Heat Treatment Process for 7Cr7Mo2V2Si Steel

7Cr7Mo2V2Si is a cold-work die steel characterized by high strength and toughness; it is widely used in industrial manufacturing due to its excellent processability, wear resistance, and high-temperature strength and hardness.
 
The physical properties of 7Cr7Mo2V2Si include:
· Critical temperatures: Ac1 856°C, Ac3 915°C, Ar3 806°C, Ar1 720°C, Ms 105°C
· Coefficient of linear expansion: Ranges from 8.2 × 10⁻⁶ to 12.9 × 10⁻⁶ 1/°C across different temperature ranges (20–700°C)
· Density: 7.8 g/cm³
· Modulus of elasticity: 225,400 MPa
 
Optimization of 7Cr7Mo2V2Si Heat Treatment Process:
• Annealing Pre-treatment:
Soak at 850–870°C for 2–4 hours; furnace cool to 500°C followed by air cooling; target hardness ≤255 HB; eliminates carbide networks.
• Quenching Process:
• Preheating: Preheat at 600–650°C to reduce thermal stress;
• Austenitizing: Soak at 1020–1050°C (0.5–1.5 min/mm); oil quench or high-pressure gas quench; hardness 60–62 HRC;
• High-temperature quenching option (1150°C): Suitable for applications requiring high toughness, such as heavy-duty cold extrusion dies.
• Tempering Strategy:
• Low-temperature tempering: 180–220°C, tempered 2–3 times; hardness 58–60 HRC; for tools requiring high wear resistance (e.g., precision blanking dies);
• Medium-temperature tempering: 450–520°C, tempered twice; hardness 54–56 HRC; balances toughness and wear resistance (e.g., cold heading dies);
• High-temperature tempering option (530–570°C): Tempered three times; hardness 59–62 HRC; optimizes the balance of strength and toughness.
• Cryogenic Treatment: Performed after tempering (-70 to -196°C) to enhance dimensional stability.
 
7Cr7Mo2V2Si is widely used in:
Cold-working dies (such as those for cold forging, cold punching, cold pressing, and cold bending), high-speed cutting tools, bearings, automotive components, and high-strength structural parts for the aviation and aerospace industries.