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.
See Cutting Speeds for Steel and the full Feeds and Speeds Chart.