AISI A2: Air-Hardening Medium-Alloy Cold Work Tool Steel
ASTM A681 · Published: 2026-06-03 · Updated: July 2026
AISI A2 is an air-hardening cold work tool steel that achieves full hardness with minimal distortion — the primary advantage over oil-hardening O1. Its 5% chromium content provides moderate wear resistance, while air cooling eliminates the quench...
AISI A2 is an air-hardening cold work tool steel that achieves full hardness with minimal distortion — the primary advantage over oil-hardening O1. Its 5% chromium content provides moderate wear resistance, while air cooling eliminates the quench cracking risk and distortion of liquid quenching. It is used for blanking and forming dies, plastic mold cavities, and shear blades.
Quick Facts
| Category | Tool Steel |
| Standard | ASTM A681 |
| Density | 7.80 g/cm³ |
| Yield Strength | 1,450-1,720 MPa |
| Tensile Strength | 1,620-1,930 MPa |
Global Equivalents & Cross-Reference
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Frequently Asked Questions
Why choose A2 over D2?
A2 offers better dimensional stability during hardening (air cool vs oil quench), better machinability in the annealed condition, and adequate wear resistance for moderate production volumes. D2 offers superior wear resistance for long-run stamping but is harder to machine and grind. A2 is the practical choice for toolrooms without extensive grinding capability.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu