Steel matchup
CPM CruWear and CPM M4, compared on the five things that decide a blade: toughness, edge retention, corrosion, heat treat and how each one grinds.
A non-stainless powder-metallurgy tool steel balancing toughness noticeably better than D2 with wear resistance that approaches it, popular for hard-use folders and fixed blades that need to sharpen easily.
A high-speed tool steel with extreme edge retention thanks to a heavy vanadium and tungsten carbide load, popular for hard-use fixed blades where long edge life matters more than rust resistance.
Dimension by dimension
Each steel's own note, its score out of five, and what separates the two in that one column. The higher score in a row is marked in purple.
| Dimension | CPM CruWear | CPM M4 | What separates them |
|---|---|---|---|
| Toughness | Notably tougher than D2, approaching A2 in impact testing, and significantly tougher than high-carbide stainless steels like S30V at comparable hardness. Not in the same class as CPM 3V, but a large step up from typical stainless tool steels. | Decent for a steel with this much carbide content, but it trades some toughness for its extreme wear resistance; not in the same class as CPM 3V or CruWear for impact resistance. | CruWear is noticeably tougher, with wear resistance that approaches D2 while keeping considerably more resilience against chipping than CPM M4's heavier carbide structure allows. |
| Edge retention | Good, though behind high-vanadium stainless steels like S90V or M390. CruWear takes a keen edge easily and touches up fast, which many users prefer over outright maximum edge retention. | Among the best edge retention available in a non-stainless steel, thanks to a very heavy load of hard vanadium and tungsten carbides. A favorite where long edge life is the top priority. | CPM M4 holds a clear advantage, among the best edge retention available in a non-stainless steel thanks to its heavier vanadium and tungsten carbide load. |
| Corrosion resistance | Not stainless. Chromium is intentionally kept below the roughly 10.5% stainless threshold so more of it is available to support toughness and carbide structure rather than corrosion resistance. Needs the same basic care as other carbon tool steels. | Only 4% chromium, well below the stainless threshold. Needs the same oiling and drying care as a plain carbon steel. | Neither is stainless, and both require the same regular oiling and drying, though CruWear's alloy balance gives it a very slight edge in resisting surface rust. |
| Heat treat | Crucible's recommended heat treatment: austenitize at 1950 F, quench (air or interrupted oil to control warping), then triple temper at 1000 F for at least 2 hours per cycle. This targets around 62 HRC. Double tempering is the minimum; triple tempering is recommended for full stress relief and dimensional stability. | Preheat at 1500-1550 F, then austenitize between 1900 and 2150 F depending on the desired balance: lower temperatures favor toughness, higher temperatures maximize wear resistance at some cost to toughness. Quench in oil, air, salt, or plate to below 125-150 F. Double or triple temper at 1000-1050 F, holding at least 2 hours per cycle, to fully convert retained austenite through secondary hardening. Typical knife hardness lands around 62-64 Rc, with a maximum near 65 Rc. | CPM M4 requires a more involved high-speed-steel process with secondary hardening tempers around 1000-1050 F. CruWear uses a more conventional tool-steel heat treat and is generally considered somewhat more forgiving. |
| Grinding | Grinds comparably to other CPM tool steels in this class; moderate belt wear from vanadium and tungsten carbides. Ceramic or zirconia belts work well for stock removal. | The heavy carbide load makes it noticeably harder on belts than simple carbon or basic stainless steels, though the powder-metallurgy process makes it more workable than conventional high-speed steel. | CruWear is easier to grind. CPM M4's heavier carbide load makes it one of the more demanding steels in this database to work. |
Best use
CPM CruWear
Choose CPM CruWear for hard-use folders and fixed blades where a balance of toughness and wear resistance, with easier shop work, is the priority.
Open the CPM CruWear referenceCPM M4
Choose CPM M4 for hard-use fixed blades and competition cutting knives where extreme edge retention outweighs the need for easy grinding.
Open the CPM M4 reference
The long answer
CPM CruWear and CPM M4 are both non-stainless tool steels built around a heavy vanadium and tungsten carbide structure, but CruWear was formulated with more toughness in mind, while CPM M4 leans harder into raw wear resistance, closer to a high-speed steel in character.
Keep comparing
Keep reading
CPM CruWear sits in the moderately demanding range for grinding, tougher on belts than simple carbon steels but generally easier than the hardest-edged…
CPM M4 sits at the top of this database’s “hardest to grind” list, alongside CPM 20CV and CPM S30V. Its heavy vanadium and tungsten carbide load, adapted…
Every knife steel is iron plus a specific recipe of other elements, and each of those elements pulls the steel’s behavior in a particular direction…
Same bench
Whichever steel wins, the grind is only as flat as the platen behind it. I machine the parts, hand-assemble, track and test Torus grinders in Sterling, Illinois.
Current dual-axis platform with a fiber-laser-cut 6061 chassis and single-knob tracking.
Current dual-axis platform with a steel chassis, more mass and less vibration.
Prior-design aluminum chassis, 90-degree tilt and 1.5-inch tooling arms.
One-man shop
Tell me what the blade is for and how you heat treat, and I will tell you which of these I would put on the bench — including when the answer is neither.
