TS · tool steel
Tool Steel H13 (hot work)
The hot-work die steel, and the one that gets the most use in this shop for aluminium die-casting tooling. Annealed it machines like a tough alloy steel; at 48–52 HRC it is a grind or hard-turn job.
Quoting this material
- Typical lead time
- 14–22 working days
- Condition
- Annealed, or supplied pre-hardened at 28–32 HRC for machining the finished cavity
- 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.
The hot-work die steel, and the one that gets the most use in this shop for aluminium die-casting tooling. Annealed it machines like a tough alloy steel; at 48–52 HRC it is a grind or hard-turn job.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Hardness (working) | 48–52 | HRC |
| Hot strength | Retained to 540 °C | - |
| Thermal fatigue resistance | High | - |
| Toughness | High | - |
| Thermal conductivity | 28.6 | W/m·K |
| Modulus of elasticity | 210 | 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, or supplied pre-hardened at 28–32 HRC for machining the finished cavity
Heat treatment
Austenitise around 1,000–1,040 °C, quench (air or oil depending on section), temper twice at 540–600 °C. The high tempering temperature is the point: it leaves the steel resistant to softening at 500 °C+, which is what a die casting die or a forging die sees.
Achievable surface finish
Ra 0.8 µm after grinding
Ra 0.2 µm (polished)
Cavity surfaces are polished, sometimes to a mirror finish; a thermal fatigue crack starts where the polish is interrupted.
Tooling and cutting parameters
Cutting speed
- 100–180 m/min annealed (carbide) · 60–100 m/min at 30 HRC pre-hardened
Feed
- 0.10–0.25 mm/rev turning · 0.06–0.15 mm/tooth milling
Tooling
- Coated carbide; the pre-hardened 30 HRC condition is a good compromise for a machined cavity
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
- Aluminium die-casting dies and inserts
- Forging dies and hammer tooling
- Extrusion tooling
- Hot shear blades
- Die casting shot sleeves and tips
DFM notes for this grade
- Pre-hardened 28–32 HRC stock lets you machine the cavity to near-final form before hardening, which is the usual way to keep a complex cavity accurate
- Thermal fatigue is the failure mode, not wear: a sharp internal corner in a die casting die cracks from the thermal cycle, so radii are functional
- Where a die needs repair welding, H13 is one of the few tool steels designed for it - preheat and a matching filler are still required
Questions buyers ask
- Why is H13 the standard die-casting die steel?
- Because it holds hardness at temperature and resists thermal fatigue. A die cycling between 200 °C and 700 °C with liquid aluminium is a thermal shock application; the steel has to keep its strength and not crack at the surface where the cycle repeats.
- Should the die be machined annealed or pre-hardened?
- Pre-hardened at 28–32 HRC for most die work - the cavity can be machined to near-final size, then hardened and only the critical fits are ground. For a very complex cavity, machining annealed and hardening afterwards gives more freedom in the tool path but more distortion to manage.