17-4 PH is a precipitation-hardening stainless combining stainless corrosion resistance with high strength. Machine it in condition A (solution annealed) or an overaged temper; it work-hardens, so keep tools sharp and feeding.
Key properties
| Property | Typical value |
|---|---|
| Density | 0.282 lb/in³ (7.80 g/cm³) |
| Hardness (condition A) | ~363 HB (~38 HRC) |
| Hardness (H900) | ~44 HRC |
| Machinability | Fair (work-hardens) |
| Composition | Fe with ~17% Cr, 4% Ni, 4% Cu |
Cutting speeds
| Operation | HSS (SFM) | Carbide (SFM) |
|---|---|---|
| Milling | 40 – 60 | 150 – 280 |
| Turning | 50 – 70 | 180 – 330 |
| Drilling | 30 – 50 | 100 – 180 |
Convert to RPM: RPM = (SFM × 3.82) / cutter diameter. Use the Feeds & Speeds calculators.
Tooling and tips
- Sharp TiAlN or AlTiN carbide, rigid setup, and constant flood coolant.
- Commit to a real chip load and never dwell — it hardens under a rubbing edge.
- Harder aged conditions (H900) cut slower than condition A.
See Cutting Speeds for Stainless Steel and the full Feeds and Speeds Chart.