Texto_welding of Tool Steel_uddeholm

Welding of tool steel

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ContentIntroduction ............................................ 3

General information onwelding of tool steel ............................... 3

Welding methods for tool steel .............. 4

The welding bay ..................................... 5

Filler-metal characteristics ...................... 6

Be careful as regards hydrogen! ............. 8

Elevated working temperature ............... 10

Welding procedure ................................. 11

Weld repair of– hot work tool steel .............................. 13– plastic mould steel .............................. 14– cold work tool steel ............................. 15

This information is based on present state of knowledge and isintended to provide general notes on our products and theiruses. It should not therefore be construed as a warranty ofspecific properties of the products described or a warranty forfitness for a particular purpose.


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IntroductionThe weldability of steels with more than0,2% carbon is usually considered to bepoor. Hence, tool steels with 0,3–2,5%carbon are difficult to weld and manysteel suppliers will actually recommendagainst welding. However, improvedquality of consumables, refined weldingequipment, developments in weldingtechnique and, not least, improvementsin tool steel quality have combined torender tool welding as a realistic possi-bility, which can have considerableeconomic consequences.

Hence, Uddeholm recognizes thattool steels often need to be welded; thisis especially true for expensive toolinglike die-casting dies, large forging dies,plastic moulds, carbody dies and blank-ing tools where repair and adjustmentvia welding is highly cost-attractive incomparison with the expense of produc-ing new tooling.

General informa-tion on welding oftool steelTool steels contain 0,3–2,5% carbon aswell as alloying elements such asmanganese, chromium, molybdenum,tungsten, vanadium and nickel. Themain problem in welding tool steelstems from its high hardenability. Weldscool quickly once the heat source isremoved and the weld metal and partof the heat-affected zone will harden.This transformation generates stressesbecause the weld is normally highlyconstrained, with a concomitant risk forcracking unless great care is exercised.

In what follows, a description isgiven of the welding equipment, weld-ing technique and weld consumablesthat are required in order to weld toolsteel successfully. Of course, the skilland experience of the welder is also a

The welding bay.

vital ingredient in obtaining satisfactoryresults. With sufficient care, it is possibleto achieve weld repairs or adjustmentswhich, in terms of tooling performance,are hardly inferior to that of the basesteel.

Welding of tooling may be requiredfor anyone of the following reasons:• Refurbishment and repair of cracked

or worn tooling• Renovation of chipped or worn

cutting edges, e.g. on blanking tools• Adjustment of machining errors in

tool making• Design changes.


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Welding methodsfor tool steelSHIELDED METAL-ARC WELDING(SMAW OR MMA)

Principle

An electric arc generated by a DC or ACpower source is struck between acoated, rod-like electrode and the work-piece (Fig. 1).

The electrodes consist of a centralwire core, which is usually low-carbonsteel, covered with a coating of pressedpowder (flux). The constitution of thiscoating is complex and consists of ironpowder, powdered ferro-alloys, slagformers and a suitable binder. The elec-trode is consumed under the action ofthe arc during welding and drops ofmolten metal are transferred to theworkpiece. Contamination by air duringthe transfer of molten drops from elec-trode to workpiece and during solidifi-cation and cooling of the weld depositis inhibited partly by slag formed fromconstituents in the electrode coatingand partly by gases created duringmelting of the electrode.

The composition of the depositedweld metal is controlled via the consti-tution of the electrode coating.

GAS TUNGSTEN-ARC WELDING(GTAW OR TIG)

Principle

In MMA welding, the electrode rod fromwhich the arc is struck is consumedduring welding.

The electrode in TIG welding is madeof tungsten or tungsten alloy which hasa very high melting point (about3300°C/6000°F) and is therefore notconsumed during the process (Fig. 2).The arc is initially struck by subjectingthe electrode-workpiece gas to a high-frequency voltage. The resulting ioniza-

tion permits striking without the neces-sity for contact between electrode andworkpiece. The tungsten electrode isalways connected to the negative ter-minal of a DC power source becausethis minimizes heat generation andthereby any risk of melting the elec-trode. Current is conducted to the elec-trode via a contact inside the TIG-gun.Any consumables which are requiredduring TIG-welding are fed obliquelyinto the arc in the form of rod or wire.Oxidation of the weld pool is preventedby an inert-gas shroud which streamsfrom the TIG tun over the electrode andweld.

Power source

TIG welding can be performed with aregular MMA power source providedthis is complemented with a TIG controlunit. The gun should be water cooledand be capable of handling a minimumcurrent of 250 A at 100% intermittence.A gas lens is also a desirable feature inorder that the inert gas protection is asefficient as possible. Welding is facili-tated if the current can be increasedsteplessly from zero to the optimumlevel.

Power source

For MMA welding, it is possible to useeither an AC or DC power source.However, whichever is used, the sourcemust provide a voltage and currentwhich is compatible with the electrode.Normal arc voltages are:• Normal recovery electrodes: 20–30 V• High recovery electrodes: 30–50 V

Uddeholm welding consumables areof normal-recovery type. A suitablepower source for these is a DC unit withan open voltage of 70 V and which iscapable of delivering 250A/30 V at 35%intermittence.

METHODSManual Metal-arc welding (MMA)

Welding conv.Welding rectifier

Electrode

Electrode holderPower source

+Pole

– Pole

Fig. 1

Weld

Filler rod

+ Pole

– Pole

Weldingrect.

METHODSTIG-Welding

Workpiece

Shielding gas

Shielding gas

Fig. 2

Workpiece

Workpiece Weld

Slag

Molten pool

Welding torch

Tungstenelectrode Power supply

Cooling water


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PREHEATING EQUIPMENT

Tool steels cannot be welded at roomtemperature without considerable riskfor cracking and it is generally neces-sary to pre-heat the mould or die beforeany welding can be attempted (seelater). While it is certainly possible toweld tools successfully by preheating ina furnace, the chances are that thetemperature will fall excessively prior tocompletion of the work. Hence, it isrecommended that the tool be main-tained at the correct temperature usingan electrical heating box supplied froma current-regulated DC source. Thisequipment also enables the tool to beheated at a uniform and controlled rate.

For minor repairs and adjustments, itis acceptable that the tool be preheatedusing a propane torch. Hence, liquidpropane cylinders should be available inthe welding bay.

Electrical elements foran insulated preheating box.

GRINDING MACHINES

The following should be available:• Disc grinder with minimum 180 Ø x

6 mm wheel (7 Ø x 0,25 inch) forpreparing the joint and grinding outof any defects which may occurduring welding.

• Flat grinder capable of ≥25 000 rpmfor grinding of minor defects and ofthe finished weld.

• If a welded mould is subsequently tobe polished or photo-etched, it maybe necessary to have a grinder capa-ble of giving a sufficiently fine finish.

The welding bayIn order to be able to effect satisfactorywelding work on tool steel, the follow-ing items of equipment are to be re-garded as minimum requirements (overand above the welding equipment).

DRY CABINET

The coated electrodes used for MMAwelding are strongly hygroscopic andshould not be allowed to come intocontact with anything other than dry air.Otherwise, the weld will be contami-nated with hydrogen (see later). Hence,the welding bay should be equippedwith a dry cabinet for storage of elec-trodes. This should be thermostaticallycontrolled in the range 50–150°C (120–300°F). The electrodes should be re-moved from their containers and lieloose on racks.

For welding of tooling outside thewelding bay, it will also be found usefulto have a portable heated container inwhich the electrodes can be carried.

Dry cabinet for storage of electrodes.

WORKBENCH

It is particularly important during criticalwelding operations, of the type per-formed with tool steel, that the welderenjoys a comfortable working position.Hence, the workbench should be stable,of the correct height a sufficiently levelthat the work can be positioned se-curely and accurately. It is advantageousif the workbench is rotatable and ad-justable vertically, since both thesefeatures facilitate the welding opera-tion.


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Filler-metalcharacteristicsThe chemical composition of a welddeposit is determined by the composi-tion of the consumable (filler metal), thebase steel composition and the extentto which the base material is meltedduring welding. The consumableelectrode or wire should mix easily withthe molten base steel giving a depositwith:• Uniform composition, hardness and

response to heat-treatment• Freedom from non-metallic inclusions,

porosity or cracks• Suitable properties for the tooling

application in question.

Since tool steel welds have highhardness, they are particularly suscepti-ble to cracking which may originate atslag particles or pores. Hence, theconsumable used should be capable ofproducing a high-quality weld. In asimilar vein, it is necessary that theconsumables be produced with verytight analysis control in order that thehardness as welded and the response toheat treatment is reproducible frombatch to batch. High-quality filler metals

are also essential if a mould is to bepolished or photo-etched after welding.Uddeholm welding consumables meetthese requirements.

TIG filler rod is normally producedfrom electro-slag remelted stock whilecoated electrodes are of basic type,which are far superior to rutile elec-trodes as regards weld cleanliness.Another advantage with basis coatedelectrodes over those of rutile type isthat the former give a much lowerhydrogen content in the weld metal.

In general, the consumable used forwelding tool steel should be similar incomposition to the base material. Whenwelding in the annealed condition, e.g.if a mould or die has to be adjustedwhile in the process of manufacture, itis vital that the filler metal has thesame heat treatment characteristics asthe base steel, otherwise the weldedarea in the finished tool will have differ-ent hardness. Large compositionaldifferences are also associated with anincreased cracking risk in connectionwith hardening.

Uddeholm welding consumable aredesigned to be compatible with thecorresponding tool steel grades (QRO90 WELD and QRO 90 TIG-WELD are

MMA welding consumables from Uddeholm.

recommended for all Uddeholm hotwork steels) irrespective of whetherwelding is carried out on annealed orhardened-and-tempered base material.

Obviously, the weld metal of weldedtools will require different properties fordifferent applications.

For the three main application seg-ments for tool steels (cold work, hotwork and plastic moulding), the impor-tant weld-metal properties are:

Cold Work• Hardness• Toughness• Wear resistance

Hot Work• Hardness• Temper resistance• Toughness• Wear resistance• Heat checking resistance

Plastic Moulding• Hardness• Wear resistance• Polishability• Photoetchability

These properties are discussed brieflyon following pages.


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TEMPER RESISTANCE

If the mould or die is to be heat treatedafter welding (base steel in annealedcondition), then the hardening andtempering characteristics of the weldmetal should be similar to those of thebase steel so that the same hardness isobtained in both (Fig. 4).

Tempering temperature(holding time 2 x 2h)

Fig. 4. Comparison of tempering curves forQRO 90 SUPREME and weld metal producedby MMA welding with QRO 90 WELDelectrodes.

55

50

45

40

35

HRC

QRO 90WELD

Austenitizing temperature1020°C (1870°F)

QRO 90SUPREME

HARDNESS

If the mould or die is welded in thehardened and tempered condition, thenit is important that the weld exhibits thesame hardness as the base steel in theas-welded condition. Such being thecase, small welds can be effected with-out the necessity of subsequently tem-pering the tool. All Uddeholm weldingconsumables fulfil this requirement(Fig. 3).

500 550 600 650 700 °C

900 1000 1100 1200 1300 °F

Fig. 3. Hardness profile across a weldin IMPAX SUPREME (MMA welding using

IMPAX WELD electrodes).

TOUGHNESS

In spite of the fact that we are dealingwith that is essentially a casting, weldmetal in tool steel can be surprisinglytough as a result of the rather finemicrostructure derived from a high rateof solidification. In general, however, thetoughness will be improved by subse-quent heat treatment. Hence, largerweld repairs on a fully-hardened toolshould always be tempered after weld-ing, even though the hardness of theweld metal and base steel may be com-patible in the as-welded condition.

For cold work steels, where very highhardness is required, it will be advisableto use a softer filler metal for the initiallayers and finish with a hard electrodeon the working surface of the tool. Thisprocedure will produce a tougher repairthan if the hard electrode had beenused throughout.

WEAR RESISTANCE

Just as with tool steel, the wear resist-ance of a weld metal increases with itshardness and alloy content. Uddeholmwelding consumables are designed togive weld metals with the same wearresistance as the compatible base steel.

▲ ▲

▲ ▲ ▲

0 2 4 6 8 10 12 mm

0,1 0,2 0,3 0,4 0,5 inch

Distance from surface

HV10 450

400

350

300

250

Heataffected

zoneBasesteel Weld metal

Surface

HEAT-CHECKING RESISTANCE

Welds in hot work tools will normallyheat-check faster than the base steelbecause of poorer hot strength, temperresistance or toughness (ductility).However, if a consumable is used whichgives a weld metal with superior hotstrength and hot hardness, then theheat-checking resistance can be equalto or even better than the base steel.

QRO 90 WELD and TIG-WELDproduce welds which exhibit excellentresistance to heat checking (Fig. 5).

QRO 90 WELD

Austenitizing temperature1020°C (1870°F)

Holding time 2 x 1h

Fig. 5. QRO 90 WELD exhibits superiortemper resistance to premium H13 base steel(ORVAR SUPREME).

200 400 600 800 1000 1200°F

ORVARSUPREME

HRC60

55

50

45

40

35

30100 200 300 400 500 600 °C

Note the uniform hardnessdistribution, only marginallyhigher than the base hardness,and the very narrow heat-affected zone with only amodest hardness increase atthe fusion line.


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POLISHABILITY

For plastic mould which need to bepolished after welding, it is essentialthat the weld metal does not differgreatly in composition or hardness fromthe base steel. Otherwise, an outline ofthe weld is visible after polishing whichwill leave a witness mark on the plasticpart.

IMPAX SUPREME and STAVAX ESRwelded with IMPAX and STAVAX WELD(or TIG-WELD) consumables, will inconjunction with correct welding proce-dure, normally give welds which are toall intents and purposes invisible afterpolishing.

PHOTOETCHABILITY(TEXTURABILITY)

The weld metal and the base steel mustalso be similar in composition of awelded surface of a plastic mould is tobe textured via photoetching. If not, theresponse to etching will vary betweenthe weld and the base metal and thiswill result in a witness mark on theplastic component. Welds in IMPAXSUPREME and STAVAX ESR with IMPAXor STAVAX WELD (or TIG-WELD) willnormally not be discernible after photo-etching, provided that the proper weld-ing procedure is used.

STAVAX WELD/TIG WELD and IMPAX WELD/TIG WELD match their corresponding tool

steel grades exactly and give perfect resultsafter polishing or texturing of a welded mould.

Be careful asregards hydrogen!Weld in tool steel have high hardnessand are, therefore, especially susceptibleto cold cracking derived from hydrogeningress during welding. In many cases,hydrogen is generated as a result ofwater vapour being adsorbed in thehygro-scopic coating of MMA elec-trodes.

(Basic)

(Rutile)

Flux-cored wire (CO2)

Very low Low Medium High

0 5 10 20

Hydrogen concentration in ml/100 g of weld metal.

Fig. 6. Typical quantities of hydrogen available and weld metalhydrogen contents for different welding processes and electrode types.

Amou

nt o

f hyd

roge

n av

aila

ble

Coated electrodesGas

meta

l arc


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The susceptibility of a weld to hydro-gen cracking depends on:• The microstructure of the weld metal

(different microstructures havedifferent hydrogen sensitivities)

• The hardness of the steel (the greaterthe hardness, the higher the suscep-tibility)

• The stress level• The amount of diffusible hydrogen

introduced in welding.

MICROSTRUCTURE/HARDNESS

The characteristic microstructures givinghigh hardness in the heat-affected zoneand weld metal, i.e. martensite andbainite, are particularly sensitive toembrittlement by hydrogen. Thissusceptibility is, albeit only marginally,alleviated by tempering.

STRESS LEVEL

Stresses in welds arise from threesources:• Contraction during solidification of

the molten pool• Temperature differences between

weld, heat-affected zone and basesteel

• Transformation stresses when theweld and heat-affected zone hardenduring cooling.

In general, the stress level in thevicinity of the weld will reach the mag-nitude of the yield stress, which forhardened tool steel is very high indeed.It is very difficult to do anything aboutthis but the situation can be improvedsomewhat via proper weld design,(bead location and sequence of runs).However, no measures to reduce stresswill help if the weld is seriously con-taminated by hydrogen.

CONTENT OF DIFFUSIBLEHYDROGEN

As regards the susceptibility of welds tocold cracking, this is the factor that it iseasiest to do something about. By ad-hering to a number of simple precau-tions, the amount of hydrogen intro-duced during welding can be reducedappreciably.• Always store coated electrodes in a

heated storage cabinet or heatedcontainer once the pack has beenopened (see earlier).

• Contamination on the surfaces of thejoint of the surrounding tool surface,e.g. oil, rust or paint, is a source ofhydrogen. Hence, the surfaces of thejoint and of the tool in the vicinity ofthe joint should be ground to baremetal immediately prior to starting toweld.

• If preheating is performed with apropane burner, it should be remem-bered that this can cause moisture toform on the tool surfaces not directlyimpinged by the flame.

Heat treatment of a die-casting die after welding.


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Preheating in an insulated box.

Elevated workingtemperatureThe basic reason for welding tool steelat elevated temperature derives fromthe high hardenability and thereforecrack sensitivity of tool steel welds andheat-affected zones. Welding of a coldtool will cause rapid cooling of the weldmetal and heat-affected zone betweenpasses with resulting trans-formation tobrittle martensite and risk for cracking.Cracks formed in the weld could wellpropagate through the entire tool if thisis cold. Hence, the mould or die shouldduring welding be maintained at 50–100°C (90–180°F) above the Ms-tem-perature (martensite-start temperature)for the steel in question; note that,strictly speaking, the critical tempera-ture is the Ms of the weld metal, whichmay not be the same as that of thebase metal.

In some instances, it may be that thebase steel is fully hardened and hasbeen tempered at a temperature belowthe Ms-temperature. Hence, pre-heatingthe tool for welding will cause a drop inhardness. For example, most low-tem-perature tempered cold-work steels willhave to be pre-heated to a temperaturein excess of the tempering temperature,which is usually ca. 200°C (400°F). Thehardness drop must be accepted inorder to perform a proper preheatingand mitigate the risk for cracking dur-ing welding.

During multi-run welding of a prop-erly pre-heated tool, most of the weldwill remain austenitic under the entirewelding operation and will transformslowly as the tool cools down. Thisensures a uniform hardness and micro-structure over the whole weld in com-parison with the situation where eachrun transforms to martensite in be-tween passes (quite apart from the riskfor cracking in the latter instance).

It will be clear from this discussionthat the entire welding operationshould be completed while the tool ishot. Partially welding, letting the toolcool down and then preheating later onto finish the job is not to be recom-mended because there is considerablerisk that the tool will crack.

Weld metal

HV10

600

500

400

0 1 2 3 4 5 6 7 8 mm

Fusion line

Parentmetal(460)

0 0,1 0,2 0,3 inch

Preheating temperature 350°C (660°F) in furnace

Preheating temperature 350°C (660°F) in insulated box

Fig. 7. Hardness distribution across welds using QRO 90 WELDwhere preheating has been performed in a furnace and in aninsulated box.

While it is feasible to pre-heat toolsin a furnace, there is the possibility thatthe temperature is uneven (createsstresses) and that it will drop exces-sively before welding is completed(especially if the tool is small).

The best method of preheating andmaintaining the tool at the requisitetemperature during welding is to use aninsulated box with electrical elements inthe walls (see earlier).

Fig. 7 shows the differences inhardness distribution across weldswhich were made on tools preheated ina furnace and in an insulated box. It isclear that the tool preheated in afurnace shows a considerably greaterscatter in hardness than that preheatedin an insulated box.


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BUILDING UP THE WELD

First of all, the joint surfaces are clad inusing an appropriate number of runs.This initial layer should be made with asmall diameter MMA electrode (3,25mm – 1/8 inch – Ø max.) or via TIGwelding (max. current 120 A).

The second layer is made with thesame electrode diameter and current asthe first in order that the heat-affectedzone is not too extensive. The idea hereis that any hard, brittle microstructures,which may form in the base-materialheat-affected zone of the first layer, willbe tempered by the heat from the sec-ond layer and the propensity to crackingwill thereby be reduced. The remainderof the joint bode can be welded with ahigher current and larger-diameterelectrodes.

The final runs should be built up wellabove the surface of the tool. Evensmall welds should comprise a mini-mum of two runs. Grind off the lastruns.

During welding, the arc should beshort and the beads deposited in dis-tinct runs. The electrode should be an-gled at 90° to the joint sides so as tominimize undercut. In addition, theelectrode should be held at an angle of75–80°C to the direction of forwardmovement.

3. Filling up

2. Second layer

1. Initial cladding

Welding procedureEven with the very best of equipmentand properly designed consumables,tool steel can not be welded success-fully unless considerable care is exer-cised in joint preparation, in the ac-tual welding operation, and i perform-ing proper heat treatment afterwelding.

JOINT PREPARATION

The importance of careful joint prepara-tion can not be over-emphasized.Cracks should be ground out so that thejoint slope at an angle of at least 30° tothe vertical. The width of the joint bot-tom should be at least 1 mm (0.04 inch)greater than the maximum electrodediameter which will be used.

Erosion or heat-checking damage onhot work tools should be ground downto sound steel.

The tool surfaces in the immediatevicinity of the intended weld and thesurfaces of the joint itself must all beground down to clean metal. Prior tostarting welding, the ground areasshould be checked with penetrant tomake sure all defects have been re-moved. The tool should be welded im-mediately joint preparation is finished,because otherwise there is risk for con-tamination of the joint surfaces withdust, dirt or moisture.

Pass sequenceJoint preparation

Right!

Wrong!

Electrode

Workpiece

Fig. 8. A copper plate as support for the weldwhen building up corners.

Space for slag Copper-plate

The arc should be struck in the jointand not on any tool surfaces which arenot being welded. The sore form strikingthe arc is likely location for crack initia-tion. In order to avoid pores, the startingsore should be melted up completely atthe beginning of welding. If a restart ismade with a partly-used MMA elec-trode, the tip should be cleaned freefrom slag; this assists striking the arc atthe same time as a potential source ofporosity is eliminated.

In building up edges or corners, bothtime and consumables can be saved byusing a piece of copper plate or gra-phite as support for the weld metal(Fig. 8). Using such support also meansthat the molten pool i hotter whichreduces the risk for pore formation (lowcurrents need to be used when buildingup sharp edges or corners).

If copper or graphite support is used,an extra 1,5 mm (0,06 inch) must beallowed between the support and therequired weld surface because the slagtakes up a certain amount of space(MMA welding).

For repair or adjustment of expensivetooling, e.g. plastic mould with a pol-ished or textured cavity, it is essentialthat there is good contact between thereturn cable and the tool. Poor contactgives problems with secondary arcingand the expensive surface can be dam-aged by arcing sores. Such tools shouldbe placed on a copper plate which pro-vides for the best possible contact. Thecopper plate must be preheated alongwith the tool.

✗ ✗


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The completed weld(s) should becarefully cleaned and inspected prior toallowing the tool to cool down. Anydefect, such as arcing sores or undercut,should be dealt with immediately. Be-fore the tool has cooled, the surface ofthe weld should be ground downalmost to the level of the surroundingtool before any further processing.

Moulds where welded areas have tobe polished or photo-etched shouldhave the final runs made using TIG-welding, which is less likely to givepores or inclusions in the weld metal.

HEAT TREATMENT AFTER WELDING

Depending on the initial condition ofthe tool, the following heat treatmentsmay be performed following welding:• Tempering• Soft annealing, then hardening

+ tempering as usual• Stress relieving.

Tempering

Fully-hardened tools which are repairwelded should if possible be temperedafter welding.

Tempering improves the toughnessof the weld metal and is particularlyimportant when the welded area ishighly stressed in service (e.g. cold workand hot work tooling).

The tempering temperature shouldbe chosen that the hardness of weldmetal and base steel are compatible. Anexception to this rule is when the weldmetal exhibits appreciably improvedtemper resistance over the base mate-rial (e.g. ORVAR SUPREME welded withQRO 90 WELD); in this case, the weldshould be tempered at the highest pos-sible temperature concomitant with thebase steel retaining its hardness (typi-cally 20°C/40°F under the previoustempering temperature).

Product brochures for Uddeholmwelding consumables and tool steelsgive tempering curves from which thetempering conditions for welded toolscan be ascertained.

Very small repairs need not betempered after welding; however, thisshould be done if at all possible.

Soft annealing

Tools which are welded to accommo-date design changes or machining er-rors during toolmaking, and which arein soft-annealed condition, will need tobe heat treated after welding. Since theweld metal will have hardened duringcooling following welding, it is highlydesirable to soft anneal the weld priorto hardening and tempering of the tool.The soft annealing cycle used is thatrecommended for the base steel. Thewelded area can then be machined andthe tool may be finished and heattreated as usual. However, even if thetool can be finished by merely grindingthe weld, soft annealing is first recom-mended in order to mitigate crackingduring heat treatment.

Further informationInformation concerning heat treatmentof the tool subsequent to welding canbe obtained from the brochures for thewelding consumable and/or the toolsteel in question.

Stress relieving

Stress relieving is sometimes carried outafter welding in order to reduce residualstresses. For very large or highly-con-strained welds, this is an important pre-caution. If the weld is to be tempered orsoft annealed, then stress relieving isnot normally necessary. However, pre-hardened tool steel, e.g. IMPAXSUPREME welded with IMPAX WELDor IMPAX TIG-WELD, should be stressrelieved after welding since no otherheat treatment is normally performed.

The stress relieving temperaturemust be chosen such that neither thebase steel nor the welded area softenextensively during the operation. IfIMPAX SUPREME is to be machinedafter welding, it is absolutely essentialthat the mould is stress relieved in orderthat adequate dimensional stability isachieved.

Very small weld repairs or adjust-ments will normally not require a stressrelieving treatment.


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The following tables give detailsconcerning weld repair or adjustment oftooling made from Uddeholm tool steelgrades for hot work, plastic mouldingand cold work applications.

WELD REPAIR OF HOT WORK TOOL STEEL

Uddeholm Welding Preheating Hardness Heattool steel Condition method Consumables temperature as welded treatment Remarks

MMA Min.VIDAR SUPREME Soft annealed (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Soft annealing

ORVAR SUPREME/ Heat treatmentORVAR 2 MMA Min. See product informa-Microdized Soft annealed (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Soft annealing tion brochure for

parent steel.MMA Min.

QRO 90 SUPREME Soft annealed (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Soft annealing

MMA MinDIEVAR Soft annealed (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Soft annealing

MMA UTP 73G4 225–275°C 340–390 HB Stress relieve largeALVAR 14 Prehardened (SMAW) ESAB OK 83.28 (430–520°F) 340–390 HB None repairs.

MMA Min.VIDAR SUPREME Hardened (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Tempering

ORVAR SUPREME/ 10–20°C (20–40°F)ORVAR 2 MMA Min. below the originalMicrodized Hardened (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Tempering tempering tempera-

ture.MMA Min.

QRO 90 SUPREME Hardened (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Tempering

MMA MinDIEVAR Hardened (SMAW) QRO 90 WELD 325°C (620°F) 50–55 HRC Tempering


TIG Min.VIDAR SUPREME Soft annealed (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Soft annealing

ORVAR SUPREME/ Heat treatmentORVAR 2 TIG Min. See product informa-Microdized Soft annealed (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Soft annealing tion brochure for

parent steel.TIG Min.

QRO 90 SUPREME Soft annealed (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Soft annealing

TIG QRO 90 TIG-WELD MinDIEVAR Soft annealed (GTAW) DIEVAR TIG-WELD 325°C (620°F) 50–55 HRC Soft annealing

UTPA 73G4 Stress relieve largeTIG ESAB OK 225–275°C 340–390 HB repairs.

ALVAR 14 Prehardened (GTAW) Tigrod 13.22 (430–520°F) 340–390 HB None

TIG Min.VIDAR SUPREME Hardened (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Tempering

ORVAR SUPREME/ 10–20°C (20–40°F)ORVAR 2 TIG Min. below the originalMicrodized Hardened (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Tempering tempering tempera-

ture.TIG Min.

QRO 90 SUPREME Hardened (GTAW) QRO 90 TIG-WELD 325°C (620°F) 50–55 HRC Tempering

TIG QRO 90 TIG-WELD MinDIEVAR Hardened (GTAW) DIEVAR TIG-WELD 325°C (620°F) 50–55 HRC Tempering


14


Heat treatmentMMA 200–250°C See product brochure

STAVAX ESR Soft annealed (SMAW) STAVAX WELD (390–480°F) 54–56 HRC Soft annealing for parent steel.

Tempering temp.MMA 200–250°C 200–250°C

STAVAX ESR Hardened (SMAW) STAVAX WELD (390–480°F) 54–56 HRC Tempering (390–480°F)

MMA 200–250°C Stress relieve largeIMPAX SUPREME Prehardened (SMAW) IMPAX WELD (390–480°F) 320–350 HB None repairs.

Tempering temp.MMA UTP 73G2 225–275°C 200–250°C

GRANE Hardened (SMAW) UTP 67S (430–520°F) 55–58 HRC Tempering (390–480°F)

Tempering temp.MMA 200–250°C 590–630°C

RAMAX S Prehardened (SMAW) STAVAX WELD (390–480°F) 54–56 HRC Tempering (1090–1170°F)

MMA 150–200°C Stress relieve largeHOLDAX Prehardened (SMAW) IMPAX WELD (300–390°F) 320–350 HB None repairs.

280 HB Welding of ELMAXELMAX Hardened MMA Inconel 625 type 250–300°C approx. 56 HRC Tempering at should generally be

(SMAW) UTP 701 (480–570°F) (initial plus 200°C (390°F) avoided, due to thefinishing layers risk for cracking.respectively)

MMA 200–250°CCALMAX Soft annealed (SMAW) CALMAX/CARMO WELD (390–480°F) 59–62 HRC Soft annealing See product brochure

MMA 180–250°C Contact your localCALMAX Hardened (SMAW) CALMAX/CARMO WELD (360–480°F) 59–62 HRC Tempering Uddeholm office.

WELD REPAIR OF PLASTIC MOULD STEEL


Heat treatmentTIG 200–250°C See product brochure

STAVAX ESR Soft annealed (GTAW) STAVAX TIG-WELD (390–480°F) 54–56 HRC Soft annealing for parent steel.

Tempering temp.TIG 200–250°C 200–250°C

STAVAX ESR Hardened (GTAW) STAVAX TIG-WELD (390–480°F) 54–56 HRC Tempering (390–480°F)

TIG 200–250°C Stress relieve largeIMPAX SUPREME Prehardened (GTAW) IMPAX TIG-WELD (390–480°F) 320–350 HB None repairs.

Tempering temp.TIG UTPA 73G2 225–275°C 200–250°C

GRANE Hardened (GTAW) UTPA 67S (430–520°F) 55–58 HRC Tempering (390–480°F)

Tempering temp.TIG 200–250°C 590–630°C

RAMAX S Prehardened (GTAW) STAVAX TIG-WELD (390–480°F) 54–56 HRC Tempering (1090–1170°F)

TIG 150–200°C Stress relieve largeHOLDAX Prehardened (GTAW) IMPAX TIG-WELD (300–390°F) 320–350 HB None repairs.

Welding of ELMAXTIG 250–300°C Tempering at should generally be

ELMAX Hardened (GTAW) UTPA 701 (480–570°F) ~56 HRC 200°C (390°F) avoided, due to therisk for cracking.

TIG CALMAX/ 200–250°CCALMAX Soft annealed (GTAW) CARMO TIG-WELD (390–480°F) 58–61 HRC Soft annealing See product brochure

TIG CALMAX/ 180–250°C Contact your localCALMAX Hardened (GTAW) CARMO TIG-WELD (360–480°F) 58–61 HRC Tempering Uddeholm office.

TIGCORRAX Solution treated (GTAW) CORRAX TIG-WELD None 30–35 HRC Ageing

TIG DependingCORRAX Aged (GTAW) CORRAX TIG-WELD None 30–35 HRC on hardness

See produc brochureCORRAX TIG-WELD


15

WELD REPAIR OF COLD WORK TOOL STEEL

AWS E312

ESAB OK 84.52

UTP 67S

Castolin 2

Castolin N 102

300 HB

53–54 HRC

55–58 HRC

54–60 HRC

54–60 HRC

280 HB

55–58 HRC

56–60 HRC

59–61 HRC

AWS ER 312

UTPA 67S

UTPA 73G2

Castotig 5

300 HB

55–58 HRC

53–56 HRC

60–64 HRC

Initial layers welded withsoft weld metal.

Choose consumable forfinishing layers whichgives suitable hardness.

For FERMO and CARMO,small repairs can bemade with tool atambient temperature.Castotig 5 should not beused for more than 4layers (cracking risk).

280 HB53–56 HRC55–58 HRC60–64 HRC60–64 HRC

Initial layers welded withsoft weld metal.

Choose consumable forfinishing layers whichgives suitable hardness.

For FERMO and CARMO,small repairscan be made with tool atambient temperature.

Inconel 625 typeUTPA 73G2UTPA 67SUTPA 696Castotig 5


TIG 200–250°CARNE Hardened (GTAW) (390–480°F)

TIG 200–250°CFERMO Prehardened (GTAW) (390–480°F) Tempering

TIG 200–250°CRIGOR Hardened (GTAW) (390–480°F)

TIG 200–250°CVIKING Hardened (GTAW) (390–480°F)

TIG 200–250°CSVERKER 21 Hardened (GTAW) (390–480°F)

TemperingTIG 200–250°C

SVERKER 3 Hardened (GTAW) (390–480°F)

Inconel 625 type 280 HBUTPA 73G2 53–56 HRC

TIG UTPA 696 200–250°C 60–64 HRC TemperingVANADIS 4 Hardened (GTAW) Castotig 5 (390–480°F) 60–64 HRC

AWS ER 312 300 HBTIG UTPA 696 60–64 HRC Tempering

SLEIPNER Hardened (GTAW) Castotig 5 250°C (480°F) 60–64 HRC

TIG CALMAX/CARMO 200–250°CCARMO Prehardened (GTAW) TIG-WELD (390–480°F) 58–61 HRC Tempering

TIGCALMAX (GTAW See “Weld repair of plastic mould steel”

Inconel 625 type

UTP 67S

Castolin 2

Castolin 6


MMA 200–250°CARNE Hardened (SMAW) (390–480°F)

MMA 200–250°CFERMO Prehardened (SMAW) (390–480°F) Tempering

MMA 200–250°CRIGOR Hardened (SMAW) (390–480°F)

MMA 200–250°CVIKING Hardened (SMAW) (390–480°F)

MMA 200–250°CSVERKER 21 Hardened (SMAW) (390–480°F)

TemperingMMA 200–250°C

SVERKER 3 Hardened (SMAW) (390–480°F)

MMA Inconel 625 type 200–250°C 280 HBVANADIS 4 Hardened (SMAW) Castolin 6 (390–480°F) 59–61 HRC Tempering

AWS E312 300 HBMMA UTP 69 60–64 HRC Tempering

SLEIPNER Hardened (SMAW) Castolin 6 250°C (480°F) 59–61 HRC

MMA 200–250°CCARMO Prehardened (SMAW) CALMAX/CARMO WELD (390–480°F) 59–62 HRC Tempering

MMACALMAX (SMAW) See “Weld repair of plastic mould steel”

Note: Consumables with high carbon content are generally not recommended for MMA welding because of the cracking risk

Documents

Texto_welding of Tool Steel_uddeholm