High-speed steel: M2 vs. 6542
M2 high-speed steel (American AISI/SAE standard) and W6Mo5Cr4V2 high-speed steel (Abbreviation: 6542，Chinese GB standard) are essentially the same material, but with different naming systems. The following is a detailed comparison:
1. Correspondence between High speed steel grades and standards
| Standard system | China GB | US AISI/ASTM | Europe EN/DIN | Japan JIS |
| Grade | W6Mo5Cr4V2 | M2 | 1.3343 | SKH51 |
Core conclusion: 6542 = M2 = W6Mo5Cr4V2, the three are equivalent to the same material, the difference is the different names under the international standard.
2. Chemical composition comparison
| Element | C | W | Mo | Cr | V |
| M2 | 0.78-0.88 | 5.5-6.75 | 4.5-5.5 | 3.75-4.50 | 1.75-2.2 |
| 6542 | 0.80-0.90 | 5.5-6.75 | 4.5-5.5 | 3.80-4.40 | 1.75-2.2 |
Consistency: The composition ranges of the two are highly overlapping. The national standard 6542 is completely aligned with the American standard M2, and the core elements (W, Mo, Cr, V) are controlled consistently.
3. Performance and application comparison
Common characteristics:
- Red hardness: Maintains HRC60+ hardness at 600℃ (due to high W, Mo, V carbide stability).
- Wear resistance: Vanadium (V) carbide hardness reaches HV2800, with excellent wear resistance.
- Application scenarios:
– High-speed cutting tools (drills, milling cutters, turning tools)
– High-temperature molds (die-casting molds, hot punches)
– Precision gear tools (hobs, gear shaping cutters)
Minor differences:
- Metallurgy process: M2 may use electroslag remelting (ESR) to improve purity, and 6542 can also be optimized by ESR (please specify).
- Non-metallic inclusions: High-end M2 has stricter inclusion control (such as ASTM ≤1.5 level), but high-quality 6542 can also meet this standard.
4. Heat treatment process consistency
The heat treatment parameters of both are completely universal:
- Annealing: 850-870℃ → slow cooling to 500℃ (hardness ≤255 HB)
- Quenching: 1210-1240℃ (salt bath/vacuum furnace) → graded cooling (500-600℃ salt bath)
- Tempering: 540-570℃ × 3 times (hardness HRC 63-66)
5. Material selection suggestions
| Scenario | Recommended selection | Reasons |
| Export tools/high-end tools | Nominal "M2" | Comply with international procurement practices |
| Domestic conventional tool production | 6542 (W6Mo5Cr4V2) | Lower cost, equivalent performance |
| Extreme working conditions (such as aerospace tools) | ESR smelted M2/6542 is preferred | Higher purity requirements |
Common misunderstandings clarified
- Misunderstanding 1: “6542 is a simplified version of M2”
–The truth: GB 6542 and US standard M2 are the same material, and the performance difference comes from the smelting/heat treatment level, not the grade itself. - Misunderstanding 2: “Imported M2 must be better than 6542”
–The truth: High-quality 6542 that complies with GB/T 9943 has the same performance as imported M2.
Summary
- 6542 is M2 high-speed steel under the Chinese national standard system. The chemical composition, heat treatment process, and core performance of the two are exactly the same.
- When choosing, pay attention to the material implementation standard (such as GB/T 9943) and supplier quality control, rather than the name difference.
- Under the premise of proper heat treatment, 6542/M2 can meet the needs of high-speed cutting, high-temperature wear resistance and other scenarios.
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