A2 is an air-hardening cold-work tool steel, prized for good wear resistance with low distortion in heat treat. Machine it in the annealed state, then harden — fully hardened A2 (57–62 HRC) is a grinding job.
Key properties
| Property | Typical value |
|---|---|
| Density | 0.284 lb/in³ (7.86 g/cm³) |
| Hardness (annealed) | ~95 HRB |
| Hardness (hardened) | 57–62 HRC |
| Machinability (annealed) | Fair |
| Composition | Fe with Cr, Mo, V |
Cutting speeds
| Operation | HSS (SFM) | Carbide (SFM) |
|---|---|---|
| Milling | 50 – 70 | 200 – 350 |
| Turning | 60 – 80 | 250 – 400 |
| Drilling | 40 – 60 | 150 – 250 |
Convert to RPM: RPM = (SFM × 3.82) / cutter diameter. Use the Feeds & Speeds calculators.
Tooling and tips
- Always machine annealed; leave grind stock for after heat treat.
- TiAlN carbide, flood coolant, and a rigid setup.
- Maintain feed pressure so the tool cuts rather than rubbing and glazing.
FAQ
Should A2 be machined before or after heat treatment? Nearly always before. A2 tool steel is far easier to machine in the annealed state, with final hardening, typically to 57 to 62 HRC, done after rough and often finish machining, and grinding used afterward for tight-tolerance surfaces.
See Cutting Speeds for Steel and the full Feeds and Speeds Chart.