulation are summarized in Table 4

19


Temperature [K] 2048

Surface energy [Jm2]

Steel 1805

Liquid slag (42Al2O3-58CaO) 0611

Solid inclusion (MgAl2O4) 0550

Interfacial energy [Jm2]

Solid inclusion-Liquid slag 0021

Steel-Liquid slag 1366

Steel-Solid inclusion 0957

Constant B 0623

Height of energy barrier W [Jm3] 521times106

Gradient energy coefficient [Jm]

KxLI 1373times10-9

Kempty 6517times10-9

Equilibrium molar fraction

xeqLI 050

xeqLM 098

Kinetic parameter [m5Jbulls] M 2times10-19

L 10-40

Steepness of free energy curve [Jm3] AL 4times108

As 4times109

Grid size (Δx=Δy) [m] 125times10-8

Time step (Δt) [sec] 1times10-4

Domain grid size 503 Δxtimes503 Δy

Size of MgAl2O4 solid inclusion Side length=60 Δx (Equilateral hexagon)

At the initial stage one Mg-Al-oxide inclusion is on the electrode tip in contact with the ESR or PESR process slag Instead of undertaken a solely thermodynamic reaction with the slag the novel evolution method for an inclusion having a core of an Al-Mg-oxide and an outer layer corresponding to the process slag take place The method is built on a collision-coalescence theory using both thermodynamics and kinetics see Figure 6


20

4 RESULTS AND DISCUSSION

41 DIFFERENCE IN INCLUSION MORPHOLOGIES

411 MATERIAL FROM DIFFERENT INGOT SIZES

In order to get a good statistical basis SEM samples from the bottom (B) middle (M) and top

(T) positions were taken from processed (rollingforging) ESR and PESR ingots and of different

ingot sizes (supplement 1) 28 samples from 9 electrode heats from 11 ESR and PESR heats of

5 different ingot sizes were studied The samples were all taken from the horizontal center

position of the ingot The field of view per sample was about 6500 mm2 Especially for steel

with a higher cleanliness as for example remelted steels a large sample area is important in

order to obtain enough statistical information to get a true picture of the inclusion

morphologies [25]

As expected it was found that larger ingots contained a higher number of inclusions as seen

in Figure 7a and b This corresponds to the theory that the majority of inclusions in an ESR

ingot are secondary in nature arising from slagmetal and deoxidation reactions

[3918232627] This finding is further supported by the presence of a large number of small

inclusions which presumably have been precipitated during solidification It can be seen that

ingots remelted in open ESR furnaces equipped with electrode changing contained a higher

amount of inclusions than equal ingot sizes remelted in PESR furnaces using a controlled

atmosphere and no electrode changing The results show that the longer LST (longest

solidification time) ie larger ingot per furnace type (ESR and PESR) the more and larger

inclusions can be found in the samples

(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-800 12samples-4

ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type

Number of oxide inclusions per mm2

8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)

Figure 7 Numbers of inclusions per mm2 and ingot size Material from an electro-slag

remelted 400 x 400 mm (ESR-400) electro-slag remelted 600 mm diameter (ESR-600) and

pressure electrondashslag remelted 500 800 and 1050 mm diameter (PESR-500 PESR-800 PESR-

1050) ingots (b) is an enlarged and zoomed version of (a)

As comparison two ingots from the same electrode heat an ESR-400 and a PESR-500 were

remelted Compared to a previous investigation performed at Uddeholm the aluminum

amount in the mother heat and during ESR deoxidation was optimized The ladle metallurgy

was also optimized in order to minimize chemical reactions with the lining Figure 8a and b

displays both the difference between the ingot sizes and the difference between the first and

this investigation The decrease in inclusion number and size indicate that the electrode

quality is important for the quality of the remelted ingots

(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot

PESR-10503 samples-1

ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2

Size class of the inclusions

Number of oxide inclusions per mm2 ESR-400

HT2012 3 samples-2 ingots

HT2013 3 samples-1 ingot

22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2


Number of oxide inclusions per mm2 PESR-500



23

412 MATERIAL FROM CONVENTIONAL AND REMELTED INGOTS

The results from supplement 1 were combined with results from material from four

conventional ingots of two sizes (supplement 2) The samples were taken from the middle

position from the conventional ingots and all from the horizontal center of the ingot The field

of view per sample was about 6500 mm2 Altogether 34 samples from 10 electrode heats

resulted in 11 ESR heats of five different ingot sizes and six conventional ingots of two ingot

sizes

The number of oxide inclusions per size class and ingot type is displayed in Figures 9a and b

The ingots are defined by either their diameter or their shortest solidification length The

result shows as expected that the conventional casted ingots of equal sizes have the same

or slightly higher amounts of small inclusions as the ESR and PESR ingots However their

amounts of large size inclusions (here 224 ndash 448 microm) are much higher

(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots

ESR-400 3samples - 2

ingots


ingot

PESR-5007 sample -

3 ingot

PESR-80012 sample- 4 ingots

PESR-10503 samples -

1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)




ingot (ESR-600) and pressure electro-slag remelted 500 800 and 1050 mm ingots (PESR-500

PESR-800 PESR-1050)

The SEM results from the software Inca Feature contain ternary diagrams of the inclusion

composition for each sample Figure 10 shows examples of diagrams from a sample from a

conventional ingot and a sample from a PESR remelted ingot in the ternary diagram

CaOMnOSiO2-MgO-Al2O3

(a) (b)




The average compositions for oxide inclusions and duplex oxide inclusions (containing sulfur)

per process and furnace type were determined from the middle position samples as seen in

Figure 11 The compositions of a corresponding ladle top slag and ESR process slag are marked

in the diagram

25

(a) (b)


furnace type

The inclusions in the conventional ingots contain higher amounts of MgO Figures 10-11 This

could be explained by the fact that the top slag in a ladle process contains more MgO than the

process slag used in the ESRPESR processes (10-15 compared to approximately 3 ) The

diagrams also show the expected increase in Al2O3 from the ESRPESR slagmetal reactions

The inclusions tend to narrow the composition of its corresponding slag (top or process) [54]

Inca Feature analyzed the three largest inclusions of each sample In material from the

conventional ingots inclusions with the look of a walnut see Figure 12 are most common

especially in the larger ingot (CONV-700) Most of the ldquowalnut inclusionsrdquo consist of a spinel

(Al-Mg-O) base together with Ca-S yet some is a duplex Ca-Al-O inclusion Some of the Ca-A-

O inclusions contain some Si in the spectra The average size of this inclusion type is 35 microm in

diameter The samples also contain a few larger inclusions seen as elongated strings and

having sizes of approximately 40-75x15 microm The strings are also often a spinel (Al-Mg-O)

combined with Ca-S The elongated strings have been formed during the deformation process

from round plastic inclusion present in the original ingot

(a) (b)




26

In material from the ESR remelted ingots the most common large inclusion is a more or less

round Ca-Al-O inclusion often seen with an Al-Mg-O (spinel) inside and sometimes with a Ca-

S attached This inclusion type have an approximate diameter of 30 microm The samples also

include a few elongated inclusions strings having sizes of approximately 50x15 microm and

containing Ca-Al-O Al-O and Ca-S see Figure 13

(a) (b)

Figure 13 Typical examples of the largest inclusions found in material from the ESR remelted

ingots (a) a round Ca-Al-O inclusion and (b) an elongated string inclusion containing Ca-Al-

O Ca-S and Ca-O

In the PESR remelted ingots the most common largest inclusions are round inclusions

consisting of an inner core of a Al-Mg-O (spinel) combined with Ca-Al-O Al-O and Ca-S having

approximately diameter of 15-20 microm The samples also contain a few strings about 40x10

mm Al-O Mg-O (spinel) and CaS see Figure 14

(a) (b)



27

42 PILOT SCALE TRIALS USING A LA2O3 TRACER IN THE PROCESS SLAG

Two bars from the same electrode heat of a common martensitic stainless steel were ESR

remelted under air into two ingots 300 mm Oslash and 500 mm in length see Figure 15

[supplement 34] Due to the short ingot length the mould could be used as a static mould

The ingot without a tracer in the process slag is named Ingot 1 and the ingot with a tracer is

named Ingot 2 For Ingot 1 a common ESR slag with about one third each of Al2O3 CaO and

CaF2 was used For Ingot 2 the process slag consisted of 80 of the same common ESR process

slag as for Ingot 1 and 20 La2O3 (9999 ) as seen in Table 5 Figure 16 shows the used slag

after remelting The lanthanum oxide provides the tracer function In order to achieve equal

conditions for both ingots no deoxidizing additives were used The amount of process slag

per ingot was 50 kg


slag) to the right

Table 5 Chemical composition of the top slags after remelting of the pilot trials with La2O3 as

a tracer in the process slag (1) is from the reference ingot and (2) is from the trial ingot 2a

(two analyses) is taken from the darker slag and 2b from the white parts see Figure 16b


1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)


(reference ingot) and (b) Ingot 2 (with La2O3 as a tracer in the process slag)

Only oxide inclusions and no sulfides or nitrides were found in the ingots The number of oxide

inclusionsmm2 and size classes for both ingot 1 and ingot 2 are displayed in Figure 17 As

expected there were no inclusions containing lanthanum in Ingot 1 where no tracer had been

added to the process slag Altogether slightly more than 50 of the inclusions in Ingot 2 with

tracer contained La However the data showed that in the Al-Mg-oxide inclusions (spinels)

approximately 25 of the inclusion contained La

(a)

0

001

002

003

004

B T B T B T

Ingot 1 Ingot 2 Ingot 2oxides with

LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot 1 reference ingot and Ingot 2 with La2O3 as a tracer in the process slagbottom (B) and top (T)


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)




The calculated composition (Inca Feature) of the inclusions is presented in Figures 18 and 19

Duplex Ca Mn or Mg represents a Ca Mn or Mg inclusion also containing sulfur AlMg

represents an Al inclusion containing gt 3 Mg Al+Mg represents an Al inclusion containing

0lt Mglt 3 AlCa represents an calcium aluminate and ldquoLa inclusionsrdquo represents all inclusions

containing lanthanum

(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot 1 reference ingot and Ingot 2 with La2O3as a tracer in the process slagg bottom (B) and top (P)

Number of oxide inclusions per mm2 zoomed

8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type

Number of oxide inclusion per mm2 - Ingot 1 bottom reference

Ingot 1B 8-112 microm



30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type

Number of oxide inclusions per mm2 - Ingot 1 top reference

Ingot 1T 8-112 microm



00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type

Number of oxide inclusions per mm2 - Ingot 2 bottom La2O3 as a tracer in the process slag




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type

Number of oxide inclusions per mm2 - Ingot 2 top La2O3 as a tracer in the process slag




31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type

Differnece in number of inclusions per mm2 between Ingot 2 with a tracer in the process slag and Ingot 1 reference ingot bottom

samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type

Differnece in number of inclusions per mm2 between Ingot 2 with a tracer in the process slag and Ingot 1 reference ingot top samples

32

The three largest inclusions per sample and their composition are shown in Figures 20 and 21

A mapping of the elements in the largest inclusion in the top sample of Ingot 2 is shown in

Figure 22 A majority of the largest inclusions in the ingot where lanthanum was added to the

process slag contained between 5 and 20 La2O3 This corresponds well with the

compositions of the process slag before and after remelting (see Table 3 and 5)



33



34

Figure 22 Mapping of the largest inclusion in the top sample of Ingot 2 where La2O3 as was


The inclusions without lanthanum in Ingot 2 did not come in contact with the slag during the

remelting process sequence That observation indicates that these inclusions have been

trapped within steel drops falling from the liquid film of the electrode tip through the slag

bath and into the molten steel pool In order to do this in this case the steel droplets have to

be larger than 35 microm However the size of the droplets leaving the electrode is generally in

the range of 1-10 mm in diameter but usually has a diameter of 5 mm [5556] The residence

time of the droplet in the slag is small [40] It would therefore be possible for large inclusions

to be trapped inside a steel droplet The largest inclusions in Ingot 2 with the tracer addition

to the process slag are analyzed as MgO-Al2O3 (magnesium spinel) It is possible that non-

metallic inclusions with a high melting point [57] survive and become trapped in the fallen

35

droplets However this is not the case for Ingot 1 where no tracer was added to the process

slag Here the majority contain elements that corresponds with the slag compositions used in

both primary and ESR processing Due to that fact the electrodes used in this trial were

manufactured bars is it not possible to distinguish between primary or secondary inclusions

The investigation indicates that the most probable inclusion to survive from the electrode is

an MgO-Al2O3 spinel The relation between oxide inclusions containing Mg and the total

amount of oxide inclusions was studied for materials from different ingot types ESR x mm

represents ingots remelted under an open air atmosphere using a moving mould process

PESR x mm on the other hand is an ingot remelted under a protective atmosphere and using

a static mould According to Figure 18 and 19 Al-containing inclusions containing gt 3 Mg

are the least influenced by the ESR process slag

Figure 23 The relation between Al oxide inclusions containing gt 3 Mg and the total amount


larger than size class 224-448microm detected

In a previous paper [58] the authors put forward the theory (based on the earlier Frazer study

of mass transfer [5659]) that due to the lower specific melt rate (melt rate per electrode

area) for large ingots the probability of an electrode inclusion being exposed to the slag is

considerably higher Therefore the share of primary surviving inclusions (most probably an

inclusion containing a spinel phase would be lower as the ingot size increases However

Figure 23 shows that the share of inclusions containing AlMg (Al inclusion with gt 3 Mg)

rather increases than decreases with an increased ingot size This is especially true for the

larger inclusions The results determine that the amount of primary inclusions is not

depending on the specific melt rate (melt rate per area) ie exposure time on the electrode-

slag interface

According to these results the cleanliness of the electrode material strongly determines the

quality of the ESRPESR ingot

0

10

20

30

40

50

60

70

80

90

100

8-112 microm 112-224 microm 224-448 microm

Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel

Share of AlMg inclusions (Al inclusions with Mg gt3 ) of total number of oxide inclusions

ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36



FROM THE SAME ELECTRODE HEAT

Three-dimensional (3-D) and two-dimensional (2-D) inclusion investigations were performed

on samples taken from one ingot cast consumable electrode of the size 300x300 mm (CE-300)

one electro-slag remelted ingot of the size 400x400 mm (ESR-400) and one pressure electro-

slag remelted ingot 500 mm diameter (PESR-500) (supplement 56) Note that all were

produced from the same electrode heat in the steel shop

The total numbers of inclusions per unit area (NA) for each size class and ingot type obtained from the 2-D studies are displayed in Figure 24 Additionally the NA values for different inclusion compositions are displayed in Figures 25andashc The most common inclusion types in the size range 8-4480 microm in the electrode (field of view of 312300 mm2) consist of almost pure MnS inclusions followed by almost pure Al2O3 and Al2O3-CaO oxides containing lt10 MgO (Types A and AC inclusions) For the ESR and PESR ingots (using a field of view of 36380 and 19800 mm2 respectively) Al2O3 and Al2O3-CaO oxides followed by Al2O3-CaO-MgO oxides (Type ACM) are the most common inclusions In addition approximately 30 fewer inclusions are present in the PESR ingot compared to the ESR ingot The compositions of various types of oxide inclusions in different samples observed by 2-D investigations on polished sample surfaces are shown in Figure 4 in an Al2O3-MgO-CaO diagram Since the sulfide inclusions are fully dissolved during electrode melting and mostly accumulated by the liquid technological slag the present investigation focused primarily on the oxide components

(a) (b)

Figure 24 Number of (a) oxide and (b) sulfide inclusions per unit area (NA) for the CE-300 ESR-400 and PESR-500 samples The contents of sulfur in the steel [S] in the ESR-400 and in the PESR-500 are 32 respectively 24 of the amount of sulfur [S] in the CE-300

37

(a) (b)

(c)


The results show that the number of smaller oxide inclusions is less in the electrode (CE-300) than in the remelted ingots (ESR-400 and PESR-500) as seen in Figure 24a The number of larger oxide inclusions is approximately similar in the electrode and the remelted ingots However it should be noted that the electrodes have a loose central structure which contains most of the large-sizes inclusions This population of large inclusions in the center of the electrode cannot be fully counted by the conventional NMIs determinations due to the large porosity of the central region of the electrode In this study the determination of NMIs in the central region was done in dense steel obtained as close to the center as practical possible As a result apparently anomalous effects can be observed in Figure 24a The number of sulfide inclusions mainly MnS is more than ten times larger in the electrode than in the remelted ingots as seen in Figure 25 Altogether the electrode contains approximately 50 more inclusions than the remelted ingots An explanation for the larger number of small oxide inclusions in the ESR and PESR ingots compared to the electrode is that primary semi-secondary and secondary inclusions are present in the ESR and PESR ingots The compositions of the oxide inclusions in different samples observed by two-dimensional (2-D) investigations on polished sample surfaces are displayed in Figure 26

OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)


The 3-D investigations were performed by using electrolytic extraction After electrolytic

extraction it was found that too many (CrFe)-C and inter metallic inclusions (IMI) which are

present in the steel also precipitated on the film filter after a completed filtration The

number of these inclusions is drastically larger in comparison to the number of investigated

non-metallic inclusions Therefore the intermetallic inclusions partially or completely covered

all surfaces of the film filters and non-metallic inclusions Thus another approach was taken

The compositions and morphologies of NMI were investigated on a surface of steel samples

after a completed electrolytic extraction process

Examples of the typical largest oxide inclusions observed in different investigated samples are shown in Figures 27 and 28 The results show that neither of the ESR-400 and PESR-500 samples contain large sulfides The Mg spinel core that is found in many of the inclusions have a size of about 1-10 microm In addition it was found that most of the inclusions in the ESR-400 and PESR-500 samples have spherical (or almost spherical) morphologies It can be concluded that the total composition or the composition of the surface layer of those inclusions corresponds to the liquid CaO-Al2O3 phase as can be seen in Figure 29

39

(a) (b)

(c) (d)

Figure 27 Typical large-sized oxide inclusions in different samples observed by two-dimensional (2-D) investigations on polished sample surfaces (a) Types A and AMAl2O3 Al2O3-MgO (b) Type ACM Al2O3-MgO + CaO-Al2O3 + (CaS) (c) Type AC Al2O3-CaO + (CaS) (d) Type AC Al2O3-CaO + CaF2

40

(a) (b)

(c) (d)


41

Type of NMI Mapping of main elements in NMI

Type AM Al2O3-MgO

Type ACM Al2O3-MgO + CaO-Al2O3 + CaF2

Type AC Al2O3-CaO-SiO2 + CaS

Type AC CaO-Al2O3 + CaF2 + CaS

Figure 29 Mapping of main elements in four different typical inclusion types observed by three-dimensional (3-D) investigations on the surfaces of steel samples after electrolytic extraction

42

The discussion above assumes that the Mg spinel both in the electrode and in the ESRPESR ingots is formed due to a reaction taking place at the liquid steelslag interface According to Kiessling [57] non-metallic inclusion nucleus with MgO as one component which may be formed as a product due to reactions between the furnace refractories and the furnace or ladle slag or due to reactions with the molten steel itself Magnesium has both a very low solubility in iron and the Mg-spinel has a high melting point of 2135 C [57] According to the low amount of MgO in the ESR process slag (about 3 ) and the lack of refractory in the remelting processes these results indicate that the primary MgO-containing inclusions from the electrode should survive the ESRPESR remelting processes As a comparison the melting points for common inclusions are presented in Table 6 where the data are taken from [57]


Type of inclusion Melting point

MgO-Al2O3 spinels 2135 C CaO-Al2O3 calcium aluminates 1455 - 1850 C CaO-SiO2 calcium silicates 1475 - 2070 C MnS manganese sulfide 1610 C CaS calcium sulfide about 2500 C

Yang et al calculated stability diagrams representing the Mg-Al-O system in molten steel at 1873 K and 1773 K [60] According to those results as well as from our observations the measured amounts of Mg O and Al Mg spinels are stable both in the electrodes as well as in the ESRPESR ingots The working temperature at the electrode tip is assumed to be about 25degC higher than the melting point of the steel which is approximately 1798 K [20234052] Yang et al [60] (as well as Shi et al [20]) also presented a mechanism that could explain the modification of Mg-spinel inclusions into MgO-Al2O3-CaO-CaS inclusions during calcium treatment However the inclusions obtained by calcium treatment are very similar to the inclusions seen in supplements 5 and 6 This indicates to a certain level that the ESR process slag itself acts in the same way as a conventional calcium treatment of a steel melt does Xuan et al suggested theory regarding the attachment behavior on evolution mechanism of Mg-Al oxides particles in steel [51] describes two possibilities to obtain an inclusion consisting of one or more Mg spinel particles as a core and with a coating layer of Ca-Al-(Mg) oxide (supplement 7) The inclusion evolution can take place by either a chemical reaction or a coalescence-collision behavior This idea may explain the appearance of this kind of inclusions in the electrode and possibly also in the ESRPESR processes according to calculations presented in chapter 3

43

4311 PRIMARY INCLUSIONS

The primary inclusions which often were Al2O3-MgO inclusions containing gt10 MgO and lt10 CaO (Type AM) are assumed to be electrode inclusions that have been trapped in steel drops or particles that have fallen from the electrode tip through the slag bath to the steel pool without been overheated and dissolved as can be seen in Figure 30 According to the literature the diameter of the droplets leaving the electrode is generally in the range of 1-10 mm but usually about 5 mm [5556] ie much larger than the individual inclusion size range Burel [17] already proposed this entrapment mechanism even though it could not be seen in his experimental work Another reason for the presence of primary inclusions could be that they were contained in solid steel fragments falling directly into the pool from the porous central region of the cast electrode This latter effect would not be seen in small-scale experiments using rolled or forged electrodes and may account for the absence of large or unaltered inclusions in those results

(a) (b)

(c) (d)


44

4312 SEMI-SECONDARY INCLUSIONS

The semi-secondary inclusions which often are almost pure Al2O3 and Al2O3-CaO oxides containing lt 10 MgO (Types A+AC) are assumed to be small Mg spinel inclusions (lt8 microm) that have survived from the electrode The Mg spinel inclusions already exist in the electrode either as a solitary spinel inclusion or as an inclusion with a core of a Mg-spinel and an outer layer corresponding to the top slag composition in the final treatment ladle When the coated Mg spinel reaches the electrode tip the outer layer melts leaving the spinel Thereafter the corresponding ESR or PESR process slags potentially coat the spinel inclusions (Type ACM) This explanation is also confirmed by the detection of some amounts of CaF2 in the outer CaO-Al2O3 layer of inclusions (see Figure 28c d and Figure 29-30) since the ESR or PESR process slags contain CaF2 and the ladle slag does not Moreover the slag inclusions (Type AC) can be carried into the liquid steel pool with metal droplets which passed down through the ESR or PESR process slags as shown in Figure 30c An alternative is the novel evolution mechanism using both thermodynamic and kinetic techniques presented by Xuan et al [51] (supplement 7) In this case this type of inclusion can have originated from a coalescence-collision between a solid Mg spinel and a liquid (Ca-Al oxide) inclusion in the liquid steel specifically this takes place (1) at the electrode tip (2) in the process slag or (3) in the molten steel pool which in cases (2) and (3) would be the ESRPESR process slag acting as an infinitive source of a Ca-Al oxide inclusion see calculations presented in chapter 3

4313 SECONDARY INCLUSIONS

The secondary inclusions for example Al2O3-MgO (with a low content of MgO) and Al2O3 are formed in the liquid metal pool as a result of the reactions between alloying elements and dissolved oxygen [40] Calcium aluminates are also assumed to precipitate in the molten steel pool The generation of these oxide inclusions during solidification of liquid steel in the mold is assumed to give a small contribution to the total amount of inclusions with the sizes larger than 1 microm in the remelted ingot (supplement 5) since the time for particle growth or agglomeration is small The population of extremely small precipitated inclusions of lt1 microm is probably high (accounting for the greater part of the inclusion-accountable oxygen content) but has not been determined in this study Their composition is driven entirely by the ESR slagmetal reactions It should be mentioned that sulfides and nitrides are predominant secondary inclusions

45

4314 GENERAL SCEMATIC OF THE THREE TYPICAL INCLUSION

TYPES

A schematic over the three inclusion types is displayed in Table 7


Inclusion Primary Inclusions

(PI) Semi-Secondary Inclusions (SSI)

Secondary Inclusions

(SI)

Schematic illustration

Type of NMI

AM ACM A and AC A AC

Size on NMI Large see below Medium (normally asymp lt 30 microm)

Small (lt 10 microm)

Source or formation mechanism

From the electrode the size depends on the size of

the inclusions in the electrode and the size of the steel droplets In the

ingot the spinels are often found in inclusion clusters

having complex shapes often together with other

inclusions and elements (C Cr Si Mn S Ca)

Primary AM oxides covered by process slag

sometimes with CaF2

attached If CaF2 is found it is proof that the

inclusion has been in contact with the

ESRPESR process slag

Precipitated in the ingot during solidification of the liquid steel

46

4315 HYPOTHETIC LIFE CYCLE OF AN OXIDE INCLUSION FROM

THE LADLE TO AN ESRPESR INGOT

A large part of the inclusions in a remelted ingot is a semi-secondary type consisting of a core

of one or more Al-Mg-oxides and an outer layer corresponding to the used process slag Due

to the high melting point and low solubility in steel the Al-Mg-oxides (spinels) are assumed to

origin from the electrode In Figure 31 a schematic presentation over the hypothetic life cycle

of an oxide inclusion from the ladle to an ESRPESR ingot is displayed

Steel shop

The spinels are usually formed due to reactions between the furnace refractories and the

furnace or ladle slag or with the molten steel itself [57] During the heating of the steel in the

ladle the number of spinels in the steel will increase Due to either thermodynamics or the

novel coalescence-collision model [51] the spinels will be coated with a layer of Ca-Al-(Si)-O

corresponding to the composition of the used top slag During the following vacuum

treatment inclusions larger than asymp 20 microm will be incorporated due to flotation to the top slag

in the ladle [33] After vacuum treatment most commonly no Al-Mg-O (spinels) gt 8 microm are

detected [33] This is probably due to either that the outer Ca-Al-(Si)-O layer or the entire

inclusion including the core of Al-Mg-O have been incorporated in the top slag During the

stirring andor casting after vacuum either the ldquostrippedrdquo Al-Mg-O or new ones from the

refractory again react with the top slag resulting in a new outer layer with a composition

corresponding to the top slag This kind of inclusions can be seen in both conventional

materials and electrodes used for remelting processes

Remelting shop

As written in chapter 4312 the outer layer of the spinels will melt on the electrode tip The

spinel will then either due to thermodynamic reactions or by the novel coalescence-collision

model [51] get a new outer layer with a composition corresponding to the process slag used

during the remelting process

47



(a) Al-Mg-O inclusions (spinels) from the refractory erode or react with the steel and top slag

in the ladle This goes on as long as the steel is in the ladle

(b) The inclusions react with the steel and the top slag and get an outer layer with a

composition corresponding to the top slags composition Average inclusions size is

approximately 20 microm

(c) During the ladle vacuum treatment the inclusion will get in contact with the top slag

Thereafter due to the stirring of the steel the inclusion dissolvesincorporates partly or fully

in the top slag

(d) Al-Mg-O inclusion (spinel)

(e) After vacuum treatment some of the Al-Mg-O inclusions (spinels) remain in the steel but

their former outer layer have been dissolvedincorporated in the top slag The size of the

spinels are lt 8 microm

(f) During ladle stirring the Al-Mg-O inclusions (spinels) once again react with the steel and the

top slag which results in a new outer layer corresponding to the top slag

(g) Electrode with inclusions containing a core of Al-Mg-O (spinels) and an outer layer

corresponding to the top slag composition

(h) During the ESRPESR remelting process the outer layer of the inclusions will melt or

dissolve on the electrode tip resulting in an Al-Mg-O inclusion (spinel) Thereafter the spinel

reacts with the ESRPESR process slag either at the tip of the electrode or in the process slag

(i) ESRPESR ingot with inclusions containing a core of Al-Mg-O (spinels) and an outer layer

with a composition corresponding to the process slag composition

48

432 COMPARISON BETWEEN ESR AND PESR INGOTS

The difference in inclusion characteristics (morphology composition size and number) between the ingots from the open-air furnace and the ingots from the PESR process is probably both due to the difference which comes from electrode changing the extra chemical reactions taking place between air and slag bath and the aluminum deoxidation during the ESR process The aluminum deoxidant dissolved in the slag pool reacts with FeO in the process slag as follows [1961]

2[Al] in slag + 3(FeO) = (Al2O3) + 3[Fe] (8)

Schematic illustrations of the mechanisms of oxygen transfers and Al deoxidation in an open ESR process are shown in Figure 32 Due to the reactions the feasibility for nucleation of a larger number of inclusions exists According to Li et al [29] an Al2O3 rod immersed in a CaO-Al2O3-CaF2 flux led to the formation of an intermediate coating compound consisting of CaO-2Al2O3 This could explain why more than a double amount of Al-Ca oxides (Type AC) were found in the ESR ingot as compared to the PESR ingot

(a) (b)


Another critical point is that in order to prevent a liquid breakout a smaller electrodeingot ratio is often used in ESR furnaces with movable molds or baseplates A smaller electrodeingot ratio concentrates the heat more towards the center of the ingot which leads to a deeper pool of molten steel in the ingot This results in a longer LST (longest solidification time) ie a longer residence time in the liquid pool This in turn promotes more nucleation and inclusion growth According to Cao et al [43] a larger filling ratio (electrodeingot diameter) also leads to more and smaller droplets as compared to a smaller filling ratio More and smaller droplets increase the contact area between the slag and steel which promotes the removal of non-metallic inclusions from the original electrode material

49

44 SOLIDIFICATION IN ELECTRODE AND ESRPESR REMELTED INGOTS

The material studied was taken from one ingot-cast consumable electrode 300x300 mm

(denoted as the CE-300 sample) one ESR remelted ingot 400x400 mm (denoted as the ESR-

400 sample) and three PESR remelted ingots 500 800 and 1500 mm in diameter (denoted

below as the PESR-500-800-1050 samples) (supplement 8) The electrode the ESR-400 and

the PESR-500 were cast from the same initial steel heat


STRUCTURE

The macro structure of the electrodes cross sections at radial bottom middle and top positions are analyzed from the cross section samples The electrode was cast with the ldquobig end downrdquo The macro structure of the ESR ingot cross section at two axial positions and the PESR ingots at the axial middle section was studied No clear surface columnar zone could be observed in the radial ESR or PESR samples as shown in Figures 33a-c The columnar zone in the electrode measured from the corner was found to be approximately 60 mm for the cross sections from the radial bottom as seen in Figure 33d 40 mm for the radial middle and 90 mm for the radial top positions

(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm

Figure 33 Examples of macro structures in the electrode and the ingots (a) Electro-slag remelted 400 x 400 mm ingot (ESR-400) from surface to position T4 (in between corner and center) (b) Pressure electro-slag remelted 500 mm diameter ingot (PESR-500) with the position T6 (inbetween corner and position T4) and position T4 marked The arrows point at the etching consentric bands (c) Pressure electro-slag remelted 1050 mm diameter ingot (PESR-1050) from surface to 155 mm The arrows point at the etching consentric bands (d) Electrode 300 x 300 mm (CE-300) from surface to 155 mm

A coarser dendritic pattern can be seen starting from 80 to 90 mm from the surface on the PESR-500 sample and 100 to 110 mm from the surface on the PESR-1050 sample as seen in Figures 33b-c Furthermore white etching concentric bands are weakly visible at a distance approximately 15 to 30 mm below the surface for the PESR-500 -800 and -1050 samples as seen in Figures 33b-c The macro structures of the center of the ingots are shown in Figures 34-36 The solidification

cavity (pipe) and the lose structure can be seen in the center of the electrode (CE-300) The

electrode and the 1050 mm diameter ingot (PESR-1050) have a coarser center structure

compared to the other ingots

52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)




The solidification of an ingot either starts with a surface zone containing small equiaxial dendrites or long radially orientated crystals [46] At a certain distance from the mould when the cooling is smaller the columnar dendritic structure (CD) appears The reason for that no clear visible columnar zone was found in the ESR and PESR samples is that remelted ingots solidify with a dendrite angle of 90deg towards the bottom of the liquid pool This is unlike the conventional cast electrode samples which solidify with a dendrite angle slightly above 90deg towards the top center The larger equiaxial structures in the center were only found in the CE-300 and the PESR-1500 This is due to their higher Longest Solidification Time (LST) The secondary dendrite arm spacing (SDAS) was measured on the cross sections of the electrode and the ESR and PESR ingots The measurement positions are shown in Table 8

54


Difficulties in resolving the fine surface structure (except for the PESR-800) resulted in measurements of secondary arm spacings (SDAS) made at position T6 (asympquarter radius near corner) instead of at the surface This is seen in Table 9 and Figure 37 where the SDAS versus the axial positions on the electrode and the ingots are displayed The curve for the PESR-1050 deviates from the other curves The data and statistics for the SDAS measurements are shown in Table 9 The SDAS values per ingot and measured distances from the surface (mm) are displayed in Figure 38 It can be seen that the relation is approximately linear for the smaller ingots but more polygonal for the PESR-1050 sample The data behind Figure 38 is shown in Table 8 and 9

Distance from surface( mm) SDAS ℷ2 (microm) versus electrode and ingot type (mm)

CE-300 ESR-400 1 ESR-400 2 PESR-500 PESR-800 PESR-1050

0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55

Table 9 Data and statistics for the secondary arm spacing (SDAS ℷ2) measurements Electrode 300 x300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

ElectrodeIngot Position SDAS ℷ2 (microm)Stdev (microm) 95 CI (microm) RA () Measurements (no)

CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101

Figure 37 Secondary dendrite arm spacing (SDAS ℷ2) (microm) for electrode 300 x 300 mm (C-300) electro-slag remelted 400 x 400 mm (ESR-400) and electro-slag remelted under pressure controlled atmosphere pressure electro-slag remelted 500-1050 mm diameter (PESR-500-800-1050) ingots Cross section positions T6 - quarter radius T4 ndash half radius and T2 ndash center

0

200

400

600

800

1000

Surface T6 T4 T2 T4 T6Surface

Den

dri

te a

rm s

pac

ing

(microm

)

SDAS ℷ2 (secondary arm spacing) on cross sections from electrode and ESRPESR ingots

CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56

Figure 38 Secondary dendrite arm spacing (SDAS ℷ2) versus distance from the surface for different ingot types Electrode 300 x 300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Longitudinal sections were cut from the cross sections of three PESR ingots The samples have been examined with respect to the angle between the dendrite arms and the axial plane The angles between dendrite arms and axial plane are shown in Table 10 The angle between the dendrite arm and the axial plane for the PESR-500 and PESR-800 samples is exactly 90deg in the position T2 at the center of the ingot For the PESR-1050 sample the angle could not be measured at T2 as the macrostructure had no distinct direction at this position According to theory [262746] the angle of the dendrites towards the bottom of the liquid steel pool is 90deg This is valid as long as the solidification results in a columnar-dendritic structure However if the solidification results in an equiaxial structure no distinct direction of the dendrites exists

0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)

Distance from ingot surface (mm)

SDAS ℷ2 (secondary dendrite arm spacing) towards distance from ingot surface

CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57

Table 10 Data and statistics for the angle between the dendrite arms and the axial plane Electrode 300 x300 mm (CE-300) the electro-slag remelted ingots 400 x 400 mm (ESR-400 12) and the pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

Electrode Position Angle 1 (deg) Angle 2 (deg) Angle 3 (deg) Angle 4 (deg) Average (deg)

PESR-500 Surface 524 57 547

T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697

T2 could not be determined

Pictures of the measured angles for the PESR-800 and PESR-1050 samples are shown in Figures 39a and b It can clearly be seen that the angle in the center is 90deg for the PESR-800 sample and that no angle could be measured in the PESR-1050 sample

58

(a)

(b)


59

442 GROWTH RATE AND TEMPERATURE GRADIENT

The relationship between the dendrite arm distance and the growth rate can be described as follows

ʋgrowthƛ2den = C (9)

where ʋgrowth is the growth rate ƛden is the distance between the secondary or primary dendrite arms and C a constant [26] It is establish that the constant is 10-6 cm3s for low carbon iron-base alloys and that it should [62] be about the same for this steel grade as seen in Figure 40 and Table 11 It can be established that the growth rates for the ingots that solidify entirely with a columnar-dendritic structure correlate best with a linear equation as seen in equation (9) However the PESR-1050 mm ingot that has an equiaxial solidification structure in the center correlates according to the results in this investigation better to a polygonal equation The reason for that is that equation (9) only is valid for the columnar dendritic zone and that it is therefore not adequate for the equiaxial zone


IngotGrowth Rate Ʋgrowth (msec) Per

Position

Surface T6 T4 T2

CE-300 396 times 10minus5 186 times 10minus5 139 times 10minus5

ESR-400 1 381 times 10minus5 203 times 10minus5 133 times 10minus5


PESR-500 121 times 10minus5 107 times 10minus5 634 times 10minus6

PESR-800 196 times 10minus5 140 times 10minus5 598 times 10minus6 309 times 10minus6


60


According to Imagumbai [63] the relation between the growth rate of the primary dendrite tip (R) and the temperature gradient around the solidliquid tip (G) correlates to the primary dendrite spacing (ℷ1) which can be expressed using the following relationship

ℷ1 [microm] = 1750R-014G-050 [Rmicroms GdegCmm] (10)

Imagumbai [63] estimated the secondary dendritic arm spacing (ℷ2) at a completely solidified zone to be approximately half of the primary dendritic arm spacing in an uni-directionally solidified C-Mn steel at steady state

ℷ2 ~ 05ℷ1 (11)

In Table 12 and Figure 41a the temperature gradient is calculated by combining equations (10) and (11) to give equation (12) G [degCmm] = radic(1750R-014ℷ1) (12) The figure shows that the PESR-1050 deviates from a linear relationship which is due to the equiaxial solidification structure in the center of the ingot The growth rate (ms) is plotted as a function of the temperature gradient (degCm) and its correlation is shown in Figure 41b (the result for position T2 for the PESR-1050 is excluded) The primary arms growth rate needed

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)


Ygrowth (cms) towards distance from ingot surface

CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61

for the CET transition is less than 4 x 10-7 ms In order to undertake the transition the temperature gradient needs to be lower than approximately 103 degCm

Table 12 Temperature gradients (degCm) and distances from surface (mm) for electrode 300 x 300 mm (CE-300) electro-slag remelted ingot 400 x 400 mm (ESR-400) and pressure electro-slag remelted ingots of 500-1050 mm in diameter (PESR-500 PESR-800 PESR-1050)

IngotTemperature Gradient G (degCm) Surface T6 T4 T2

CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)


Temperature Gradient G (degCm) towards distance from ingot surface (mm)

CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)


Figure 42 displays the growth rate of the electrode and ingots (center positions) in this investigation together with representive data from Kurz solidification diagram [40] The figure shows the growth rate Ʋgrowth (ms) (calculated on primary dendrite arm spacings) versus the temperature gradient G (degCm) According to Kurz [40] the area above the black curve solidifies in an equiaxial manner and the area below the line solidifies in a columnar-dendritic manner The red dots for the electrode (CE-300) and the 10500 mm ingot (PESR-1050) indicates that they both solidify in an equiaxial manner and that the used Equation (1) is not valid for them

y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)

Temperatur Gradient (Cdegm)

Solidification diagram martensitic stainless steelCE-300 ESR-400-1 ESR-400-2 PESR-500 PESR-800 PESR-1050

63

Figure 42 Growth rate Ʋgrowth (ms) (calculated on primary dendrite arm spacings) versus the temperature gradient G (degCm) around the solidliquid tip The black line represents data from Kurz solidification diagram [64] The area above the line solidifies in an equiaxial manner and the area below in a columnar-dendritic manner [64] Data from Uddeholms martensitic stainless steel are included the electrode 300x300 mm (CE-300) the electro-slag remelted ingots 400x400 mm (ESR-400) and the pressure electro-slag remelted ingots 500-1050 mm diameter (PESR-500 PESR-800 PESR-1050) All samples have been taken from the center position of the ingots The electrode and the PESR-1050 that both solidifies equiaxial dendritic in the center are marked () This is due to that the equations used not are valid for the equaxial solidification structure

100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)

Temperature Gradient G (Cdegm)

Growth Rate Ʋgrowth (ms) towards Temperature Gradient G (Cdegm) (calculated on primary arm spacing) Results combined with results from

Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]

ColumnarDendrites [40]

64

443 METAL COMPOSITION OVER THE CROSS SECTIONS

The deviations between the content of carbon (C) in the electrode and ingots compared to their initial corresponding electrode heats are displayed in Figures 43a and b The radial segregation of the element C between the top and bottom samples of the electrode as well as the larger axial segregation in the larger ingots relative to the smaller ingots can clearly be seen The axial segregation of carbon in the ESR and PESR ingots increases as the ingot diameter increases

(a)

(b)

Figure 43 (a) The deviations between the content of carbon (C) over the cross sections at the bottom (B) and top (T) of the electrode 300 x 300 mm (C-300) and the corresponding electrode heat (b) The deviations between the content of carbon (C) over the cross sections in the ingots and their corresponding electrode heats Electro-slag remelted ingot 400 x 400 mm (ESR-400) and pressure electro-slag remelted ingots 500 -1050 mm diameter (PESR-500 PESR-800 PESR-1050)

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)

Number of samples from surface to surface

Analyzes C over the cross sections of the electrode in percentage of C in the electrode heat ()

CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)


Analyzes C over the cross sections of the ingots in percentage of C in the electrode heats ()

PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65

The amount of sulfur (S) in the remelted ingots is approximately 25 of the amount in their corresponding electrode heats The amounts of manganese (Mn) chromium (Cr) and vanadium (V) are relatively stable compared to the amounts in their corresponding electrode heats However the elements Cr and Mn can have a slight decrease in the axial center of the larger ingots Silicon is 0-5 lower in the remelted ingots compared to the corresponding values in the electrode heats This decrease is due to the reactions with the ESR or PESR process slags The axial segregations of C correspond to both the measured SDAS values and the dendrites

orientations towards the bottom of the liquid pool The more C segregation the larger SDAS

value and the larger the orientation angle The reason is that both the segregation and the

size of the SDAS and orientation angle correspond to the Longest Solidification Time (LST)

which increases towards the center of the ingot Carbon is an interstitial element and will

therefore segregate more than the more stable elements such as Cr and Mo The decrease of

the contents of the elements S and Si are due to reactions with the process slag

66

444 SIZE DISTRUBUTION OF INCLUSIONS IN VARIOUS INVESTEGATED

MATERIALS AND INGOTS

The number of oxide inclusions per unit area in different size ranges in materials from various investigated ingot types at different axial positions is displayed in Figure 44 The samples are taken at position T2 at the center of the ingot The ingots used in this investigation are the same as in the solidification structure samples supplemented with results from a 650 mm in diameter ingot The ESR-400 mm and the PESR-500Oslash ingots are from the same electrode heat from the steel shop Typically the number of inclusions increase almost linear with the ingot size specifically when a larger statistical basis is studied It should also be mentioned that no inclusions gt 448 microm were detected in the processed material


The number of oxide inclusions per size class and ingot position measured as the percentage of the largest number of inclusions per size class measured over the cross section for the unprocessed ingot types PESR-800 and PESR-1050 is displayed in Figure 45 It can be seen that the numbers of inclusions increase with an increased distance from the surface In laboratory andor pilot scale this phenomena may be neglected due to the samples short solidification time No inclusions gt 448 microm were detected in the ingots

0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2

Ingot type and vertical position

Inclusions per mm2 per processed material and vertical position in ingot

8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)


As expected both this (except the 800Oslash mm ingot in this investigation) and the previous supplements (156) showed that larger ESR and PESR ingots contained a higher number of inclusions than the smaller ingots This corresponds to the former universal theory that the majority of inclusions in ESR or PESR ingots are secondary in nature and that they are formed due to slagmetal and de-oxidation reactions [379232627] The larger the LST value the longer time for the inclusions to precipitate and grow This finding is further supported by the presence of a large number of small inclusions which presumably were precipitated during solidification However Sjoumlqvist Persson et al stated in previous supplements (56) that the inclusions in a remelted ingot can be primary semi-secondary or secondary inclusions The result also corresponds to the new theory (chapter 4311-4) since even the semi-secondary inclusions will have a longer time to grow Furthermore the primary inclusion maybe more numerous due to the probable differences in the liquid film formation on the electrodeacutes melting surface

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s

Horizontal Ingot position surface to surface

Inclusions per mm2 over the cross section of the 800 mm in diameter ingot (PESR-800)

8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68

Previous investigations have shown that the amount of larger inclusions (in size range 224 ndash 448 microm) is higher in material from the 1050 mm diameter ingot (PESR-1050) compared to in material from the smaller PESR ingots In order to improve the statistical accuracy the results from the previous presented supplements (15) unpublished results from material from six PESR-1050 ingots and the new results from this investigation are put together in Figure 46 for evaluation of inclusions larger than 224 microm As seen in the picture the number of the larger inclusions (224-448 microm) is nearly doubled in the material the PESR-800 to the PESR-1050 ingots This result demonstrates that the relation between the amount of larger inclusions (here 224 ndash 448 microm) in material from different ingot sizes is strongly related to whether or not the ingot has solidified with a columnar-dendritic or an equiaxial structure It should be noted that the PESR-1050 ingot is no longer in production use for this steel grade

Figure 46 Number of oxide inclusions per mm2 in materials from different ingot types All positions are from the axial center with a field of view of approximately 6000 mm2 each The figure is enlarged and zoomed in Y-axis in order to focus on the large inclusions No inclusions gt 448 microm were detected

0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots

PESR-50010 positions

4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot types and number of positions and ingots


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69

5 CONCLUDING DISCUSSION

This thesis was carried out with the aim to evaluate the origin morphology and distribution of the non-metallic inclusions (NMI) in electro-slag remelted steels (ESR) and electro-slag remelted steels using a pressured controlled inert atmosphere (PESR) In addition to the NMI studies the solidification structure in different ingot sizes was studied in order to define the NMIs dependence on the solidification process The investigated steel grade was a common martensitic stainless steel The focus was on the origin and the distribution of oxide inclusions with the assumption that sulfides and nitrides are secondary inclusions in remelted materials Beneath is a chronological presentation of the progress and results of the work On the whole the results illustrated that the overall cleanliness of the electrode (as well as the composition of the inclusions in the electrode) has an extremely large influence on the cleanliness in ESR and PESR remelted steels The majority of the failure critical inclusions originates direct or indirect from the inclusions in the electrode Moreover the solidification structure (ingot size) also has a direct bearing on the inclusion sizes and content of the ESR and PESR ingots In order to get a good statistical basis SEM samples from bottom (B) middle (M) and top (T)

positions were taken from eleven processed (rollingforging) ESR and PESR ingots of different

ingot sizes (supplement 1) Especially for steel with a higher cleanliness as for example

remelted steels a large sample area is important in order to obtain enough statistical

information to get a true picture of the inclusion morphology [25] For the PESR ingots the

increase in number of inclusions was much smaller from an ingot size of 500 mm diameter

(PESR-500) to an ingot size of 800 mm diameter (PESR-800) However the number of

inclusions in the ingot with a size of 1050 mm diameter (PESR-1050) was much higher

especially with respect to the largest inclusions (224-448 microm) This is an approximately 50

higher value compared to an ingot size of 800 mm diameter (PESR-800) The ESR ingots have

a higher number of inclusions than the PESR ingots in the same size class A visible decrease

in the number of inclusions could be observed after changes in the production of the

electrodes in the steel shop

As an attempt to evaluate the origin of the NMI samples were taken from processed

(rollingforging) conventional ingots of the same steel grade and compared to the result from

the processed material from remelted ingots (supplement 2) The result showed as expected

that the number of inclusions in the material from the conventional ingot was higher than in

the material from the remelted ingots of the same size class In addition both the sizes and

the morphologies differed from the conventional cast material compared to the remelted

material The inclusions in the as-cast material are larger and have compositions that are more

complex In addition the inclusions in the as-cast material contain on average more MgO and

the inclusions in the remelted material contain more Al2O3 Even so the most common

inclusion types in the PESR remelted material were small (8-112 microm) Al-Mg oxides (spinel)

while in the ESR remelted material the most common types were Ca-duplex inclusions (Ca-Al-

S-O) (8-224 microm) Furthermore in the conventional material the most common inclusions

were small Al-Mg oxides (8-112 microm) duplex Ca inclusions (containing sulfur) (112-224 microm)

70

and CaS Overall the study concluded that the average composition of the inclusions tends

to approach the composition of their corresponding slag (top and process slag)

In order to study the origin of the inclusions in remelted ingots a pilot trial using La2O3 as a

tracer in the process slag was performed (supplement 3) Two 300 mm diameter ESR ingots

one with the addition of a tracer in the process slag and one as a reference were remelted

and analyzed The result showed that just above 50 of the inclusions in the trial ingot (and

none in the reference ingot) contained La2O3 The remaining inclusions must have passed

through the remelting process without having any contact with the process slag This is an

evidence showing that a remelted ingot not only contains secondary inclusions but also

primary inclusions The proposed theory (supplement 3) is that the primary inclusions have

been trapped inside a steel drop falling from the electrode to the molten steel pool

Deeper investigations of the sample from the remelted pilot ingots with and without a La2O3

tracer in the process slag were performed in order to demonstrate the influence of the

inclusions in the electrode and the composition of the process slag on the inclusions in the

remelted ingots (supplement 4) The examination showed that the most likely inclusion path

from electrode to ingot involves two distinct routes namely a direct transfer without any

significant transformation or solutionre-precipitation of the inclusions The differences in

number of inclusions per inclusion type in ESR remelted ingots with different process slags

were smallest for Al-oxides containing gt 3 Mg These results indicate that this type of

inclusions never have been in contact with the process slag Also the proportion of this kind

of inclusions increase with increasing ingot sizes These results show that it is not depending

on the specific melt rate (melt rate per area) ie exposure time on the electrode-slag

interface which was an earlier proposed theory [58] Instead the study shows that the

cleanliness of the electrode material strongly determines the quality of ESR or PESR remelted

ingots

Studies on an electrode and an ESR and a PESR ingot of the same size class (all from the same

electrode heat) were performed using both 2-D and 3-D determinations (supplement 5) As

expected the remelted ingots contained a larger number of small oxides while the electrode

contained a much higher number of sulfides It could also be seen that the amount of Al2O3

inclusions was higher in the ESR ingot compared to the PESR ingot The most probably reason

is the remelting under an air atmosphere and the continuous aluminum deoxidation which is

used in the ESR process The difference of the inclusions between the electrode and the

remelted material especially with respect to sulfides (mainly MnS) and duplex inclusions

(mainly Mn-oxides containing S) supported the theory that the majority of the inclusions in

the ESR or PESR remelted materials are secondary inclusions These have melted on the

electrode tip and once again nucleated in the steel pool However some of the inclusions

contained an inner core of an Al-Mg oxide (spinel) and an outer layer of CaO-Al2O3 This was

an indication that Al-Mg-oxides (spinel) could have survived from the electrode and thereafter

acted as nuclei during the precipitation of the inclusions in the remelted steel The most likely

inclusion type to survive is a MgO or Al-MgO (spinel)

Many of the inclusions in the remelted ingots contain a core of an Al-Mg oxide (spinel) having

an outside layer corresponding to the process slag (supplement 56) The theory behind is that

71

the Al-Mg oxides due to the high melting point and low solubility in steel do not melt on the

electrode tip Thereby the Al-Mg oxide will act as a nucleus for this kind of inclusions in the

remelted ingots The formation mechanism could be either due to chemical reactions or due

to the novel collision-coalescence theory based on both thermodynamics and kinetics

(supplement 7) This and the previous findings gave rise to a new classification of the

inclusions in ESR or PESR remelted steels involving three types of inclusions (supplement 6)

1 The primary Inclusions are assumed to have survived from the electrode because they were

trapped inside a steel drop or a fallen steel fragment without being in contact with the

ESRPESR process slag The size depends on the size of the inclusions in the electrode and the

size of the steel droplets In the ingot the spinels are often found in inclusion clusters having

complex shapes and often together with other inclusions and elements (C Cr Si Mn S Ca)

2 The semi-secondary inclusions are the most common inclusion types in the remelted ingots They contain a core of MgO-Al2O3 with an outer layer that corresponds to their corresponding process slag composition However inclusions containing Al-Mg oxides are characterized by having an exogenous origin where the main sources of MgO are refractories or the furnace or ladle slags Due to the low solubility of Mg in iron and the high melting point of MgO it is more likely that at least the majority of the Mg spinel inclusions in the remelted ingots are primary inclusions which survived from the electrode These kind of inclusions were therefore denoted as semi-secondary inclusions The primary Al-Mg oxides are covered by a process slag In some cases the inclusion contains a little amount of CaF2 If CaF2 is found it is a proof that the inclusion has been in contact with the ESRPESR process slag since it contains CaF2 A typical inclusion size class is le 30 microm 3 The secondary inclusions are assumed to be precipitated during solidification of the liquid steel as a result of the reactions between dissolved alloying elements and the dissolved oxygen A typical inclusion size class is lt 10 microm According to the literature the inclusions after a calcium treatment modification (used to modify MgO-Al2O3 to softer inclusions with a lower melting point of the outer layer of inclusions) are very similar to the inclusions found in the ESRPESR ingots (supplement 56) This observation indicates that the ESR process slag acts in some way like a calcium treatment modification of inclusions during the ladle treatment does This hypothesis is supported by the observed appearance of the semi-secondary inclusions The influence of the solidification structure on the inclusion number morphology and distribution was studied by investigation of horizontal sliceslices taken from the electrode ESR and PESR ingots (supplement 8) The second dendrite arm spacing (SDAS) and the angles of the dendrites against the bottom of the steel pool were measured as well as inclusion measurement and chemical analyze across the diameter The columnar-dendritic to equiaxial transition (CET) can readily be seen by measuring the angle towards the surface on the side of cross sections from the remelted ingots Up to the ingot size with an 800 mm in diameter (PESR-800) the dendritic growth direction in the center of the ingot is parallel to the ingot axis In the case of a 1050 mm in diameter ingot (PESR-1050) it was not possible to determine a dendrite growth direction in the center of the material

72

This result in supplement 8 shows that a CET transition in the center of the ingot had a strong effect on the number and size of the inclusions As long as the center of the ingot solidifies in a columnar-dendritic manner the increase of inclusion number and size is almost linear with an increasing ingot size However after the CET transition in the center the inclusion number and sizes are much larger There are approximately 50 more of the largest inclusions (224-448 microm) For this steel grade the transition from columnar-dendritic to equiaxial take place between the 800 mm in diameter (PESR-800) ingot and the 1050 mm in diameter (PESR-1050) ingot The primary arms growth rate needed for the CET transition is less than 4 x 10-7ms In order to undertake the transition the temperature gradient must be less than approximately 103 degCm The axial segregations of carbon (C) correspond both to the measured SDAS values and the dendrites angles towards the bottom of the liquid pool (supplement 8) The more C segregation the larger the SDAS value and the larger (or no angle as for the PESR-1050) the angle Also the larger the ingot and the further towards the center of an ingot the larger the inclusion sizes The results show that the measurement of the amount of larger inclusions (here gt 228 microm) on different ingot sizes will give a good indication of where the transition from a dendritically to equiaxial solidification take place

The layout of the thesis with a few main conclusions from each supplement is given in Table

13 In addition the table shows how the results can be applied in production

73


Study Results Application

1 Study on the inclusion distribution in materials from several ingots of different sizes remelted by the ESR or PESR processes

Statistical basis for the inclusion distributions in ESR and PESR remelted materials A higher understanding of the influence of the electrode cleanliness on the inclusions in remelted material

The results gave rise to an optimization of the electrode heats in the steel shop as well as to the termination of using the largest ingot (PESR-1050) for this steel grade

2 Study differences in inclusion morphologies between remelted and conventional materials

Inclusions morphologies and NMI distributions in conventional ESR and PESR remelted materials of different ingots sizes

A first step to identify the inclusions from the steel shop and the inclusions after remelting

3 Study the difference of the inclusions between an ingot with and an ingot without a tracer in the process slag

Primary and secondary inclusions are both present in a remelted ingot

A better understanding of the origin of the inclusions in remelted ingots

4 Deeper studies of the data from trial with La2O3 as a tracer in the process slag

Description of primary inclusions most likely an Al-oxide inclusion gt 3 Mg

Importance of the cleanliness of the electrode gives a high incentive to improve the process in the steel shop

5 3-D study of inclusions in an electrode and ESR and PESR ingots all from the same electrode heat

A deeper understanding of the morphologies of the inclusions in electrode ESR and PESR ingots and of the difference between 2-D and 3-D studies

Better basis for describing the inclusions in remelted materials

6 Describe inclusions and inclusion types in electrode ESR and PESR ingots from the same electrode heat Link results to literature survey

A new classification of inclusions in remelted ingots A general schematic of the three types of inclusions

Important knowledge when producing clean steel in the steel shop as well as in the ESR shop

7 Formation of Mg-Al oxides A novel mechanism of Mg-Al oxide inclusion evolution by combining thermodynamic and kinetic techniques

Explain the mechanism of formation of semi-secondary inclusions


Solidification data from different ingot types Inclusion morphologies in different solidification structures Temperature gradients and the primary arms growth lengths needed for the DC to EQ transitions

Importance when choosing ingot size for different material dimensions (reduction in forgingrolling)

74

6 CONCLUSIONS

On the whole the results illustrated that the overall cleanliness of the electrode (as well as the composition of the inclusions in the electrode) has an extremely large influence on the cleanliness in ESR and PESR remelted steels The majority of the failure critical inclusions originates direct or indirect from the inclusions in the electrode Moreover the solidification structure (ingot size) also has a direct bearing on the inclusion sizes and content of the ESR and PESR ingots The most important conclusions from supplement 1 were the following

- Statistical basis for the inclusions in remelted material in ingots in different sizes - A linear increase of the number of inclusions in the material from the ingot PESR-500

to the ingot PESR-800 but more inclusions in the material from the ingot PESR-1050 - A visible decrease in the number of inclusions could be observed after changes in the

production of the electrodes in the steel shop

The most important conclusions from supplement 2 were the following

- The conventional material had a higher number of inclusions than the remelted material

- The conventional material had larger and more complex inclusions than the remelted material

- The composition of the inclusions is similar to the composition of their corresponding slag (top and process slag)

The most important conclusions from supplement 3 were the following - Just above 50 of the inclusions in a trial ingot with La2O3 as a tracer in the process

slag (and none in the reference ingot) contained La2O3 - The inclusions without La2O3 must have passed through the remelting process without

having any contact with the process slag

- This is an evidence showing that a remelted ingot not only contain secondary

inclusions but also primary inclusions

- The proposed theory is that the primary inclusions have been trapped inside a steel

drop falling from the electrode to the molten steel pool

The most important conclusions from supplement 4 were the following - The most likely inclusion path from electrode to ingot involves two distinct routes

namely a direct transfer without a change and solutionre-precipitation - Al-oxide inclusions containing gt 3 Mg are most likely to never have been in contact

with the process slag

- The number of Al-oxide inclusions gt 3 Mg is not depending on the specific melt rate

(melt rate per area) ie exposure time on the electrode-slag interface

- The study shows that the cleanliness of the electrode material strongly determines the

quality of ESR or PESR remelted ingots

The most important conclusions from supplement 5 were the following - The remelted ingots had a larger number of small oxides while the electrode had a

much higher number of sulfides

75

- The amount of Al2O3 inclusions was higher in the ESR ingot compared to the PESR ingot - The inclusions containing an inner core of an Al-Mg oxide (spinel) and an outer layer

of CaO-Al2O3 was an indication that Al-Mg-oxides (spinel) could have survived from the

electrode and thereafter acted as a nucleus during the precipitation of the inclusions

in the remelted steel

- The most likely inclusions to survive are MgO or Al-MgO (spinels)

The most important conclusions from supplements 6 and 7 were the following - The ESR process slag acts in some way like a calcium treatment modification does This

hypothesis is supported by the observed appearance of the inclusion compositions - A new classification of the inclusions in ESR or PESR remelted steel was implemented

involving three types of inclusions o Primary Inclusions o Semi-secondary Inclusions o Secondary inclusions

- The formation of the semi-secondary inclusions could be either due to thermodynamics or due to the novel formation mechanism of collision-coalescence based on both thermodynamics and kinetics


- The larger the ingot and the further towards the center of an ingot the larger the inclusion sizes

- As long as the center of the ingot solidifies with a columnar-dendritic structure the increase of the inclusion number and size is almost linear with an increased ingot size However after the CET transition in the center the inclusion number and sizes are much larger

- For this steel grade the transition from a columnar-dendritic to an equiaxial structure is between the 800 mm in diameter (PESR-800) and the 1050 mm in diameter (PESR-1050) ingot

- The columnar-dendritic to equiaxial transition (CET) can readily be seen by measuring the angle towards the surface on the side of cross sections from the remelted ingots

- The primary arms growth rate needed for the CET transition is less than 4 x 10-7ms In order to undertake the transition the temperature gradient must be less than approximately 103 degCm

- The axial segregations of carbon (C) correspond both to the measured SDAS values and the dendrites angles towards the bottom of the liquid pool

76

7 SUSTAINABILITY AND FUTURE WORK

In this section the sustainability aspect of this project is discussed first and the avenues for

further research is mentioned later

71 SUSTAINABILITY

This work contributes to the 17 goals for sustainable development [66] by addressing a few of them On quality education goal number 4 this work adds to the understandings in the field of inclusions and solidification in remelted ingots thereby increasing the available knowledge of the field On industry innovation and sustainable industrialization upgraded or new remelted tool steel grades prolongs the life of the produced tools In addition the market of remelted hot work steels are growing rapidly as tool material for producing the battery pack for electrical vehicles On responsible consumption and production goal number 12 and climate action goal number 13 this work contributes by a longer life cycle of the steel due to longer life for the tools Even though a high quality remelted steel material is expensive the total cost is lower if the tool can be in production for a longer time Not to forget the author of this work is an elderly female engineer Therefore the work also contributes to goal 4 and 5 life-long learning and equality

72 FUTURE WORK

This work has described the origins of the inclusions production-scale remelted material as

well as the impact of the solidification structure on the inclusion distribution Based on the

results the following studies are suggested as future work

Verify the results of this study on other steel grades

Further studies on the impact of different refractory materials on the

inclusions in the electrodes with the aim of minimizing the content of

inclusions containing Al-Mg-oxides (spinels)

Further studies of using different process slags during remelting of

production-scale ingots in order to influence the semi-secondary and

secondary inclusions Laboratory results of thermodynamic optimal process

slags do not always apply to large production-scale ingots

Further studies on the ingot geometry in order to get as low longest

solidification time (LST) as possibly for the demanded dimension

77

8 REFERENCES

1 Monnot J Heritier B Cogne JY Relationship of Melting Practice Inclusion Type and

size with Fatigue Resistance of Bearing Steels Symposium of Effect of Steel

Manufacturing Processes on the Quality of Bearing Steel Phoenix Arizona USA 1986

152

2 Juvonen P Effect of non-metallic inclusions on the fatigue properties of calcium

treated steels PhD Thesis Technical University of Helsinki 2004

3 Mitchell A Oxide inclusion behavior during consumable electrode remelting

Ironmaking and Steelmaking 1974 1 (3) 172

4 Dong Y Jiang Z Cao Y Fan J Yu A Liu F Effect on fluoride containing slag on oxide inclusions in electroslag ingot In Proceedings of the Liquid Metal Processing amp Casting Conference Austin TX USA 22ndash25 September 2013

5 Dong Y-W Jiang Z-H Cao Y-L Hou D Effect of slag on Inclusions during

electroslag remelting process of die steel Metall Mater Trans B 2014 45B 1315ndash1324

6 Schneider R Schuler C Wurstinger P Reiter G Martinez C Einfluss eines houmlheren

SiO2-Gehaltes in der Schlacke beim Umschmelzen eines Varmarbeitsstahles auf ESU-prozess Berg Und Huumlttenmaumlnnische 2015 160 117ndash122 (In German)

7 Du G Li J Wang Z-B Effect on operating conditions on inclusion of Die Steel

duringElectroslag remelting ISIJ Int 2017 29 1ndash10

8 Reiter G Schuetzenhoefer W Tazreiter A Martinez C Wurstinger P Loecker C The incluence of different melting and remelting routes in the cleanliness of high alloyed steels In Proceedings of the Liquid Metal Processing amp Casting conference LMPC 2013 Austin TX USA 22ndash25 September 2013

9 Hoyle G Electroslag processes Principles and Practice London and New York NY

Applied Science publisher LTD 1983 29-32

10 Korp JC Einfluss der Schmelzrate auf die Charakteristiken nichtmetallischer

Einschlusse beim Elektroschlacke-Umschmelzen unter Schutzgas BHM Berg- und

Huttenmaumlnnische Monatshefte 2012 157(5) 174-180 (In German)

11 Kay DAR Pomfret RJ Removal of inclusions during AC Electroslag remelting J Iron

Steel Inst 1971 209 962ndash965

78

12 Li ZB Zhou WH Li YD Mechanism of removal on non-metallic inclusions in the ESR process Iron Steel 1980 15 20ndash26

13 Shi C Chen X-C Guo H-J Oxygen control and its effect on steel cleanliness during

Electroslag remelting of NAK80 die steel In Proceedings of the Iron and Steel Conference and Exposition AISTech 2012 Atlanta GA USA 7ndash10 May 2012 947ndash957

14 Shi C Chen X-C Guo H-J Zhu Z-J Ren H Assessment of oxygen control and its

effect on inclusion characteristics during ESR remelting of die steel Steel Res Int 2012 83 472ndash486

15 Shi C Chen X-C Guo H-J Characteristics of inclusions in high-Al steel during

electroslag remelting process Int J Miner Mater 2012 19 295ndash302

16 Chen XC Shi CB Guo HJ Wang F Ren H Feng D Investigations of oxide inclusions and primary carbon nitrides in Inconel 718 Superalloy refined through electroslag remelting process Metall Mater Trans B 2012 43 1596ndash1607

17 Burel BC A Study of Inclusion Behavior during Electroslag Remelting PhD Thesis

Department of Metallurgy University of British Columbia Vancouver BC Canada 1969

18 Chan JCF Miller JWGD Cameron J The Re-solution of Inclusions in Remelted

Stainless Steels Metall Mater Trans B 1976 7B 135ndash141

19 Shi C Chen X-C Luo Y-W Guo H-J Theory analysis of steel cleanliness control during electroslag remelting In Materials Processing Fundamentals Springer Cham Switzerland 2013

20 Shi C Chen X-C Guo H-J Sun XL Zhu Z-J Control of MgOmiddotAl2O3 spinel inclusions during protective gas electroslag remelting of die steel Metall Mater Trans B 2013 44B 378ndash389

21 Shi C Zhu Q-t Yu W-t Song H-d Li J Effect on oxide inclusions modification

during electroslag remelting on primary carbides and toughness of a high-carbon 17 Cr tool steel J Mater Eng Perform 2016 25 4785ndash4795

22 Chang LZ Shi XF Cong JQ Study on mechanism of oxygen increase and

countermeasure to control oxygen content during electroslag remelting process Ironmak Steelmak 2014 41 182ndash186

23 Shi C Park JH Evolution of Oxide inclusions in Si-killed Steel during Protective

Atmosphere Electroslag remelting Metall Mater Tans B 2019 50B 1139ndash1147

24 Wang H Li J Shi CB Li J Evolution of Al2O3 inclusions by magnesium treatment in H13 hot work die steel Ironmak Steelmak 2017 44 128ndash133

doi1010800301923320161165498

79

25 Franceschini A Ruby-Meyer F Midroit F Diawara B Hans S Poulain T Trempont C Hegravenault E Rouffieacute A-L An assessment of cleanliness techniques for low alloyed steel grades Metall Res Technol 2019 116 509 doi101051metal2018128

26 Fredriksson H Aringkerlind U Materials Processing During Casting John Wiley amp Sons

Ltd Hoboken NJ USA 2006 pp 27 185 207 219 265 Homepage httpswwwwileycomlegacywileychifredriksson

27 Mitchell A Solidification in remelting processes Mater Sci Eng A 2005 413ndash414 10ndash18

28 Mitchell A Burel B The solution of aliumina in CaF2-Al2O3slags Metall Trans B 1970

1 2253ndash2256

29 Li JL Shu QF Liu YA Chou KC Dissolution rate of Al2O3into molten CaO-Al2O3-CaF2flux Ironmak Steelmak 2014 41 732ndash737

30 Gang-Du Li J Wang Zh Effect of initial large sized inclusion content on removal in

ESR Ironmak Steelmak 2018 45 919ndash923

31 Paton BE Investigation Methods removal of non-metallic inclusions during ESR Proc 5th International Symposium on ESR eds G K Bhat and A Simcovitch publ Mellon Institute Pittsburgh USA 1974 433ndash448

32 Zhang L Rietow B Thomas BG Eakin K Large inclusions in plain carbon steel

ingots cast by bottom teeming JISI 2006 46 670ndash679

33 Xuan C Persson ES Sevastopolev R Nzotta M Motion and Detachment Behaviors of Liquid Inclusion at Molten Steel-Slag Interfaces Metall Mater Trans B 2019 4 1957-1973 httpsdoiorg101007s11663-019-01568-2

34 Voronov VA Kinetics of dissolution of MgO in CaF2 slags Izv Akad Nauk SSSR Met

1975 3 62ndash65

35 Shi C- Guo HJ Chen XC Kinetic study on Oxygen during Protective Gas Electroslag Remelting Process Special Steel 2012 (in press)

36 Medina SF Cores A Thermodynamic Aspects in the Manufacturing of Microalloyed

Steels by the Electroslag Remelting Process ISIJ Int 1993 33 1244ndash1251

37 Wang CS Liu SG Xu MD Reducing oxygen content in Electro-slag Remelted Bearing Steel GCr15 Special Steel 1997 1831ndash35

38 Chang LZ H Yang S Li ZB Study on Oxygen Behavior Steelmaking during

Electroslag Remelting Steelmaking 2010 26 46ndash50

80

39 Wang F Chen XC Guo HJ Aluminum Deoxidization of H13 Hot Die Steel through Inert Gas Protection Electroslag Remelting In Proceedings of the Iron and Steel Conference and Exposition ATS Tech 2012 Atlanta GA USA 7ndash10 May 2012 1005-1015

40 Mitchell A The chemistry of ESR slag Canadian Metall Q 1981 20 101ndash112

41 Mitchell A Electrochemical Aspects of the ESR process LMPC 2015 Leoben Austria

2015

42 Shin JH Park JH Optimization of slag-metal reaction model for prediction of inclusion composition Scanmet V Lulearing Sweden 2016

43 Stefanescu DM Microstructure Evolution during the solidification of Steel ISIJ Int 2006 46 786

44 Mitchell A Industrial effects associated with the columnar to equiaxed transition in remelt ingots Int J Cast Met Researc 2009 22 216 doi101179136404609X367768

45 Mitchell A Estimation of Melting Rates Confidential Internal Report Ordered

Uddeholms AB Hagfors Sweden 1999

46 Fredriksson H Jarleborg O Solidification of electroslagremelted ingots JOM 1971 23 32

47 Korp JC Einfluss det scmeltzrate auf die Charakteristiken nichtmetallisher Einschluumlsse

beim Elektroschlacke-umschmeltzen unter schutzgas BHM 2012 157 174ndash180

48 Borodin IP Gorayainov VA Koshman VS Zaitseva LA Tsapaeva LL Influence of solidification conditions on dendritic structure and segregation of elements in electroslag remelted ingots Steel in the USSR 1985 15 533-537 INFLUENCE OF SOLIDIFICATION CONDITIONS ON DENDRITIC STRUCTURE AND SEGREGATION OF ELEMENTS IN ELECTROSLAG REMELTED INGOTS (researchgatenet)

49 Xuan C Persson ES Sevastopolev R Nzotta M Motion and Detachment Behaviors of Liquid Inclusion at Molten Steel-Slag Interfaces Metall Mater Trans B 2019 4 1957ndash1973 doi101007s11663-019-01568-2

50 Voronov VA Kinetics of dissolution of MgO in CaF2 slags Iz Akad Nauk SSSR Met

1975 3 62ndash65

51 Xuan C Persson ES Jensen J Sevastopolev R Nzotta M A novel evolution mechanism of Mg-Al-oxides in liquid steel Integration of chemical reaction and coalescence-collision J Alloys Comp 2019 812 doi101016jjallcom2019152149

52 Mitchell A Szekely J Elliott FJ Electroslag Refining The Iron and Steel Institute

London UK 1973 3ndash15

81

53 Chen LQ Shen J Applications of semi-implicit Fourier-spectral method to phase field equations Computer Phy Com 1998 108 147-158

54 Steneholm K Andersson M Joumlnsson PG Tilliander A Removal of Hydrogen

Nitrogen and Sulfur from Tool Steel during Vacuum Degassing Ironmaking and Steelmaking 2013 40 (3) 199-205

55 Frazer ME Mitchell A Mass transfer in the electro slag process Part 2 Mass-

transfer model Ironmak Steelmak 1976 3 288

56 Cao Y Dong Y Jiang Z-h Cao H-b Feng Q-l Research on droplet formation and dripping behavior during the electroslag remelting process Metall Mater 2016 23 399ndash407

57 Kiessling R Lange N Non-Metallic Inclusions in Steel Part 2 The Institute of Materials London UK 1977 1ndash6 Available online

httpstrovenlagovauwork11762170

58 Paton BE Medovar BI Removal of inclusions during ESR Proc 5th International

Conference on ESR Mellon Institute Pittsburgh USA 1973 561-566 Klyuev MM Mironov YM Reaction surface in ESR Stal 6 1967 480

59 Klyuev MM Mironov YM Reaction surface in ESR Stal 6 1967 480

60 Yang SF Wang QQ Zhang L Li J Peaslee K Formation of MgOmiddotAl2O3-based inclusions in alloy steels Metall Mater Trans B 2012 43 731ndash750

61 Reyes-Carmona F Mitchell A Deoxidation of ESR Slags ISIJ Int 1992 32 529ndash537

62 Personal communication Hasse Fredriksson KTH May 2017

63 Imagumbai M Relationship between Primary- and Secondary-dendrite Arm Spacing of C-Mn Steel Uni-directionally Solidified in Steady State ISIJ Int 1994 34 986ndash991

64 Kurz W Fischer DJ Fundamentals of Solidification 4th ed CRC Press Boca Raton FL USA 1998

65 UNs web site about the 17 goals for sustainable developmwnt Take Action for the

Sustainable Development Goals ndash United Nations Sustainable Development


Doctoral Thesis in Materials Science and EngineeringKTH Royal Institute of TechnologyStockholm Sweden 2021

Academic Dissertation which with due permission of the KTH Royal Institute of Technology is submitted for public defence for the Degree of Doctor of Philosophy on Friday the 28th May 2021 at 200 pm Digital and Green room Osquars backe 31 Soumldra tornet plan 4 Stockholm



- Marie Osmond

i

Abstract






























ii


iii

Sammanfattning








omsmaumllt material


















microm


iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81





















- Marie Osmond

i

Abstract






























ii


iii

Sammanfattning








omsmaumllt material


















microm


iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















i

Abstract






























ii


iii

Sammanfattning








omsmaumllt material


















microm


iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















ii


iii

Sammanfattning








omsmaumllt material


















microm


iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















iii

Sammanfattning








omsmaumllt material


















microm


iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















iv

Acknowledgement









Hagfors 2021

v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















v

Supplements














vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















vi










the conference












writing






vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















vii

List of Tables














viii

List of Figures


[45]























800 PESR-1050)





furnace type

ix






Ca-S and Ca-O




slag) to the right























x


















xi





















1050)

xii




xiii











B Bottom

M Middle

T Top

X Random position

2-D Two-dimensional












xiv

CONTENTS









































xv






ESRPESR
















1

1 INTRODUCTION









2

12 LITERATURE STUDY
























3

121 INCLUSIONS




4



5





3(MgO) + 2[Al] = 3[Mg] + (Al2O3) (4)


6

122 SOLIDIFICATION



7


[45]


8



9

13 PRESENT WORK












10




































11


21 MATERIAL










ingot









1 335-36 295-32 315-34 0 15-2 3-4

2 268-288 236-256 252-272 20 12-16 24-32

12



(a) (b) (c)


13



(a) (b)








14



15




16





Karlskoga













17

25 CHEMICAL ANALYZE



the other elements



18

3 THEORY


IN REMELTED INGOTS


partempty


As

2(xLI-B)

2 minusAL

2(xLI-xeqLI)

2(xLI-xeqLM)

2]



partxLIpartt


2

+ (1199091198901199021198711198682 + 4119909119890119902119871119868 ∙ xeqLM + 119909119890119902119871119872

2)119909119871119868 minus 2119909119890119902119871119868


2119909119871119868


19




Steel 1805







Constant B 0623



KxLI 1373times10-9



xeqLI 050

xeqLM 098


L 10-40


As 4times109







20











morphologies [25]











(a)

0

002

004

006

008

01

012

014

016

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot


ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

21

(b)












(a)

0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0005

ESR-400 3samples -2

ingot

ESR-600 3samples-1

ingot

PESR-500 7samples-3

ingot

PESR-80012 samples-

4 ingot


ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





22

(b)




0

0005

001

0015

002

0025

003

0035

004

0045

8-112microm

112-224microm

224-448microm

gt=448microm

Nu

mb

ers

of

oxi

de

incl

usi

on

s p

er m

m2





23







sizes






(a)

0

002

004

006

008

01

012

014

016

CON-6004 samples -

4 ingots

CON-700mm 2

samples - 2ingots


ingots


ingot

PESR-5007 sample -

3 ingot



1 ingot

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Ingot type


8-112 microm

112-224 microm

224-448 microm

gt=448 microm

24

(b)





PESR-800 PESR-1050)





(a) (b)







in the diagram

25

(a) (b)


furnace type















(a) (b)




26






(a) (b)



O Ca-S and Ca-O





(a) (b)



27











per ingot was 50 kg


slag) to the right





1 326 28 336 002 261 373

2a - 1 289 234 222 228 235 302

2a - 2 279 244 249 193 264 330

2b 26 254 287 149 383 328

28

(a) (b)









(a)

0

001

002

003

004

B T B T B T


LaNu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

29

(b)









(a)

0

0002

0004

0006

0008

001

B T B T B T


La

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





30

(b)

(c)

(d)




0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





00002000400060008

001001200140016

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





0

0005

001

0015

002

0025

003

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2

Inclusion type





31

(a)

(b)




OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2B-1B 8-112 microm -000106 -000227 -000453 000483 -000302

Ingot 2B-1B 1120-2240 microm 000015 000076 -000196 000211 000106

Ingot 2B-1B 2240-4480 microm 000000 000000 -000015 000000 -000015

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fere

nce

in n

um

ber

of

incl

usi

on

s p

er m

m2

Inlusion type


samples

OxideAlMg

OxideAl+Mg

OxideAlCa

Lainclusions

Tot

Ingot 2T-1T 8-112 microm 000065 -000549 -000485 000840 -000129

Ingot 2T-1T 1120-2240 microm 000032 -000404 -000679 000291 -000759

Ingot 2T-1T 2240-4480 microm 000000 000000 -000016 000032 000016

-000900-000800-000700-000600-000500-000400-000300-000200-000100000000000100000200000300000400000500000600000700000800000900

Dif

fern

ce in

nu

mb

er o

f in

clu

sio

ns

per

mm

2

Inclusion type


32








33



34













35
























slag interface



0

10

20

30

40

50

60

70

80

90

100


Shar

e o

f A

lMg(

gt 3

M

g) in

clu

sio

ns

of

tota

l in

clu

sio

n n

um

ber

(

)

Inclusion sizel


ESR-400

ESR-600

PESR-500

PESR-650

PESR-800

PESR-1050

36










(a) (b)


37

(a) (b)

(c)



OS AM ACM A+AC MnS

224-448 microm

112-224 microm

8-112 microm

NA (

incl

m

m2)

Type of NMI

002

001

0OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

OS AM ACM A+AC MnS

Type of NMI

NA

(in

cl

mm

2)

004

002

0

001

003

38

(a) (b)

(c)











39

(a) (b)

(c) (d)


40

(a) (b)

(c) (d)


41


Type AM Al2O3-MgO





42






43



(a) (b)

(c) (d)


44





45


TYPES






(SI)


Type of NMI











sometimes with CaF2





46








Steel shop














Remelting shop





47










in the top slag














48





(a) (b)



49








STRUCTURE


(a)

50

(b)

(c)

Surface to 155 mm

51

(d)

Surface to 155 mm






52

(a) (b) (c)



(a) (b)




(a)

53

(b)

(c)





54





0

30 159

33 162 173

44 226

83 287

75 232

136 222 229 267

123 306

150 268

171 488

202 274 280 409

249 397

257 788

395 569

510 847

R2 linear 08907 09929 09903 0995 09591 06368

R2 polynome 1

55



CE-300 Near corner 159 38 8 5 88T4 232 61 13 5 90T2 268 65 13 5 89

ESR-400 1 Near corner 162 55 11 7 88T4 222 66 14 6 91

T2 276 70 15 5 88

ESR-400 2 Near corner 173 47 10 6 82T4 229 68 14 6 88

T2 280 70 15 5 81

PESR-500 T6 287 74 17 6 70

T4 306 104 24 78 73

T2 397 124 27 68 82

PESR-800 Surface 226 62 14 6 76T6 267 75 17 6 76T4 409 148 30 7 91

T2 569 199 42 7 85

PESR-1050 T6 488 142 28 57 101T4 788 218 44 56 94

T2 847 213 41 49 101


0

200

400

600

800

1000


Den

dri

te a

rm s

pac

ing

(microm

)


CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

56



0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600

Seco

nd

ary

den

dri

te a

rm s

pac

ing

(microm

)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

57




T6 655 661 66

T4 722 718 72

T2 90 90 90

PESR-800 Surface 45 517 585 522 519

T6 698 72 655 733 702

T4 60 584 543 651 595

T2 90 90

T4 661 626 622 625 633

T6 725 779 722 725 738

Surface 44 395 406 402 411

PESR-1050 Surface 382 456 518 588 486

T6 737 739 654 67 70

T4 658 726 725 68 697



58

(a)

(b)


59







Position

Surface T6 T4 T2







60





ℷ2 ~ 05ℷ1 (11)


0

00005

0001

00015

0002

00025

0003

00035

0004

00045

0 100 200 300 400 500

Y gro

wth

(cm

s)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

61




CE-300 1998229 1744105 1655845

ESR-400 1 1984828 177199 1642699

ESR-400 2 1938437 1752296 1629939

PESR-500 1615514 157866 143742

PESR-800 17606344 1658075 1422092 1262722

PESR-1050 1334495 1123049 1094234

(a)

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 100 200 300 400 500

Tem

per

atu

re G

rad

ien

t G

(degC

m)



CE-300

ESR-400 1

ESR-400 2

PESR-500

PESR-800

PESR-1050

62

(b)



y = 5E-21x55556

0

0002

0004

0006

0008

001

0012

1000 1200 1400 1600 1800 2000 2200

Vgr

ow

th p

rim

ary

den

dri

te a

rm (

mm

s)



63


100E-07

100E-06

100E-05

100E-04

100E-03

100E-02

100E-01

100E+00 100E+01 100E+02 100E+03 100E+04 100E+05 100E+06 100E+07

Gro

wth

Rat

e Ʋ

gro

wth

(ms

)



Kurz diagram [40]

Kurz [40]

Uddeholms

PESR-800

PESR-500

PESR-

CE-300

ESR-400

1 ESR-

Equiaxial

Dendrites [40]


64



(a)

(b)


9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 2 3 4 5

Per

cen

t (

)



CE-300 B

CE-300 T

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

1 3 5 7 9 11 13

Per

cen

t (

)



PESR-1050

PESR-800

PESR-500

ESR-400 1

ESR 400 2

65








66






0002004006008

01012

ESR

-40

0 B

ESR

-40

0 M

ESR

-40

0 T

PES

R-5

00

BP

ESR

-50

0 M

PES

R-5

00

T

PES

R-6

50

BP

ESR

-65

0 M

PES

R-6

50

T

PES

R-8

00

BP

ESR

-80

0 M

PES

R-8

00

T

PES

R-1

05

0 B

PES

R-1

05

0 M

PES

R-1

05

0 T

Nu

mb

er o

f in

clu

sio

ns

per

mm

2



8‒112 microm

112‒224 microm

224‒448 microm

gt=448 microm

67

(a)

(b)



0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13

o

f th

e la

rges

t N

Ap

er s

ize

clas

s



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

68



0

00005

0001

00015

0002

00025

0003

ESR-4006 positions

3 ingots


4 ingots

PESR-6503 positions

1 ingot


4 ingots


8 ingots

Nu

mb

er o

f o

xid

e in

clu

sio

ns

per

mm

2



8-112 microm

112-224 microm

224-448 microm

gt=448 microm

69




























70

























ingots


















71













72




73


























74

6 CONCLUSIONS

























75

















76




71 SUSTAINABILITY


72 FUTURE WORK














77

8 REFERENCES




152




















78






















doi1010800301923320161165498

79






1 2253ndash2256









1975 3 62ndash65







80




2015












1975 3 62ndash65




81



















doctoral thesis in materials science and engineering n the

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