O2 vs O1
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.
O2
Tool Steel
O2 is an oil-hardening manganese tool steel that hardens deeper and more uniformly than O1 at the same simple heat treatment. It is a long-standing European and Asian shop standard as 1.2842 / 9Mn2V.
Standards: DIN 1.2842 · AISI O2 · JIS SKS31 (near) · GB 9Mn2V
O1
Tool Steel
O1 is a general-purpose oil-hardening tool steel — cheap, easy to heat treat with basic equipment, and dimensionally stable enough for short-run tooling.
Standards: DIN 1.2510 · AISI O1 · JIS SKS3 · GB 9CrWMn
Chemical composition compared (%)
| Element | O2 | O1 |
|---|---|---|
| C | 0.85–0.95 | 0.85–0.95 |
| Si | 0.10–0.50 | 0.10–0.40 |
| Mn | 1.40–1.80 | 1.00–1.20 |
| Cr | ≤0.50 | 0.50–0.70 |
| V | ≤0.30 | 0.05–0.15 |
| W | — | 0.50–0.70 |
Properties compared
| Property | O2 | O1 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 57–62 HRC | 57–62 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
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: O2 · O1. Substitution decisions for certified parts stay with the design authority.