A8
Data under reviewA8 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.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.50–0.60 |
| Si | 0.75–1.10 |
| Mn | 0.20–0.50 |
| Cr | 4.75–5.25 |
| Mo | 1.15–1.65 |
| W | 2.00–2.50 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness (hardened) | 52–58 HRC |
| Density | 7.85 g/cm³ |
Heat treatment
Harden 980–1010 °C air; temper 480–540 °C for secondary hardness in warm service.
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | A8 |
Compare side by side: A8 vs A2 · A8 vs H42
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Warm forming dies, extrusion tooling, blanking dies for heated stock, shear blades.
Processing: Air hardening with low distortion; toughness is better than D2, wear resistance lower.
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Ask for a quotationVisit NasteelSource: ASTM A681 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.