M2 high-speed steel (such as AISI M2 in the United States or W6Mo5Cr4V2 in China) is a high-carbon, high-alloy tool steel known for its excellent red hardness (ability to maintain hardness at high temperatures) and wear resistance. Its hardness mainly depends on the heat treatment process. The following are detailed data and analysis:
1. Conventional Hardness Range of M2 High Speed Steel
Hardness after quenching + tempering:
- Rockwell hardness (HRC): usually reaches 63~67 HRC (the hardness of common applications such as tools and drills is about 64-65 HRC).
- If cryogenic treatment or optimized tempering process is performed, the hardness can be close to 68 HRC (close to the lower limit of hardness of cemented carbide).
2. Comparison With Other Materials
| Material | Typical hardness (HRC) | Comparison description |
| M2 high-speed steel | 63~67 | High wear resistance, suitable for high-speed cutting |
| D2 tool steel | 58~62 | Wear resistance but not as red hard as M2 |
| Cemented carbide (YG8) | 70~75 | Harder but brittle and expensive |
| Ordinary carbon steel (such as 1045 steel) | 20~25 | For reference only, much lower than tool steel |
3. Key Factors Affecting Hardness of M2
- Quenching temperature: usually 1220~1240°C oil quenching to ensure carbide dissolution and austenitization.
- Tempering process: multiple tempering (such as 560°C×3 times) can eliminate residual austenite and improve hardness.
- Alloy composition: high vanadium (V) and tungsten (W) content forms hard carbides (such as VC, WC), which directly enhances wear resistance.
4. Performance in Practical Applications
- Cutting tools: can still maintain ≥60 HRC below 600°C, suitable for processing difficult-to-cut materials such as stainless steel and titanium alloy.
- Limitations: Although the hardness is high, the toughness is lower than that of low-alloy steel (such as S7), and the edge may break under extreme impact loads.
5. Common User Questions
Q: Can M2 reach 70 HRC?
A: Conventional heat treatment is difficult to achieve, and the surface hardness needs to be improved through coating (such as TiN) or surface treatment (such as nitriding).
Q: How does it compare with M42 high-speed steel?
A: M42 (containing cobalt) has better red hardness (68~70 HRC), but M2 is more cost-effective.
If you have a specific application scenario (such as tool design or heat treatment parameter optimization), you can further discuss the process details!
