A4
Data under reviewA4 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.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.95–1.05 |
| Si | 0.10–0.50 |
| Mn | 1.80–2.20 |
| Cr | 0.90–1.20 |
| Mo | 0.90–1.40 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness (hardened) | 56–61 HRC |
| Density | 7.85 g/cm³ |
Heat treatment
Harden 940–980 °C air; temper 175–260 °C, double temper recommended.
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | A4 |
| gb | Cr5Mo1V (near) |
Compare side by side: A4 vs A2 · A4 vs A6
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Blanking dies, forming dies, punches, bushings, machine-tool parts.
Processing: Good machinability annealed; low distortion on air hardening; less carbide than A2, so edges are tougher but wear life is shorter.
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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.