A36 is structural hot-rolled steel sold by mechanical spec rather than exact chemistry, so machinability varies from bar to bar. Expect mill scale on the surface and a tendency toward built-up edge.
Key properties
| Property | Typical value |
|---|---|
| Density | 0.284 lb/in³ (7.85 g/cm³) |
| Hardness | ~120 HB |
| Tensile strength | ~58,000–80,000 psi |
| Machinability | Fair (variable) |
| Composition | Low-carbon mild steel |
Cutting speeds
| Operation | HSS (SFM) | Carbide (SFM) |
|---|---|---|
| Milling | 70 – 100 | 250 – 450 |
| Turning | 80 – 110 | 300 – 500 |
| Drilling | 50 – 80 | 180 – 320 |
Convert to RPM: RPM = (SFM × 3.82) / cutter diameter. Use the Feeds & Speeds calculators.
Tooling and tips
- Get under the abrasive mill scale on the first pass rather than skimming it.
- Sharp TiN/TiAlN carbide and flood coolant; expect some built-up edge.
- Composition varies, so treat published speeds as a starting point and adjust.
See Cutting Speeds for Steel and the full Feeds and Speeds Chart.