A6 vs A4
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.
A6
Tool Steel
A6 is a low-temperature air-hardening cold work steel: its high manganese content lets it harden from temperatures normally used for oil-hardening grades. The result is very low distortion with moderate wear resistance.
Standards: AISI A6
A4
Tool Steel
A4 is an air-hardening medium-alloy cold work steel using high manganese plus about 1% chromium and molybdenum for deep hardening. It offers A2-like dimensional stability with simpler chemistry and lower cost.
Standards: AISI A4 · GB Cr5Mo1V (near)
Chemical composition compared (%)
| Element | A6 | A4 |
|---|---|---|
| C | 0.65–0.75 | 0.95–1.05 |
| Si | 0.10–0.50 | 0.10–0.50 |
| Mn | 1.80–2.50 | 1.80–2.20 |
| Cr | 0.90–1.20 | 0.90–1.20 |
| Mo | 0.90–1.40 | 0.90–1.40 |
Properties compared
| Property | A6 | A4 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 54–59 HRC | 56–61 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: A6 · A4. Substitution decisions for certified parts stay with the design authority.