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STEEL FOR COLD WORK TOOLING 1

UDDEHOLM TOOL STEELS FOR

COLD WORKTOOLING

STEEL FOR COLD WORK TOOLING2

This information is based on our present state of knowledge and is intended to provide generalnotes on our products and their uses. It should not therefore be construed as a warranty ofspecific properties of the products described or a warranty for fitness for a particular purpose.

Classified according to EU Directive 1999/45/ECFor further information see our “Material Safety Data Sheets”.

Edition: 13, 08.2016

© UDDEHOLMS ABNo part of this publication may be reproduced or transmitted for commercial purposeswithout permission of the copyright holder.


Selecting a tool steel supplier is a key decision for all parties, including the tool maker,

the tool user and the end user. Thanks to superior material properties, Uddeholm’s

customers get reliable tools and components. Our products are always state-of-the-

art. Consequently, we have built a reputation as the most innovative tool steel

producer in the world.

Uddeholm produce and deliver high quality Swedish tool steel to more than 100,000

customers in over 100 countries. We secure our position as a world-leading supplier

of tool steel.

Wherever you are in the manufacturing chain, trust Uddeholm to be your number

one partner and tool steel provider for optimal tooling and production economy.

Quite simply, it pays to go for a better steel.

CONTENTS

Introduction 4

Tool steel fundamentals 5

Tool steel selection 12

Tool making 15

Surface treatment 19

Product programme 21

The Uddeholm tool steel grades for cold work tooling 23

– Executions and products 25

– Chemical composition 26


IntroductionRows of presses continuously producing the samecomponents were a common sight in earliertimes. Unplanned production halts due to toolingproblems were not so serious because high levelsof work in progress were held. Repairs or newtools could be quickly made by dedicated in-house tool rooms from stocks of one or twosteel.

On the whole, work materials were simplerand the operating speeds of presses were slower.Thus major tool failures did not occur so often.

Production technology has, however, advancedvery considerably. Equipment and plant are beingscrutinised these days because greater accuracyand higher productivity are a must. Much greateremphasis has been placed on profit and reducingproduction costs. High speed presses producingcomponents just-in-time from more difficult workmaterials on tools manufactured off-site is be-coming more common.

Tool design, the method of tool manufacturing,the tooling material and the work material are allpart of the package in trying to optimize produc-tivity and to reduce costs.

Tools are the final link in the hardware chain.To obtain optimum productivity, tool steel thatcan meet today’s demands and a knowledge oftool steel selection are necessary.

UdUdde

Uddeholm VUddeh

Uddeho

Uddeholm CaldieUddeholm Vanadis 4 ExtraUddeholm Vanadis 8Uddeholm Vancron 40

Uddeholm CaldieUddeholm SleipnerUddeholm Vanadis 4 ExtraUddeholm Vanadis 8Uddeholm Vancron 40





Sill re

Roof rail

A-pillar

Door beams

Crash box

Front side member

Bumper reinforcement


Tool steel fundamentalsWe at Uddeholm can help the tool user in anumber of very important ways.

Our world wide marketing organization is ableto provide a well balanced programme of highquality tool steel. This programme not onlyincludes a number of standard grades but alsogrades specifically designed to meet the highrequirements now placed on much cold worktooling.

We can help the tool user to choose the righttool steel for the application. We do this byselecting the tool steel grade after identifying thereasons for the tool failure. A selection made inthis way will result in lower tooling costs, lowermaintenance costs and a less downtime.

DEMANDS ON COLD WORK TOOLING

Choosing the right tool steel for the applicationbecomes more and more important as thedemands on the tool increase. What are thesedemands?

• The tool must have sufficient wear resistance.• The tool must perform reliably and not fail due

to premature chipping, cracking or plasticdeformation.

An optimal tooling economy—the lowestpossible tooling cost (including maintenance) perpart produced—can only be achieved if thecorrect tool steel for the application in questionis used.

Uddeholm CaldieUddeholm Sleipner

Uddeholm Vanadis 4 ExtraUddeholm Vanadis 8

Uddeholm Vancron 40 Uddeholm CaldieUddeholm Sleipner


Uddeholm Vancron 40



Uddeholm Vancron 40


Uddeholm Vanadis 4 Extra


Uddeholm Vanadis 4 Extra



Uddeholm Vancron 40



Uddeholm Vancron 40



Uddeholm Vancron 40

deholm Caldieeholm SleipnerVanadis 4 Extraholm Vanadis 8lm Vancron 40

inforcement

Seat track

Seat frame

Recliner

Cross member

Waist reinforcement

B-pillar

C-pillar

Roof bow


Figure 1. Factors inf luencing tool life in cold work applications.

HEAT TREATMENTTOOL MATERIAL

PRODUCTION CONDITIONS

TOOL DESIGN

TOOL MAINTENANCE

WORK MATERIAL

TOOL PRODUCTION

▲

▲

“Cutting particle”

Wear

Direction of movement

Workmaterial

RELATIONSHIP BETWEENFAILURE MECHANISMS AND TOOLSTEEL PROPERTIES

In recent years a lot of work has been carriedout in this field, especially for the cold work toolsteel. A better understanding of the importantrelationship between failure mechanisms and thetool steel properties has been attained and ourknowledge of this is reviewed as follows.

Figure 2. Schematic representation of abrasive wear.

Tool

ABRASIVE WEAR

This type of wear dominates when the workmaterial is hard and/or contains hard particlessuch as oxides or carbides.

These hard particles scour the tool surface asshown schematically in Figure 2. An example ofa punch worn by abrasive wear is shown inPhoto 1 on page 8.

Abrasive wear is dominant with such workmaterials as hardened steel, ceramics and wood.

The tool steel properties that are importantfor good resistance to abrasive wear are:• high hardness• high volume of carbides• high hardness of the carbides• large carbide size

TOOL PERFORMANCE

The performance of a cold work tool depends onmany factors. These are shown in Figure 1.

The performance of a tool is often monitoredby examining the quality of the parts it produces.In most applications, there are special require-ments on surface finish and dimensional toler-ances etc. for the parts being produced. A worndown or damaged tool usually results in rejectionof the parts and the tool must be reconditionedor replaced.

The work material itself has a fundamentalinfluence on the failure mechanisms. The mostfrequent failure mechanisms in cold work toolingare shown in Figure 3.


Wear

Cracking/total failure

Plastic deformation

Chipping

Figure 3. The most frequent failure mechanismsin cold work tooling.

▲▲

▲

▲

Direction of movement

Tool

Figure 4. Schematic representation of adhesive wear.

ADHESIVE WEAR AND GALLING

Adhesive wear or galling is a material transferfrom one metallic surface to another when theyslide over each other and is caused by the proc-ess of micro-welding (solid phase welding).

The metallic surfaces are never absolutelysmooth—they consist of microscopic asperities.Bonding can occur between the two surfaces atthese asperities and this may be stronger thanthe basic strength of the weaker of the twomaterials in contact. If there is a relative motionbetween these two surfaces, the weaker of thetwo materials in contact will fail and materialfrom it will be transferred to the other contact-ing surface.

The situation for a tool and production ma-terials is shown in Figure 4. If the microweldfractures on the tool side, small fragments of thetool steel will be torn out of the tool surface andthis leads to adhesive wear. If the microweldsbreak on the production material side, the frag-ments of production material will gall onto thetool surface.

Adhesive wear may also be the origin of chipp-ing. A fatigue mechanism gradually takes overfrom the adhesive wear dominant in the earlystages.

Microcracks start to nucleate and these willstart to deepen and spread. The cracks can theninitiate a large scale spalling (chipping) or evenlead to a catastrophic failure. An example of apunch worn by adhesive wear is shown in Photo 2on page 8. Fatigue cracks can be clearly seen.

Adhesive wear and galling are normally associ-ated with soft, adhesive metallic work materialssuch as aluminium, copper, stainless steel and lowcarbon steel. However, galling is also a problem

Galling

Microwelds

Work material

= Possible shear fracture = wear


encountered during the manufacture of compo-nents from high strength production materialssuch as the advanced high strength steel.

Adhesive wear and galling can be decreased bymaking the microwelding and/or tearing offmechanisms more difficult. The tool steel proper-ties that are critical for good resistance to adhe-sive wear and galling are:• high tool hardness• a low coefficient of friction (suitable surface

topography and the use of a suitable lubricant)• high tool steel ductility• use of a surface treatment or coating

The newly developed nitrogen alloyed highperformance PM steel Uddeholm Vancron 40SuperClean has an excellent resistance to gallingand adhesive wear. This can often be used in theuncoated condition and frequently performsbetter than coated tooling.

MIXED WEAR

Sometimes, during adhesive wear, torn off frag-ments of tool steel stick to the productionmaterial and cause abrasive wear on the toolsurface. The result is a wear type consisting of acombination of adhesive and abrasive wear andthis is referred to as mixed wear. It should benoted that mixed wear can only occur if adhesivewear occurs first.

Photo 2. SEM photograph of a D2 punch worn byadhesive wear (work material austenitic stainless steel).

CHIPPING

Chipping often occurs after the tool has been inservice for a relatively short time. This failuremechanism is one of low cycle fatigue. Micro-cracks are initiated in the active surface of thetool, propagate and finally result in pieces chip-ping out along edges or at corners.

To obtain good resistance to chipping it is im-portant to make microcrack initiation and propa-gation more difficult. One tool steel propertythat gives a good resistance to chipping is highductility.

PLASTIC DEFORMATION

Plastic deformation occurs when the yieldstrength of the tool steel has been exceeded.

Plastic deformation causes damage to or shapechanges on the working surfaces of the tool.

The tool steel property that is important for agood resistance to plastic deformations is highhardness.

Note: Sufficient resistance to chipping and crack-ing must be taken into account when selectingthe working hardness level.

CRACKING

Cracking is a failure mechanism which tends tooccur spontaneously and usually means that thetool has to be replaced. Unstable crack propaga-tion is the mechanism causing this type of failure.

The formation of cracks is very much enhancedby the presence of stress concentrators, e.g.grinding marks and machining marks or designfeatures such as sharp corners or radii. EDMlayers on the tool surface are also a frequentcause.

The tool steel properties that give a goodresistance to cracking are:• low hardness• high microstructural toughness

Note: Low hardness will have a detrimental effecton the resistance to the other failure mecha-nisms. Thus working with a low hardness is notnormally a good solution. It is better to use asteel with a good microstructural toughness.

Photo 1. SEM photograph of a D2 punch worn byabrasive wear (work material 1% C-steel at 46 HRC).


CRITICAL TOOL STEEL PROPERTIES

The resistance a tool steel offers to the varioustool failure mechanisms depends on its chemicalcomposition, method of production and thequality of the process used.

The table on page 26 shows the chemical com-positions of the tool steel in Uddeholm’s stand-ard cold work programme. It includes premiumquality standard international grades as well asspecially developed shock resistant grades andhigh performance powder metallurgical (PM)SuperClean grades.

This well balanced basic programme is suffi-cient to cover most cold work applications andproduction run volumes.

The resistance of these steel to the varioustool failure mechanisms is shown on a relativescale in Table 2.

Table 2. The longer the bar, the better the resistance. The Vancron and Vanadis steels mentioned in the table are UddeholmPM SuperClean tool steels.

THE UDDEHOLM STANDARD STEELFOR THE INACTIVE ELEMENTS OF COLDWORK TOOLS

Uddeholm has also introduced a number of con-ventionally produced shock resistant grades withproperties profiles suitable for heavy duty blan-king and forming applications. These are Udde-holm Calmax and the two fully Electro-Slag-Remelted grades Uddeholm Unimax and Udde-holm Caldie.

CONVENTIONALLY PRODUCEDTOOL STEEL

From Table 2 it can be seen that there is anincreasing abrasive wear resistance of the stand-ard international grades in the order O1–A2–D2–D6.

For a long time tool wear was considered tobe of an abrasive nature. For this reason most ofthe older, well established high-alloyed cold workgrades such as D2 and D6 have a pronounced

abrasive profile. Such steel perform a good jobin cases where abrasive wear dominates but it iswell known that they do not perform well inapplications where adhesive wear, chipping orcracking dominate.

The majority of work materials used in coldwork operations subject the tooling to adhesivewear, mixed wear and/or chipping and cracking.For this reason steel like A2 were introduced.

Uddeholm Chemical composition %Grade AISI C Si Mn

Sleipner – 0.9 0.9 0.5

Sverker 21 AISI D2 1.55 0.3 0.4

Formax – 0.18 0.3 1.3

UHB 11 AISI 1148 0.50 0.2 0.7

Table 3.

RELATIVE COMPARISON OF THE RESISTANCE TO FAILURE MECHANISMS

Arne

Calmax

Caldie (ESR)

Rigor

Sleipner

Sverker 21

Sverker 3

Vanadis 4 Extra

Vanadis 8

Vanadis 23

Vancron 40

UddeholmGrade

Hardness/ Resistance to Fatigue cracking resistanceResistance Ductility/ Toughness/to plastic Machin- Grind- Dimension Abrasive Adhesive resistance to gross

deformation ability ability stability wear wear chipping cracking


INNOVATION IN TOOL STEEL—THE PM STEEL

The need for high performance tool steel hasgrown dramatically because of constant competi-tive demands from the markets to achieve thelowest tooling costs per part produced. Theirsuccess is based on their powder metallurgy(PM) production route.

Traditionally, tool steel are melted the sameway as engineering steel but generally they arecast as smaller ingots. The molten metal is castinto moulds and the resulting ingots are forgedand rolled into steel bars. The bars are then softannealed or prehardened.

▲

▲

▲

Figure 5. Breakdown of the carbide networks during hot forming.

Microstructure ofsolidified ingot

Microstructure offorged bar

Carbidenetworks

In the finished bars these networks are brokendown to form carbide stringers and these ad-versely affect the mechanical properties of thetool steel, particularly in the transverse and shorttransverse directions. Despite a high degree ofreduction during forging and rolling, tool steelgrades like Uddeholm Sverker 3 and UddeholmSverker 21 pay heavy toughness penalties fortheir carbide-influenced abrasive wear resistance.

To avoid segregations and large carbides withtheir detrimental effect on fatigue life, a totallydifferent way of producing tool steel ingots hasto be used. The powder metallurgy (PM) route isthe industrial process used to produce macro-segregation free ingots of high alloy tool steel.The PM route is shown schematically in Figure 6.The melt is atomized and the resulting tiny drop-lets solidify very rapidly to form a powder. Thepowder is hot isostatically pressed in a capsule.The ingot so produced is then ready for hotworking (forging and rolling) into bar form. ThePM steel are fully wrought products.

The PM process eliminates the macro-segrega-tion problem and this means that more highlyalloyed steel can be manufactured than wouldbe possible by conventional ingot metallurgy.Photo 3 compares the microstructure of a con-ventionally produced 12%-Cr steel (UddeholmSverker 21) with a PM steel (Uddeholm Vanadis 4Extra SuperClean). In the PM steel, very small andhard alloy carbides greatly increase the wearresistance and at the same time the fatigue life

However, due to the events takingplace during the solidification of theliquid steel in the ingots, segregationtakes place and carbide networks areformed and these are particularlypronounced with high alloyed toolsteel.

These networks are graduallybroken down during hot working asshown schematically in Figure 5.

Tool for powder compacting.


Photo 3. Comparison of the microstructuresof a conventionally produced 12% Cr-steel(Uddeholm Sverker 21) and a PM cold worksteel (Uddeholm Vanadis 4 Extra SuperClean).

Uddeholm Vanadis 4 Extra SuperClean

Uddeholm Sverker 21

Figure 6. Schematic representation of the powder metallurgy (PM) route for producing tool steel.

In the past the PM steel have been designedmainly to cope with the failure mechanisms ofwear and chipping in high performance tooling.The latest innovation in PM technology for pro-ducing high performance tool steel is alloyingwith nitrogen to obtain an excellent galling resist-ance without having to resort to surface treat-ments or coatings. The result of this is the highperformance PM grade Uddeholm Vancron 40SuperClean.

All of Uddeholm high performance PM gradesare produced with the latest PM technique avail-able and of superclean quality level.

(which governs chipping and cracking resistance).This is in contrast to the conventionally pro-duced steel where increased chipping and crack-ing resistance can only be gained by lowering theworking hardness which in turn lowers the wearresistance.

Thus in the PM steel shown in Table 2, page 9,there is enhanced resistance to wear (both abra-sive and adhesive) but at the same time improvedchipping resistance.

Sintering of powder compacted parts.


Tool steel selectionThe selection of a tool steel for a given applica-tion will depend on which failure mechanismsdominate.

The choice of a tool steel for a specific applica-tion requires more than just a knowledge of thesteel properties. The number of parts to be pro-duced, the type of work material, the thickness ofthe work material and the hardness of the workmaterial must also be taken into consideration.

The basic idea is to select a tool steel withsuch properties that all the failure mechanismsexcept wear are eliminated. The wear can thenbe optimized to match the number of compo-nents required.

The following step by step penetration of somesimple cases indicates how a tool steel selectionshould be made.

IDENTIFY THE TYPE OF WEAR

The following production material propertiesmust be considered in order to establish thedominating wear type (abrasive, adhesive ormixed) to be expected:• type of work material• hardness of work material• presence of hard particles in the work

material

This is the most fundamental step because it willdetermine which wear resistance profile the toolsteel should have.

OCCURRENCE OF CHIPPINGOR PLASTIC DEFORMATION

The following will indicate the extentof the risk for chipping and/or plastic deforma-tion, i.e. whether high chipping resistance (ductil-ity) and/or high hardness are needed:• type of application• thickness and hardness of the production

material• geometrical complexity of parts to

be produced

The tool user will normally have sufficientexperience here.

RISK OF CRACKING

The following will give an indication of the riskfor cracking, i.e. whether a tough tool steel and/or moderate hardness levels have to be used:• type of application• geometry of part to be produced• tool design and tool size• thickness and hardness of the production

material

NUMBER OF PARTS TO BE PRODUCED

Very long runs often require more than one tooland demand the use of a high performance toolsteel to obtain optimum tooling economy. Onthe other hand, short runs can be made with alower alloy grade tool steel.

Progressive tool.


SELECTION OF THE TOOL STEEL

The tool steel with the most suitable profile toovercome the dominant failure mechanisms canbe selected using the information given in Table 2,page 9.

The procedure for tool steel selection:

1. Blanking of a thin (0.5 mm) hardened strip steel (45 HRC)• Abrasive wear will be the dominating wear

mechanism.• The risk of chipping or cracking is minimal for

geometrically simple parts but rises as thegeometry becomes more complicated.

• The risk for plastic deformation is minimal asthe production material is thin.

For a short run of parts with a simple geometry,the tool steel Uddeholm Arne would be suffi-cient for a moderate size tool. For a larger tool amore highly alloyed steel is necessary for reasonsof hardenability. Here the steel UddeholmCalmax would be a good choice.

For a longer run where much more abrasivewear resistance is required, Uddeholm Sverker 21would be a good choice for parts with a rela-tively simple geometry. However, for parts with amore complicated geometry, the risk of chippingis higher and Uddeholm Vanadis 8 SuperCleanwould be a better choice.

For very long runs an extremely high abrasivewear resistance is needed. Here UddeholmVanadis 8 SuperClean would be the best choice.

2. Blanking of a thick (5 mm) and soft (150 HV) austenitic stainless steel

• Adhesive wear is the dominating wearmechanism.

• The risk for chipping or cracking is significant.• There is a moderate risk for plastic deforma-

tion but this can be overcome by using asufficient working hardness.

For short runs of parts with simple or compli-cated geometries, Uddeholm Calmax would be agood choice.

For longer or very long runs of parts withsimple or complex geometries, UddeholmVanadis 4 Extra SuperClean would be theobvious choice.

SELECTION OF TOOL STEELBASED ON PRODUCTION VOLUMES

In the past production volumes have beendefined empirically as low, medium or high. Lowproduction volumes have been defined as up to100,000 parts, medium production volumes asbetween 100,000 and 1 million parts and highproduction volumes as over 1 million parts. Sucha definition takes however not the influence ofhardness and thickness into account, which bothincrease the risk for chipping and cracking. Thisproblem can be overcome by redefining produc-tion volumes as follows:

low production volumes: one tool made oftool steel belonging to the low performancegroup can produce the required number of parts

medium production volumes: one tool madeof medium performance group of steel can pro-duce the required number of parts

high production volumes: more than one toolof the medium performance group is needed toproduce the required number of parts. In thiscase a tool steel from the high performancegroup always gives the best tooling economy

The cold work steel from Uddeholm can bedivided into three groups related to the batchsize aimed for low production volumes, mediumproduction volumes and high production vol-umes according to Table 4, page 14.

Fine blanking. Courtesy of Feintool, Switzerland


Seriallength Adhesive wear Mixed wear Abrasive wear

Short Arne 54–56 HRC Arne 54–58 HRC Arne 54–60 HRCCalmax 54–59 HRC Caldie 56–62 HRCUnimax 54–58 HRC

Medium Calmax 54–58 HRC Caldie 58–62 HRC Sleipner 60–64 HRCUnimax 54–58 HRC Rigor 54–62 HRC Sverker 21 58–62 HRCCaldie 58–60 HRC Sleipner 58–63 HRCSleipner 56–62 HRC

Long Vanadis 4 Extra Vanadis 4 Extra Sverker 3 58–62 HRCSuperClean 58–62 HRC SuperClean 58–63 HRC Vanadis 8Vancron 40 Vanadis 8 SuperClean 60–65 HRCSuperClean 60–64 HRC SuperClean 60–64 HRC

Each group contains steel grades with differentproperties profiles. The selection of a suitablegrade for the application in question and theproduction volume required is determined by thedominating failure mechanisms. Steel selection isvery often based on the experiences from anongoing or similar production.

The properties profiles of the different gradesare given in Table 2, page 9.

A general rule for tool steel selection is thatchipping and cracking should be avoided as far as

Table 4.

possible even if this means an increase in the toolwear. Wear has a number of advantages overchipping and cracking. It is predictable and it re-sults in the cheapest refurbishing costs. If a tool isonly wearing, maintenance is easier to plan andmore costly production stops can be avoided.

If production experience is lacking, the Table 4below can be used as a guide for selection of thetool steel to be used.

Tool of solid Uddeholm Vancron 40 SuperClean for production of dishwashers.

UDDEHOLM TOOL STEEL SELECTIONFOR DIFFERENT PRODUCTION VOLUMES AND WEAR MECHANISMS


decarburized skin but there may be a surfacezone containing less carbon than in the bulk ofthe bar.

It is important to remove the decarburizedlayer from the surface of the bar before the steelis used to manufacture the tool. If this is notdone, the following can happen:

• the tool may crack during heat treatment(quenching) or in service

• the working surfaces of the tool can plasticallydeform

• the wear resistance of the tool will be reduced

It is also good practice to remove the decar-burized layer from black bar used for EDMstarter blocks. These have been known to crackduring quenching due to the presence of thedecarburized layer.

The amount of skin to be removed depends onthe dimensions and shape of the bar. Variousorganizations such as AISI provide standards towork on.

Tool makingIf a tool is to give an optimum production with aminimum of maintenance and downtime, it is notonly necessary to select the correct tool steelfor the application. It is just as essential that thetool making is carried out properly. If this is notdone, a number of problems can arise during themanufacture of the tool. But this is not all—theperformance of the tool in service can be seri-ously reduced. This is because the failure mecha-nisms discussed in the previous sections canoccur at an earlier stage if the tool making proce-dures are not correct.

BASIC TOOL DESIGN

It goes without saying that the tool must be de-signed properly to do the job intended. Toolsdesigned for a particular application and produc-tion material thickness may not function if theyare later used to perform an operation on amuch thicker and/or harder production materialas they could be severely overloaded.

The following recommendations concerning de-sign features, although very basic, are intended toavoid premature failure either in heat treatmentor in use.

• Use adequate overall dimension to ensure basictool strength and support.

• Avoid sharp corners – wherever possible,incorporate a generous fillet radius instead.

• Wherever possible, avoid adjacent heavy andlight sections in the tool.

• Avoid potential stress raisers, e.g. machiningmarks, grinding marks and letter stamping.

• Leave sufficient stock thickness between holesand surface edges.

• Complicated tool shapes are often best builtup from sections which are safer in heat treat-ment and easier to refurbish or replace.

DECARBURIZED LAYER

During production of tool steel bars it is virtuallyimpossible to avoid decarburization of the sur-face layer. The degree to which a bar may bedecarburized depends on the steel analysis andalso on the practice used during heating of thebar. Sometimes there will be no completely

GRINDING

The use of correct grinding techniques willalways have a positive influence on tool makingand tool performance. The stress created locallyin the tool surface by the combination of hightemperatures, friction and pressure during thegrinding operation can be kept to a minimum by:

• using properly dressed, free-cutting grindingwheels

• restricting the wheel pressure/metal removalrate or depth of cut

• using plenty of coolant

Tools made from high alloy steel which have beentempered at low temperatures are particularlysensitive during grinding operations. Extra care isdemanded here. As a rule of thumb, the harderthe steel, the softer the wheel and vice-versa.

Stamping tool for production of medals.


Under unfavourable grinding conditions the toolsteel can be affected as follows:

• surface hardness is reduced (temper burn) andthis will adversely affect wear resistance

• rehardening of the ground surface may takeplace and result in the formation of grindingcracks and problems with tool breakage andchipping

• severe stresses are introduced into the tooland these can enhance the risk of failure

After a rough grinding operation it is importantthat a finish grinding is made so that the stressaffected surface layer due to the rough grindingoperation is removed. Grinding stresses can alsobe released by means of a stress tempering op-eration at about 25°C (50°F) below the previ-ously used tempering temperature.

It should be noted that the risk of surface crack-ing is high when grinding tools that have beenoverheated, over-soaked or undertempered dur-ing heat treatment. This is caused by the pres-ence of the soft constituent retained austenite inthe microstructure. The heat and pressure pro-duced during grinding usually transform this intountempered martensite. The resultant very hardand brittle condition at the tool surface can leadto the formation of surface cracks.

Grinding marks on the working surfaces of thetool can cause problems in service.

• They are potential stress raisers and can leadto chipping or flaking or even cracking.

• They can cause galling, especially if they aretransverse to the direction of the metal flow.

Tool for deep drawing.

Hub cover for truck.


What has been said about heating also applies toquenching. Very powerful stresses arise duringquenching. As a general rule, the slower thatquenching can be done, the less distortion willoccur due to thermal stresses.

When the die surface is finish ground or re-ground, the feather edge which is created shouldbe carefully removed by a light hand stoning op-eration. This will reduce the possibility of chipp-ing or flaking of the cutting edge at the beginningof the production run. This is particularly impor-tant in tools being used at high hardnesses forcutting of thin materials.

The PM steel Uddeholm Vanadis 4 ExtraSuperClean and Uddeholm Vanadis 8 Super-Clean, with their extremely small carbides, pos-sess considerably better grindability than onewould expect from an equivalent conventionallyproduced highly alloyed material.

Further details and grinding wheel recommen-dations can be found in the Uddeholm brochure“Grinding of Tool Steel”.

HEAT TREATMENT

The purpose of heat treating a tool is to obtainsuitable properties such as wear resistance,toughness and strength. The principal problemsthat arise in association with heat treatment are:• distortion• dimensional changes• decarburization• carburization• grain boundary precipitation (proeutectoid

carbide)

DISTORTION

Distortion of tools following heat treatment mayresult from:• machining stresses• thermal stresses• transformation stresses

In order to reduce machining stresses, the toolshould always be stress relieved after roughmachining. In this way the stresses introduced bythe machining operation are reduced. Any distor-tion can then be adjusted during finish machiningprior to heat treatment.

Thermal stresses are created when the tool isheated. They increase if heating takes place rap-idly or unevenly. The fundamental rule for heatingto hardening temperature is that it should takeplace slowly so that the temperature remainsvirtually equal through the piece. A number ofpreheating stages are normally used.

DIMENSIONAL CHANGES

Transformation stresses arise when the micro-structure of the steel is transformed. Dimen-sional changes due to transformations in the steelare difficult to influence except by changing toanother steel grade.

Dimensional changes occur both in hardeningand tempering. In estimating size changes, theeffects of hardening and tempering should beadded together. Uddeholm’s product brochurescontain data on these dimensional changes.

DECARBURIZATION

It is important that the tools are protectedagainst oxidation and decarburization. The bestprotection is provided by a vacuum furnace,where the surface of the steel remains un-affected. Decarburization will result in loss ofwear resistance.

CARBURIZATION

Carburization is a result of pick-up of carbon inthe surface of the steel when the medium usedto protect the tool during hardening containsfree carbon. It results in a hard, brittle layer onthe surface of the tool and increases the risk ofchipping or cracking.

GRAIN BOUNDARY PRECIPITATION

Carbides can precipitate out during quenching ifthe quench is carried out too slowly. The carbideprecipitates out mainly at the grain boundaries ofthe tool steel and results in loss of toughness andfinal hardness.

For further information on heat treatment seethe Uddeholm brochure “Heat Treatment of ToolSteel”.


Photo 4. Surface of Uddeholm Sverker 21 after roughspark EDM. The white layer is brittle and contains cracks.

ELECTRIC DISCHARGE MACHINING (EDM)

When EDM’ing, one or two very importantpoints should be noted in order to obtain satis-factory results. During the operation the surfacelayer of the heat treated steel is rehardened andconsequently in a brittle state. This very oftenresults in chipping, fatigue cracking and a short-ened tool life. To avoid this problem the followingprecautions should be taken.

• Finish the EDM operation by “fine” sparking(i.e. low current, high frequency). Correctdimensioning of the “fine” sparking electrode isessential to ensure removal of the surface layer(see Photo 4) produced by the “rough” spark-ing operation.

• The surface layer produced by “fine” sparkingoperation should, if possible, be removed bypolishing or stoning.

• If there is any doubt about the completeremoval of the surface affected layer, the toolshould be re-tempered at a temperature 15–25°C (25–45°F) below the last used temperingtemperature.

WIRE EDM

This process makes it easy to cut complicatedshapes from hardened steel blocks. However,hardened steel always contain stresses and whenlarger volumes of steel are removed in a singleoperation, this can sometimes lead to distortionor even cracking of the part. The problem ofcracking during wire EDM is normally encoun-tered in cross sections over 50 mm (2”).

The risk of cracking can be reduced by:

• lowering the overall stress level in the part bytempering at a high temperature. This assumesthe use of a steel grade which exhibits a sec-ondary peak in its tempering curve

• correct hardening and double tempering isimportant. A third tempering is advisable forheavy cross sections

• a conventional machining of the work-piecebefore heat treatment to a shape near to thefinal form.

• drilling several holes in the area to be removedand connect them by saw-cutting before hard-ening and tempering

The rehardened surface layer produced by wireEDM’ing is normally relatively thin and can becompared more to “fine-sparking” EDM. How-ever, it is often thick enough to cause chipping orcracking problems, especially on more geometri-cally sensitive tooling with high hardness levels. Itis, therefore, advisable to make at least one “fine”cut after rough cutting. One or more fine cutsare often necessary anyway to achieve the re-quired dimensional tolerances.

For further information see the Uddeholmbrochure “Electric Discharge Machining (EDM)of Tool Steel”.


PVD coated punch and die.

Surface treatmentGAS NITRIDING

Gas nitriding gives a hard surface layer with goodresistance to abrasion. However, the hard ni-trided case is brittle and can chip or spall if thetool is subjected to impact or rapid temperaturechanges. The risk increases with the thickness ofthe case. Prior to nitriding, the tool must behardened and tempered. The tempering tempera-ture should be about 25°C (45°F) higher than thenitriding temperature.

NITRO-CARBURIZING

The nitrided case produced by the nitro-carbu-rizing process is normally thinner than the caseproduced by ion or normal gas nitriding. It is alsoconsidered to be tougher and to have lubricatingproperties.

It has been found that nitro-carburizedpunches give particularly good results in the cut-ting of thin, adhesive materials such as austeniticstainless steel. The nitrided case reduced adhe-sion between the punch and work material.

The following Uddeholm cold work tool steelcan be nitrided:Rigor, Caldie, Sleipner, Unimax, Calmax, Sverker 21,Sverker 3, Vanadis 4 Extra SuperClean, Vanadis 8SuperClean and Vanadis 23 SuperClean.

The case hardness is 900–1250 HV10, depend-ing on the grade and nitriding process.

SURFACE COATING

Surface coating of tool steel may be used formany types of cold work tooling.

The hard material deposited on the tool sur-face is often titanium nitride, titanium carbide ortitanium carbonitride. However, nowadays thereare many other recently developed coatings tochoose from. The very high hardness and lowfriction properties of the coating give a wearresistant surface that lowers the risk for galling.The coating method, tool geometry and toler-ance requirements place certain demands on thetool material.

• PVD (Physical Vapour Deposition)is a method of applying a wear resistant surfacecoating at temperatures around 500°C (930°F).Even lower temperatures can be used for

deposition today. A base material with suffi-cient hardness after high temperature temper-ing is necessary and the coating is put on asthe last operation.

• CVD (Chemical Vapour Deposition)is used for applying wear resistant surfacecoatings at temperatures of around 1000°C(1830°F). With CVD coating, it is necessary tocarry out hardening and tempering (in avacuum furnace) after the coating operation.With this procedure, there is a risk of dimen-sional changes taking place, making it lesssuitable for tools with very tight tolerancedemands.

The Uddeholm cold work steel Vanadis 4 ExtraSuperClean, Vanadis 8 SuperClean and Vanadis 23SuperClean have been found to be particularlysuitable for titanium carbide and titanium nitridecoatings. The uniform carbide distribution inthese steel facilitates bonding of the coating andreduces the spread of dimensional changes re-sulting from hardening. This, together with thematerials’ high strength, improves the bearingproperties of the surface layer deposited.

Uddeholm Vancron 40 SuperClean is normallyused in the uncoated condition to prevent galling.However, sometimes it is necessary to coat if thecontact pressure in the application in question isparticularly high. Excellent results can then beobtained.

The surface coating of tools should bediscussed for specific applications, taking intoaccount the type of coating, tolerance demands,etc., and it is recommended that you contactyour Uddeholm representative for further infor-mation.


PART UDDEHOLM GRADE HRC

1 Die-block Arne, Caldie, Sleipner, Rigor, Sverker 21, Sverker 3,Vanadis 4 Extra, Vanadis 8, Vanadis 23, Vancron 40 54–65

2 Die-insert Sverker 21, Sverker 3, Caldie, Sleipner, Unimax,Vanadis 4 Extra, Vanadis 8, Vanadis 23, Vancron 40 58–65

3 Stripper plate UHB 11 – Fine-machined, Ground Flat Stock

4 Punches Arne, Caldie; Sleipner, Rigor, Sverker 21, Sverker 3,Unimax, Vanadis 4 Extra, Vanadis 8, Vanadis 23,Vancron 40 54–65

5 Backing plate UHB 11 —

6 Die support UHB 11 —

7 Punch holder plate Arne – Ground Flat Stock —

8 Punch backing plate Arne 58–60

9 Top plate UHB 11, Formax —

10 Bottom plate UHB 11, Formax —

11 Strip guide UHB 11 – Fine-machined, Ground Flat Stock —

GENERAL RECOMMENDATIONS—BLANKING DIE SET

PUNCH/DIE CLEARANCES

The optimum punch/die clearance will naturallybe decided at the tool design stage and will takeinto account the thickness and hardness of thework material. Tool users will be aware that in-sufficient or excessive clearance can be respon-sible for severe tool wear. Having established theoptimum clearance, care must naturally be takento ensure that the punch is properly located inrelation to the die aperture to avoid unevencutting pressures, leading to uneven wear andpossibly premature tool failure.

The Vancron and Vanadis steels mentioned in the table are Uddeholm SuperClean cold work tool steels.


Product programmeAVAILABILITY OF UDDEHOLMCOLD WORK TOOL STEEL

From our long experience serving the cold work-ing industry we have become familiar with sizes,grades and tolerances most frequently used.

The ready availability is determined by localstocks, reliable delivery service and comprehen-sive product and size ranges.

LOCAL STOCKS

The location of stock is important if gooddelivery service is to be maintained.

With our world wide marketing organizationwe place great emphasis on matching our stocksize programme and our stock levels to the localneeds of each individual market.

RELIABLE DELIVERY SERVICE

Our widespread network of Uddeholm ware-houses and our complete range of products formthe basis for our delivery service. Each of ourstock locations has a well established distributionsystem.

TAKE THE SHORT CUT TO PRODUCTIVITY!

Purchasing steel in a prefinished form is a smartway of releasing tool making capacity for themore skilled machining operations. Our steelgrades are obtainable in a number of formsand finishes. And many of them have been pre-machined to a greater or lesser degree. Udde-holm tool steel are available as machined and finemachined bars.

It is always possible to find asuitable stock size for the workin hand and thus reduce theamount of unnecessary andexpensive machining.

In all cases a plus machining allowance is made onall sizes to allow for final finishing to a standarddimension.• No machining costs for removal of the decar-

burized surface layer are involved.

• The manufacturing time is shortened, whichmakes planning simpler and calculations moreaccurate.

MACHINED STEEL PLATES

Machining costs can be reduced already at thedesign stage. One way of doing this is to con-struct a tool from machined steel plates, i.e.ground or fine milled to specific dimensions onall sides.

Uddeholm Service Centres are equipped witha full line of processing machinery, includinggrinders, milling machines, cut-off saws and otherequipment.

FINE MACHINED STEEL

Uddeholm’s long experience with tooling materi-als has shown that the most important require-ments stipulated by users of fine machined barsand plates (apart from carefully controlled analy-sis and proper microstructure) are:

• flatness and thickness variation within specifiedtolerances

• minimum risk of shape changes due to therelease of residual stresses during furthermachining

• technically acceptable surface finish

Fine machined bars.


As a result of an extensive development andinvestment programme, Uddeholm can nowsupply an entire range of fine machined bars andplates.

In addition to the advantages for machinedmaterial mentioned above, the use of fine ma-chined material offers the following advantages:

• machining down to final external dimensions isreduced to a minimum

• given a suitable tool design, machining down tofinal external dimensions may be eliminatedcompletely

The fine machined bar is delivered roller markedand wrapped in protective paper in convenientand easy to handle 1030 mm lengths.

Fine machined materials are available in allmajor grades.

WELDING ELECTRODES

Welding consumables are available for the Udde-holm tool steel grades Calmax, Carmo, Caldieand Unimax.

Uddeholm Calmax/Carmo Weld and Udde-holm Caldie Weld basic coated electrodes areavailable in the dimensions 2.5 mm (0.10 inch)and 3.2 mm (0.13 inch) Ø.

Uddeholm Calmax/Carmo Tig-Weld filler rodis available in 1.6 mm (0,06 inch) Ø.

Uddeholm Caldie Tig-Weld filler rod is avail-able in the dimensions 1 mm (0,04 inch) and1.6 mm (0.06 inch) Ø.

Uddeholm Unimax Tig-Weld filler rod is avail-able in the dimension 1.6 mm (0.06 inch) Ø.


UDDEHOLMSTEEL

Uddeholm Arne

(AISI O1, W.-Nr. 1.2510)

Uddeholm Rigor

(AISI A2, W.-Nr. 1.2363)

Uddeholm Sleipner

Uddeholm Sverker 3

(AISI D6, W.-Nr. 1.2436)

Uddeholm Sverker 21

(AISI D2, W.-Nr. 1.2379)

Uddeholm Calmax(W.-Nr. 1.2358)

Uddeholm Unimax

Uddeholm Arne is a general purpose tool steel suitable for a wide variety of cold workapplications. Its main characteristics include good machinability and a good combinationof high surface hardness and toughness after hardening and tempering. These charac-teristics combine to give a steel suitable for the manufacture of short run tooling, back-up and punch holder plates.

Uddeholm Rigor is a tool steel characterized by good machinability, high compressivestrength, good hardenability, moderate toughness and medium wear resistance (mixedtype of wear profile). These characteristics combine to give a steel suitable for themanufacture of medium run tooling.

Uddeholm Sleipner is a tool steel characterized by very high compressive strength,good hardenability, good machinability and grindability, good WEDM’ability, good resist-ance to both adhesive and abrasive wear and high resistance to chipping.

Uddeholm Sleipner has a very wide properties profile and can be used for manydifferent cold work applications in medium production runs. It is particularly suited forblanking and forming of plates with high/ultra high strength.

Uddeholm Sverker 3 is a tool steel characterized by high compressive strength, highsurface hardness after hardening, good through hardening properties and very high wearresistance (abrasive type of wear profile). These characteristics combine to give a steelsuitable for the manufacture of long run tooling for applications where the work mate-rial is particularly abrasive and the demands on toughness are low, e.g. blanking of trans-former plate and pressing of ceramics.

Uddeholm Sverker 21 is a tool steel characterized by high compressive strength, highsurface hardness after hardening, good though-hardening properties and high wearresistance (abrasive type of wear profile). These characteristics combine to give a steelsuitable for the manufacture of medium run tooling for applications where abrasivewear is dominant and the risk of chipping or cracking is not so high, e.g. for blanking andforming of thinner, harder work materials.

Uddeholm Calmax is a tool steel characterized by high compressive strength, highsurface hardness after hardening, good through hardening properties, extremely goodtoughness, good wear resistance (adhesive profile), good flame and induction harden-ability and easy repair welding. These characteristics combine to give a steel suitable forthe manufacture of short to medium run tooling for a very wide range of cold workapplications where adhesive wear dominates and where the risk of chipping or crackingis very high, e.g. for heavy duty blanking and forming.

Uddeholm Unimax is a tool steel characterized by very good chipping and crackingresistance (toughness and ductility are almost the same in all directions), good harden-ability, good machinability and grindability, good WEDM’ability, good resistance toadhesive wear and adequate resistance to abrasive wear

Uddeholm Unimax is a unique problem solver for tooling for medium productionvolumes in severe applications such as heavy duty blanking and cold forging where avery high chipping and cracking resistance are needed.

Uddeholm tool steel grades for cold work tooling


Uddeholm Caldie

UddeholmVanadis 4 Extra SuperClean

UddeholmVanadis 8 SuperClean

UddeholmVanadis 23 SuperClean(AISI M3:2, W.-Nr. 1.3395)

UddeholmVancron 40 SuperClean

Uddeholm Caldie is a tool steel characterized by extremely good combination of highcompressive strength and chipping resistance, good hardenability, good machinability andgrindability, good WEDM‘ability, good resistance to adhesive wear and rather goodresistance to abrasive wear.

Uddeholm Caldie is a unique problem solver in severe cold work applications inmedium production runs where a very good combination of high compressive strengthand chipping resistance is needed. Cold forging of difficult work materials and geo-metries and blanking and forming of advanced high strength sheets are good examples.Uddeholm Caldie is also very suited as substrate material at all types of surfacecoatings.

Uddeholm Vanadis 4 Extra SuperClean is a PM (Powder Metallurgical) tool steel whichis characterized by high compressive strength, high surface hardness after hardening,very good through hardening properties, very high chipping resistance, very good wearresistance (adhesive wear profile) and very good stability in hardening. These charac-teristics combine to give a steel suitable for the manufacture of long run tooling for avery wide range of applications where adhesive wear is dominant and/or the risk ofchipping or cracking is very high, e.g. for blanking and forming of thicker work materialsuch as austenitic stainless steel, mild carbon steel, copper, advanced high strength steeland aluminium, etc. Uddeholm Vanadis 4 Extra SuperClean is a particularly goodsubstrate for CVD coatings.

Uddeholm Vanadis 8 SuperClean is a PM (Powder Metallurgical) tool steel charac-terized by extremely high wear resistance (abrasive wear profile), high compressivestrength, high surface hardness after hardening, very good through hardening properties,good toughness and very good stability in hardening. These characteristics combine togive a steel suitable for the manufacture of very long run tooling where abrasive wear isdominant, e.g. blanking and forming of abrasive material, blanking of electrical steel sheet,blanking of gaskets, paper and foil slitting, granulator knives, extruder screws, etc.

Uddeholm Vanadis 23 SuperClean is a PM (Powder Metallurgical) high speed steelcharacterized by high compressive strength, high surface hardness after hardening, verygood through hardening properties, good toughness, very good wear resistance (mixed/abrasive wear profile), very good stability in hardening and very good temperingresistance. These characteristics combine to give a steel suitable for the manufacture oflong run tooling for a very wide range of applications where mixed or abrasive wear isdominant and where the risk of a plastic deformation of the working surfaces of thetool is high, e.g. blanking of cold rolled steel or hard materials. Uddeholm Vanadis 23SuperClean is a particularly good substrate for PVD coatings.

Uddeholm Vancron 40 SuperClean is a PM (Powder Metallurgical) tool steelcharacterized by very high galling resistance, very high adhesive wear resistance, goodchipping and cracking resistance, high compressive strength, good through hardeningproperties and good dimensional stability in hardening.

Uddeholm Vancron 40 SuperClean’s anti-galling profile means that it is an ideal steelfor high volume production tooling where coatings would normally be needed toprevent galling. It is often not necessary to coat Uddeholm Vancron 40 SuperCleantooling.


UDDEHOLMHOLDER STEEL

Uddeholm Formax

Uddeholm UHB 11

(AISI 1148, W.-Nr. 1.1730)

Uddeholm Formax is a low carbon bolster steel suitable for large top and bottom platesand medium strength supports. Uddeholm Formax is easy to flame cut, weld and caseharden.

Uddeholm UHB 11 is a medium-carbon bolster steel suitable for top and bottom platesand higher strength support parts.

EXECUTIONS AND PRODUCTS

UN- ROUGH HOLLOW FINE PRECISION WELDMACHINED MACHINED BARS MACHINED MACHINED PLATES ELECTRODES

Arne X X X X X

Rigor X X X X

Sleipner X X X X

Sverker 3 X X X

Sverker 21 X X X X X

Calmax X X X X

Unimax X X X

Caldie X X X X

Vanadis 4 Extra* X X X X X

Vanadis 8* X X X X

Vancron 40* X

Vanadis 23* X X X X

UDDEHOLMHOLDERSTEEL

Formax X X X X X

UHB 11 X X X X X

UDDEHOLMSTEEL

OTHER TYPES OF PRODUCTS BAR EXECUTIONS

* PM SuperClean tool steels


SUPPLIEDANALYSIS % HARDNESS

C Si Mn Cr Mo W V S max. Brinell

Arne 0.95 0.3 1.1 0.6 – 0.55 0.1 – 220

Rigor 1.0 0.3 0.6 5.3 1.1 – 0.2 – 235

Sleipner 0.9 0.9 0.5 7.8 2.5 – 0.5 – 240

Sverker 3 2.05 0.3 0.8 12.7 – 1.1 – – 260

Sverker 21 1.55 0.3 0.4 11.3 0.8 – 0.8 – 235

Calmax 0.6 0.35 0.8 4.5 0.5 – 0.2 – 212

Unimax 0.5 0.2 0.5 5.0 2.3 – 0.5 – 200

Caldie 0.7 0.2 0.5 5.0 2.3 – 0.5 – 215

Vanadis 4 Extra* 1.4 0.4 0.4 4.7 3.5 – 3.7 – 270

Vanadis 8* 2.3 0.4 0.4 4.8 3.6 – 8.0 – ≤ 270

NVancron 40* 1.1 0.5 0.4 4.5 3.2 3.7 8.5 1.8 300

Vanadis 23* 1.28 0.5 0.3 4.2 5.0 6.4 3.1 – 260

UDDEHOLMHOLDER STEEL

Formax 0.18 0.3 1.3 – – – – – 230

UHB 11 0.50 0.2 0.7 – – – – – 210

CHEMICAL COMPOSITION

UDDEHOLMSTEEL

* PM SuperClean tool steels


Network of excellenceUddeholm is present on every continent. This ensures you

high-quality Swedish tool steel and local support wherever you

are. We secure our position as the world’s leading supplier of

tooling materials.


UD

DEH

OLM

08.2016.200 / STR

OKIR

K KNA

PPEN 08.2016

Uddeholm is the world’s leading supplier of tooling materials. This

is a position we have reached by improving our customers’ everyday

business. Long tradition combined with research and product develop-

ment equips Uddeholm to solve any tooling problem that may arise.

It is a challenging process, but the goal is clear – to be your number one

partner and tool steel provider.

Our presence on every continent guarantees you the same high quality

wherever you are. We secure our position as the world’s leading

supplier of tooling materials. We act worldwide. For us it is all a matter

of trust – in long-term partnerships as well as in developing new prod-

ucts.

For more information, please visit www.uddeholm.com

Documents

UDDEHOLM TOOL STEELS FOR COLD WORK … TOOL STEELS FOR COLD WORK TOOLING. ... Roof bow. 6 STEEL FOR COLD WORK ... ties that are critical for good resistance to adhe-