M2 is the most widely used high speed steel. Tungsten, molybdenum and vanadium let it stay hard at the high temperatures of fast cutting, so it is used for drills, taps, milling cutters, tool bits and long-life punches. It hardens to about 62–65 HRC.
Quick facts
- Type
- Molybdenum-tungsten high speed tool steel
- Working hardness
- About 62–65 HRC
- Red hardness
- Keeps cutting hardness up to about 550–600 °C
- As supplied
- Annealed, about 240–270 HB
- Machinability
- Fair in the annealed condition; grind after hardening
- Also called
- HSS, 1.3343, SKH51, BM2
Equivalent grades
| Standard | Grade |
|---|---|
| AISI | M2 |
| DIN / EN | 1.3343, HS6-5-2 |
| JIS | SKH51 |
| BS | BM2 |
Equivalents are close, not identical. Name the grade and standard on the drawing.
Typical chemical composition
| Element | % |
|---|---|
| Carbon (C) | About 0.85–0.95 |
| Tungsten (W) | About 6 |
| Molybdenum (Mo) | About 5 |
| Chromium (Cr) | About 4 |
| Vanadium (V) | About 2 |
Values are typical. The exact limits depend on the standard and supplier; ask for the mill test certificate when it matters.
Heat treatment
- Preheat in stages (about 500 and 850 °C) to avoid cracking
- Harden at about 1190–1230 °C (vacuum or salt bath)
- Quench in oil, salt or high-pressure gas
- Temper two or three times at about 540–560 °C
- Final hardness about 62–65 HRC
Typical uses
- Drills, taps, reamers and milling cutters
- Tool bits and form tools
- Punches and dies for long runs
- Broaches and saw blades
Need parts made in M2 high speed steel (HSS)?
Post your requirement free. Workshops that take your kind of work see it and get in touch. You only talk to the ones that fit.
Get startedRelated
Questions
- What is the hardness of M2 HSS?
- About 62–65 HRC after hardening and triple tempering, depending on the hardening temperature and tempering.
- M2 or D2 for punches?
- D2 is cheaper and very wear resistant for general blanking. M2 is tougher and keeps its hardness when the punch gets hot, so it is chosen for fast, long runs and thicker material.
- Why is HSS tempered three times?
- After hardening, some austenite remains in the steel. Each tempering converts more of it, so double or triple tempering gives a stable, tough tool with the full hardness.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 15 October 2026.