STEELS FOR HOT WORK APPLICATIONS. Torbjörn Spångberg, Olle Tönnberg, Bengt Klarenfjord, Uddeholm Tooling AB

Transcription

1 STEELS FOR HOT WORK APPLICATIONS Torbjörn Spångberg, Olle Tönnberg, Bengt Klarenfjord, Uddeholm Tooling AB

2 Hot work Plastics HPS Cold work 2

3 Hot work applications h Die casting h Extrusion h Forging 3

4 Typical failures in hot work applications Heat checking ( thermal fatigue ) Gross cracking Erosion / Hot wear Soldering 4

5 The demand on the die steel 5

6 Important die steel properties Temper resistance Hot yield strength Creep strength Thermal expansion Heat conductivity Ductility / Toughness 6

7 For a good performance you need both a good die steel and a good heat treatment 7

8 Uddeholm hot work programme ALVAR ALVAR ORVAR 2 Microdized VIDAR 1 ORVAR SUPREME ORVAR SUPERIOR VIDAR SUPERIOR QRO QRO SUPREME HOTVAR DIEVAR UNIMAX 8

9 Steel Chemical composition % C Si Mn Cr Ni Mo V ALVAR 0,45 0,7 0,8 1,8 0,6 0,3 0,2 ALVAR 14 0,55 0,3 0,7 1,1 1,7 0,5 0,1 VIDAR ,0 0,4 5,0 1,3 0,4 VIDAR SUPERIOR 0,36 0,3 0,3 5,0 1,3 0,5 ORVAR 2M 0,39 1,0 0,4 5,3 1,3 0,9 ORVAR SUPREME ORVAR SUPERIOR 0,39 1,0 0,4 5,2 1,4 0,9 0,39 1,0 0,4 5,2 1,4 0,9 DIEVAR 0,35 0,2 0,5 5,0 2,3 0,6 UNIMAX 0,50 0,2 0,5 5,0 2,3 0,5 QRO 90 SUPREME 0,38 0,3 0,8 2,6 2,3 0,9 HOTVAR 0,55 1,0 0,8 2,6 2,3 0,9 9

10 PRODUCTION LINE ESR Electric arc furnace Ladle furnace Vacuum degasing Up-hill casting Control / Inspection Machining Homogenizing treatment Test certificate Heat treatment Forging Rolling Warehouse 10

11 Process development Total oxygen content (ppm) and toughness, KV, (J) Toughness Oxygen content Remelting under protected atmosphere Special heat treatments 11

12 Microstructural influence on the ductility 12

13 Test certificate Chemical composition Microcleanliness Annealed microstructure and hardness As quenched hardness and grain size Impact toughness Ultrasonic inspection 13

14 Effect of time on hardness at 600 C ORVAR SUPREME and ALVAR HRC ORVAR SUPREME ALVAR h 14

15 Effect of time on hardness at 550 C HRC hours ORVAR SUPREME QRO 90 SUPREME HOTVAR VIDAR SUPERIOR 15

16 Effect of time on hardness at 600 C HRC hours ORVAR SUPREME QRO 90 SUPREME HOTVAR VIDAR SUPERIOR 16

17 Yield strength at elevated temperatures HOTVAR, 58 HRC; QRO 90 SUPREME, 48 HRC; ORVAR SUPREME, 53 HRC; VIDAR SUPERIOR, 45 HRC; DIEVAR, 47/48 HRC MPa Temperature C ORVAR SUPREME QRO 90 SUPREME HOTVAR VIDAR SUPERIOR DIEVAR 17

18 Toughness at elevated temperatures centre and short-tranverse direction Charpy V, J DIEVAR 45 HRC ORVAR SUPREME 45 HRC QRO 90 SUPREME 45 HRC C VIDAR SUPERIOR 45 HRC 18

19 Toughness at elevated temperatures centre and short-transverse direction Charpy V, J DIEVAR 38 HRC DIEVAR 45 HRC C DIEVAR 47 HRC 19

20 Testing of creep resistance 20

21 Creep testing at 550ºC and 500MPa 6 5 Strain [%] H13 Hotvar Dievar QRO 90 Supreme 1030ºC Hours 21

22 Testing of heat checking Air 22

23 Heat checking test result Max sprickdjup (um) C/air/800 cycles DIEVAR ORVAR SUPREME T A =1025 C/30min Hårdhet (HRC)

24 Min toughness values in short-transverse direction at 44 46HRC Charpy V Min toughness values ORVAR SUPREME ORVAR SUPERIOR VIDAR SUPERIOR DIEVAR 24

25 Rersistance to hot wear, plastic deformation and thermal fatigue Product mapping HOTVAR QRO 90 SUPREME UNIMAX ORVAR 2M VIDAR 1 DIEVAR ORVAR SUPERIOR ORVAR SUPREME VIDAR SUPERIOR ALVAR 14/ALVAR 25 Resistance to cracking

26 ALVAR 14 / ALVAR Application areas eg support tools in extrusion and also forging dies 26

27 ORVAR 2 Microdized VIDAR 1 Typical application area is Al-extrusion. Dies and components. 27

28 ORVAR SUPREME / SUPERIOR Used in hot work applications as an universal steel grade. Die casting and forging. 28

29 VIDAR SUPERIOR Used in die casting and forging. 29

30 DIEVAR Used in die casting and forging when the demands on hot strength and ductility/toughness are high. 30

31 DIEVAR Customer benefits Fewer interruptions in in production Better surface quality of of produced parts Increased die life Possibility for producing larger parts Possibility for larger multi-cavity dies Longer running periods between maintenance work 31

32 QRO 90 SUPREME Used in small dies, inserts and cores. Eg brass die casting and forging. Also for hard loaded extrusion dies and components. 32

33 HOTVAR Used in applications where hot wear or plastic deformation are the dominating failure mechanisms. Eg small forging dies. 33

34 UNIMAX Recommended in hot work applications where high hardness in combination with high ductility and toughness are needed. Eg Mg - die casting, forging dies and large extrusion dies. 34

35 The Cost Iceberg Visible costs Material / heat treatment Die making Hiden costs Maintenance Interruptions in production Less availability in production line Less after-treating of parts Delivery delays 35

36 Trends in hot work and demands on tool steels Larger dies needed with highest quality for long run production Better wear resistance Improved hardenability Improved ductility and toughness Improved strength at elevated temperatures 36

37 TRUST IS SOMETHING YOU EARN, EVERY DAY.