SHIP PRODUCTION COMMITTEEFACILITIES AND ENVIRONMENTAL EFFECTSSURFACE PREPARATION AND COATINGSDESIGN/PRODUCTION INTEGRATIONHUMAN RESOURCE INNOVATIONMARINE INDUSTRY STANDARDSWELDINGINDUSTRIAL ENGINEERINGEDUCATION AND TRAINING

THE NATIONALSHIPBUILDINGRESEARCHPROGRAM

August 1988NSRP 0298

1988 Ship Production Symposium

Paper No. 11A: ElectroslagSurfacing: A Potential Processfor Rebuilding and Restorationof Ship Components

U.S. DEPARTMENT OF THE NAVYCARDEROCK DIVISION,NAVAL SURFACE WARFARE CENTER

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Electroslag Surfacing: A Potential Process for No.11A

Rebuilding and Restoration of Ship ComponentsD. W. Yu, Visitor, and J. H. Devletian, visitor, Oregon Graduate Center, Seawton, CR

ABSTRACT

With construction of new commer-cial ships in U.S. shipyards at enall-time low and Congressional appro-priations insufficient to maintain aU.S. fleet of 600 ships, the prioritiesof the surviving U.S. shipyards arechanging from that of shipbuilding toship rebuilding, restoration and re-pair.

This paper presents a review ofthe international literature on themost recent developments in thick sec-tion surfacing by electroslag surfacing(ESS) using strip or wire electrodes.The advantages of this newly-developedtechnique from Japan are explained incomparison with the conventional sur-facing processes, such as submerged arcsurfacing (SAS). A number of innova-tions and applications in this area areintroduced to emphasize the substantialeconomical advantage of strip ESS forship repair end manufacturing.

ESS with strip electrodes is cap-able of overlaying a wide variety ofcorrosion and/or wear--resistant depos-its on structural ship components withhalf the dilution level and twice thedeposition rate of its closest competi-tor, SAS. Because of its significanteconomical merits, strip ESS has al-ready become the dominant thick-sectionsurfacing process in many industrial-ized countries, particularly in Japan,the Soviet Union and parts of Europe.

NOMENCLATURE

ESS -- Electroslag SurfacingESW -- Electroslag WeldingESR -- Electroslag RemeltingSAS -- Submerged Arc Surfacing

SMAW -- Shielded Metal Arc WeldingGMAW -- was Metal Arc Welding

INTRODUCTION

The future requirement for newShips forecast by the Association ofWest European Shipbuilders (1) impliesover a third of the world's shipyard

capacity active in 1985 will have toclose if it is to be brought into linewith demand. The Japanese shipbuildershave tried to maintain their capacityto meet the predicted market upturn inthe early 1990's. The south Koreanshipbuilding industry has flourishedsince 1978, and a concerted sales driveis presently under way to utilize esmuch capacity as possible.

Unfortunately, international com-petition and foreign labor rates haveput virtuallv all commercial shiubuild-inq contracts out of reach for U.S.shipbuilders (2,3). This has created afiercely competitive environment forthe dwindling U.S. Naval contracts.With construction of new commercialships in U.S. shipyards et an all-timelow and Congressional appropriationsinsufficient to maintain a U.S. fleetof 600 ships (4), the priorities of thesurviving U.S. shipyards are changingfrom that of shipbuilding to that ofship rebuilding, restoration and re-pair.

Various surfacing processes havebeen utilized to repair and rebuildcorroded or worn ship components. Thenear-future need for more economicalrepairing methods must be increasinglyemphasized in order to remain competi-tive internationally. Surfacinq by theShielded Metal Arc Welding (SMAW) andGas Metal Arc Welding (GNAW) techniquesare labor intensive with little oppor-tunity for innovation and improvement.For many years, SAS with strip elec-trodes was considered the most cost-effective method to overlay large com-ponents, such as ship propeller shafts,and now still prevails in the Unitedstates. The Japanese and Soviet ship-builders, in particular, have developedhighly cost-effective methodologies torebuild large ship components using aninnovative concept known es "Electro-slag Surfacing". Strip ESS exhibitssubstantial advantages over strip SASin the areas of "recess control. sur-facing quality and economic produotiv-ity. It has completely replaced theless economical surfacing methods in

IIA-1

Japan and the Soviet Union, but has yetto be "discovered" in U.S. shipyardsand manufacturing industries. In fact,except for the current program spon-sored by the National Coastal Researchand Development Institute at the OregonGraduate center, virtually none ofAmerica's manufacturing and shipbuild-ing industries have benefited from thisnew technology.

Due to the relative newness ofESS , the terminology throughout theworld varies. For example, ESS iscommonly referred to as (1) resistanceelectroslag surfacing, (2) e1ectros1agoverlay welding, and (3) electroslagcladding. The "strip" term is oftenadded into these terminologies becausefiller metals are commonly utilized inthe form of strip material.

In 1980, Kawasaki Steel (5) ofJapan first developed a reliable stripESS process and registered severalpatents in the Western world. Thistechnique rapidly spread throughoutJapanese industries (6). Several west-ern European countries also adoptedthis process and are commercially manu-facturing standard ESS equipment.

For the last seven years, a greatnumber of innovations in ESS have beendeveloped. However, it is surprisingthat strip ESS had not caught on inAmerican industries. In 1985, Forsbergof Sandvik Steel published the firstarticle about this technique in anAmerican journal (7). Since that time,the manual, semi-automatic and SASmethods continue to dominate virtuallyall overlaying applications in theUnited States.

The purpose of this study is tocritically review the internationalliterature on ESS and strip ESS. Ofparticular emphasis will be the fluxchemistries and the electrochemicalreactions that ate associated with thisprocessing innovation. The advantagesof surfacing with the strip ESS methodwill be reported. Also included willbe the results of preliminary studieson strip ESS for practical applicationson ships currently underway at OregonGraduate Center.

CHARACTERISTICS OF ELECTROSLAG SURFAC-ING

Although the strip ESS process isnew, the fundamental principle of ESSis similar to that of the ElectroslagWelding (ESW) and Electroslag Remelting(ESR) processes. Heat is generated byohmic heating of a resistive slag bythe passage of an electric currentthrough a strip electrode, which iscontinuously fed into the molten slagpool. Figure 1 shows a schematic dia-gram of the ESS process.

Fig. 1 Diagram of the ElectroslagSurfacing process

Considerable differences in proc-ess detail exists between ESW and ESS.These include:

Welding position in ESW is ver-tical or near-vertical, whereasESS is performed in the flat posi-tion:The depth of slag pool and basemetal dilution are substantial inESW, whereas ESS requires only ashallow slag pool and produces lowdilution:The chemical composition of elec-trodes in ESW are usually similarto that of the base metal, whereasin ESS, they may (or may not) besubstantially different; andTravel speed in the ESS process isabout 10 to 15 times greater thanconventional ESW.

The process appearance of stripESS is nearly identical to that ofstrip SAS, except SAS is primarilyarc-functioning while ESS is generallyarcless and produces heat by I2R(ohmic) heating of the molten slag.However, strip ESS exhibits a series ofadvantages over strip SAS in providinglow dilution deposits, high depositionrates and better productivity.

The first important feature ofstrip ESS is low dilution in the depos-its. I" any surfacing process, a crit-ical factor requiring precise controlis the dilution ratio. The term, "di-lution ratio", is expressed as:

% Dilution = B/(A + B) x 100

where A is the cross sectional area ofreinforcement of. deposits above the

base metal surface, end B is the crosssectional area of the melted base metalbelow the workpiece surface. In termsof surfacing, it is necessary to keeplow dilution levels because the sur-faced layer has to maintain its desiredinherent properties, like wear the Cor-rosion resistance. I" SAS,tends to penetrate more deeply end meltmore base metal in comparison to ESS.For exmple, the strip SAS processtypically produces a dilution ratio of18% at a current density of 25 A/mm2

(16.1 kA/in2), compared to approximate-ly a 9% dilution ratio for the stripESS process et 41.A/mma (26.5 kA/in2)(8). Thus, the chemical composition ofthe overlay deposited by ESS will moreclosely resemble that of the fillermetal.

The second important feature ofESS is its high deposition rate, whichis a function of the current density.The use of a high current density inthe SAS process will effectively makethe arc hotter and stiffer, thus caus-ing it to penetrate more deeply intothe workpiece to increase the dilutionratio. On the other hand, the stripESS process allows the use of almostdouble the current density to produce amuch higher deposition rate while Stillmaintaining a lower dilution level.This desirable combination of a highdeposition rate and a low base metaldilution was the main incentive forJapanese industries to eliminate SAS infavor of ESS.

The third important feature of ESSthe feasibility of single layer

deposition By virtue of its low dilu-tion and high deposition rate, surfac-inq can be most economically attainedfor the desired thickness of a corro-sion or wear resistant layer with adesigned chemical composition. Sincethe dilution level for strip ESS isalmost half that of strip SAS, thestrip ESS process can more likely elim-inate the necessity for multiple layerdeposits and result in greater costeffectiveness. Furthermore, thin over-lays (about 3 mm or l/8 in. thick) arefar more advantageous by ESS becausedilution decreases with overlay thick-ness for ESS but increases by SAS.

Further economical advantage isgained by the use of wide strip whichdeposits a greater surface area perunit time. Large strip widths (> 60 mm12.4 in.]) are particularly more diffi-cult to apply by SAS than ESS.SAS process, the arc is struck at onecorner of the strip and then startstraversing the entire width of thestrip (5.9). The strip is consumed bythe oscillatory movement of the arcacross the strip. However, in ESS thestrip is consumed uniformly across itsentire width. This phenomenon is

illustrated in Figure 2 (5). The move-ment of the arc in SAS is not necessar-ily uniform and leads to inconsistentpenetration and lack of fusion. Forthis reason, SAS has been limited to astrip width of 75 mm, whereas usingstrips es wide as 300 mm (11.8 in.) isnot uncommon in ESS. A comparisonbetween the strip ESS and SAS processis presented in Table I.

Base metal

Base metal

Fig. 2 Penetration characteristicsof SAS and ESS

FURTHER INNOVATIONS IN ESS FROM JAPAN

External Magnetic Field for ESS

In 1980, Nakano and his colleaguesin Japan (5) first developed an elec-tromagnetic controlled strip ESS methodcalled the MAGLAY process. Duringsurfacing with wide strips (> 60 mm[2.4 in.]), the formation of undercut-ting and lack of fusion defects werefound to be related to the flow patternof molten slag and metal, which isdriven by the electromagnetic forceinduced by the high values of the sur-facing current. Electric current,flowing parallel from the strip to thebottom of the molten pool, makes bothslag and metal move from the edges ofthe-pool toward the center as illus-trated in Figure 3. To counteract thisforce in the MAGLAY process, two directcurrent coils are mounted adjacent tothe edges of the strip electrode re-sulting in counterbalancing magneticforces. The use of an external mag-netic field effectivelyundercut(b) eliminates slag

bead (a) avoidstie-ins,

entrapment, and(c) produces a more uniform thicknessof overlay.

The MAGLAY process was patented inboth Japan and Europe, and adopted as

Table I Comparison between submerged arc surfacing and electroslag surfacingwith stainless steel strip electrodes (6)

SAS ESS

Strip: dimension (mm) 60 x 0.5 60 x 0.5carbon content (%) 0.015 0.015

Parameters: I (A) 750 1250v (V) 26 24v (cm/min) 10 16

Current density (A/mm2) 25 41.7

Heat input (KJ/cm) 117 112.5(KJ/cm2) 19.5 18.7

Bead thickness (mm) 4.5 4.5

Dilution (%) 16 9

Deposition rate (Kg/h) 14 22

Flux consumption 0.65 0.5

Carbon content of single depositlayer (base metal: 0.18% C) 0.045 0.030

of magnetic devices (6). Their processis called "PZ" and is illustrated inFigure 4. The important feature of

strip electrode

Fig. 3 Mechanism for eliminatingundercutting by use of an

external magnetic field (5)

the classical method of strip ESS inEurope and in many other countries.The strip-feeding head made by Souda-metal (Belgium), which is now commer-cially available in the United States,employs a magnetic stirring devicesimilar to the NAGLAY design.

"PZ" Arc-Facilitating Process

Strip surfacing at the Japan SteelWorks also utilizes the electroslagmode of deposition but without the aid

Fig. 4 PZ welding operation using150 mm wide stainless steel

strip (6)

this process is that an arc is alwaysmaintained at the strip extremitieswhile most of the strip tip is still inthe electroslag mode. The auxiliaryarc facilitates bead tie-in and pene-tration, but avoids excessive dilutionat the center of the bead caused by theLorentz force. The 150 mm (6 in.) widestrips used in the "PZ" process providea uniform overlay surface and a lowdilution level in each bead.

"HS Process"

Kobe Steel Ltd. developed the highspeed overlay welding technique calledthe HS Process (High Speed Strip Over-lay Welding Process) which utilizes astrip that can be applied to an actualvessel even as a single layer process[10]. In terms of efficiency, the EStechnique is claimed to utilize only a75 mm (3 in.) wide electrode but com-petes attractively with the ordinaryESS process using a 150 mm (6 in.) wideelectrode.

The key points of this techniqueare a high travel speed and a forwardelectrode inclination angle. usuallywhen the electrode travel speed exceeds200 mm/min (7.8 in/min), the electricaltransfer through the slag pool shiftsfrom electroslag to submerged arc dueto an increase in slag resistivity withdecreasing slag superheating. Theinclination angle of electrodepermits molten metal to enter the gapbetween the base metal and electrodeand produces a buffer by preventingdeep penetration into the base metal,and reduces the dilution of the sur-facing layers.

INNOVATIONS IN THE SOVIET UNION

The ESS process is also widelyused in the Soviet Union and EasternEurope. A great amount of innovationswere frequently reported in their tech-nical journals. Although most articlesare often lacking technical details,their basic designs and functions couldstill be reviewed.

Multi-Strip Feeding

The Paton Welding Institutestarted studies on ESS with two elec-trode strips in the late 1970's. Thismethod was virtually unknown in theWest but was widely used in the SovietUnion and the Eastern European coun-tries (11-13). When two strips arearranged as in Figure 5, the moltenslag may rise between the two stripelectrodes and directly contact withair, causing considerable convectionalagitation. Thus, the distance betweentwo strips has become another importantparameter to be taken into account.

Fig. 5 Diagram illustrating depositionwith two strip electrodes: 1) parentmetal, 2) flux funnel, 3) flux feedguide: 4) strip electrodes, 5) feed

roller, 6) spool, 7) currentconducting jaws, 8) separator,9) flux, 10) deposited metal,

11) slag, and 12) power source (12)

ESS with more than two wire elec-trodes has also been reported by V.Melikov (14). As many as 15 stainlesssteel electrodes (all 3 mm [l/8 in.]diameter were simultaneouslydeposited over the entire width of theworkpiece in the downhand position withartificial cooling. The low-carbonsteel base plates were 70 mm (2.8 in.)thick, 500 mm (20 in.) long, and 340 mm(13.4 in.) wide.

A. Shyartser (15) claimed twohardfacing processes with a group ofplate electrodes. In one case, thehigh Mn steel electrodes were depositedon worn dredger buckets. In anothercase, the high Cr casting iron elec-trodes were deposited on worn steelblades, as shown in Figure 6. Theabsence of cracks and formation defectsmade it possible to greatly increase

Service durability of hardfacedcomponents and reduce the productioncost. For example, tests on the bladesshowed that their wear resistance wasvirtually identical to that of thoseblades hardfaced by brazing expensivealloys, whereas the cost of the formerwas almost a factor of 8 lower.

Plasma-Electroslag Deposition

A plasma-ESS method was reportedby A. F. Batakshev et al. (16) to de-posit high purity copper on low alloycarbon steels, as shown in Figure 7.The requirement of an auxiliary plasmais to counteract the high conductivityof the copper overlay.

Fig. 6 The hardfacing of buckets:the diagram of the process 1) compo-

nent, 2) electrode, 3) deposited metal,and 4) solidification mold (15)

Fig. 7 Technological diagram of theplasma-ESS method (16): 1) plasma,2) slag pool, 3) deposit, 4) basemetal, 5) shaping/cooling device,

6) filler metal, and 7) electrode ofplasma torch

In this process, the pilot arc isinitially ignited in the plasma torch,followed by ignition of the plasma arcbetween the workpiece and the electrodeof the plasma torch. A special flux isfed into the acting zone of the plasmajet. This flux contains elements withlow ionization potentials (Ca, Na, Be,etc.), which increase the stability ofthe plasma jet due to a decrease inelectrical resistance. The flux soonmelts and forms a slag pool. When thebase plate is heated to a sufficientlyhigh temperature, the copper fillermetal is fed into the slag pool, andthe plasma torch and the mold are movedat the same time, resulting in thesurface overlay.

The plasma ESS process provides ameans to control the time dependence ofheating the parent metal without theuse of consumable electrodes. It alsoprevents contamination of the depositedcopper. In a steady-state operationwith the optimum parameters of 450-500A/55-60V and a 30-40 mm (1.4-1.6in.) deep molten slag pool, the processcould produce a 2-3 mm (0.1 in.) thickand 15-20 mm (0.6-0.8 in.1 wide depositin a single pass. The deposits ofcopper are free from pores, cracks andinclusions end contain no Si, W, Mn,and other commonly found impurities.The strength of bonding in the deposi-ted metal is close to the strength ofcopper. The inventors (16) of thismethod claim that it could be used forrepairing casting defects and hard-facing the surfaces of cutting tools.

Surfacing of Shaped Parts

A variety of examples could befound in the Soviet technical journals,reporting the use of ESS for the res-toration of worn components havingcomplex shapes. The surfacing of thoseshaped parts is performed by a modifiedelectroslag welding process. A spe-cially designed water-cooled mold isused to confine the molten slag andmetal pool into the desired shape.Figure 8 illustrates the use of ashaped mold for surfacing the teeth ofexcavator buckets.

3

Fig. 8 Diagram illustrating the ESSof an excavator shovel tooth with

varying chemical composition metal:1) tooth blank, 2) standard head,3) consumable electrode, 4) mold

base, and 5) frame

As K. Valits indicated (17), torestore a complicated shape, the energy

of the melt must be sufficient to en-sure both the transfer of the melt tothe remote part of the mold end thecomplete fusion at that location. Hisexperimental results verified that anincrease in the voltage or the currentdensity improved the quality of thedeposited metal. However, when thecurrent density was excessive, the slagpool could be "thermally saturated".The thickness of the deposited layer nolonger increased, and the risk ofshort-circuiting was eminent.

For large-scale parts, the ESSoperations were reported lasting morethan 30 hours. To ensure a high qual-ity of the deposited layer, the processmust be stable and maintained withoutinterruption. Stepanov (18) pointedout that the non-uniform adhesion ofmolten metal and the presence of a slagskull in long term ESS could causerapid abrasive wear and local super-heating in the tail part of the shapedmold. , the inner surface of themold has to be made of materials withhigh thermal conductivity and also highresistance to the action of molten slagand metal pools. In this case, copperand its alloys do not ensure the re-quired thermal efficiency. He reportedan application using a damping heatconducting layer in the solidificationmolds. The inner contact surface ofthe mold was made of a less thermallyconductive alloy steel, followed by adamping heat conducting layer made ofpure copper, and finally by the water-cooled structural steel base. Thismethod provides proper control of thecooling rate of the deposited metal,and ensures a uniform temperature dis-tribution in the molds.

Surfacing of Thin-Walled Components

Multi-electrode surfacing usuallymakes it possible to deposit, in asingle pass, a layer of metal havingthe required thickness and width nearlyequal to that of the components. Al-though its use for thin-walled compo-nents risks the possibility of burningthrough, a report from the TashkentInstitute of Railway Transport Engi-neers claimed the development of asuccessful example for the ESS of thefriction wedge of the damper of wagonswhose maximum wall thickness was only 5to 6 mm (6 0.2 in.) (19), as shown inFigure 9.

In this process, nine electrodewires (each 3 mm [l/8 in.] in diameter)are deposited simultaneously, and an AC(not specified in that paper, but be-lieved) power source with a hard exter-nal characteristic is used. The mainparameters of this process include: 32volts, an electrode feed rate of 0.51m/hr (20 in/hr) and a surfacing speedof 1.8 m/hr (70 in/hr). A few factors

Fig. 9 Diagram of multi-electrodeESS of vertical surface of the friction

wedge of the damper of a wagon:1) axes of electrode, 2) slag pool,3) metal bath, 4) flux, 5) copper

shaping device, and 6) component (19)

are critical to prevent burn-throughdefects, including the slag pool depth,the electrode extension, end the sta-tionary (without longitudinal displace-ment) feeding time of electrodes in theinitial stage of surfacing for inducingthe slag pool and the final stage ofsurfacing for filling the crater. Byincreasing the initial stationary feedtime, the molten filler metal spreadahead of the electrode tip thermallyprotecting the base metal. A wear-resistant layer of 6-12 mm (0.24-0.47in.) thick and 135 x 180 mm (5.3 X 7in.) in size is reported being depos-ited in a single pass on the surface ofmild steel.

surfacing Layers With CompositionalGradients

In many cases of service, thedifferent portions of an individualhardfaced work piece experience differ-ent degrees of wear. The geometricalloss due to the uneven wear reduces itslife prematurely. The rational solu-tion to this problem is to make theworking surface from composite metal,whose wear resistance changes graduallyto accommodate the differences in theseverity of wear at different locationson the workpiece. By producing a partthat wears uniformly, the functionallife of the part is lengthened.

Shyartser (20,211 developed aspecial surfacing process to provide awear gradient for an excavator shovel,which is illustrated in Figure 8. Inservice, the abrasive wear on its rearface increased substantially from thetail end of a tooth to its apex. Inorder to extend its life, a prescribedvariation in chemical composition ofthe deposited metal was obtained bydepositing a special composite elec-trode which consisted of two dissimilarmetals meeting along an inclined plane(Figure 10). In this case, the

Fig. 10 Two composite electrodesdesigned to provide surfacing layerwith compositional gradient (20,211

electrodes consisted of a high Mn steeland a high chromium iron. A calcula-tion had to worked out for determiningthe combination ratio of electrodematerials to obtain an overlay with thedesired gradient in chemical composi-tion. As illustrated in Table II, thesurfacing deposits adjacent to thefront face of teeth were a wear-resistant Cr iron, changing (towardsthe rear face) into a high Mn steel.In service, those hardfaced teeth main-tained a consistent geometry (21).

Recently, Gulakov et al. (22)analyzed both the buffer effect of theweld pool and the element transfer fromthe base metal (or the previous depos-ited layer) on the final gradient ofthe chemical composition. They con-structed a model of the molten sur-facing pool and proposed ways of re-ducing the difference between the re-quired and actual compositional

variation. A programming device wasalso designed to facilitate the gra-dient method of surfacing (23).

PROCESS DETAILS

Equipment

The strip feed rates required forthe ESS process are within the rangeswhich characterize submerged arc wirewelding and strip SAS. The equipmentfor strip SAS is essentially the sameas that required for strip ESS (8),schematically illustrated in Figure 1.Thus, conventional DC constant voltagewelding machines. capable of 1200 ampsor more at 100% duty circle, can beeasily converted to ESS by attaching aspecial strip feeding head. A fewtypes of strip feeding heads are com-mercially available in European coun-tries. Oerlikon provides a popularstrip feeding head for strip electrodesin the width range of 50 to 125 mm (2to 5 in.), which is made by SoudometalCompany of Belgium.

The popular strip feeding head isbasically an improved MAGLAY processdevice originally developed by KawasakiSteel. The wheels and counterwheelsprovide pressure and guide the stripinto the feeding nozzle. Both thepressure and the gap are adjustable toallow variation in the thickness ofstrips. A pair of magnetic solenoidsare fitted along the sides of the stripfeeding nozzle. The magnetic intensityof the solenoids can be adjusted sepa-rately by a control box to ensure thedesired fluid flow characteristics ofthe overlay.

Direct current, constant voltage(DC-CV) power sources are recommendedfor ESS. Surfacing is always carriedout using reversed polarity (the strip

Table II Variation in Chemical Composition and Mechanical Properties of DepositedMetal from the Front to the Rear Faces of Teeth Shown in Figure 8 (23)

specimenNo.

Distance fromFront Facemm (in.)

10 (0.4)

30 (1.2)

50 (2.0)

70 (2.8)

90 (3.6)

110 (4.4)

Content of %Coefficient

of WearNi MO HRC Resistance

1.5 1.0 50 4.3

1.2 0.8 46 3.2

0.9 0.6 38 2.8

0.6 0.4 32 2.2

0.3 0.2 26 1.8

-- -- __ 1.3

electrode is connected to the positiveterminal of the power source) in orderto ensure adequate fusion to the basemetal. Since the optimal current den-sity for ESS is around 40 A/mm2, theoutput rate of power sources at a 100%duty cycle should meet the followingminimum load handling requirements:1250A for 60 x 0.5 mm (2.4 x 0.02 in.)strips: 1800A for 90 x 0.5 mm (3.5 x0.02 in.) strips; and 2400A for 120 x0.5 mm (4.7 x 0.02 in.) strips (8). Inpractice, such high current levels areusually obtained by connecting twopower sources in parallel.

Flux Chemistry

The flow of electrons in a sur-facing or welding process may takeplace either through an arc or moltenslag depending on the relative conduc-tivity of the medium through which theelectrons pass. In strip ESS, it isvery critical to establish stable ohmic(arcless) conduction of electricitythrough a shallow slag pool of onlyabout 20 mm (0.79 in.) depth. otherfactors which are essential in ESS arethe wettability of the slag, the beadprofile, the slag removal, the recoveryof alloying elements, and the reductionof gas generating components.

To maintain a stable electroslagmode through a shallow slag, a specialflux composition had to be developed.Such fluxes must provide greater elec-trical conductivity than would beneeded for normal electroslag weldingof the same plate material. Addinglarge quantities of fluorides, mainlyCaF2

and NaF and/or semiconductors,such as TiO2, and FeO, can greatly raisethe electracal conductivity of moltenslag without risk of generating arcs.However, large quantities of TiO2 inslag cause a deterioration in the de-tachability of the slag. Therefore,additions of fluorides are more prefer-able (8).

The level of electrical conductiv-ity of slag is closely related to thefluoride content in the flux, as illus-trated in Figure 11. The IIW (Inter-national Institute of Welding) DocumentXII-A-4-81 (24) described the effect ofcalcium and sodium fluoride additionson the electrical conductivity of the3CaO-3SiO 2-Al2O3 ternary system, endindicated that when the fluorides wereless than 40% (balance ternary), thesubmerged-arc mode prevailed: and whenmore than 50% fluorides, the electro-slag mode prevailed. In terms of theelectrical conductivity of the slag,this corresponded to a transition rangeof 2 to 3 n-1 cm-1. Above 3 n-l 1cm- ,a stable electroslag mode is easilyachieved. However, to restrict thegeneration of fluoride type gases (dueto a reaction: 2CaF2 + SiO2 + 2CaO +

TransitionA r c Slag

= 3 : 3 : 1

20 40 60 80 100

Fluoride content (%)

Fig. 11 Effect of fluoride content influx on electrical conductivity and

current conduction type duringStrip ESS (24)

SiFt4), additions of CaF2 were usuallyheld at slightly less than 50%.

In Japan, fluxes for stainlesssteel overlays are principally suppliedby Kawasaki Steel and Kobe Steel (6).The Kawasaki XFS-150 is a fused fluxwith an electrical conductivity ofabout 3 n-l cm-' at 17000C. It waspatented in the United States in 1984(25). The composition of Kawasaki'spatented flux contains 50-60% CaF2,l0-20% SiO2, 5-25% CaO and l0-30% Al2O3

in a ratio of SiO2/CaF2 of et least0.20 and a ratio of CaO/SiO2 of atleast 0.50.

In the Soviet Union, a series offluxes were developed for ESS. The ANFseries fluxes are of high fluoridecontents (> 50%) and high electricalconductivities (26). The AN-seriesfluxes, which were originally used inESW, are also used for the thick layerbuild-up. Their fluoride contents arebelow 25% and electrical conductivitiesare comparatively low (26). Some newfluxes were occasionally reported being

11A-9

developed for certain special ESS proc-esses (27). however, no concrete com-positional information was presented.

In Western Europe, fluxes EST 122and 201 are commonly used [8]. Somecharacteristic data of these two ag-glomerated fluxes are given in TableIII. The flux EST 122 is specificallydesigned to be used for the depositionsof all types of 300 and 400 seriesstainless steel strips. The flux EST201 is designed for the deposition ofthe Ni-base alloys, such as 825, 600,625 and 400 (7).

In the United States. the commer-cially available fluxes for ESS can beordered through Sandvik Steel or Oerli-kon, which are basically very close tothose available in the European market.The Sandvik 375 welding flux is a uni-versal flux for ESS (Table III). I t selectric conductivity is 5 to 6 timesgreater than an ordinary submerged arcwelding flux. It can be used to de-posit corrosion-resistant claddingusing 300 and 400 series stainlesssteel strip electrodes and certainhardfacing electrodes. Fluxes suitablefor depositing nickel-base alloys arealso available in the Sandvik series17).

In a recent study (28) of ESS withstainless steel wire electrodes, fluxesof the CaF2-CaO-Al 3O3 system were stud-

. It was noticed that at higherCaF2 percentages, (i.e. beyond 70%),the process was once again that of arcconduction. As the percentage of theCaF2 in the flux increased, there was acorresponding increase in the conduc-tivity level. This, in effect, raisedthe current at the same wire feedspeed, and gave rise to burn back prob-lems . Hence, at higher CaF2 percen-tages, arcing could be visible on thesurface of the molten slag. On the

other hand,served

below 40% CaF2,arcing

the ob-was

submerged-arc type as illustrated inFigure 12.

Fig. 12 Effect of CaF2 content in fluxon electrical conductivity and currentconduction mode during wire ESS (28)

Usually, CaO, SiO2 and Al2O 3 arecommon additions for optimizing theconductivity level of a CaF2-basedflux. The practice at the Oregon Grad-uate Center (28) indicated that opti-mizing the viscosity level of moltenflux is of the same importance. Sinceconductivity and viscosity have aninverse relationship, adjusting theflux composition becomes a complexproblem. SiO2 is one compound whichhas a major influence on slay viscosityand slag flow (25). TO maintain thedesired viscosity, it is necessary tocontrol a SiO2/CaF2 ratio of at least0.2 and to avoid evolution of toxicgases like SiF4 by the reaction:

Table III Fluxes Available From European Sources (7,8)

content

(%) Alkaline & alkaline earthoxides (Ca0, MgO, K20, Na20)

(5) Amhoteric & alkaline earthoxides (A1 20 3, Ti02, Zr0 2)

(%) Silicon dioxide (Sio2)

(%) Fluorides (expressed in F)

Flux density (kg/dm3)

Flux consumption rate(kg flux/kg strip)

EST 122 EST 201

50 50

25 25

10 max 5 max

30 25

0.85 0.85

0.5 0.5

Sandvik 37S

50

25

10

30

0.85

2CaF2 + Si02 = 2CaO + SiF4

In addition, es specified by the Kawa-saki patent (25), the minimum reguire-ment.for CaO/SiO2 ratio should be about0.5 for stable ESS (Figure 13).

45 50 55 60 65

Caf2 (%)

Fig. 13 Effect of CaF2 and SiO2

content on slay viscosity andprocess stability (25)

Fluxes can be either bonded orfused. The particle size of fluxes isgenerally controlled to 18/60 mesh,being smaller for SAS than for ESS (7).Because all fluxes are prone to mois-ture pick-up, they should be baked et250-35O'C (480-6600F) before using andheld warm in the production area.Kawasaki claims that the ESS process ismore tolerant of moisture pick up inthe flux than the SAS process (6).However, the studies (28) have foundthat baking is necessary fof the bondedfluxes because of their strong tendencyto absorb moisture. Moisture in theflux induces porosity in the overlay.and this is especially severe when thealloy of the strip has a narrow temper-ature gap between its liguidus andsolidus.

Strip Electrode Sizes

The thickness of the strip elec-trode is always expected to be thinenough to facilitate coiling intorolls, in order to conveniently feedcladding during ESS. The Japaneseappear to have standardized the 0.4 mm(0.016 in.) thickness for all stripwidths. This differs from the Europeanpractice where a 0.5 mm (0.02 in.)thickness is most common.

The ESS process favors the "se ofwide strip as long as the capacity ofthe power supply is adequate to provide1000-2000 amps, typically. That isbecause, at a given layer thickness,the most marked effect of increasingthe strip width is a decrease in dilu-tion and penetration. Usually, thepenetration of overlay deposits isalways more accentuated et the sides ofthe bead. However, the relative impor-tance of this localized higher penetra-tion is lessened when (a) the stripwidth is increased, and (b) bead over-

mon in Japan; while widths of 60 mm(2.4 in.), 90 mm (3.5 in.), and 120 mm(4.8 in.) are more popular in Europe.In the U.S., through Sandvik Steel (7),a variety of strip electrodes areavailable commercially for ESS.

Voltage

Voltage is perhaps the most crit-ical controlling parameter in the ESSprocess. In most ESS practice, theworking range of voltage values isquite narrow, because of the shallowdepth of the molten slay pool (5-10 mm[O-2-0.4 in]). Forsburg (7) reportedthat, for a fluoride-based flux, thestable range is usually 26-28 volts.When the voltage is below 24 volts, itis difficult to initiate the process,and the strip tends to stick to thebase metal resulting in short circuit-ing. On the other hand, above 28volts, the process starts arcing on thesurface of the flux, and slag spatterbecomes violent. Therefore, an accu-rate control in voltage is extremelyimportant. Practices et the OregonGraduate Center (28) found that theoptimum voltage was closely related tothe actual depth of the molten slaypool, and a stable ESS process could beperformed et 22-24 volts. In addition,it was also shown (28) that en inten-tionally increased open-circuit voltageis beneficial to the initiation of ESS.

Even within the stable voltagerange, fluctuations in voltage alsoaffect the dilution, penetration endgeometry of the surfacing layer asshown in Figure 14.voltage,

By increasingthe rising heat input in-

creases the volume Of base metalmelted, thereby increasing the level ofpenetration and altering the geometry(width/thickness) of overlays. Never-theless, the dilution level still re-mains essentially constant orslightly decreases with

only

voltage.increasing

Current

ESS has been reportedly used onlywith DC reverse polarity (electrode

Fig. 14 Influence of voltage for stripelectrode, size 60 x 0.5 mm at 1250A

surfacing current and 150 mm/mintravel speed (7)

positive). DC straight polarity re-sults in an unstable operation at thenormal working current density range forESS, which is approximately twice thatfor the SAS process.

At a given voltage and surfacingspeed, variations in the ESS currentdirectly affects penetration, beadwidth and thickness, as shown in Figure15. The dilution of surfacing layersis the result of two factors--the pene-tration into the base metal, and thethickness and width of the beads.Hence, the combined effects of bothfactors cancel each other, resulting inlittle change in the dilution.

Stable and quiet welding condi-tions can be achieved within a givenrange of ESS current. The optimumcurrent density for strip ESS is around40-45 A/mm2 (26-29 kA/ina2). At thehigher values of current density, theamount of slay spatter increases andthe depth of the slay pool has to beraised to stablize the operation.

Travel Speed

At a given welding current andvoltage, increasing the travel speed

Fig. 15 Influence of current for stripelectrode size 60 x 0.5 mm at 26V and

150 mm/min travel speed (7)

tends to increase dilution and penetra-tion, while decreasing bead width andthickness, as shown in Figure 16. In-creasing the travel speed in effectreduces the heat input and, thereby,decreases the electrical conductivityOf slag. The ESS process can only bestable when sufficient contact areabetween the molten slay pool and themelting strip is maintained. An ex-cessively fast surfacing speed maycause the strip to be in contact withcold flux or insufficiently heatedslag, thus resulting in sporadic arcingand process instability.

In general, the travel speedshould be optimized for both economy(fast speed) and an adequate thicknessof surfacing layer (about 4-6 mm [z 0.2in.]) (81. Excessive travel speedresults in not only a bead thicknessless than 4 mm, but also in the risk ofthe formation of undercutting. On theother hand, too slow a travel speedresults in a bead thickness above 6 mm.Then, the wetting angles of beads be-come too steep and slay entrapment mayoccur at the overlaps. In general, theoptimum travel speed range is about160-200 mm/min (6-8 in/min), whichresults in about a 10% dilution level,

Fig. 16 Influence of travel speed forstrip electrode 60 x 0.5 mm at

1250A and 26V (7)

and consumes about 0.15 kJ/mm2 (96kJ/in 2) heat input (28).

Other ESS Parameters

The strip extension, i.e. theconventionally called "stick-cut" (thefree length of the strip extending fromthe contact jaws to the slag pool), isnot critical in this process. Usuallyit may vary from 25-40 mm (1-1.5 mm)(7). However, the greater the stripextension, the greater will be thedeposition rate for a given setting asin normal welding operations due toohmic heating of the filler strip.

The depth of flux burden shouldjust cover the strip extension or up to5 mm over the extension length. Typi-cal flux depth ranges from 30-45 mm(1.2-1.8 in) (7). If the flux is tooshallow, arcing develops as the slagdepth is less than the arc gap" for thegiven voltage and conduction throughthe slay is "open-circuited".

The limitation of parent metalthickness depends on the heat inputduring ESS and the width of stripsused. Forsburg (7) reported that inorder to ensure sound ESS with a 60 x0.5 mm (2.4 x 0.02 in) strip, the

minimum parent metal thickness is 40 mm(1.6 in.). The minimum diameter ofcurved surface for ESS with the 60 x0.5 mm strip electrodes is 250 mm (10in.) for external surfacing, and 450 mm(18 in.) for internal surfacing. Thisis ideally suited for the rebuilding ofship propeller shafts. Practices atthe Oregon Graduate Center (28) havefound the above limitation was rela-tively conservative. For example, witha 60 x 0.5 mm strip, ESS could be per-formed on 25 mm (1 in.) thick plates.

QUALITY CONTROL

Stability of Process

Although economically desirable,the major problem associated with usinga faster surfacing speed is the stabil-ity of the process. If the surfacingspeed is excessive, the slag pool be-comes cold and erratic submerged arcingwill occur.

One possible way to avoid thistrouble is to judiciously select anangle of inclination (downhill) for thebase plate. This causes the moltenslag and metal pool to flow slightlyahead of the strip, thus ensuring thatthe strip is in appreciable contactwith the molten pool in spite of anincrease in the surfacing speed.

The inclination angle of the par-ent metal also affects the dilutionlevel of surfacing layers, as shown inFigure 17. It has been recognized thatthe downhill position slightly favors adecrease in dilution, which is some-times important for the quality ofmicrostructure of single pass deposits.

As mentioned above, the currentand voltage of the ESS process can onlyvary within a narrow range. Maintain-ing optimum power parameters is verycritical in order to continue a stablesurfacing process. If disturbances incurrent or voltage can be monitored andrecorded, a coefficient of stabilitycould be used for quantitative deter-mination, which has been used in theSoviet Union since 1962 (11,29).

The electrode inclination anglealso influences the dilution, the widthof bead and the thickness of overlay(7,8,10), as illustrated in Figures 18,19 and 20. A greater electrode inclin-ation angle (forehand) results in de-creased dilution, wider bead and re-duced thickness. In fact, the Japanese"HS" process (mentioned in the previouschapter) is based on this principle.When attempting to increase the sur-facing speed for better economy, thisgeometrical parameter becomes extremelyimportant. At aangle,

greater electrodeslag is pushed ahead of the

electrode. Hence, care must be taken

11A-13

heat affected zone of the parentmetal are stressed in high ten-sion, whereas the parent metal incontact with the overlay is incompression (Figure 21). A goodexample of this case is the clad-ding of mild steels with acorrosion-resistant stainlesssteel coating.

Fig. 21 Stresses in a component of lowcarbon steel surfaced with a soft

alloy (30)

12) Surfacing a mild steel with ahardenablestates are just oppof case 1,

osite to thoseas shown in Figure 22.

Here the surfacing layer is incompression while the base metalis in a tensile state of stress.This situation is common for somehardfaced parts.

Fig. 22 Stresses in a component ofmild steel surfaced with hardenable

material (30)

(3) Surfacing a hardenable steel withan austenitic alloy. The stressstates can become very complicated(Figure 23). The surfacing layeris subjected to tensile state ofstress. The hardened part of theheat affected zone is subjected togreater compressive stress. Belowthis hardened layer in the heataffected zone, tensile stresses

11A-15

appear to be enhanced. In thepart of parent metal farthest awayfrom the surface overlay, thestress state becomes compressiveonce again.

Fig. 23 Stresses in a camponent ofhardenable steel surfaced with an

austenitic alloy (30)

Blaskovic (13) reported measure-ments of stress in the ESS layers de-posited by the dual strip method. Itwas show" that annealing (620°C/20hr +650°C/10hr) eliminated the stress peak,but a tensile stress zone still re-mained.

The actual values Of stressesdepends on a variety of factors. Amongthem are the surfacing procedure, theconsideration of the intermediate layerand the stress state of surfaced partsin service. TO minimize the harmfulresidual stresses in surfaced workpieces, the following are recommended:

11) The proper selection of both thebase metal and the filler stripmaterials to provide satifdactorymetallurgical bonding and thedesired chemical and mechanicalproperties;

(2) The selection of process param-eters, such as the travel speed,the heat input, and the number ofpasses to produce the requireddilution, penetration and beadshape;

(3) The possible application of anintermediate layer with transitionchemical composition and proper-ties having the strength and ther-mal expansion properties to bufferthe undesirable metallurgicalproperties of a direct bond be-tween filler metal and parentmetal;

(4) The cost-effective "se of preheat-ing for the parent metal only whennecessary.

Disbanding Problem

Since the surfacing process mayinvolve depositing a layer of materialhaving different chemical compositionand mechanical properties (particularlythe thermal expansion coefficient) thanthose of the parent metal, bondingstrength between the overlay and thesubstrate becomes an important metal-lurgical consideration. This can becritical when surfaced parts are de-signed for special environments, suchas elevated temperature or high hydro-gen pressure.

For example, consider the surfac-ing of steel with the corrosion-resistant austenitic stainless steel.Depending on the ratio of thedeposited layer, a dual effect is no-ticed:

(1) Austenite grains may coarsen atthe fusion zone between depositedmetal and the base metal. Thiscoarse grained austenitic struc-ture, being lower in strength, issusceptible to disbonding. Fur-thermore, for applications insevere chemical or nuclear en-vironments, diffusion of hydrogento the grain boundaries also pro-duces a weakening of the fusionzone structure, which once againleads to disbonding (31). Toavoid this, it is desirable tolimit the austenitic grain coars-ening to 0.5%. The coarse grainpercentage is defined as thelength of the austenite grainboundary, which is parallel to thefusion boundary, divided by thelength of the fusion boundary. Toachieve this, a ratio ofat least 1.85 is used, accordingto the Kawasaki Steel Europeanpatent, as shown in Figure 24 (31)

Fig. 24 Effect of ratio oncoarse grain percentage (31)

(2) The percentage of delta ferritepresent in the fusion zone is afunction of the ratio.Although, the presence of deltaferrite has a beneficial effect ofpreventing both hot cracking andprecipitation of grain boundarycarbides, it can also transforminto the sigma phase at 500°C orabove. The presence of the sigmaphase leads to disbonding, aswell. Thus, the acceptable levelof the delta ferrite content isabout 8 to lO%, and this is onceagain achieved by maintaining aCr/Ni equivalent ratio of at least1.85, as predicted by the standardSchaeffler diagram (31).

I" Japan, a number of researchprojects were devoted to hydrogen-induced disbonding susceptibility inpressure vessels made of 2-1/4Cr-1Mosteel with an austenitic stainlesssteel overlay deposited by strip ESS.Tanaka 110) claimed that the Kobe SteelLtd. HS process could improve the dis-bonding problem. This improved dis-bonding resistance was attained by agreater cooling rate and much finergrains near the interfaces. The HSprocess inhibited the development ofcoarser grains in the heat affectedzone of the base metal, and might beeffective in the prevention of under-clad cracking or cold cracking. TheJapan Steel Works long-term studies(32-35) considered that the surfacingparameters hardly affected the disbond-ing resistance of surfaced parts. Forexample, austenitic/martensiticduplex structure provided the overlaylayer with good disbonding resistance,which was obtained by modulating theprocess in a manner similar to the KobeSteel "HS" process. They claimed theresidual stress in the through-thickness direction at the bond betweenthe first layer deposit and the basemetal was smaller than that of theconventional ESS. The low residualstress provided an ESS technique thatcould produce overlays with good dis-bonding resistance.

APPLICATIONS OF STRIP ESS

Presently, strip ESS is entirelyforeign technology, which has furtherwidened the construction cost gap be-tween the Asianshipbuilders.

shipyards and U.S.However, utilization of

this foreign technology and the sub-stantial improvements in strip ESSanticipated at the Oregon GraduateCenter will enhance the economic posi-tion of U.S. shipyards to rebuild worn,eroded or redesigned structural shipcomponents, such as large propellershafts, rudder horns, strut shafts,deeply corroded portions of the hull,hawse pipes and leading edges of ruddercastings.

This process, though fully auto-matic, is also portable in the shipyardwhen a conventional land inexpensive)carriage system is used to mobilize thestrip ESS system in remote locations.A typical carriage system can handle1500 amps and can pull power cables 30m (100 ft.) long while being eithertrack or manually guided. These car-riage systems have been commerciallymanufactured in the United States formany years for Submerged arc weldingapplications, particularly in ship-yards.

CONCLUSIONS

Based on a computerized search ofthe international technical journals onthe subject of electroslag surfacing, acritical review was performed and thefollowing can be concluded:

1. ESS with strip electrodes is themost economical and productivemethod to overlay a wide varietyof corrosion and/or wear resistantdeposits on Structural ship com-ponents, such as propeller shafts.

2. The highest deposition rates com-bined with the lowest base metaldilution are characteristic of ESSwith strip electrodes compared toconventional surfacing methods,such es strip SAS, GMAW and SMAW.

3. The dominant thick-section surfac-ing process in Japan, the SovietUnion and several European coun-tries is ESS.

4. Neither U.S. shipyards nor U.S.manufacturing industries haveadopted the ESS process. Conven-tional surfacing methods are stillutilized in the U.S.

5. Technically, the key differencebetween the newly-developed ESSprocess and other similar pro-cesses, such as SAS and ESW, isthe flux chemistry.

ACKNOWLEDGMENT

The authors are grateful to theU.S. National Coastal Research Insti-tute for financial support under Con-tract 51-01-38RO-D. The authors alsowish to thank Mr. Sin-Jang Chen and Mr.subhayu se" for their contributions inthis work.

1. P. A. Milne, "High Technology inShipbuilding", Proc. Inst. OfMech, Engrs., Vol. 201, No. B2.1987, pp 59-72.

2. L. M. Thorell and T. Watanabe,"Technical Collaboration BetweenMitsubishi Heavy Industries andTodd Shipyards", in the Proceed-ings of the National ShipbuildingResearch Program, 1986 Ship Pro-duction Symposium, Paper No. 5,

Sponsored by SNAMS Ship ProductionCommittee, 1986.

3. T. S. Upham and W. M. Crawford,"Decentralization--The ManagementKey to Effective Accuracy Con-trol", in the Proceedings of theNational Shipbuilding ResearchProgram 1986 Ship Production Sym-posium, Paper NO. 4, Sponsored bySNAME Ship Production Committee,1986.

4. "600 Ship Navy Won't be Sus-tained", Marine Log. January,1988, pp 49-51.

5. S. Nakano, N. Nishiyama, T. Biroand J. Tsuboi, "Maglay Process-Electro-Magnetic Controlled Over-lay Welding Process with ESW',Kawasaki Steel Technical Report,No.2, March (1981), p 31.

6. "Welding Technology in Japan",Welding Research Council, N.Y.,(1982), p 16-22.

7. S. Forsburg, “Resistance Electro-slag RES) surfacing", WeldingJournal, August 1985, p 41.

8. "Electroslag Strip Cladding"--Adraft, Oerlikon Industries,(1985).

9. V. Pilous and R. Xovarik, "Experi-mental Determination of The Metal-lurgical and Technological Parem-eters in Surfacing with AusteniticStrip Electrodes', Welding Inter-national, No.1, (1987), p 84.

10. 0. Tanaka, K. Takeba and Y. Matsu-shita, "High Speed Overlay WeldingWith Strip Electrodes", StainlessSteel, Nov., (1985). p 58.

11. V. Mastenko, E. Starchenko and V.Khodakov, "Stability of The Elec-troslag Process in Two ElectrodeStrip Surfacing", Welding Produc-tion, March, (1982), p 23.

12. v. Mastenko and E. Starchenko,"Effects of Variation in WeldingParameters on Weld Surfacing WithTwo Strip Electrodes", AutomaticWelding, July 1984, p 50.

13. P. Blaskovic, S. Lesnak and J.Zajac, "Electroslag Surfacing inthe Horizontal Position Using TWOStrip Electrodes', Surfacing J.Int. 1. (2). (1986), pp 75-78.

1lA-17

14. V. Melikov, E. Sheinman and M.Brodyanski, "Special Features ofthe Multielectrode Wide-LayerDeposition of Austenitic Layers onLow-carbon Steel", Welding Produc-tion, Feb. 1982, p 7.

15. A. Shvartser, "The ESS of Compo-nents With a Group of Electrodes",Welding Production, Jan. 1981, p27.

16. A. Batakshev, S. Berezhnitskii, A.Lamzin and 0. Steklov, "Plasma-electroslag Deposition of Copper

Steel", WeldingJuly 1984, p 17.

Production,

17. X. Valits, A. Shvartser, V. Dorok-hov and B. Matveev, "The Effect ofthe Conditions of ESS of the Qual-ity of the Deposited Layer", Weld-ing Production, May 1981, p 26.

18. B. Stepanov, V. Yakovlev, G.Surovtsev and I. Izyur'ev, “Usinga Damping Heat Conducting Layer inSolidification Moulds for Electro-slag Surfacing", Welding Produc-tion, May 1984, p 39.

19. E. Ashkinazi and E. Sheinmass.“Factors Affecting the Quality ofBonding in Wide-Layer Surfacing ofThin-Walled Components", WeldingProduction. Feb. 1986, p 24.

20. A. Shavartser, V. Shvarts andNikitenko, "Calculating the

-Amounts of Components in a VaryingChemical Composition Alloy DuringElectroslag Surfacing", AutomaticWelding, Feb. 1980, p 17.

21. A. Shvartser, V. Stoiko, Z. Niki-tenko and I. Morgachev, "ExcavatorShovel Teeth Reconditioned bySurfacing with Varying CompositionMetal", Automatic Welding, March1985, p 43.

22. S. Gulakov and B. Nosovskii "Spe-cial Features of Production ofWelded Joints with Regulated Dis-tribution of Chemical ElementsAlong The Length", Welding Produc-tion, July 1982, p 8.

23. S. Gulakov and B. Nosovskii, "APrograming Device for Depositing aLayer of Metal with a VaryingChemical Composition", WeldingProduction, July 1985, p 52.

24. S. Nakano, T. Hiro, N. Nishiyamaand J. Tsuboi, "The New StripEleotroslag Overlay Technique withElectra-Magnetic Control--TheMaglay", IIW Document, XII-A-4-81,(1981).

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

J. Tatershi, T. Ishikawa, S. Nakanoend N. Nishiyama, United StatesPatent 4,437,406, (1984).

B. paton, (ed.), "ElectroslagWelding 6 Surfacing", Vol.1, MIRPublishers, Moscow, (1983), p 172.

K. Valits, A. Shvartser and V.Stoiko, "A Flux For ElectroslagHardfacing of High-ManganeseSteel", Adv. Spec. Electrometall.,Vol. 1, No. 4. (1985), pp 162-165.

D. Yu and J. Devletian, Unpub-lished research, Oregon GraduateCenter, (1987).

E. Starchenko and V. Msatenko, "AProcedure for Determining theStability of the Electroslag Proc-ess in Mechanised Surfacing WithElectrode Strip and Flux", Auto.Weld., May 1982, p 49.

S. Babiak, "Stress and Deforma-tions During Surfacing", SurfacingJournal, Vol. 16 (4),(1985), P

Kawasaki Steel, European PatentApplication 114 893 Al, publ: Aug.

K. Ohnish, A. Fuji, R. Chiba, T.Adachi, K. Naitoh and H. Okada,"Study on a Stainless steel Over-lay Welding Process for SuperiorResistance to Disbonding (Report

of Jap. Weld. Soc.,vol. 15 (2), (1984), p 49.

A. Fuji, E. Kudo, T. Takahashi andK. Mano, "Study on a StainlessSteel Overlay Welding Process forSuperior Resistance to Disbonding(Report 2)". Trans. of Jap. Weld.Soc., Vol. 17 (1), (1985), p 27.

A. Fuji, E. Kudo, T. Takahashi,"Study on a Stainless Steel Over-lay Welding Process for SuperiorResistance to Disbonding (Report3)", Trans. of Jap. Weld. Soc.,vol. 17 (2), (1986), p 145.

A. Fuji, E. Kudo and T. Takahashi,"Study on Stainless Steel OverlayWelding Process for Superior Re-sistance to Disbonding (Report

of Jap. Weld. Soc.,Vol. 18 (1), (1987), p 19.

A. Yan Bemst and P. Dargent,"Electroslag Strip Cladding withNickel Alloys”, Proceedings ofConference on Coating by WeldingProcesses,1983, ISBN 3-87155-!-%7,

Germany,pp 53-

56.

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