thermal analysis.pdf

7/25/2019 Thermal analysis.pdf

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Rio TintoIron & Titanium

Thermal

Analysis&

CoolingCurves

ThermalThermal

AnalysisAnalysis&&

CoolingCoolingCurvesCurves


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Every body know this

system, frequently found

near the furnaces or thecupolas

Its a Thermal Analysis Systemto check especially:

eq, , T!, Si or "ndercoolin#


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$ow does it work %$ow does it work %

It records the different steps of the coolin# for the liquid and

solid alloy, by measurin# of different electrical values& A

specific electrical value corresponds to each step of the

physical aspect of the ' alloy (& These values are translated toa #raph&


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Some definitions:

TL: Liquidus temperature

TE low: Low eutectictemperature

TE upper: High eutectictemperature

TE Gray: Gray eutectictemperature

TE White: White eutectictemperature

TS: Solidus temperature

T: Undercooling

R: Recalescence

1100

1150

1200

1250

0 50 100 150 200 250 300

Time: s

Temperature:C

Te Low

Te Upper

Te Gray

Te White

T Liq

T Sol

RT


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)or Iron:Each iron #rade has a specific curve:

*: !amellar #raphite iron

+: I

-: I with low nodules count

.: /hite iron

0: pseudo lamellar #raphite 1 lamellar #raphite


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)or E2ample:


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)or I, there are different typical curves:

3ase Iron3ase Iron3ase Iron


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Treated ironTreated ironTreated iron


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Treated iron

1

Inoculation

Treated ironTreated iron

11

InoculationInoculation


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/hy usin# Thermal Analysis%:A last efinition&

Undercooling = TE gray TE low


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/hy usin# Thermal Analysis%:/hat happens if undercoolin# 4 T 5 becomes too hi#h %

Fe3CFe3CFe3C


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/hy usin# Thermal Analysis%:/hat happens if ' TS ( becomes too low %

Inverse ChillInverse ChillInverse Chill


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/hy usin# Thermal Analysis%:

Inverse ChillInverse ChillInverse Chill


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/hy usin# ThermalAnalysis%:

The A, 3, curves

That gives

differentCooling curves


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6

Small elta T 6

$i#h 7ucleation

TE

8ray


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$i#h 7ucleation 6

less shrinka#e

Thermal Analysis

can prevent

shrinka#e


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/hy usin#

ThermalAnalysis%:

Thermal Analysiscan check the

iron quality

durin#

elaboration:

Especially after a

lon# maintain in

the furnace


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9resent 9ossibility:Thermal Analysis with usin# the first and second derivations

This value could qualify the #ood nucleation


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Thermal Analysis with - cups: presently for #ray iron

This #ray value is the ri#ht estimation of what we will probably obtain

in the castin# re#ardin# the white and the #raphitic iron

9resent 9ossibility:


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1 = Fonte de Base avec ajout de graphite

C=3.66 Si=1.72 Temprature four=1512

Caldobase = Fonte de Base

C=3.64 Si=1.72 S=0.011 Cu=0.05 Mn=0.15 Temprature four=1494

oncreteE2amples:


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2inoculada = Fonte traite _ en poche

C=3.69 Si=2.34 S=0.002 Mg=0.041 0.4% inoc. Temprature poche=1395

1inoculada = Fonte traite _ en poche

C=3.62 Si=2.4 S=0.003 Mg=0.044 0.4% inoc. Temprature poche=1405

oncreteE2amples:


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1100

1120

1140

1160

1180

1200

13:40 13:55 14:09 14:24 14:38 14:52

Liquidus

Eutect ique bas

Eutectique haut

-5

0

5

1015

20

25

30

35

13:55 14:30 14:40 14:50 3.75

3.8

3.85

3.9

3.95Surfusion

Recalescence

Ceq

Super

8ray Iron8ray Iron

*.:-0 with Te

T solidus 6 ***

Time

13:55 without Te

14:30

without Te + 1 Kg/T of good

graphite, Tfurnace = 1394C

14:40

without Te + strong

inoculation in the cup

14:50

graphite + 1.5Kg FeSi

correction, T furnace = 1470C


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1125

1130

1135

1140

1145

1150

1155

1160

15:36 15:50 16:04 16:19 16:33

Liquidus

Eutect ique bas

Eutect ique haut

0

510

15

20

25

15:45 15:50 15:55 16:10 16:20 16:25

4.05

4.1

4.154.2

4.25

4.3

4.354.4

Surfusion

Recalescence

Ceq

*;:


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onclusions:

Thermal Analysis can check:

the risk to obtain )e- and inverse chill

the risk to obtain shrinka#e or porosities

Thermal Analysis #ives a very #ood quality inde2 by

the undercoolin# value

Thermal Analysis is cheap, has a #ood reproducibility,

human influence is low, traceability is easy

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thermal analysis.pdf

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