O1
Data verifiedO1 is a general-purpose oil-hardening tool steel — cheap, easy to heat treat with basic equipment, and dimensionally stable enough for short-run tooling.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.85–0.95 |
| Si | 0.10–0.40 |
| Mn | 1.00–1.20 |
| Cr | 0.50–0.70 |
| W | 0.50–0.70 |
| V | 0.05–0.15 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness (hardened) | 57–62 HRC |
| Density | 7.85 g/cm³ |
Heat treatment
Harden 790–820 °C oil; temper 150–250 °C. Simple hardening, forgiving for small shops.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.2510 |
| aisi | O1 |
| jis | SKS3 |
| gb | 9CrWMn |
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Gauges, bushings, short-run blanking dies, woodworking tools, forming rolls.
Processing: Machines well; harden in oil with modest distortion. Not for large or intricate dies (use A2/D2 air-hardening instead).
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Ask for a quotationVisit NasteelSource: ASTM A681 / EN published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.