The universal cold-work tool steel — A2 offers good wear resistance and excellent dimensional stability in heat treatment (minimal distortion because it air-hardens instead of quenching in oil). Slightly lower wear resistance than D2 but much tougher; easier to grind and polish. The default for punches, dies, form tools, and precision fixtures where dimensional control matters.
Size change during heat treat typically <0.05%, vs 0.2%+ for oil-hardening tool steels. Critical for tight-tolerance dies.
Chromium content (5%) gives decent wear; carbon level (1%) balances wear with impact resistance.
Softer in annealed state than D2 or M2 — faster to rough-machine and finish.
| Element | Content |
|---|---|
| Iron | Balance |
| Carbon | 0.95–1.05% |
| Chromium | 4.75–5.50% |
| Molybdenum | 0.9–1.4% |
| Vanadium | 0.15–0.50% |
| Manganese | 1.0% max |
Composition per ASTM A681. Specific mill test reports (MTR) available on request for production orders.
A2 machines at ~65% of 1018 in annealed condition. Never attempt to cut hardened A2 with conventional carbide — grinding only.
After heat treat, surfaces must be ground to final dimension. Budget 0.25–0.50 mm grinding stock on critical surfaces.
A2 is the balance point. If tooling fails by wear, step to D2; if it fails by chipping, step to S7.
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