CrWMn 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.
CrWMn
Tool Steel
CrWMn is the classic Chinese gauge and die steel (GB/T 1299): a Cr-W-Mn oil-hardening grade famous for minimal size change on hardening, used across China for precision gauges and intricate dies.
Standards: AISI O1 family (near) · JIS SKS2 (near) · GB CrWMn (GB/T 1299)
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 | CrWMn | O1 |
|---|---|---|
| C | 0.90–1.05 | 0.85–0.95 |
| Si | ≤0.40 | 0.10–0.40 |
| Mn | 0.80–1.10 | 1.00–1.20 |
| Cr | 0.90–1.20 | 0.50–0.70 |
| W | 1.20–1.60 | 0.50–0.70 |
| V | — | 0.05–0.15 |
Properties compared
| Property | CrWMn | O1 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 58–62 HRC | 57–62 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Distortion | Very low (oil hardening) | — |
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: CrWMn · O1. Substitution decisions for certified parts stay with the design authority.