Tool Steel
O1
The classic oil-hardening cold-work grade: easy to machine and heat-treat with low distortion. The default for one-off tooling, gauges, and dies.
Last verified: 2026-07-10
| AISI classTool-steel group (hardening method / application). | O — oil-hardening |
|---|---|
| Carbon(%C)Nominal carbon content. | 0.9 |
| Key alloyingPrincipal alloying elements (nominal). | Mn, Cr, W |
| Working hardness(HRC)Typical hardened + tempered working range. | 57–62 |
| Wear resistance | Moderate |
| Toughness | Moderate |
| Typical uses | Gauges, jigs, cutting tools, low-volume blanking/forming dies |
- Typical uses: gauges, jigs and fixtures, cutting and forming tools, low-run dies.
- Oil-hardening with low distortion; the general-purpose, economical tool steel.
- Lower wear resistance than A2/D2 — choose those for long production runs.
Other tool steels
Sources
- AISI tool-steel classification (type letters and nominal compositions)
- ASM International — Tool Steels / Heat Treater's Guide (typical properties and working hardness)