CPM M4 Steel Review

CPM M4 Steel Review

What is CPM-M4 steel? What's its makeup? How does it behave when it comes to taking and holding an edge, resisting chipping, wear, and corrosion? How does it compare to other steels? Is it even a good candidate for a knife? If all these questions are running in your head right now, you've come to the right place.

We have come across many other knife users desperately searching for information about the CPM M4 steel knife performance. So, we decided to research this steel deeply before stitching up this piece to provide you with lots of good info about this steel.

What is CPM M4 steel?

CPM M4, simply referred to as M4, is powdered high-speed tool steel developed by US-based Crucible Industries. As you can easily tell from its name, Crucible uses their CPM (Compacted Powder Metallurgy).

The steel boasts higher impact toughness and excellent wear resistance than M2 and M3 steel grades, making it one of the top choices for cutting competition knives. It's widely used for creating custom knives. However, some leading companies like Spyderco and Benchmade have used it to make a handful of knives.

What is CPM M4 steel

Keep in mind that this steel is ranked in the high-end steels realm. Needless to say, it comes at a higher cost than standard steel.

CPM M4 Tool Steel Chemical composition

The key elements for CPM m4 steel include Carbon, Chromium, Molybdenum, and Vanadium. These are responsible for M4's high toughness, excellent corrosion resistance, and wear resistance.

This is how the complete M4 chemical composition looks like:


Composition (%)

















CPM M4 Steel

1.42% Carbon increases tensile strength, edge retention, and hardness. It also improves wear and corrosion resistance.

4% Chromium increases the tensile strength, toughness, and hardness of this steel. It also improves corrosion resistance.

5.25% Molybdenum increases the steel strength, hardness, toughness, and hardenability.

4% Vanadium increases strength, toughness, and wear resistance.

5.5% Tungsten improves hardenability while increasing strength and toughness.

0.3% Manganese increases hardenability, tensile strength, and wear resistance.

0.55% Silicon increases strength and corrosion resistance.

0.03% Phosphorous improves strength, hardness, and machinability.

CPM M4 steel properties

CPM M4 Steel

CPM M4 steel hardness

CPM M4 steel HRC is 63.5 to 65.5 RC. As indicated in this datasheet from its Crucible. The high hardness comes from the high carbon content used in making this alloy. With such a high hardness, CPM M4 steel knives usually deliver high resistance to surface deformation, penetration, deformation, and even scratching. In other words, high hardness equals high wear resistance.

Edge retention

You should expect nothing short of exceptional edge holding capabilities from a CPM m4 knife with its high hardness. Mark you, it offers better edge retention than popular grades like S30V, D2, and CPM 154. As you already know, these grades are popular for their excellent edge retention. You can guess how far M4 goes to keep its fine edge.

CPM M4 Steel


M4 is extremely tough steel and ranks higher above the popular steels available today. You might have already heard that harder steels tend to be less tough. So stating that M4 is tough and hard at the same time might be confusing to you, right? The reason this steel breaks this rule of thumb comes at a sacrifice, which is low corrosion resistance. The high toughness explains why M4 is a tool steel. And thanks to this high level of toughness, CPM M4 steel knives don't easily chip or break under the influence of lateral forces.

CPM M4 steel

CPM M4 Corrosion resistance

M4 can rust…but not easily. This steel contains 4% chromium only and is NOT stainless. Although it offers a certain level of corrosion resistance, you'd want to take good care of your CPM m4 steel knife to ensure it doesn't get rust. This is as simple as ensuring your blade is clean and dry before storage. Adding a layer of oil on your blade before storage also helps keep off rust and corrosion.

Still, at it, a CPM m4 steel knife with an anti-corrosion finish can also go a long way in keeping off corrosion and ensuring long knife life.


Another great thing about this steel is that it sharpens much easily. Despite being hard steel, M4 sharpens easily. It obtains a razor-sharp edge fairly easily. You also don't need to use any complex sharpeners other than the simple methods, like sharpmaker brown stones, to keep your knife honed. If you're not confident with your honing skills, this steel will give you a good start and pace to learn the art.

CPM M4 steel equivalent

CPM M4 steel equivalent

CPM M4 steel vs S30V

M4 blows S30V out of the water with far superior edge retention, easier sharpening, and higher toughness. But S30V steel offers high corrosion resistance than the M4.

M4 steel vs S90V

M4 also has close performance to S90V steel. But there exist some key differences between the two, like M4 being tougher and much easier to sharpen. And the S90V has better anti-corrosion properties.

M4 vs M390

M390 is also close to M4 performance-wise. Both steels offering the same level of edge retention and toughness. However, M390 gets better in corrosion resistance and being slightly easier to sharpen.

Is CPM M4 steel good for knives?

CPM M4 is high-end modern steel and one of the best steels for knives available. It delivers exceptional edge holding, extreme sharpness, and excellent toughness. The steel is also easy to sharpen and offers high wear resistance, so your blade won't get deformed after a few uses.

The only area where this steel fails is low corrosion resistance since it's not stainless. But it offers considerable anti-corrosion properties, and it's not the worst compared to some non-stainless grades out there.

Is CPM M4 steel good for knives

Popular brands like Spyderco and Benchmade continue to rely on CPM-M4 steel to make their knives. These have earned a good reputation and countless positive feedback from knife users across the states

So, what is M4 steel used for? M4 steel is the ideal candidate for making premium cutting tools. This is due to its exceptional abrasion resistance, high toughness, and superior edge holding capabilities.

Best CPM m4 steel knives

1. Benchmade - Bailout Tanto Blade

Benchmade - Bailout Tanto Blade

If you're a Benchmade fan, this is a good folder for you. This is one of the most popular knives featuring a premium CPM-M4 steel blade. It comes in a sleek, slim design that nicely disappears in your pocket. And its lightweight nature makes it the perfect choice for everyday carry.

The Bailout screams excellent workmanship and quality inside out. It comes with a Tanto-shaped M4 steel blade, which comes hair shaving sharp out of the box and keeps its edge for longer than most steels out there. All its edges appear flawless and scratch-free. Its edge grind is even too.

A grey coating runs across the entire blade to help compliment the steel's low corrosion resistance.

It offers you a smooth and quick opening, just as expected of any premium pocket knife. It appears perfectly centered when closed and doesn't offer any wiggle or play when open.

This Benchmade features a lightweight aircraft-grade aluminum handle. This not only keeps the weight low but also comes textured to offer you a comfortable and secure grip. And although the knife has a thin profile, you'll still enjoy a comfortable, solid, full hand grip on it.

Overall, if you're looking for a high-end knife to add to your collection, this knife is totally worth considering.

Highlighted Features:

  • American made CPM-M4 blade
  • Slim and lightweight design
  • Green anodized aluminum handle
  • Mini reversible deep-carry pocket clip
  • Gray anti-corrosion blade coating

2. Spyderco Advocate Premium Flipper Knife

Spyderco Advocate Premium Flipper Knife

Spyderco also trusts M4 steel to make some of their high-end knives like this premium flipper. 100% made in Spyderco's Taiwan-based factory, this knife ticks the box for lightweight, sturdy, and a sharp pocket knife for everyday carry.

It features a beautiful 3.49-inch blade precision machined out of high-end M4 steel. This modern steel grade is known to hold an edge better than other steels and lets you easily hone it back to hair-splitting sharpness if it gets dull.

The knife boasts Spyderco's Compression Lock, which offers solid blade opening and lockup performance. It leaves no room for blade play and is incredibly easy for you to use.

The integrated flipper lets you swiftly deploy the blade with one hand. Alternatively, this knife features Spyderco's trademark hole—the Spyderhole—which also allows for a smooth and swift opening experience with just one hand.

The knife also comes designed for maximum ergonomics, thanks to the textured titanium handle. The high tensile strength, lightweight, and great corrosion resistance make it the perfect handle material. The blade edge co-linears with the bottom of the handle scales, further facilitating great cutting ergonomics.

With an overall lightweight feel (3.84oz only), compact design, plus the included reversible pocket clip, this Advocate flipper is highly portable, and carrying it with you every day will be a breeze.

Highlighted Features:

  • 3.49" CPM M4 steel blade
  • Scaled titanium handle
  • Closed length: 4.55 inches
  • Overall knife length: 8.04 inches
  • Secure compression lock
  • Reversible pocket clip

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Final Verdict

Now that you have everything you need to know about CPM-M4 steel, deciding whether it's a good steel for your knife should be easy. We have said that the steel excels in high wear resistance, exceptional edge retention, great toughness, and extreme sharpness. The downside is that it's less corrosion resistant and comes at a higher price. But considering what you get from this steel in comparison to other grades out there, you'll agree that the price tag is well worth it.

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