M4 vs T15
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
M4
Tool Steel
M4 raises carbon and vanadium to about 4% each over the M2 base, giving outstanding abrasive wear resistance among conventional (non-PM) high-speed steels. It is a premium choice for punches and heavy-duty cutters.
Standards: DIN — (HS6-5-4 family) · AISI M4 · JIS SKH57 (near) · GB W6Mo5Cr4V3
T15
Tool Steel
T15 combines high carbon, about 5% vanadium and 5% cobalt on a 12% tungsten base — the wear-resistance flagship of the conventional T-series. It serves abrasive cutting and cold work where M4-class steels wear too fast.
Standards: DIN 1.3202 · AISI T15 · JIS SKH10 · GB W12Cr4V5Co5
Chemical composition compared (%)
| Element | M4 | T15 |
|---|---|---|
| C | 1.25–1.40 | 1.50–1.60 |
| Si | ≤0.45 | ≤0.40 |
| Mn | ≤0.40 | ≤0.40 |
| Cr | 3.75–4.75 | 3.75–5.00 |
| Mo | 4.00–5.50 | — |
| W | 5.25–6.75 | 11.75–13.00 |
| V | 3.75–4.75 | 4.50–5.50 |
| Co | — | 4.75–5.25 |
Properties compared
| Property | M4 | T15 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 63–66 HRC | 64–67 HRC |
| Density | 7.95 g/cm³ | 8.20 g/cm³ |
| Wear resistance | Very high (4% vanadium) | Extreme (5% vanadium + cobalt) |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: M4 · T15. Substitution decisions for certified parts stay with the design authority.