S2 vs S5
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.
S2
Tool Steel
S2 is a water-hardening shock-resisting steel with high silicon and molybdenum but no chromium or tungsten. It delivers S-class toughness in small hand and pneumatic tools at the lowest alloy cost.
Standards: AISI S2
S5
Tool Steel
S5 uses about 2% silicon to reach exceptional toughness — in classic tool steel comparisons it tops the shock-resistance chart. It is chosen for the most violent impact tools in the shop.
Standards: DIN — (1.2419 family, near) · AISI S5
Chemical composition compared (%)
| Element | S2 | S5 |
|---|---|---|
| C | 0.40–0.55 | 0.50–0.65 |
| Si | 0.90–1.20 | 1.75–2.25 |
| Mn | 0.30–0.50 | 0.60–1.00 |
| Mo | 0.30–0.60 | 0.20–0.40 |
Properties compared
| Property | S2 | S5 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 50–58 HRC (water quench, shallow) | 52–59 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Toughness | — | Among the highest of all tool steels |
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: S2 · S5. Substitution decisions for certified parts stay with the design authority.