WELDING IN THE TOOL SHOP WITH UTP WELDING CONSUMABLES. High speed steels Cold working steels Hot working steels Injection mould steels Cast iron

Transcription

1 WELDING IN THE TOOL SHOP WITH UTP WELDING CONSUMABLES High speed steels Cold working steels Hot working steels Injection mould steels Cast iron

2 G e n e r a l I n d e x Page Page 1. General introduction 3 2. Welding methods Welding with coated electrodes 2.2 TIG welding 2.3 MIG/MAG welding 3. General guide lines for welding of tool steels Reasons for failure of build up welding Welding high speed steels Summary of high speed steels 5.2 Data of high speed steel Appropriate UTP welding consumables for high speed steels 6. Welding of cold working tool steels Ledeburitic Cr-cutting steel with 5-12 % Cr 6.2 Summary of cold working steels 6.3 Data for cold working tool steels Appropriate UTP welding consumables for cold working tools 7. Welding for hot working tool steels Summary of hot working tool steels 7.2 Data for hot working tool steel Data for hot working tool steel Appropriate UTP welding consumables for hot working tools 8. Welding for steels for plastic injection moulds Summary of steels for plastic moulds 8.2 Data for plastic mould steel Appropriate UTP welding consumables for steels for injection moulds 9. Welding of cast iron Summary of cast iron materials 9.2 Appropriate UTP products for cast iron welding 9.3 Appropriate UTP TIG rods or MIG wires for cast iron welding 10. Availability of the UTP products for tool welding 51-52

3 by E. Villinger SFI/EWE 1. General introduction Tool steels are split up into 2 groups, cold working tools and hot working tools. Cutting tools such as blanking punches, cutting blades, trimming tools, shear blades etc. predominately belong to the group of cold working tools. Cold working tools are designed to work (cut, punch, form etc.) on cold materials such as sheet metal, bars, profiles, tubes etc. where heat is generated as a result of the actual working process of cutting, forming, punching and from the friction of the tool on the metal. The temperature of the tool rarely reaches 250 C, eliminating the need of heat resistance in the base metal. In the case of hot working tools such as forging dies, injection moulds, hot shear blades, ingots, press rolls and similar, the metal is worked on in hot condition. Here the properties required are high temperature resistance, good tempering properties and good hot wear resistance against shock, pressure and friction. For many years, repair of worn and damaged tools has been standard procedure in many workshops, bringing enormous financial and technical advantages, since reconditioning by machining or grinding is reduced or even unnecessary. New production of cutting tools in series by build up welding is only economic, if the savings on base metal cost are higher than the welding cost. Therefore, in general, only large tools are produced by build up welding. However, the costs are not always the deciding factor. By using a softer base material the crack resistance is higher and the possibility of dressing the tool is better and, last but not least, delivery problems of special tool base materials may be solved.

4 2. Welding methods 2.1. Welding with coated electrodes In the tool steel welding, coated welding electrodes account for approximately 50 of consumables used. For maintenance welding on tools, the guidelines of the steel manufacturers concerning preparation, pre- heating and interpass temperature should be followed carefully. High chrome- and tungsten containing alloys should be preheated slowly and thoroughly to avoid heat stress and cracks due to the low heat conductibility. Depending on the requirement electrodes with rutile or basic coatings are available. Rutile coated electrodes have a stable, soft spray arc, which allows welding with low amperage. The weld bead is finely rippled with a smooth appearance, which is ideal for welding cutting edges. The slag is self detaching. Basic coated electrodes have a more intense arc with a deeper penetration and a higher bead build up. The bead appearance is not as fine as that of a rutile coated electrode. The weld deposit has a high toughness. The slag does not have to be removed on multi pass welding which is an advantage on large welding jobs. Whenever possible use the stringer bead welding technique. Weaving should be avoided. lf several layers are needed it is advisable to apply 3 layers with an electrode of 2,5 mm diameter instead of 2 layers with an electrode of 3,2 mm diameter. Deposit short stringer beades, remove the slag and lightly peen the bead immediately. Use this procedure until sufficient build up is achieved. Slow cooling in air, under a heat insulating cover or in an oven is advisable. A post heat treatment may be needed.

5 Manual metal arc welding with coated electrodes 1 Mains connection 2 Power source 3 Welding cable 4 Electrode holder 5 Earth cable 6 Work piece A B C D E F G H I Core wire Coating Protective gas Solidfied slag Welding bead Melt bath Metal drop in molten slag Base metal Drop transfer 78-80

6 Tool repair with coated electrode

7 2.2 TIG welding The TIG welding process is particularly suitable for smaller tools and small repair jobs. The advantage is that complicated cutting edges and particularly detailed shapes can be repaired. A small diameter tungsten electrode allows the welder to concentrate high temperature on a small spot and deposit the welding consumable accordingly, without damaging the base material and without any deformation. To control the amperage to the lowest possible setting, the machine should be equipped with a foot switch. TIG rods are available in a wide range of alloys. The shielding gas should be Argon with a purity of 99,996 vol%. The principle of TIG welding 1 Mains connection 2 Power source 3 Welding cable 4 Earth cable 5 Shielding gas bottle 6 Shielding gas hose 7 Welding torch 8 Welding rod 9 Base material A B C D E F G H I Gas nozzle Electrode clamp Non consuming tungsten electrode Shielding gas cover Welding bead Melt bath Arc Welding rod Base material

8 2.3 MIG/MAG welding The MIG/MAG welding process is suitable for depositing large quantities of welding consumable economically. Typical applications are the production of large shear blades out of low alloy base metal or the filling of forging dies to change the pattern or building up on rolls and cones etc. With synergic pulsed arc welding sets, a spatter free deposit can be achieved which, in turn, prevents welding inclusions due to welding over spatter. Generally welding is done with solid wires of 1,2 mm or 1,6 mm diameter. As shielding gas for high alloy tool steel wires Argon or a multi component gas should be used. Flux cored wires are used when no solid wire in the required alloy is available, such as a cobalt alloy. These wires are also welded with shielding gas. The principle of MIG/MAG welding 1 Mains connection 2 Power source 3 Spool of electrode wire 4 Wire feeder unit 5 Shielding gas bottle 6 Welding cable 7 Wire electrode 8 Shielding gas hose 9 Earth cable 10 Welding torch 11 Base material A B C D E Gas nozzle Wire nozzle Wire electrode Shielding gas cover Welding bead F G H I Melt bath Drop transfer Base material Arc

9 3. General guide lines for welding of tool steels Clean welding area, removing all contaminants, i.e. paint, oil, grease. Chamfer sharp edges. Prepare broken out parts and cracks in U-form. Check surface with dye penetrant to ensure that there are no further defects or cracks. Select the appropriate filler material and welding electrode or wire diameter for the job in hand. Wires must be perfectly clean (to avoid porosity); electrodes must be dry. Re-dry if necessary in accordance with the suppliers recommendations. Tool steels are usually not welded at room temperature. Pre-heating- and interpass temperature is determined by the type of base metal, the size and shape of the tool. (Danger of hardness peaks and cracks) Welding has to be done with lowest possible heat input, which means using the lowest possible amperage and voltage. Clean welding bead often, removing slag and residues. On crack susceptible cold working tools apply short stringer beads with small diameter electrodes or wires to avoid risk of cracks caused by shrinkage stress. To obtain heavier deposits angle the tool and weld slightly upwards. Changing of pattern or other substantial welding work should be done in a soft annealed condition and with a high preheating temperature. The welding deposit has to be peened IMMEDIATELY after a weld has been deposited and before the temperature falls below 350 C, which is the lowest interpass temperature for high alloyed tool steel. Never peen cold material! Deposit enough material, in general to a depth of about 1,5-2 mm, to allow correct machining/grinding. After welding slow cooling is necessary and eventually an annealing to reduce welding stress. A post heat treatment is a must after a large welding deposit has been made, such as a filling for pattern change or similar.

10 Welding boot equipped for tool welding Pre-heat and heat maintaining table

11 4. Reasons for failure of build-up welding Mistake in the heat application To hard Thermal shock 1. Pre-heating to low 2. No slow cooling 3. Pre-heating to fast 4. Cooling to fast Mixing to big 5. To big electrode or to high amps Structure problems To much stress Prep. incorrect 6. Bevelling to big 7. No peening or cold peening Welding mistakes 8. To long welding beads 9. Welding cond. not considered pre-heating or cold welding H 2 embrittlement 10. No re-drying of electrodes Porosity 11. No thorough cleaning of weld area Reduc. of hardness 12.To little hardsurfacing on top of buffer layer Hardness to low or not constant Mixing to big 13.Less than 3 layers of hard surfacing 14.To big electrode or to high amps 15. Wrong selection of electrode Not enough hardness 16.Heat treatment not corresponding to the weld deposit To high hardness 17.Pre-heating to low Bead appearance, result after machining Not enough deposit after machining 18. No measuring of depos. Before stopping the building up 19. Qualification of welder not sufficient

12 5. Welding high speed steels High speed steels have, depending on the chemical composition and the heat treatment, a high retention of hardness and high heat resistance up to 600 C. Cutting tools made of high speed steel have good edge retention properties at high temperature giving a high cutting performance. High speed steels are also used for cold cutting tools combining abrasion resistance with toughness. These properties are obtained through a high percentage of special carbides. For repair of high speed steels tools, UTP 690 is used. This easy to use rutile coated electrode is distinguished by its spray arc, smooth bead surface and self detaching slag. Complimentary products: TIG wire UTP A 696 is available. These welding consumables have been developed predominantly for the production of new cutting tools using non- or low alloy base materials. They are also used for repairs on large cutting and forming tools. The hardness of the untreated welding deposit is approx. 60 HRC. A second or third tempering at 550 C is needed to eliminate the remaining austenite (during cooling the remaining austenite is changed to martensite), producing a final hardness of HRC (secondary hardening). When repairing cutting edges, the damaged area has to be cleaned first and pre- heated to appr. 150 C. This pre-heating is sufficient if the damage is small and/or the crack does not go into the base metal. If large parts are broken out or if large surfaces need to be built up, the tool has to be pre- heated thoroughly to C.

13 For small repairs use a TIG torch with a small diameter tungsten electrode. Use lowest possible amperage, fuse the surface carefully and deposit the TIG wire in stringer beads. Cutting tool with edge built up with UTP 690

14 Typical tools made out of high speed steel

15 5.1 Summary of high speed steels Material No. DIN-Design. Chemical composition in % C Cr Mo V W Co S ,35 4,0 0,8 3,8 12,0 4, S ,23 4,0 3,8 3,3 10,0 10, S ,92 4,0 5,0 1,9 6,4 4, S S 0,92 4,0 5,0 1,9 6,4 4, S ,0 4,0 9,5 1,2 1,5 8, S ,8 4,0 0,7 1,6 18,0 4, S ,8 4,0 0,8 1,6 8, S ,0 4,0 2,6 2,3 2, SC S 0,97 4,0 5,0 1,9 6, S 6-5-2S 0,9 4,0 5,0 1,9 6, SC ,97 4,0 5,0 1,9 6, S ,9 4,0 5,0 1,9 6, S ,2 4,0 5,0 2,9 6, S ,8 4,0 8,5 1,2 1, S ,0 3,8 8,6 2,0 1,7 -

16 BÖHLER S600

17 5.2 Data for high speed steel DIN Designation: S Chemical composition: C Si Mn Cr Mo W V 0,9 0,3 0,3 4,0 5,0 6,4 1,9 Properties: Standard alloy for high speed steels, high toughness and good cutting properties, heat resistant up to 600 C, universally applicable Application: Cutting tools for rough work and planing with spiral drill, milling cutter, broaching tools, thread drill, reamers, wood working tools. Also for cold working tools for punching, deep drawing, pressing and cutting. Hot forming: C slow cooling in vermiculite or in the oven Soft annealing: C / 4 h oven cooling annealing hardness HB Stress relief annealing: C / 1-2 h oven cooling Heating: C (0,5 min/mm) = 50 mm thick = 25 min Pre-heating: a) 850 C air circulation oven b) 850 and 1050 C in a salt bath Hardening: a) C / warm bath 550 C/air or b) C / oil or c) C / air Tempering: C min. 2 x Hardness after tempering: HRC

18 5.3 Appropriate UTP welding consumables for high speed steels Coated electrode TIG rod MIG / MAG wire Application Hardness weld deposit UTP 690* UTP A 696* Build up welding on worn tools and of broken out parts on cutting tools. New production of tools in combination with low class base metals HRC UTP 65 D UTP 653 UTP A 651 High strength and tough joints on cracked and broken tools. Cover with 3 layers UTP 690 / UTP A 696 approx. 220 HB * The welding deposit can be heat treated in accordance with the base material.

19 6. Welding of cold working tool steels 6.1 Ledeburitic Cr- cutting steel with 5-12 % Cr These cold working steels are mainly used for press tools for car body parts due to their high resistance against sliding and frictional wear. For large repairs on these air hardened tool steels, the correct preheat is critical. The tools are prepared for welding by grinding. The pre- heating has to be done slowly but thoroughly to C. Allow one hour for every 25 mm of thickness of material to be welded. The build up welding should be applied as follows: Quick repair small repairs on the hard tool, 1-2 layers Large repair multi layer build up on the hard tool Repair with identical material changing of shape or pattern on a soft annealed tool Quick repairs can be carried out with little or no pre- heat of approx. 150 C using Chromium steel electrode UTP 665 or TIG rod UTP A 66. With the pick up of C from the base material, the welding deposit will reach a hardness of approx. 55 HRC. For large repairs (more than 2 layers), the tool has to be pre- heated completely to C. The consumables to be used for welding are the electrode UTP 67 S (basic coated), or the UTP 673 (rutile coated), or the TIG wire UTP A DUR 600. The hardness of the weld deposit is HRC.

20 6.2 Summary of cold working steels Material No. DIN-Design. Chemical composition in % C Si Mn Cr Mo V W C 45 W 0,45 0,3 0, C 60 W 0,6 0,3 0, Cr 1 0,75 0,4 0,7 0, Cr 6 1,45 0,3 0,6 1, Cr 6 1,0 0,3 0,3 1, X 210 Cr 12 2,0 0,3 0,3 12, MnCr 5 0,2 0,3 1,3 1, X165CrV1 2 1,6 0,3 0,3 12,0-0, CrV 3 1,2 0,2 0,2 0,7-0, X63CrMoV5-1 0,6 1,0 0,4 5,3 1,3 0, X100CrMoV5-1 1,0 0,3 0,3 5,3 1,1 0, X220CrVMo12-1 2,2 0,2 0,3 12,0-2, X155CrVMo12-1 1,55 0,3 0,3 12,0 0,7 1, X210CrW12 2,1 0,3 0,3 12, , WCrV7 0,35 0,9 0,9 1,0-0,2 2, WCrV 7 0,5 0,9 0,9 1,0-0,2 2, WCrV7 7 0,5 0,9 0,9 1,6-0,2 2, WCrV 7 0,6 0,6 0,6 1,1-0,2 2, X 1 6 5CrMoV12 1,6 0,3 0,3 12,0 0,6 0,5 0, NiCr 10 0,55 0,2 0,2 0,6 - Ni 2, X45NiCrMo 4 0,45 0,3 0,3 1,4 0,3 Ni 4, MnCrV 8 0,9 0,3 0,3 0,4-0,1 -

21 BÖHLER K110

22 6.3 Data for cold working tool steel DIN Designation: X 155 CrVMo 12 1 Chemical composition: C Cr Mo V 1,55 12,0 0,7 1,0 Properties: Application: Ledeburitic 12 % Cr steel. Highest wear resistance, good toughness. Good cutting edge- and hardness retention. Nitridable after special heat treatment. Thread rollers and -dies, cold extrusion-, cuttingand punching tools for sheet metal up to 6 mm. Cold pilger tools, circular shear knives and deep drawing tools. Hot forming: C slow cooling in vermiculite or in the oven Soft annealing: C / 4 h oven cooling annealing hardness max. 250 HB Hardening: C/warm bath 550 C/air Hardness after quenching: 63 HRC Tempering C: Hardness after tempering HRC:

23 Cutting jaw with partial edge repair Punching die with build up cutting edge

24 6.4 Appropriate UTP welding consumables for cold working tools Coated electrode TIG rod M I G /MAG wire Application Hardness weld deposit UTP 665 UTP A 66 Cutting edge build up on annealed Cr-cutting tools. Crack resistant tough, for one or max. two layers (quick repair) approx. 55 HRC UTP 67 SST Multi layer build up on soft annealed Cr steel, colour and structure match. 40 HRC untreated UTP 67 S UTP A DUR 600 Universal build up alloy for tempered cold steel and unalloyed base steel. Natural hardness for multi layer build up UTP 673 UTP A 673 Multi layer build up on annealed cold working tools and unalloyed base material, natural hardness UTP 65 D UTP A 651 High tensile and tough joints on cracked and broken cutting tools. On cutting edges overlay with hard deposit HRC untreated HRC untreated approx. 220 HB

25 Welding preparation and seam build up on cutting edges a) Low cutting pressure (bevelled edge preparation) b) High cutting pressure (saddle preparation with rounded edges and corners)

26 7. Welding of hot working tool steel Hot working steels have, due to their chemical composition, high heat resistance, reteniton of hardness and good hot wear resistance against impact, pressure and friction up to 550 C. The Mo- Cr steels are, due to their good heat conductibility, very resistant against hot cracks under thermal shock, making them ideal for press dies, injection moulds and hot rolling rolls etc. (1.2343, , ). The Ni- Cr- Mo steels are, due to their toughness, particularly suitable against impact load (1.2713, ). Welding on hot working tool steels can be done with precipitaion hardening, martensitic or workhardening welding consumables. lt is also important that cracks are gouged out completely. The Cr- Mo steels must be pre-heated to approx. 400 C, the Ni- Cr- Mo steels to min. 300 C. The welding can be done with consumables with characteristics similar to the base metal, which give the required hardness. These tool steels should after substantial quantities of welding material have been deposited, be stress relieved at approx. 550 C.

27 Filling of a defect with UTP 73 G 3 Partial repair of an Al-injection mould

28 For build up welding on injection tools the use of age hardenable martensitic material (Maraging Steel) is recommended, due to its high wear resistance. For this repair the tool is pre-heated to approx. 150 C and welded by maintaining this temperature. The deposited material has a hardness of approx. 37 HRC. Age hardening at 480 C / 3-4 h will bring the tool to a hardness of 53 HRC. On forging tools, very good results are obtained by using work hardening high Ni- and Co-base alloys. These alloys have an initial hardness after Build up of the whole die pattern with Ni-alloy deposition of approx. 240 and 320 HB respectively. In operation, due to impact and pressure the hardness will increase to approx. 45 HRC. The available welding consumables can be used for partial repairs, for complete reconditioning, or for filling whole defects. For their particulars see table 7.3.

29 Build up welding on an axial roller with UTP AF CELSIT 721 Build up welding on a mandril with UTP A 73 G 3

30 Material No DIN-Design. Chemical composition in % C Si Mn Cr Mo Ni V W 7.1 Summary of hot working tool steels CrMnMo 7 0,4 0,3 1,5 1,9 0, CrMnMoS 8-6 0,4 0,4 1,5 1,9 0,2 - - S 0, CrMoV 6-7 0,45 0,3 0,8 1,5 0, X 38 CrMoV 5-1 0,38 1,0 0,4 5,3 1,3-0, X 40 CrMoV 5-1 0,4 1,0 0,4 5,3 1,4-1, X 63 CrMoV 5-1 0,6 1,0 0,4 5,3 1,2-0, X 32 CrMoV 3-3 0,32 0,3 0,3 3,0 2,8-0, X 40 CrMoV 5-3 0,4 0,4 0,5 5,0 3,0-0, X 30 WCrV 4-1 0,3 0,9 0,4 1, ,2 3, X 30 WCrV 5-3 0,3 0,2 0,3 2, ,6 4, X 30 WCrV 9-3 0,3 0,2 0,3 2, ,4 8, X 37 CrMoW 5-1 0,37 1,0 0,5 5,3 1,5-0,3 1, X 45 CoCrWV ,45 0,4 0,4 4,5 0,5 2,0 Co 4,5 4, NiCr 6 0,45 0,3 0,8 1,4-1, NiCrMoV 6 0,55 0,3 0,8 0,7 0,3 1,7 0, NiCrMoV 7 0,56 0,3 0,8 1,1 0,5 1,7 0, NiCrMoV7-7 0,57 0,3 0,8 1,1 0,8 1,7 0, X 19 NiCrMo 4 0,2 0,3 0,3 1,2 0,2 4, X 45 NiCrMo 4 0,45 0,3 0,3 1,3 0,3 4, X 20 Cr 13 0,2 0,5 0, X 22 CrNi 17 0,22 0,4 0,5 16,5-1, X 30 CrNiMoV 3-1 0,3 0,3 0,7 2,8 0,6 1,0 0, X 50 NiCrWV ,5 1,3 0, , X 32 CrMoCoV ,32 0,3 0,3 3,0 2,8 Co 2,8 0, X 20 CoCrWMo ,2 0,25 0,5 8,5 2,2 Co 9,5-6, X 45 CoCrMoV ,45 0,4 0,4 4,5 3,0 Co 4,5 2, X 30 CoCrMoV , ,0 2,8 Co 2,8 0, X 3 NiCoMoTi ,03 < 0,1 < 0,15-5,0 18 Co 10 Ti 1

31 BÖHLER W500

32 7.2 Data for hot working tool steel DIN Designation: 56 NiCrMoV 7 Chemical composition: C Cr Mn Mo V 0,55 1,1 1,7 0,5 0,1 Properties Application Die steel with high toughness and excellentthrough hardening Forging dies of all kinds, forming dies shear knives, extruder screws, cutting blades Hot forming: C slow cooling in vermiculite or in the oven Soft annealing: C / 4 h oven cooling annealing hardness max. 250 HB Hardening: C / oil C / air Hardness after quenching: Oil 58 HRC Air 56 HRC Tempering: Hardness after tempering HRC Oil HRC Air

33 BÖHLER W302

34 7.2.1 Data for hot working tool steel DIN Designation: X 40 CrMoV 5 1 Chemical composition: C Si Cr Mo V 0,40 1,0 5,3 1,4 1,0 Properties: Application: High heat resistance, high hot wear resistance, good heat conductibility and hot crack resistance. Universally suitable, particularly for injection- and continuous cast moulds for AI-alloys, for forging tools and dies and hot shear knives. Hot forming: C slow cooling in vermiculite or in the oven Soft annealing: C / 4 h oven cooling annealing hardness max. 230 HB Hardening: C oil / air or C hot bath Hardness after quenching: 54 HRC (1910 N/mm²) Tempering C Hardness after tempering HRC N/mm²

35 Filled up engraving of a forging die (UTP A 73 G 3) New engraving in forging die

36 Coated electrode TIG rod MIG /MAG wire Application Hardness weld deposit 73 G 4 73 G 3 73 G 2 A 73 G 4 A 73 G 3 A 73 G 2 Single- and multi-layer build up on similar CrMo- and NiCrMo steels for shear blades, moulds, dies, trimming dies, rolls fill welding HRC HRC 7.3 Appropriate UTP welding consumables for hot working tools 702 A 702 Build up on CrMo steels in particular injection moulds (Maraging steel) Celsit 706 Celsit 712 Celsit 701 A Celsit 706 V AF Celsit 706 A Celsit 712 SN AF Celsit 712 A Celsit 701 N AF Celsit 701 Heat resistant Co-alloys for applications involving thermal shock such as hot shear blades, hot punching- and trimming tools. Partial build up welding HRC untreated HRC aged 4 h / 480 C HRC HRC HRC Celsit 721 A 776 A 776 A 776 A Celsit 721 AF Celsit 721 High heat resistant Ni-alloy for tools having to support very high pressure and thermal shock such as forging tools, mandrils, shear blades. Machinable with cutting tools 220 HB (400 K) 240 HB (400 K) 260 HB (450 K) 320 HB (450 K) (Co-alloy) 65 D Mo 6218 Mo A 651 A 651 A 068 HH A 6222 Mo Buffer layers, welding of cracks, joining, as well as easy machinable, high heat resistant build up. 220 HB (350 K) 240 HB (350 K) 190 HB (350 K) 230 HB (450 K)

37 Hot cutting blade of a billet shear Cutting edge build up with Ni-alloy

38 8. Welding of steels for plastic injection moulds Steels are selected for plastic moulds according to the operating conditions and for economical purposes. Depending on the working process we can differentiate between Press- and injection tools for hardenable plastics (Duroplast) and Injections tools for non hardenable plastics (Thermoplast) The welding consumable requirements can differ, however high wear resistance, good heat conductibility, dimensional accuracy at temperatures of C, and a polishable deposit are required in both cases. In addition, press tools have to have high pressure resistance and toughness. For certain plastics corrosion resistance is also needed. The decision to use either low- or high alloy steel as a base material depends on the application of the form of the die. Frequently used are the annealable steels quality and Welding on these materials is done with a pre-heat of C. In general the weld filler metal used has a similar alloy to the base metal and is applied either as an electrode or a TIG rod (see table 6.3). In case where a tool has been surface hardened and has to be repair welded, the hard layer must be removed prior to welding. For this kind of repair, the TIG rod UTP A 702 has proved to be very useful.

39 Material-No. DIN-Design. Chemical composition in % C Si Mn Cr Mo Ni V S Hardened steel Mn Cr 5 0,21 0,3 1,3 1, X 6 CrMo 4 0,04 0,1 0,1 3,8 0, X 19 NiCrMo 4 0,19 0,3 0,3 1,3 0,2 4,1 8.1 Summary of steels for plastic moulds Heat treatable steel CrMnMo 7 0,4 0,3 1,5 1,9 0, CrMnMoS 6-8 0,4 0,4 1,5 1,9 0,2 0, X 40 CrMoVS 5-1 0,4 1,0-5,2 1,3 1,0 0, CrMnNiMo ,4 0,3 1,5 2,0 0,2 1, NiCrMo 16 0,35 0,3 0,5 1,3 0,3 4,0 Corrosion resistant steel X 21 Cr 13 0,2 0,4 0,4 13, X 40 Cr 13 0,42 0,4 0,3 13, X 36 CrMo 17 0,36 0,4 0,4 17,0 1, X 20 CrMo 13 0,2 0,4 0,4 13,0 1,2 Through hardening steel NiCrMoV 6 0,55 0,3 0,8 0,7 0,3 1,7 0, X 38 CrMoV 5-1 0,38 1,0 0,4 5,3 1,3 0, X 45 NiCrMo 4 0,45 0,3 0,3 1,4 0,3 4, MnCrV 8 0,9 0,3 2,0 0,4-0, X 210 Cr 12 2,0 0,3 0, Nitriding steel CrAINi 7 0,35 0,5 1,7 0,2 1,0 Al 1,0 Age hardening steel X 3 NiCoMoTi ,03 0,1 0,15 Ti 1,0 5,0 18,0 Co 10,0 Block steel C45W 0, 45 0, 3 0, 7 - -

40 8.2 Data for plastic mould steel DIN Designation: 40 CrMnMoS 8 6 Chemical composition: C Si Mn Cr Mo S 0,4 0,4 1,5 1,9 0,2 0,07 Properties: Application: Through heat treatable, good machinability also in heat treated condition, polishable Plastic forms and - moulds, form holding blocks, receiver coatings Hot forming: C slow cooling in vermiculite or in the oven Soft annealing: C / 4 h oven cooling / 235 HB Hardening: C oil / air or C hot bath Hardness after quenching: 51 HRC (1730 N/mm²) Tempering C Hardness after tempering HRC N/mm²

41 Die cast form for plastic made from material No

42 8.3 Appropriate UTP welding consumables for steels for injection moulds Coated electrode TIG rod MIG /MAG wire Application Hardness weld deposit 641 Kb A 641 Build up and joints on case hardening and heat treatable steel approx. 200 HB 73 G 4 73 G 3 73 G 2 A 73 G 4 A 73 G 3 A 73 G 2 Build up on similar heat treatable and through hardened steel with corresponding hardness HRC HRC HRC A 651 A 66 Build up welding on corrosion resistant steels with high C-content approx. 220 HB approx. 350 HB A 63 Crack resistant and tough joints and build up, stainless approx. 180 HB 6025 A 6025 Build up and joints on Ni-containing case hardening- and heat treatable steel 702 A 702 Build up on nitriding and aged steels approx. 180 HB approx. 37 HRC

43 Plastic press die lower and upper part made from material

44 9. Welding of cast iron Welding of cast iron is needed when cracks or surface wear appear and/or when a change of pattern is required. Cast iron tools are generally used for forming sheet metal for the car industry and are, as such, large parts. Due to this, welding can only be carried out using the cold welding" method. In addition to the standard forms of cast iron, with lamellar or nodular graphite structure, there are also CrMoand CrNi alloyed cast irons in use. Cast iron with lamellar graphite is very brittle, has virtually no yield strength and no elongation. The pressure resistance is approx. 6 x higher that the tensile strength and is therefore similar in its behaviour to that of concrete. It is therefore evident, that the flakes of graphite reduce the resistance of the ferritic of the perlitic structure. On the other hand, graphite improves the gliding properties of the cast iron material and gives good wear resistance when forming tools. The most successful way to carry out cold welding on cast iron is by using either pure Nickel or Ferro- Nickel electrodes with a graphite coating. Steel electrodes have, due to their very limited elongation, a tendancy to produce cracks or even to break out. Prior to welding, the base material surface has to be cleaned thoroughly. A skindrying with an oxyacetylene torch with a reducing flame may be necessary to clean oil and grease from the welding area. From experience it has been shown that organic residues on the surface to be welded lead to porosity. If porosity appears in the first layer, this layer must be removed again by grinding.

45 UTP 86 FN UTP 8 C Substantial change of the form of a cast iron press tool

46 As a buffer layer for a build up, and for buttering on a joint the electrode recommended is a pure Nickel type. These types of electrode have in general a very good alloying characteristic and can be welded with DC straight polarity or with AC. The crack resistance is improved by depositing short beads followed immediately by a peening. The welding deposit of Nickel is highly ductile and workable. Residual stress is relieved during cooling by peening the weld lightly. Ferro- Nickel type electrodes are recommended for cover layers on build up and joints. The welding deposit has a slightly higher tensile strength, corresponding to GGG 50. To grind Nickel base deposits Fe- and S- free grinding discs are recommended. The discs are normally marked accordingly. The highest crack resistance on multi layer welding is obtained by using an electrode with a Bi- metallic Ferro- Nickel core wire (UTP 86 FN), weldable on DC straight polarity or AC. The current carrying capacity of this electrode is very high and prevents overheating completely. Also this deposit should be peened to reduce welding stress. Very large and substantial building up repairs can be done by using our Ferro- Nickel MIG wire UTP A 8051 Ti.

47 Form change on a cast iron press tool Micrograph of the transition zone GGG 40 to UTP 86 FN

48 Material Mat. No. Structure Tensile Hardness Yield strength Elong. typ strength HB (min) R p0,2 (min) A 5 N/mm² N/mm² % GG ferritic GG GG Summary of cast iron materials GG GG GG GG perlitic GGG ferritic GGG GGG GGG GGG GGG GGG perlitic GG - CrMo alloyed cast iron GG - CrNi Tensile strength values are minimum values in accordance with DIN 1691 and DIN 1693

49 Edge build up on a cast iron press tool with UTP 807

50 9.2 Appropriate UTP products for cast iron welding UTP Electrodes Application Hardness Current 8 C Buffer layer on joints and building up on large cast iron parts with lamellar graphite structure. approx. 180 HB = - / -. Joint welds on thin walled cast iron parts 85 FN 86 FN Joining and build up welding on GG and GGG cast iron parts, particularly for multi-layer welding and for wear resistant building up on worn out tools. approx. 190 HB approx. 220 HB = + / 807 Nickel free special electrode for colour matching and wear resistant build ups on GG and GGG cast iron. A buffer layer with Nickel or Ferro-Nickel is recommended. approx. 230 HB - + / 82 AS Electrode for gouging and chamfering - - / --

51 9.3 Appropriate UTP TIG rods and MIG wires for cast iron welding UTP type Application Hardness A 80 Ni TIG rod with approx. 95 % Ni for build up and joints approx. 150 HB A 387 A 80 M A 068 HH A 8051 Ti Cu-Ni type TIG rod with approx. 70 % Cu and 30 % Ni for build up on cast iron. High ductility, low tensile strength. Ni-Cu type TIG rod with approx. 70 % Ni and 30 % Cu (Monel) for joining and build up on all kinds of cast iron. Ni-Cr-Fe type rod with approx. 70 % Ni and 20 % Cr for joining and build up on all kinds of cast iron, high tensile strength Ferro-Nickel type MIG wire for high strength joints and build up on all types of cast iron. approx. 120 HB approx. 150 HB approx. 180 HB approx. 220 HB

52 UTP type Electrodes Ø mm TIG rods Ø mm MIG/MAG-wires Ø mm * 6302* A 63 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 65 D A 651 * 1,5 / 2,0 / 2,5 / 3,2 / 4,0 1,2 / 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 10. Availability of the UTP Products for 67 S A DUR 600 2,5 / 3,2 / 4,0 67 SST* 2,5 / 3,2 / 4,0 1,2 / 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 tool welding 73 G 2 A 73 G 2 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 1,0 / 1,2 / 1,6 73 G 3 A 73 G 3 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 1,0 / 1,2 / 1,6 73 G 4 A 73 G 4 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 1,0 / 1,2 / 1,6 82 AS 2,5 / 3,2 / 4,0 641 Kb* A 641 * 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 653* 2,0 / 2,5 / 3,2 / 4,0 665* A 66* 2,5 / 3,2 / 4,0 1,2 / 1,6 673 A 673 2,0 / 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 1,2 / 1,6 690 A 696* 2,0 / 2,5 / 3,2 / 4,0 1,6 / 2,4 1,2 702 A 702 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 1,2 807* 2,5 / 3,2 / 4,0 *) available on demand 6025* A 6025* 2,5 / 3,2 / 4,0 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6

53 UTP type Electrodes Ø mm TIG rods Ø mm MIG/MAG-wires Ø mm 8 8 C* A 80 Ni 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 A 80 M 1,6 1,0/1,2/1,6 10. Availability of the UTP Products for tool welding 85 FN 86 FN A 8051 Ti 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 2,4 0,8 / 1,2 A 387 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 700* * A 776 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1, Mo* A 6222 Mo 7015 Mo A 068 HH Celsit 706 A Celsit 706 V AF Celsit 706 Celsit 712 A Celsit 712 SN AF Celsit 712 Celsit 701 A Celsit 701 N AF Celsit 701 Celsit 721 A Celsit 721 AF Celsit 721 2,5 / 3,2 / 4,0 2,5 / 3,2 / 4,0 3,2 / 4,0 3,2 / 4,0 3,2 / 4,0 3,2 / 4,0 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 1,6 / 2,0 / 2,4 0,8 / 1,0 / 1,2 / 1,6 3,2 / 4,0 1,2 / 1,6 3,2 / 4,0 1,2 / 1,6 3,2 / 4,0 1,2 / 1,6 3,2 / 4,0 1,2 / 1,6 *) available on demand