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What is CPM M4 Steel? Is CPM M4 Steel Good for Knives? Top CPM M4 Steel Knives Review

CPM M4 SteelMany knife enthusiasts start out willing and ready to compromise with the first products they’ll get. Something affordable that performs better than what can be bought for cheap at big box stores might already do the trick until they learn more about the finest steels and how great they can be.

One of the varieties that tend to get a lot of people investing in a good knife would be the CPM M4 steel. This variant is a bit of a superstar in the knife world promising toughness, sharpness retention, and amazing wear resistance. If you’re one of the many who want to learn more about it, you’re in the right place.

What is CPM M4 Steel?

Technically referred to as CPM Rex M4 HC, the CPM M4 steel is a special-purpose high-speed steel that is created by the Crucible Industries using the powder metallurgy process. It’s noted for its high vanadium content and its unique composition that promise great wear resistance, high transverse bend strength, and exceptional high-impact toughness.

Designed to provide a significant improvement to the M2, M3, and M7 steel varieties in terms of wear resistance and toughness for various purposes. Its high Vanadium and Tungsten content make it tougher and more wear-resistant than other types of steel with high Chromium and Carbon content.

Common Uses of CPM M4 Steel

The CPM M4 steel is used for a wide range of applications. Its most popular uses are the following:

  • For cold work tooling applications
  • For creating knives
  • For broaching
  • For creating gear hobs and rolls
  • For milling, shaving, and shaper cutters
  • For punches and dies

CPM M4 Steel Chemical Composition

What sets the CPM M4 steel apart from the other tool steel and specialty alloy materials in the market is its combination of elements that are carefully selected and mixed to create a premium type of steel. Its primary components include:

  • Carbon 1.42%
  • Manganese 0.30%
  • Tungsten 5.5%
  • Molybdenum 5.25%
  • Vanadium 4%
  • Chromium 4%

Carbon 1.42%:  This is a very high level of carbon, which is part of the reason for why it’s regarded as a super-steel. This amount of carbon leads to extreme hardness.

Manganese 0.30%: In importance, this is second only to carbon. It enhances the hardenability of the steel, along with the tensile strength. It also increases wear resistance.

Tungsten 5.5%: The tungsten helps the steel to maintain its hardness at high temperature after heat treatment, making it particularly suitable for cutting tools.

Molybdenum 5.25%: It enhances creep strength, elevated temperature strength, and hardenability. It also improves corrosion resistance. This is a lot of molybdenum, actually, with other steels only containing 0.1% molybdenum.

Vanadium 4%:  You also get a lot of vanadium in the mix. This improves the hardenability, its toughness against fracturing, and ability to resist shock loading.

Chromium 4%:  While it’s not enough to make this stainless steel, it still helps with corrosion resistance.

On some occasions, a 0.20 to 0.25% of Sulfur is added when producing large diameter rounds. This helps improve the steel’s machinability and grindability without compromising its hardness. It also has 0.55% Silicon and 0.03% Phosphorous which both add strength to the mix.

With the high percentage of Vanadium and Molybdenum, it promises great wear resistance and toughness. However, the low amount of Chromium makes it a non-stainless type of steel. And since it contains more than one percent of Carbon, it can be considered as carbon steel already.

CPM M4 Steel Hardness

The CPM M4 steel has a relatively high Rockwell hardness rating at 63 to 65 HRC. This guarantees that it’s a hard kind of steel which is useful for knives. With this feature, it can retain its edge quite well, making it less prone to deformation.

On the flip side, however, this makes the steel a bit hard to sharpen when used in knives. The hardness makes it tricky to make a dent on the steel. Luckily, it retains sharpness quite well so there’s no need to sharpen the best CPM M4 steel knives often.

Properties of CPM M4 Steel

Man sharpening a knife in the workshopTo help you get to know the CPM M4 steel better, here are some of its core principles that make it a popular material for various applications including knifemaking:

Edge retention

Sharpness is one of the first things most folks look for in a knife since it’s the very characteristic that you need for such a tool to work well. This is achieved with good edge retention in the material and the M4 steel is designed for such. Engineered to retain its edge and resist damage from regular use, it promises to achieve a nice sharpness and to stay sharp for a long time.

This feature is often attributed to its carbon content but its hardness can also be a major factor in this feature. It comes in handy since CPM M4 steel knives are typically used on rough tasks and objects.


Knives may be versatile tools but they do more than just cut and slice. They also have to be tough enough to be versatile as they can be subjected to quite a bit of twisting, beating, force, and impact. Without this characteristic, a blade can easily chip, dent, or even break.

With its high Carbon and Vanadium content, as well as the proprietary Crucible powder metallurgy technique, using CPM M4 steel for knife products makes the output quite tough. This is a reason why it’s classified as a high-end steel. It can withstand great tension and force.

Wear resistance

With a material that is tough and capable of retaining its edge and sharpness for a long time, it can be expected that it can stave off wear as well. With its Vanadium and Molybdenum content, the M4 steel is made to be tough, stable, and hard. As a result, its edges don’t easily wear out even with constant abrasive and adhesive damage.


Many high-end blades are made to be very hard in order to provide toughness and ensure strength. In the case of the CPM M4 steel, a high amount of Tungsten amps up its composition to make it seriously hard. As mentioned above, its Rockwell hardness rating is 63 to 65 HRC, putting it in the upper range.

Ensuring the hardness of a blade guarantees that it can retain its edge. So, with the M4 steel’s composition, it can promise to stay sharp for a long time. Unfortunately, this also means that it can be a challenge to sharpen since the material is hard. Luckily, it also retains its sharpness alongside its edge so it doesn’t require sharpening all too often.

Corrosion resistance

As cutting and slicing tools, it should be expected that knives will be exposed to the elements. This is why it’s ideal if they are resistant to corrosion so it won’t be easily damaged by the conditions it gets exposed to.

While the CPM M4 steel is not of the stainless variety, it doesn’t promise that it will not experience corrosion when exposed to high humidity, saltwater, and other similarly wet conditions. It can develop a patina overtime, especially if it’s not properly cleaned and stored after every use.

It’s not a rust monster, however, so don’t worry about the maintenance. The patina also adds character to the overall look of the knife, so it might not be a significant issue.


CPM M4 Equivalent Steels or Alternative

In case you’re having a hard time picturing what the CPM M4 steel is like, comparing them to other blades might be of great help. Despite being of premium variety, it can still be likened to other materials that you may be familiar with like the M390, D2, S30V, and the 3V.

CPM M4 VS D2 Steel

Classified as a mid-range steel, lots of knife enthusiasts may be more familiar with the D2 than the more expensive M4. The D2 is also a classic and traces its roots back to WWII so it’s more established than the other.

In terms of features, however, the two are very similar. They both have great edge retention and are very tough. Both are also prone to some staining if not maintained properly, so the pros and cons are there.

However, in terms of sharpness, the M4 wins out. It gets really sharp and holds it well. The D2 is more affordable, though, so there’s a significant tradeoff between the two.

CPM M4 VS M390 Steel

With the powerhouse composition of the M390, it’s quite a super steel that is often pitted against the CPM M4. It’s newer so it has a number of what can be considered as updates to the older material.

While both materials are tough, wear-resistant, and can hold their edge and sharpness well, the M390 has a high Chromium content. This makes it a stainless steel, making it a lot easier to maintain. It will not rust or patina as quickly as the M4, so it’s a less fussy pick. Knives with both materials are within the same price point, too, so it’s a toss-up between the two.

CPM M4 VS S30V Steel

These Crucible steel creations are also normally compared to each other as the CPM S30V is one of the most popular knife materials in the market. Since the steel is among the few that are engineered specifically for making knives, it was designed to cater to the knife fans’ requirements and demands. It’s tough, wear-resistant, holds sharpness for long periods, and easy to maintain.

The biggest difference really between the CPM M4 and S30V is that the latter is stainless steel. This can also explain why it’s popularly used for kitchen cutlery and as an everyday carry.

CPM M4 VS 3V Steel

Both are from Crucible, and people also find themselves torn between the M4 and 3V. Both are highly rated for their toughness and wear resistance. The 3V, however, is more popular as a fixed blade since it’s very tough. Unfortunately, it doesn’t hold its edge as well as the M4 which might explain why the latter is classified as a premium super steel.

Price-wise and performance-wise, the 3V will already give you a good run for your money. However, choose based on your intended use to make the most out of your purchase.

Is CPM M4 steel good for knives?

While the CPM M4 is not made just for making knives, it can be a good material for such applications. In fact, it’s popularly used in survival knives, custom knives, and even as a blade sport knife. This means that it’s high-performing, strong, and very durable, which are all of the things many knife enthusiasts look for in a good knife.

Pros & Cons of CPM M4 Steel

  • Relatively low maintenance (has excellent edge and sharpness retention so frequent sharpening is not necessary)
  • Very tough and hard construction (will not get damaged or deformed easily)
  • Top pick for competition knives (this promises excellent performance in the toughest situations)
  • Popularly used as a survival knife (its durability and sharpness retention make it very reliable for tough conditions)
  • Available in different designs (lots of options are easily available)
  • Gets very sharp and holds its sharpness well
  • Sharpening can be challenging (since the material is too hard)
  • Still requires a bit of maintenance (it’s not a stainless steel so it can still rust if not cared for properly)
  • Quite pricey (it’s classified as a high-end steel)

Best CPM M4 Steel Knives

Want to know where to start looking for an M4? Here’s a CPM M4 steel knife review that might help you out:

#1: Spyderco Bradley Folder 2 Specialty Folding Knife

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Quick Specification
  • Blade Length: 3.66″ (93mm)
  • Edge Length: 3.42″ (87mm)
  • Blade Thickness: 0.118″ (3.0mm)
  • Lock Type: Liner Lock
  • Origin: Taiwan
  • Weight: 4.5oz (128g)

As the name suggests, the Spyderco Bradley Folder 2 Specialty Folding Knife is a folding knife from the popular Bradley Folder line. This product is an update, however, with its slimmer profile, lighter weight, and better ergonomics.

Aside from the premium steel material used, it also features a carbon fiber/G-10 laminate handle. This takes the knife a few notches higher in terms of build and quality.

Roughly five inches in length when folded and nearly nine inches when unfurled, the blade of this item measures 3.6” which makes it a good size for a wide range of users. Handling is quite easy, eliminating a common problem among compact folding knives.

  • Attractive appearance
  • High-end materials used for the blade, frame, and handle
  • Reasonably priced
  • Easy and comfortable to handle
  • Very portable
  • Remains sharp for a very long period
  • Some find the deployment and closure a bit tricky
  • Can get patina when not properly cared for


There are lots of premium and high-end steel varieties that are worth considering if you’re planning on investing in the best knife. The CPM M4 steel makes one of the best cases for such with its incredible wear resistance, impressive edge retention, and superb toughness as this CPM M4 steel review discussed in detail.

If you have any additional questions or details you wish to know about this top-shelf knife material, don’t hesitate to put them in the comments.

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