Material · Carbon, Alloy & Tool Steels
Tool Steel O1
The gauge-maker steel: predictable oil quench, fine edges, the easiest tool steel to work with.
Price index: $$$
Material properties
| Parameter | Value |
|---|---|
| Tensile strength | — (specified by hardness) |
| Yield strength | — (specified by hardness) |
| Hardness | 57–62 HRC (hardened) |
| Density | 7.81 g/cm³ |
Choose it when
For gauges, knives and small tooling made in ones and twos: the most forgiving tool steel to machine annealed and heat treat, holding fine edges and tight dimensions after an oil quench.
Look elsewhere when
Oil quench distorts more than A2/D2 air hardening on large or asymmetric tools, and wear life trails both in production dies. Rusts readily — oil or black-oxide after finishing.
Compatible finishes
As-Machined
The baseline finish: straight off the machine, fastest and cheapest.
Black Oxide
Black with zero dimensional change: the gauge-and-tool finish for precision steel.
PTFE Coating (Teflon)
The slippery armor: fluoropolymer for low friction, non-stick release and chemical inertness.
Laser Marking
Permanent identification with zero dimensional change: serials, logos and codes burned in, not stuck on.
Typical applications
- Gauges and inspection tooling
- Knives and cutting tools
- Small forming dies and bushings
Compared with similar grades
| Property | Tool Steel O1 | Low-Carbon Steel 1018 | Carbon Steel 1045 | Structural Steel A36 |
|---|---|---|---|---|
| Tensile strength | — (specified by hardness) | 440 MPa (cold drawn) | 625 MPa (cold drawn) | 400–550 MPa |
| Yield strength | — (specified by hardness) | 370 MPa (cold drawn) | 530 MPa (cold drawn) | 250 MPa (min) |
| Hardness | 57–62 HRC (hardened) | 126 HB | 179–229 HB | ~120 HB |
| Density | 7.81 g/cm³ | 7.87 g/cm³ | 7.85 g/cm³ | 7.85 g/cm³ |
| Price index | $$$ | $ | $$ | $ |
| Machinability | 2/5 | 4/5 | 3/5 | 4/5 |
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