Is CPM M4 a Good Knife Steel? (Plus, Best M4 Knives)

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At A Glance
CPM M4 is a high-end tool steel renowned for its toughness and wear resistance, making it an excellent choice for knife-making. Manufactured by Crucible Industries, CPM M4 has a fine microstructure that contributes to its superior edge retention and moderate toughness. Despite its limited corrosion resistance, the steel is still highly favored for its durability and performance, especially in custom knives. Comparatively, CPM M4 steel outperforms other knife steels in terms of toughness and wear resistance, though it may be more challenging to sharpen due to its high hardness.

CPM M4 is a high-end tool steel that has gained popularity in the knife industry due to its impressive combination of toughness and wear resistance. Manufactured by Crucible Industries using their patented Crucible Particle Metallurgy process, this steel boasts a fine microstructure that lends itself well to knife-making. Known for its excellent edge retention and moderate toughness, CPM M4 steel is often used in custom knives, making it a favorite choice among knife enthusiasts and experts alike.

In evaluating whether CPM M4 is a good knife steel, it’s essential to consider the properties that contribute to its performance. This steel has been noted for its hardness, superior edge retention, and impressive wear resistance. However, it has limited corrosion resistance, meaning it requires proper maintenance to prevent rust and corrosion.

Taking these factors into account, it’s clear that CPM M4 steel has a lot to offer in terms of performance and durability. Although it may require some extra care in terms of corrosion prevention, CPM M4’s balanced combination of qualities makes it a top choice in knife-making for those who value a high-performing, long-lasting blade.

Overview of CPM M4 Steel

Origin and Production

CPM M4 is a high-speed tool steel developed by Crucible Industries, an American steel manufacturer. The steel is produced using Crucible’s patented Crucible Particle Metallurgy (CPM) process, which involves melting and atomizing the alloy, followed by consolidating the powder into a solid state. This results in a uniform and fine-grained microstructure, providing excellent performance and edge retention in knife applications.

Chemical Composition

The chemical composition of CPM M4 steel includes higher amounts of elements such as Molybdenum, Vanadium, and Tungsten, which contribute to its wear resistance and toughness.

Here’s a breakdown of its key elements:

  • Chromium: 4.00%
  • Vanadium: 4.00%
  • Molybdenum: 5.25%
  • Tungsten: 5.50%
  • Silicone: 0.55%
  • Manganese: 0.30%

This combination of elements gives CPM M4 steel a boost in performance over other tool steels like M2, M3, and M7. The high Vanadium and Tungsten content increases wear resistance, while the Molybdenum contributes to its toughness, making it a popular choice for premium and custom knives.

Properties of CPM M4 Steel

Hardness and Strength

CPM M4 steel has a high hardness level, ranging from 63.5 to 65.5 on the Rockwell hardness scale. This hardness is attributed to the high carbon content present in its composition, enhancing its strength. The increased hardness offers excellent wear resistance and edge retention capabilities.


Thanks to its high molybdenum and vanadium content, CPM M4 steel exhibits impressive toughness. High toughness means it’s less likely to chip or crack under stress or impact, making it suitable for various demanding applications.

Wear Resistance

One of the standout features of CPM M4 steel is its exceptional wear resistance. The steel’s high hardness, combined with its unique chemical composition, results in knives that can withstand extended use and resist abrasion, maintaining their performance for a long time.

Edge Retention

CPM M4 steel is well-known for its excellent edge retention properties. The high hardness and wear resistance of this steel help maintain sharp edges longer, even through prolonged use and tough cutting tasks.

Corrosion Resistance

While CPM M4 steel offers several advantages, its corrosion resistance is relatively lower than other stainless steels. However, the addition of 0.55% silicon in the steel increases its corrosion resistance to some extent.


The high hardness of CPM M4 steel can make sharpening more challenging than other, softer steels. However, with proper sharpening methods and regular maintenance, it’s still possible to maintain a razor-sharp edge on your CPM M4 knife.

Comparison with Other Steels

In this section, we will compare CPM M4 with other popular knife steels to help you understand their respective strengths and weaknesses.

CPM M4 vs S30V

CPM M4 and S30V are both high-quality steels used in premium knives. CPM M4 is known for its exceptional toughness and wear resistance, making it an excellent choice for hard-use knives. On the other hand, S30V is a stainless steel with well-rounded properties, including good edge retention, corrosion resistance, and toughness. While CPM M4 provides better wear resistance and toughness, S30V offers superior corrosion resistance.

CPM M4 vs M390

Both CPM M4 and M390 are high-performance steels, but they cater to different requirements. M390 is a stainless steel prized for its excellent edge retention and corrosion resistance, making it ideal for everyday carry knives. CPM M4, with its high wear resistance and toughness, is better suited for hard-use applications where edge stability matters more. If you prioritize corrosion resistance, M390 is the better choice. If toughness and wear resistance are more important, consider a knife made of CPM M4.

CPM M4 vs 3V

CPM 3V is a well-regarded tool steel known for its outstanding toughness and great wear resistance, which are comparable to those of CPM M4. However, 3V has a slight edge in toughness, while CPM M4 is slightly better in wear resistance. Both steels are not stainless and require proper maintenance to avoid corrosion. The choice between CPM M4 and 3V depends on the specific balance of properties you prioritize in your knife.

CPM M4 vs D2

D2 is a popular semi-stainless tool steel often used in budget to mid-range knives. Although it has reasonably good wear resistance and decent edge retention, it lags behind CPM M4 in both of these aspects. CPM M4 steel also offers better toughness than D2. However, D2 is easier to sharpen and might be more affordable in some cases.

CPM M4 vs Maxamet

Maxamet is a high-speed tool steel known for its extraordinary wear resistance and edge retention. It significantly outperforms CPM M4 in these properties. However, Maxamet is more challenging to sharpen and has lower toughness compared to CPM M4. If you prioritize wear resistance and edge retention above all else, Maxamet could be the better option. For a compromise between toughness and wear resistance, CPM M4 is a great choice.

CPM M4 vs S110V

S110V is a high-end stainless steel renowned for its incredible edge retention and excellent corrosion resistance. While S110V outshines CPM M4 in terms of corrosion resistance and edge retention, it does not match the toughness provided by CPM M4. A knife made with S110V steel is a good choice for everyday carry, while CPM M4 is better suited for hard-use applications.

CPM M4 vs K390

K390 is a high-performance tool steel with outstanding wear resistance and edge retention, similar to Maxamet. Compared to CPM M4, K390 offers better edge retention but slightly lower toughness. Additionally, both steels are not stainless and require proper maintenance. The decision between CPM M4 and K390 depends on whether you prioritize edge retention or toughness in your knife.

Applications and Use Cases

Knife Designs

CPM M4 steel is a popular choice for various knife designs due to its unique combination of toughness, wear resistance, and edge retention. With a high carbon content of 1.42%, it provides excellent hardness and tensile strength, making it suitable for a wide range of cutting tasks. Its impressive wear resistance ensures that knives made from CPM M4 steel can maintain their performance even after extended use.

Custom Knives

Custom knives can greatly benefit from the use of CPM M4 steel, as its fine microstructure, achieved through Crucible Particle Metallurgy, allows for intricate patterns and precise finishes. Additionally, its exceptional edge retention and ability to withstand daily wear and tear make it an ideal choice for those seeking a personalized and high-performing cutting tool.

Tool and Die Making

Beyond the knife industry, CPM M4 steel has found applications in tool and die making. Its exceptional toughness and wear resistance are crucial in the manufacturing of tools such as punches, dies, and broaching instruments. These qualities make CPM M4 a reliable and efficient choice when producing tools that need to withstand repeated stress and abrasive contact.

Machinability and Grindability

General Processing

CPM M4 steel is known for its excellent machinability, making it easy to work with when crafting knives. Its high vanadium content of 4% improves wear resistance and allows for better grindability, resulting in a sharp and durable edge. The presence of 0.06% sulfur also increases machinability, allowing for smoother processing of the steel when making knives.

Chipping and Edge Geometry

CPM M4 steel combines the properties of toughness and edge retention very well, making it resistant to chipping. The higher carbon and manganese content provide increased toughness and strength, while its edge geometry can be properly maintained over time. It should be noted that although CPM M4 steel is tough, it can still rust if not properly maintained, so regularly applying a thin coat of oil is beneficial.

When it comes to edge geometry, CPM M4 excels due to its excellent grindability. This feature allows for easier sharpening of knives, as well as achieving an extremely sharp edge. The combination of toughness, edge retention, and the ability to maintain its geometry make CPM M4 a reliable and popular choice for knife enthusiasts and professionals alike.

CPM M4 Steel Maintenance

Rust Prevention

CPM M4 steel is known for its excellent edge holding, toughness, and ease of sharpening. However, it can be susceptible to rust if not well maintained. To prevent rust, it’s essential to keep your CPM M4 knife clean and dry. After using your knife, make sure to wipe off any moisture and dirt before storing it. Additionally, applying a thin layer of oil on the blade can help protect it from corrosion. While developing a patina may aid in slowing down rust formation, it’s not a guarantee. Regular care is still crucial.

Basic Care Tips

Caring for your CPM M4 knife is relatively simple, but, following these tips ensures that your knife remains in good condition:

  • Always clean your knife after each use, even if it was only exposed to a minimal amount of moisture.
  • Use a soft cloth or sponge (non-abrasive) and a gentle detergent, if necessary, to clean the blade.
  • Dry your knife thoroughly after cleaning, ensuring there are no leftover water spots.
  • Apply a light coat of oil to the blade, especially if you don’t plan to use the knife for an extended period.
  • Store your knife in a cool, dry place, preferably in a sheath or case to minimize exposure to humidity.

Sharpening Ease

One of the benefits of CPM M4 steel is its ease of sharpening. Despite its excellent edge-holding capabilities, it’s relatively simple to sharpen when needed. You can use standard sharpening equipment like whetstones, ceramic rods, or diamond plates to achieve a razor-sharp edge. Remember though, while sharpening is generally not a complicated task, it’s essential to practice proper technique and consistently maintain your blade’s angle.


CPM M4 steel is considered a high-alloy steel that is quickly gaining popularity for its versatile performance in knives. Its combination of vanadium and molybdenum gives it excellent toughness and wear resistance, making it a popular choice in the knife industry, especially for custom knives.

One of the major strengths of CPM M4 steel is its edge retention and moderate toughness. These properties make it an ideal choice for knives that require excellent cutting performance and durability. However, one aspect to consider is its corrosion resistance, which is not as high as some other steel varieties like CPM MagnaCut or other stainless steels.

In terms of performance, CPM M4 steel has been compared to other popular knife steels like S30V, D2, and M390. While each steel variety has its own advantages and disadvantages, CPM M4 stands out for its impressive combination of hardness, edge retention, toughness, and wear resistance.

Considering its properties and performance, CPM M4 steel can be a suitable choice for those in search of a high-quality knife steel. While its corrosion resistance may not be the best, proper care and maintenance should ensure the longevity of knives made with this steel. With its numerous advantages, it is no surprise that CPM M4 steel is earning a reputable position among knife enthusiasts and professionals alike.

When you visit a merchant by clicking a link on this site we may make a commission on anything you buy (at no additional cost to you).   Affiliate programs and affiliations include, but are not limited to Amazon Associates and the eBay Partner Network.”