TS · tool steel
Tool Steel D2 (high chromium cold work)
Annealed it machines reasonably but it is abrasive on the tool because of the chromium carbides. At 60 HRC the only options are grinding, hard turning or EDM.
Quoting this material
- Typical lead time
- 12–20 working days
- Condition
- Annealed; hardened 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.
Annealed it machines reasonably but it is abrasive on the tool because of the chromium carbides. At 60 HRC the only options are grinding, hard turning or EDM.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Hardness (working) | 58–62 | HRC |
| Wear resistance | Very high | - |
| Toughness | Moderate | - |
| Distortion in hardening | Higher than A2 | - |
| Thermal conductivity | 20 | 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; hardened and tempered for service
Heat treatment
Austenitise around 1,010–1,040 °C, quench in air, oil or a vacuum furnace, then temper at 150–250 °C for maximum hardness or higher for toughness. D2 has significant dimensional movement in hardening, so it is normal to machine oversize and grind to finish.
Achievable surface finish
Ra 0.8 µm after grinding
Ra 0.2 µm (polished)
The carbide structure polishes to a very high gloss, which is why D2 is used for polished mould surfaces as well as cutting tools.
Tooling and cutting parameters
Cutting speed
- 80–150 m/min annealed (carbide) · 30–50 m/min at 60 HRC (CBN)
Feed
- 0.08–0.20 mm/rev turning · 0.05–0.12 mm/tooth milling
Tooling
- Coated carbide annealed; CBN for hardened; EDM for detail
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
- Blanking and punching dies for abrasive stock
- Wear plates and guides
- Shear blades and slitters
- Cold forming rolls and dies
- Polished mould surfaces
DFM notes for this grade
- Allow more stock for the grind than with A2 - D2 moves further in the quench, and on a thin section that difference is the whole tolerance
- Do not use it as a toughness application: D2 is wear-resistant and comparatively brittle, and a shock-loaded tool in D2 will chip
- Abrasive stock (filled plastics, coated sheet, GRP) is where D2 earns its cost - on clean mild steel A2 usually outlasts it in practice because it chips less
Questions buyers ask
- Why does D2 move so much in heat treatment?
- The high chromium carbide content and the hardening temperature - D2 austenitises hotter than A2 and the transformation on cooling causes more dimensional change. It is predictable, not random, which is why the standard practice is to harden oversize and grind the final dimension.
- D2 or M2 for a cutting tool?
- M2 for a tool that cuts and gets hot doing it (drills, reamers, milling cutters). D2 for a tool that wears without getting hot (blanking dies, wear plates, slitters). The distinction is temperature: D2 loses hardness around 200 °C, M2 holds it to 500 °C and beyond.