TS · tool steel
Tool Steel O1 (oil hardening)
A classic oil-hardening tool steel: machines well in the annealed state, hardens to 60–64 HRC, and needs a careful quench because it moves more than an air-hardening grade.
Quoting this material
- Typical lead time
- 10–18 working days
- Condition
- Annealed; hardened in oil and tempered for service
- Achievable finish
- Ra 0.8 µm after grinding typical · Ra 0.2 µm (polished) best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
A classic oil-hardening tool steel: machines well in the annealed state, hardens to 60–64 HRC, and needs a careful quench because it moves more than an air-hardening grade.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Hardness (working) | 60–64 | HRC |
| Wear resistance | High | - |
| Toughness | Good | - |
| Distortion in hardening | Moderate to high | - |
| Thermal conductivity | 30 | W/m·K |
| Modulus of elasticity | 205 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Annealed; hardened in oil and tempered for service
Heat treatment
Austenitise around 780–820 °C, quench in oil, temper twice at 175–260 °C. Oil quenching is a faster, more severe quench than air, so the section change and the masking for the quench have to be thought about on a complex tool.
Achievable surface finish
Ra 0.8 µm after grinding
Ra 0.2 µm (polished)
Grinds easily, which is one reason it remains popular despite the harder quench.
Tooling and cutting parameters
Cutting speed
- 100–170 m/min annealed (carbide) · 35–55 m/min at 62 HRC (CBN)
Feed
- 0.10–0.25 mm/rev turning · 0.05–0.12 mm/tooth milling
Tooling
- Coated carbide annealed; CBN for hardened
Coolant
- Flood
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Cutting tools and form tools
- Punches and small dies
- Gauges and measuring fixtures
- Woodworking and press tooling
- Knives and shear blades
DFM notes for this grade
- It is an oil-quench steel: on a thin, unsupported section the quench can crack the part, and the geometry has to be designed for it
- A classic choice for gauges and small tools where the grindability matters more than the distortion
- Where distortion would be unacceptable, move to A2 - the air quench moves less for a modest cost in wear resistance
Questions buyers ask
- Why is O1 still used when A2 is easier to harden?
- Because it is cheaper, it grinds easily and it takes the finest edge of the common tool steels. For a small cutting tool or a gauge, the grindability and edge quality are worth more than the quench convenience.
- What is the risk with oil quenching?
- Warping and cracking, especially at a sharp section change or on a long thin part. The part has to be designed so heat can leave evenly; a die with a standing boss next to a thin section is a crack waiting to happen unless it is quenched in a fixture.