CPM M4 steel commonly referred to as M4 is high-speed tool steel manufactured by Crucible Industries, a company in the US, following the Compacted Powder Metallurgy.
It contains high amounts of Vanadium and Tungsten in its composition, giving it a boost in wear resistance and toughness. This makes it better than M2, M3, and M7 steel varieties.
The improvements in toughness and wear resistance make this steel a top choice for premium and custom knives. What’s more, it is more expensive than standard steel types.
CPM M4 is used in the manufacture of knives, cold working tools, punches and dies, for broaching to mention a few.
CPM M4 Steel Chemical composition
- Carbon C 1.42%: Increases the edge retention, hardness and tensile strength. It also improves steel resistance to wear, abrasion and corrosion.
- Chromium Cr 4.00%: Formation of Chromium carbide Increases hardness, tensile strength and toughness of the blade.
- Molybdenum Mo 5.25%: It improves machinability and hardness.
- Vanadium V 4.00%: Increase wear resistance and toughness, it also improves corrosion resistance. High vanadium content enables formation of Vanadium Carbide giving M4 an edge over other steel that rely on Chromium Carbides in wear resistance.
- Tungsten W 5.50% Improves wear resistance and hardness, mostly added to tool steel.
- Manganese Mn 0.30%: Increases Hardness and brittleness.
- Silicon Si 0.55%: Increases strength and heat resistance.
- Phosphorus P 0.03%: Improves machinability and hardness.
- Sulfur S 0.06%: Improves machinability.
CPM M4 properties
CPM M4 hardness is 63.5 to 65.5 HRC as per the Rockwell hardness scale. This high hardness is associated with the high carbon in its composition.
This hardness explains the great wear resistance and edge retention exhibited by this steel.
With its high hardness, CPM M4 steel offers exceptional edge retention. It offers better edge retention than most popular steel varieties out there.
If you are on the market for a knife that offers excellent sharpness and remains sharp for long, look no further because the varieties of CPM M4 knives will sort you out.
You must have read or heard somewhere that hard steels offer poor toughness, which is true in many cases, but this does not apply with CPM M4 steel because it offers excellent toughness.
If you are wondering why this steel performs well in both hardness and toughness, it is because of the carbon and vanadium in its composition, in addition to the CPM technique used in its production.
Consumers prefer knives that do not chip, break, or bent when exposed to force and tension, and this is what you get from CPM M4 knives.
Another area where this steel shines is in wear resistance which is linked with the Vanadium and Molybdenum in its composition.
With its great toughness and edge retention, knives made from this steal cannot wear out easily even when constantly used for abrasive applications.
CPM M4 steel is not stainless steel because of its low chromium composition, making it prone to corrosion and rusting.
Knife-making steels are expected to be resistant to corrosion because knives are exposed to humid and acidic environments which activate rusting.
However, this downside should not discourage you from buying knives made from this steel because with proper maintenance they will serve you for long without rusting.
Despite being hard steel, M4 is easy to sharpen. With simple sharpening tools and skills, you should be able to get a sharp edge easily.
Knife users who are not well versed with sharpening skills are encouraged to use this steel to learn and perfect their skills.
CPM M4 equivalents
CPM M4 steel vs S30V
M4 beats S30V steel in edge retention, toughness, and ease of sharpening, while S30V shines in corrosion resistance because it has more Chromium in its composition.
CPM M4 VS D2 Steel
Both D2 steel and M4 steel offer good edge retention, toughness, and wear resistance. Also, they hold poor corrosion resistance features.
However, M4 is easier to sharpen and holds an edge for longer than D2 steel.
M4 vs M390
Both steel types offer very close performance in terms of edge retention and toughness. However, M390 steel is better in corrosion resistance and wear resistance.
Is CPM M4 steel good for knives?
CPM M4 steel is among the best knife steels out there. It offers excellent edge retention, wear resistance, and sharpness. It fails in corrosion resistance, which is easily managed through proper care.
My name is Jonathan M, and I’m a passionate Mechanical Engineer, a knife enthusiast, and the author of this website. I have a bachelor's degree in Mechanical engineering with a specialization in material science. I am particularly interested in researching knife steel, knife properties, and brands. I hope you will find value in the articles on this website. Contact me if you have any questions or input!