31CrMoV9
Chemical Composition:
Carbon C: 0.27~0.34
Silicon (Si): ≤0.40
Manganese (Mn): 0.40~0.70
Sulfur S: ≤0.035
Phosphorus P: ≤0.025
Chromium (Cr): 2.30~2.70
Molybdenum (Mo): 0.15~0.25
Vanadium V: 0.10~0.20
Material Parameters:
Delivery Hardness: 245~255 HB.
Forging Temperature: 1100℃-850℃.
Physical Parameters:
Density: (kg/dm³) 7.73
Modulus of Elasticity: (MPa) 210
20℃ Resistance: (Ω mm²/m) 0.19
Thermal Conductivity at 20℃: (W/m·K) 43.0
20℃ Specific Heat Capacity: (J/kg K) 441
Thermal expansion coefficient under annealing conditions: (1/1,000,000)
20 – 100 ℃ 11.5
20 – 200 ℃ 12.5
20 – 300 ℃ 13.3
20 – 400 ℃ 13.9
Mechanical properties
Diameter (mm) | ≥ 16 ≤ 40 | > 40 ≤ 100 | > 100 ≤ 160 | > 160 ≤ 250 |
Yield Strength (MPa) | 900 | 800 | 700 | 650 |
Tensile Strength (MPa) | 1100-1300 | 1000-1200 | 900-1100 | 850-1050 |
Elongation (L0 = 5 d0) (%) | 9 | 10 | 11 | 12 |
Pendulum Impact Test ISO-V (J) | 25 | 30 | 35 | 40 |
Heat Treatment
Editor
Ms： 360℃
AC1： 775℃
AC3： 835℃
Annealing and Softening
The softening annealing is carried out at temperatures between 680℃ and 720℃, followed by a slow cooling process.
Hardening
Quench in water at temperatures between 840℃-870℃.
Quench in oil at temperatures between 850°C and 880°C.
Hardening is carried out at temperatures between 540℃ and 680℃, followed by air cooling.
