How Good is CPM 20CV Knife Steel?

Jeremy Dodd
April 28, 2021
CPM 20CV knife steel

CPM 20CV Steel is Crucible’s answer to Bohler’s M390 stainless steel. It also helped Carpenter to create CTS-204P, which is also quite similar. These facts alone should tell you something. CPM stands for “Crucible Particle Metallurgy” and is one of the single most coveted stainless “super steels” for knife enthusiasts in the world at this moment in time. 

Few other types of steel can invoke the visceral reactions that are exhibited from this metal. As with the steels mentioned above, 20CV is a powder metallurgy tool steel. According to Crucible, CPM 20CV is “a Martensitic stainless steel with a high volume of vanadium carbides for excellent wear resistance.” 

CPM 20CV Steel Chemical Composition

It is used in industrial applications for granulator knives, pelletizing equipment, and wear components for food and chemical processing. The uniform carbide distribution provides toughness for high alloy steels. The chemical composition for CPM 20CV is as follows:

Chemical CompositionChemical %
Iron72.5%
Carbon1.9%
Chromium20%
Vanadium 4%
Molybdenum1%
Tungsten0.6%

WITH AN HRC RATING OF AROUND 61, WEAR AND CORROSION HAVE MET THEIR MATCH! … SORT OF.

CPM 20CV Properties

Hardness

Harness measures how well a steel or metal can resist external forces that try to deform it. During the 20th century, scientific measurements of material hardness have been deduced from a set of lab tests called the Rockwell scales, named after its founder, Hugh Rockwell.

Among these scales, the particular C scale represents and describes hardness values and properties for knife steels, consisting of a numeric value followed by ‘HRC.’ When we test alloy hardness, a particular force drives a diamond-shaped tip into a sample of the metal. The depth of the resulting dent signifies the metal’s ability to withstand the pressure.

With an HRC rating of around 61, wear and corrosion have met their match! … sort of.

It is essential to note that even though you can use Rockwell scores to compare a particular steel’s hardness results with another steel, you cannot correlate the scores to any particular observation or outcome of the test itself since the Rockwell scores are abstractions. Usually, most steels score between 58-62 HRC.

A knife steel blade that bends perpetually while used proves that the particular steel lacks adequate hardness for the tasks. In some instances, the designer tends to compensate for this lack by making all or either part of the blade thicker or modifying how the steel has been manufactured to increase its hardness. 

In some instances, you can only choose a harder steel alloy.

In the Crucible Industries CPM 20CV steel, the hardness measure ranges between 59 to 61 HRC. Since heat treatments affect the final hardness of a steel blade, a different manufacturer might quote a different HRC value for the same steel. This hardness is mildly higher than Benchmade’s implementation of 440 C steel, a rather famous and renowned alloy for making knives with an HRC rating ranging between 50-60.

Toughness

The toughness of steel represents how well steel can withstand impact or force without breaking, chipping, or cracking. A toughness inadequacy can lead to a terrible outcome if a knife happens to break while in use, resulting in injury to the user and derailing the task at hand.

It is much easier for a knife steel blade to predict the gradual and natural course of wear and tear than the sudden instance of a toughness failure, and it is safer for a blade to wear out than break.

Inadequate toughness can result from the alloy formula itself, or from the way the alloy was heat-treated, from inappropriate grinding during fabrication, or from a mixture of other factors.

Toughness is much harder to quantify than hardness since no single test provides a standardized measure of the property. Usually, toughness testing relies primarily on how far steel can bend before it breaks or how well it survives an impact. 

Crucible Industries CPM 20CV steel offers a significantly equal toughness to that of the 440C steel, which is a good amount of toughness.

Wear resistance

The wear resistance is meant to measure a steel’s ability to withstand a wide variety of substances and rough surfaces without losing part of its volume or picking up bits of material from other items. The causes of wear and tear can originate from the same materials that the user wishes to cut and other factors in the environment. 

Wear testing simulates real-life contact between a steel knife blade and a source of destructive interface.

When a rough surface comes in contact with the blade and rubs away at it, and removes part of the metal, that sort of wear constitutes abrasion. Abrasive wear can lead to the sharp edge of the blade turning into a dull and rounded one, even without applying any high pressure to the knife.

When the smooth and clean surface of the steel knife blade comes into contact with another smooth and hard substance such as another steel, it can lead to a transfer of material onto the steel blade knife. Unlike abrasion, adhesion requires a high pressure to generate enough friction to tear the surface of the blade.

Crucible Industries CPM 20CV steel offers nearly five times the wear resistance of 440C steel. Hence, it is a trustworthy steel to invest your money if you keep your knife in demanding environments.

Corrosion resistance

Corrosion resistance is supposed to signify how well a steel or metal can avoid developing oxidation due to exposure to moisture, humidity, salt, and the environment. The most used method to improve corrosion resistance lies in the addition of Chromium into the alloy’s chemistry.

 Although the highly familiar term ‘stainless steel’ represents a highly optimistic misnomer, Chromium content levels correlate with resisting corrosion oxidation and applying preventive maintenance to delay it.

Crucible Industries CPM 20CV showcases exceptional corrosion resistance compared to other alloys in its grade, especially the 440C steel.

Edge Retention

Edge retention mainly aims to quantify how well and how long a steel blade stays sharp throughout usage. CATRA (Cutlery and Allied Trade Research Association) has developed a test machine that attempts to assess and determine edge retention of various steels.

In the test methodology, the knife being assessed is mounted up with the cutting edge point up, and a stack of specific synthetic paper with a chemical combination of 5% silica lowers onto the blade. The blade is then moved back and forth to cut the paper while the silica content generates mild wear onto the blade’s edge.

The particular test measures and quantifies the blade’s performance and the number and depth of cuts that the blade can complete. 

Crucible Industries CPM 20CV achieves a CATRA test score of 180, which is an impressive score and denotes that this steel can hold its edge in adverse conditions and is durable.

CPM 20CV Vs Other Steels

The Rockwell hardness of CPM 20CV is 59 – 61 HRC. That is just slightly harder, and has the same toughness as 440C, which is a benchmark steel for knives. 20CV has five times the wear resistance of 440C, and has 30% more corrosion resistance. 440C has a cutting edge retention score of 100 on the CATRA test, while 20CV has a score of 180.

CPM 20CV vs. M390 

CPM 20CV vs. M390  steel comparison chart
Properties20CVM390
Edge retention9/109/10
Corrosion resistance7/107/10
Ease of sharpening2/102/10
Toughness6/106/10

From this table, it is fair to deduce that CPM 20CV and M390 are equal in all properties.

CPM 20CV vs. S30V

CPM 20CV vs. S30V steel comparison chart
Properties20CVS30V
Edge of retention9/108/10
Corrosion resistance7/107/10
Ease of sharpening2/105/10
Toughness6/105/10

From this table, it is fair to deduce that CPM 20CV provides slightly better edge retention and toughness, whereas S30V provides improved ease of sharpening.

CPM 20CV vs. Elmax

CPM 20CV vs. Elmax Steel Comparison Chart
Properties20CVElmax
Edge of retention9/109/10
Corrosion resistance7/105/10
Ease of sharpening2/104/10
Toughness6/106/10

From this table, it is fair to deduce that CPM 20CV is equivalent to Elmax in e retention, toughness, and slightly better corrosion resistance, whereas Elmax provides better ease of sharpening.

Favorites using CPM 20CV Stainless Steel

Benchmade Knife - Proxy 928, Plain Drop-Point

The first utilizing CPM 20CV stainless steel is the Benchmade 928 Proxy; This folder exceeds all expectations of a folding knife. The 928 was designed by Warren Osborne and featured a 3.87″ drop point blade with a thickness of 0.15.” The blade is plain ground with thrust-bearing washers and a flipper for easy one-handed operation. The handle is made of titanium and utilizes a monolock mechanism with an adjustable lock face and tan G-10 wrap-around scales. 

This week I have TWO favorites for CPM 20CV steel bladed knives.  The first utilizing CPM 20CV stainless steel is the Benchmade 928 Proxy; This folder exceeds all expectations of a folding knife. The 928 was designed by Warren Osborne and featured a 3.87″ drop point blade with a thickness of 0.15.” The blade is plain ground with thrust-bearing washers and a flipper for easy one-handed operation. The handle is made of titanium and utilizes a monolock mechanism with an adjustable lock face and tan G-10 wrap-around scales. 

Finishing off the 5.08″ handle is the tip-up, reversible pocket clip. The design is perfect, and the knife seems to almost melt into the hand. Benchmade broke the mold on this knife and shows that their capabilities go far beyond the more standard blades in their lineup, such as the Griptilian. It is as pleasing to the eye as it is to the hand.

My second favorite is the Benchmade Mini Griptillian Axis Lock knife.  I’ve reviewed Griptillians before, but this is a member of the 550 series (555-1 actually), and it has all the features of any Griptillian (with the Sheepsfoot blade). Because it uses the AXIS lock system, it’s easy to open for both lefties and righties!

Conclusion

The key to a great knife is, obviously, the steel. We enjoy a vast array of knife steels today. From yesterday’s carbon steels have come today’s stainless and “super” stainless steels. The average knife customer isn’t concerned as much with the type of steel as they are with the look, the usefulness, and, more importantly, the price.

By keeping that in mind when we, the “knife junkies”, look at the knives currently using the latest iconic stainless steels, we look for something different. We want something that stands out among the pack. CPM 20CV does just that.  It is tough enough to take whatever you throw at it, and it takes only a few laps on the leather strop to bring back the edge to almost scary sharpness. 

20CV is at the head of the pack in many respects, but more importantly, it is a steel good enough to belong there.


 

About The Author
Jeremy Dodd is a columnist for KnifeUp Magazine covering outdoor, tactical, hunting, and fishing topics. He served eight years in the United States Navy and attended Vincennes University for Conservation Law Enforcement. Jeremy lives in Washington, Indiana.

One comment on “How Good is CPM 20CV Knife Steel?”

  1. I’ve got to disagree with the “ease of sharpening” metric that rates S30V a 6, and 20CV a 2. I suppose it makes sense if the measurement is just about how easily steel wears away on the edge of a blade, but as someone who sharpens lots of knives by hand, usually on wet stones, “ease of sharpening” to me also means what kind of work must be put in to maintain an existing edge; if the steel works well with coarse edge, or if it has to be polished up to a very high grit to get maximum performance; how forgiving (or not) it is with a small variation from the edge angle; and if the bur is likely to become a wire edge if not sharpened perfectly on both sides. In all those things–especially the first and last–20CV excels, and in my experience, is noticeably superior to S30V. In short, 20CV is no trouble to sharpen, maybe just because it takes so much to get it dull, but whatever the reason, I in terms of practical application, I think it rates higher than a score of 2.

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