S1 vs S7
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.
S1
Tool Steel
S1 is the original tungsten shock-resisting tool steel, built for tools that take repeated hammer blows. Its Cr-W chemistry gives safe hardening with outstanding toughness at working hardness.
Standards: DIN 1.2550 (close) · AISI S1 · GB 5CrW2Si (near)
S7
Tool Steel
S7 is an air-hardening shock-resisting steel with 3.25% chromium and molybdenum, combining S-class toughness with low distortion and some hot hardness. It bridges cold work, impact tooling and light hot work.
Standards: DIN 1.2357 (close) · AISI S7 · GB 5Cr3Mn1SiMo1 (near)
Chemical composition compared (%)
| Element | S1 | S7 |
|---|---|---|
| C | 0.40–0.55 | 0.45–0.55 |
| Si | 0.15–1.20 | 0.20–1.00 |
| Mn | 0.10–0.40 | 0.20–0.90 |
| Cr | 1.00–1.80 | 3.00–3.50 |
| W | 1.50–3.00 | — |
| V | 0.15–0.30 | ≤0.35 |
| Mo | — | 1.30–1.80 |
Properties compared
| Property | S1 | S7 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 50–58 HRC | 52–60 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Toughness | Excellent (shock-resisting) | Outstanding, air 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: S1 · S7. Substitution decisions for certified parts stay with the design authority.