A8 vs A2
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.
A8
Tool Steel
A8 is an air-hardening 5% chromium cold work steel with tungsten and molybdenum, positioned between A2 and the hot work family. Its secondary-hardening response suits cold work tools that run warm, such as extrusion backers and warm-heading dies.
Standards: AISI A8
A2
Tool Steel
A2 is an air-hardening 5% chromium cold work steel with much better toughness than D2 and far less distortion than oil-hardening grades. It is the default upgrade from O1 where die size or intricate shapes make quench cracking a risk.
Standards: DIN 1.2363 · AISI A2 · JIS SKD12 · GB Cr5Mo1V
Chemical composition compared (%)
| Element | A8 | A2 |
|---|---|---|
| C | 0.50–0.60 | 0.95–1.05 |
| Si | 0.75–1.10 | 0.10–0.50 |
| Mn | 0.20–0.50 | 0.40–1.00 |
| Cr | 4.75–5.25 | 4.75–5.50 |
| Mo | 1.15–1.65 | 0.90–1.40 |
| W | 2.00–2.50 | — |
| V | — | 0.15–0.50 |
Properties compared
| Property | A8 | A2 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness (hardened) | 52–58 HRC | 57–62 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Toughness | — | Good for cold work |
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: A8 · A2. Substitution decisions for certified parts stay with the design authority.