General-purpose cold-work tool steel — gauges, jigs, punches, form tools, knives. Sold as “ground flat stock / gauge plate”.
| Property | Typical value |
|---|---|
| Density | 7850 kg/m³ |
| Hardness | Annealed ~190–220 HB |
| Hardened | 57–62 HRC (oil quench, temper 150–250 °C) |
| Young's E | 210 GPa |
| CTE | ~11 µm/m·K |
| Thermal cond. | ~30–33 W/m·K |
| Max service | ~180 °C (tempered 150–250 °C — softens above temper) |
| Poisson ν | ~0.29 |
| Shear modulus G | ~81 GPa (derived) |
| Specific heat | ~460 J/kg·K |
| Elec. resistivity | — |
| Melting range | ~1410–1420 °C |
Machines well annealed; finish-grind after hardening (some distortion in oil quench).
Not welded; specialist repair with full preheat/PWHT only.
| System | Designation |
|---|---|
| EN | 100MnCrW4 / 1.2510 |
| DIN | 100MnCrW4 / 1.2510 |
| AISI | O1 |
| ASTM | A681 O1 |
| JIS | ≈SKS3 |
| BS | BS 4659 BO1 |
| UNS | T31501 |
Equivalents & alternatives: BO1 / 1.2510 (100MnCrW4); AISI O1. Alt: A2 (air-hardening, stabler), D2 (wear resistance).
