CPM M4
Crucible Particle Metallurgy high-speed steel with exceptionally high vanadium (4%) and carbon (1.42%) content. Combines the red hardness of M2 HSS with wear resistance approaching carbide. PM process ensures uniform fine carbide distribution impossible in conventional melting. Hardened to 62–66 HRC. Used for end mills, broaches, hobs, form tools, cold heading dies, slitter knives and applications where conventional HSS wears too fast but carbide is too brittle. Popular in knife community for extreme edge retention.
Chemical composition comparison (wt%)
Side-by-side: CPM M4 (CRUCIBLE) (Crucible Data) vs ASTM
| Element | CPM M4 (CRUCIBLE) | ASTM | Overlap |
|---|---|---|---|
| C | 1.42% | — | — |
| S | ≤ 0.06% | — | — |
| Cr | 4% | — | — |
| Mo | 5.25% | — | — |
| V | 4% | — | — |
| W | 5.5% | — | — |
Mechanical properties
Annealed
| Property | Value | Unit |
|---|---|---|
| Hardness HB | ≤ 260 | HB |
Hardened + Tempered
| Property | Value | Unit |
|---|---|---|
| Hardness HRC | 62–66 | HRC |
General
| Property | Value | Unit |
|---|---|---|
| Density | 7.97 | g/cm³ |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| Hardening | 1165–1190 °C | Oil/Salt/Vacuum | — | Preheat 845°C then 1050°C, soak 3-5 min |
| Tempering | 525–565 °C | Air | — | Triple temper 2h each: 540°C→64-65 HRC |
| Cryogenic treatment | -73–-73 °C | Cryo | — | 1h between tempers, improves toughness |
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