CPM M4 steel
CPM M4 is a powder metallurgy high-speed steel from Crucible. It rates 8/10 for edge retention, 5/10 for toughness and 2/10 for corrosion resistance, and is usually hardened to 62–65 HRC.
At a glance
- Type
- High-speed powder steels
- Hardness
- 62–65 HRC
- Maker
- Crucible (USA)
- Process
- PM
- Price tier
- Premium
- Used by
- Spyderco (Gayle Bradley, Manix 2 M4), Benchmade (Contego, 940-1), Zero Tolerance, Kershaw (Blur M4)
- Also called
- M4, CPM-M4, CPM REX M4
Composition
| Element | Weight % |
|---|---|
| Carbon (C) | 1.42 |
| Chromium (Cr) | 4 |
| Vanadium (V) | 4 |
| Molybdenum (Mo) | 5.25 |
| Tungsten (W) | 5.5 |
| Manganese (Mn) | 0.3 |
| Silicon (Si) | 0.55 |
| Sulfur (S) | 0.06 |
Source: manufacturer datasheet. Nominal values; where a range is published, the midpoint is shown. Phosphorus and sulfur, where listed, are maximums.
What makes CPM M4 behave the way it does
CPM M4 contains 1.42% carbon, a high level that supports high hardness and a large volume of hard carbides; 4% chromium, too little for stainless behaviour.
Its 4% vanadium forms vanadium carbides, among the hardest carbides in knife steels, which drive wear resistance and slow edge loss but also make the steel slower to sharpen; tungsten (5.5%) adds hard carbides and helps the steel keep its hardness; molybdenum (5.25%) improves hardenability.
It is made by powder metallurgy: the alloy is atomised into fine powder and consolidated, which keeps the carbides small and evenly spread. That is what lets a highly alloyed steel stay tough enough for a knife blade.
Popular competition-cutting steel; excellent toughness for its wear resistance.
Knives in CPM M4
| Knife | Brand | Blade | Weight | Lock | List price | Buy |
|---|---|---|---|---|---|---|
| Benchmade Bailout 537GY-1 | Benchmade | 3.38" | 2.7 oz | AXIS lock | $350 | Blade HQ |
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Shop CPM M4 knives at Blade HQ
How to sharpen CPM M4
CPM M4 is slow to sharpen (3/10). Its vanadium and tungsten carbides are harder than the aluminium oxide in conventional stones, so diamond or CBN plates cut it far more efficiently. Once sharp, it needs touch-ups less often.
Compare CPM M4 with
FAQ
Is CPM M4 a good knife steel?
CPM M4 is strongest in edge retention (8/10) and weakest in corrosion resistance (2/10). Its average across the four ratings is 4.5/10, and it sits in the premium price tier.
Does CPM M4 rust?
Yes. CPM M4 rates 2/10 and will rust or patina without care; dry it after use and keep a thin coat of oil on it.
Is CPM M4 hard to sharpen?
CPM M4 is slow to sharpen (3/10). Its vanadium and tungsten carbides are harder than the aluminium oxide in conventional stones, so diamond or CBN plates cut it far more efficiently. Once sharp, it needs touch-ups less often.
What hardness is CPM M4?
Knives in CPM M4 are usually hardened to 62–65 HRC. Makers can run it outside that range; harder means better edge retention but lower toughness.