Figure 1 – Hot stability of GW650 and H13 (HRC)

Temperature/

       Time

 620°C 640°C
Grade 2h 4h 11h 2h 4h 11h
GW650 46.3 44.0 40.6 43 40.2 33.6
H13 43.1 42.30 38.0 40.2 37.4 32.0

 

Figure 1-1 – Hot stability of GW650 and 3Cr2W8V(~H21/1.2581) (HRC) at 650°C

Time\

Grade

 0 20' 40' 1h 2h 4h 5h
3Cr2W8V 49.2 46.5 44.0 41.7 39.9 36.1 34.8
GW650 49.5 49.1 47.8 46.9 44.8 41.6 40.2

** 3Cr2W8V steel quenching at 1150°C, tempering at 500°C x 1h x 3 times, air-cooled
** GW650 steel quenching at 1080°C, tempering at 590°C x 3h, 580°C x 3h, oil-cooled

 

Mechanical properties:

 

Figure 2 – Examples of hot die steel’s mechanical properties under high temperature

Grade 600°C 650°C 700°C

Бb

Mpa

Бs

Mpa

δ

%

ψ

%

Бb

Mpa

Бs

Mpa

δ

%

ψ

%

Бb

Mpa

Бs

Mpa

δ

%

ψ

%
5CrNiMo 313 262 69.0 91.1 177 142 101 96.1 99.0 76.0 105.9 96.4
H13 946 834 20.5 72.9 620 556 24 83.2 198 160 53.4 98.8
3Cr2W8V 1104 959 11.2 15.4 808 718 5.4   415 364 26.6 70.8
GW650 1104 922 11.3 40.7 855 745 8.8 22.5 489 448 19.2 81.9

 

Figure 3 – Examples of hot die steel’s impact toughness (ak-cm2)

Temperature\

Grade

 20°C 200°C 250°C 300°C 350°C 400°C
5CrNiMo 6.08 21.36 22.16 24.22 22.56 22.07
4Cr5W2VSi 14.61 30.18 37.07 38.25 39.03 40.01
GW650 9.12 65.66 68.94 82.57 75.22 79.14

** 5CrNiMo is similar to DIN 1.2711/1.2713, GOST 5XHM steel

** 3Cr2W8V is similar to DIN 1.2581, AISI H21, GOST 3Х2В8Ф steel

** 4Cr5W2VSi is similar to GOST 4Х5В2ФС steel

 

Thermal fatigue performance:

 

Figure 4 - Thermal fatigue cracks of GW650 steel

Cycle times Thermal fatigue crack length /mm
Distance from surface /mm
0.45 0.90 1.35 1.70 2.35
500 0.855 0.762 0.427 0.421 -
1000 1.827 1.901 1.292 1.170 0.605
1500 - 2.870 1.775 1.170 1.122
2000 - - 2.156 1.120 1.340

** Test environment: 650°C ⇋250°C, water cooled

 

Figure 5 - Thermal fatigue performance comparison

Grade Thermal fatigue crack length /mm
longitudinal crosswise
5CrNiMo 3.39 1.20
4Cr5W2VSi 0.45 0.42
GW650 0.31 0.26

 

Depth and surface hardness of ion nitriding layer:

 

Figure 6 - Depth and surface hardness of ion nitriding layer of GW650 steel

Nitriding temperature

/°C

Holding time

/h

Depth

/mm

Surface hardness

/HV0.5
460 10 0.12 114~1320
530 10 ~0.16 1120
580 10 0.28 1095
640 10 0.35~0.38 810~824

 

Coefficient of thermal conductivity : λ W/(m·K)

 

Temperature °C 100 200 300 400 500 600 700 800 900
λ(annealed) 35.17 35.58 35.58 36.0 36.0 36.0 35.17 33.50 31.40
λ(Q+T) 30.15 31.0 31.82 32.24 32.66 32.66 32.66 32.66 31.40

 

Coefficient of linear expansion : α(mm/(mm·°C))

Temperature °C 20~100 20~200 20~300 20~400 20~500 20~600 20~700
Αx 10-6 10.07 10.81 11.58 11.94 12.28 12.64 12.91