How Good is CPM S35VN Knife Steel?

Jeremy Dodd
February 4, 2021
knife steel

Introduction

If you’re someone who is an avid hunter or an outdoorsman who likes to venture out into the hard and unfriendly terrains and encounter a situation where you might need a knife or tool with sharp edges, the CPM S35VN steel might interest you!

To be able to understand the utility of this steel as a knife, let’s walk through various factors which will help us make our decisions, such as: 

  • Hardness
  • Toughness
  • Wear Resistance
  • Corrosion Resistance
  • Edge Retention
  • Ease Of Sharpening

The CPM S35VN is a high-end martensitic stainless steel made by Crucible; this steel consists of high Carbon, Chromium, and Vanadium and has been carefully designed and customized to provide a great balance between toughness, corrosion resistance, and hardness. It also provides improved and better toughness over CPM S30V.

This steel is mostly used in long-wearing and durable specialty cutlery, extrusion feed screws, plastic injections, pelletizing equipment, knife industry, and wear components for Food and Chemical processing.

Composition of S35VN steel

  • 14% of Chromium: For tensile strength and edge retention, and improves corrosion resistance and wear resistance.
  • 0.03% of Phosphorus: which increases strength.
  • 0.4% Tungsten: which improves wear resistance and hardness.
  • 1.4% of Carbon: It improves hardness and wear/corrosion resistance, but a high amount decreases strength.
  • 2% of Molybdenum: which increases Machinability and strength.
  • 0.1% to 0.4% Nickel: which improves toughness.
  • 3% of Vanadium: which improves wear resistance and hardenability.
  • 0.5% Silicon: which improves Strength.
  • 0.03% of Sulfur: which increases machinability.
  • 0 to 0.5% Cobalt: which boosts the individual effects of other components.
  • 0.5% of Manganese: which increases hardness and brittleness.
  • 0.5% Niobium: which increases hardness, wear resistance, and corrosion resistance.

By taking a single look at the list, you can see that the chemical composition of S35VN steel is a combination of high Carbon, Vanadium, Chromium, and Molybdenum, which provides the steel with corrosion resistance, excellent wear resistance, and toughness.

Edge retention

Edge retention or also known as the strength of the knife, is the knife’s ability to hold its sharpness during use. Whether it’s cutting apart nylon ropes, chopping up cardboard boxes, feather sticking firewood, or maybe even chopping up some meat for your dinner, no one wants to work with a dull knife. The results you find when putting premium steels to cut tests compared to lower-end options are pretty remarkable.

In the S35VN datasheet, the edge retention of S30V and S35VN are both listed approximately as 145% (of 58-59 Rc 440C). 

A CATRA (Cutlery and Allied Trades Research Association) study performed by Bohler-Uddeholm discovered that lower edge retention in S35VN is approximately 132% compared to lower edge retention of S30V, which is 149%; when both are tested at 61 Rc.

However, the S45VN datasheet shows a revised and different value for lower edge retention of S35VN at 140%. Due to the shift in the value within the datasheet and lower MC estimate in Thermo-Calc relative to S30V, it is agreed that 132% value is the most accurate estimate for S35VN.

Toughness

A tough and durable steel blade resists chipping and complete failure when subjected and underwent impact, beating, twisting, and torsion. Tough steel blades are ideal and best suited for camping and hard-use, like cutting through pesky ropes and handling wood. 

Whereas standard and low-level steel would chip, premium steel blades will be able to sustain themselves for intense batoning sessions, slide through steel strapping, and staples.

A renowned knifemaker Michael Drinkwine heat-treated and machined a set of S35VN specimens for toughness specification; each condition was tested with the three examplesYou can see similar behavior examples, you and then averaged. We will follow his experiment to determine the toughness.

If you look at the trend of hardness vs. toughness, the results seem somewhat flat, with a slight peak around 61c. This does not precisely settle with our logic that tells that lower hardness means improved toughness: 

However, when we analyze the trends of toughness, we can see why the toughness ended up going flat. Firstly, increasing austenitizing temperature leads to both increased hardness and toughness. You can see similar behavior with the S45VN where a refinement in the carbide structure was noted to be the reason.

One particular specimen was tempered at 500 Fahrenheit, which led to subsequent reduction hardness and toughness, which is possible due to tempered martensite embrittlement. 

Tempered martensite embrittlement refers to the phenomenon where some steels with low alloy content are tempered in the range of 260 and 340 C (500-644 F), which results in decreased ductility and increased brittleness.

Although, it could be possible that the 500 F tempering did not help in improving toughness relative to the 400 F, and statistical differences in toughness testing might have resulted in a slightly lower value.

From the graphs, we can deduce that austenitizing in the upper end led to a higher toughness. Tempering within the range of 300-400 F leads to the best properties depending on the desired hardness.

Note: Lower tempering leads to a higher amount of hardness.

Hardness

Hardness is referred to the steel’s ability to resist deforming when it is subjected to stress and other applied forces. In steel knives, hardness is directly correlated to strength and is usually measured using the Rockwell C scale (HRC). 

The measured hardness for S35VN in the Rockwell C scale runs from 58 to 61HRC depending on the heat treatment that the blade is subjected to. This indicates that the steel sits on the higher end of the HRC scale, which makes it pretty hard to steel. 

The high level of hardness gives it amazing durability and makes it quite suitable and ideal for everyday wear and tear in tough and harsh environments.

CPM S35VN steel has a very respectable Rockwell Hardness value of 58 – 61, which is indicative of premium steel, only this steel is not typically priced as a premium metal.

Hardening Response

After treating a variety of S35VN steel samples using a 30 minute austenitize for 1925 and 1950 F, and 15 minutes for higher temperatures. After this, the samples were plate quenched, subjected to a cryo treatment with liquid nitrogen, and once again, tempered twice for the duration of 2 hours. 

The heat treatment tests resulted in similar hardness to the datasheet as shown below:

From the above graphs, we can deduce that S35VN has good potential hardness and it is capable of reaching a minimum of 64 Rc. This should ideally provide a good range of hardness values to knifemakers.

Corrosion Resistance

Corrosion resistance refers to a steel’s capability to resist and prevent corrosion such as rusting which is caused by external factors namely humidity, salt, and moisture. It is crucial that we keep in mind that higher resistance to corrosion comes at the expense of the overall edge performance of that particular steel.

A corrosion resistance test performed on S35VN and S45VN revealed that S35VN did fairly well in the corrosion testing, almost as well as S45VN which was specifically designed to have better corrosion resistance with an increased Chromium content. Below is a table showing ratings of S35Vn vs. Elmax vs. S45VN vs. M390 vs. Vanax.

S35VN Corrosion Resistance Rating vs Other Steel Comparison Chart
SteelCorrosion Resistance Rating
S35VN7.8
Elmax7.8
S45VN8.4
M3909.1
Vanax10

Wear Resistance

S35VN steel has been noted to deliver good quality wear resistance, despite its high levels of toughness. In this steel, Niobium combined with Carbon forms Niobium Carbides that facilitate in making S35VN more effective at offering quality wear resistance. The high level of Vanadium also contributes to and facilitates the steel’s great wear resistance.

Also, Molybdenum binds with Carbon to form hard Carbides that make the steel harder which subsequently improves its wear resistance. Overall, S35VN offers excellent abrasion resistance which will last for years without deforming at the first sign of tear, as cheap steel grades do.

Ease of Sharpening

The ease of sharpening or sharpening ability is correlated with the hardness of the steel. Taking into account that the S35Vn is not ultra-hard, sharpening it with ease will not be too much of a challenge. But this does not mean that it is the easiest steel to sharpen and will present challenges to a certain extent.

It would be helpful for you to know that you can give your S35VN steel knife a razor-sharp edge with somewhat ease and with lesser effort as compared to harder steel grades.

Machinability

Not a high number of high-end martensitic stainless steels are everyone’s favorite to work with, but the S35VN will give you a rather smooth time while working on it. Most knife smiths love the S35VN steel since it is easy to machine, grind, and even polish. 

This steel requires little power to cut and remains the top contender for bladesmiths who wish to create high-quality blades without wearing out the steel with heavy machining.

S35VN Heat Treatment

After reading the graphs and comprehending them, it would be recommended to treat S35VN by austenitizing for 15 minutes at 2025 F, plate quenching, followed by a liquid nitrogen treatment for at least 30-35 minutes, and then tempering between 300 and 400 F twice for a duration of 2 hours each time.

This heat treatment should result in at least a 60 Rc accompanied by good toughness, corrosion resistance, fine microstructure, and toughness.

S35VN Pros and Cons

Pro #1 – Improved Toughness

A pocket knife’s toughness depends on its ability to resist cracks, chips, and other damage caused by impact. This sort of damage is extremely tiring to fix and can lead to permanent indentions or damage to the blade.

The CPM methodology produces steel that is generally tougher and more resistant than other steel grades. When compared to CPM S30V, the Niobium Carbides in CPM S35VN stainless steel make the steel approximately 15-20% tougher, resulting in the blade becoming more resistant to chipping and cracking.

Pro #2 – Improved machinability 

CPM S35VN is usually preferred by craftsmen and bladesmiths since it is easier to machine, grind, and even polish. The machinability in metal is measured and calculated by the ease with which it can be cut and still be able to retain a good finish. S35VN steel usually requires little to minimal power to cut, making it a top contender for craftsmen.

Pro #3 – Ability to withstand prolonged use

CPM S35VN knives can stand up to long-term usage without diminishing or tampering with quality. S35VN steel generally has a Rockwell Hardness rating ranging between 58 and 61, depending on the heat treatment of the blade. The Rockwell scale measures a metal’s hardness by measuring and calculating how deep an indenter can penetrate a metal under a really heavy load.

Super hard steel (like the ones used in chisels) has an HRC rating ranging between 55-66. For example, axes generally have a rating ranging between 45 and 55.

CPM S35VN steel’s high HRC rating facilitates it in becoming highly durable steel for everyday usage in harsh conditions. For most pocket knife users, everyday utility is a huge parameter that needs to be fulfilled.

Con #1 – Costlier than other steels

CPM S35VN steel is considered to be moderately higher quality steel than its most counterparts, hence it does not seem unusual to realize it has a higher price to it as well. The most common stainless steel in the ‘mid-range category can cost nearly 3 to 4 times less than a CPM alloy steel.

After adding in the additional costs that come with machining, grinding, and heat treating higher quality steels, the end product usually tends to be on the higher end of the cost spectrum.

CPM S35VN pocket knives usually range anywhere from $100 to $300, whereas, on the other hand, a mid-range pocket knife is generally under $100.

Con #2 – Requires slightly more effort to sharpen

CPM S35VN steel’s most significant advantage is that it can be sharpened to exceptional levels. This makes this pocket knife blade ideal for outdoorsmen and regular hunters who require the use of sharp, tough, and wear & tear resistant blades. 

Manufacturers of pocket knives made from CPM S35VN steel knives often agree that such highly durable and tough steel can be difficult to sharpen. Such a hard and tough material requires special sharpening skills and stones.

Pro #3 – Minor differences between S35VN and S30V steel

When the S30V steel was first launched back in 2001, the community was impressed with its high quality and comparatively low price range. Such factors made it an easy choice for the everyday pocket knife user.

S35VN was launched in 2009 with slight improvements to the S30V formula. Its chemical composition made it a tougher and more wear-resistant steel, but some feel that the enhancements are too minor to justify the hiked-up price.

Steel Comparisons

S90V vs. S35VN

S90V vs. S35VN Steel Comparison Chart
ParametersS90VS35VN
Toughness2/106/10
Ease of Sharpness3/106/10
Corrosion Resistance6/107/10
Edge Retention8/106/10

From studying the above table, it is fair to deduce that S35VN provides improved toughness, ease of sharpness, and corrosion resistance as compared to S90V steel.

S35VN vs. M390

S35VN vs. M390 steel comparison chart
ParametersS35VNM390
Toughness6/106/10
Ease of Sharpness6/105/10
Corrosion Resistance7/108/10
Edge Retention6/108/10

From studying the above table, it is fair to deduce that S35VN provides improved ease of sharpness but cannot be at par with the M390 steel in terms of edge retention and corrosion resistance. They are equally tough.

S35VN vs. Elmax

S35VN vs. Elmax Steel comparison chart
ParametersS35VNElmax
Toughness6/106/10
Ease of Sharpness6/104/10
Corrosion Resistance7/105/10
Edge Retention6/109/10

From studying the above table, it is fair to say that S35VN provides improved ease of sharpness and corrosion resistance as compared to the Elmax steel. Elmax scores higher in edge retention. They are both equally tough steels.

S35VN vs. 3V

S35VN vs. 3V steel comparison chart
ParametersS35VN3V
Toughness6/1010/10
Ease of Sharpness6/105/10
Corrosion Resistance7/105/10
Edge Retention6/107/10

From studying the above table, it is fair to say that the CPM S35VN provides improved corrosion resistance and ease of sharpness as compared to the CPM 3V. The 3V steel provides improved edge retention and toughness as compared to S35VN.

S35VN vs. D2

S35VN vs. D2 steel comparison chart
ParametersS35VND2
Toughness6/106/10
Ease of Sharpness6/103/10
Corrosion Resistance7/104/10
Edge Retention6/107/10

From studying the above table, it is fair to say that S35VN provides improved ease of sharpness and corrosion resistance as compared to the D2 steel. D2 steel provides improved edge retention as compared to the S35VN and both are equally tough.

Recommendation of best S35VN knife

Spyderco, Bark River, Kizer Cutlery, and Zero Tolerance are amongst many top manufacturers who have utilized the S35VN steel for their premium blades. The versatile Bark River Bravo 1 is widely recognized as one of the nest survival/bushcraft knives in the market as of now, and the Bravo 1 knife is a top contender in almost every category. 

The bravo 1 was created after several members of the Marine Corps Force Recon bought several knives from multiple manufacturers and tested them in harsh conditions. The big, fat winner was the Bark River Gamekeeper. After receiving a few feedback ideas from the Marine Corps, Bark River created the Bravo 1. 

This particular knife has a 4.25 inches drop point blade, a convex ground, with a satin-like smooth finish. The S35VN steel blade is .22 inches thick and features a ramp-up thumb rest.

bark river natural micarta

Conclusion

To conclude, S35VN is a great knife for the trained outdoorsmen and hunter who ventures into slightly harsh terrains. It is a high-end premium steel blade and provides a decent amount of toughness, ease of sharpness, edge retention, and corrosion resistance. It can easily withstand daily wear and tear for a long period of time

It falls in the higher end of the cost spectrum but most people can argue that it worth the buy due to its durability and composition. From the above-presented comparison tables, you can decide which steel suits your needs best.


 

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.

14 comments on “How Good is CPM S35VN Knife Steel?”

  1. S35vn is most certainly not the best stainless blade steel. So many manufacturers are using other powdered stainless Steel’s with better results !!!

  2. I just purchased a Spartan Horkos Combat / Utility Knife, which is made of S35VN. Your outstanding write up gives me more insight on this type of steel.

    Thank You & Great Job!

    1. Wow – Our whole team here at KnifeUp appreciates even the 30 seconds it takes someone like you to write us a note of encouragement/thanks instead of mean and hateful comments. It’s truly amazing what a word of encouragement can do vs. a vitriolic diatribe.
      Blessings to you Leopold,
      J.

  3. Bought an Emerson CQC-7 folder…researched the S35VN steel used a little bit before buying, but this article filled in a lot of holes in the story I had. Great steel, great knife, great information. Thanks.

  4. I have a 3″ paring knife from the 1980s bought at Warther in Ohio. Bought a new one @3.25″ @ Warthers a few years ago. The new one made with CPM S35VN is all rusted! Both washed & cared for the same way & the one from 1983 doesn’t have a speck on it. Why?

  5. Great write up on S35VN, I’m just getting into high end knives and have purchased a Benchmade and a Spyderco, both S30V. I’ve been doing more research on S35VN and I’m definitely sold on it.

  6. How can you do a write-up on S35VN (for a knife publication no less) and not mention it’s co-developer and legendary knifemaker Chris Reeve?

    Or fail to mention Chris Reeve’s Knives (which uses this steel almost exclusively) in the roll call of companies that use this steel?

    Not trying to start anything, just seems like a pretty big (and possibly biased) oversight.

  7. Great article S30V is a Great steel but the ease of sharping and manufacturing I would choose S35vn

  8. Thanks for the Great info, I have the Zero Tolerance 0452CF folder and the its an amazing everyday carry knife. A bit pricey at $250 but awesome none the less.

  9. Jeremy;
    Great article and insight. I work with SMKW but my background is in metallurgy and metal fabrication. It is tough to write an article or talk about blade steel because it is subjective and there are so many opinionated individuals. You did a fantastic job with this article. S35VN is in my opinion one of the best “all around” blade steel and I have put it and many others to the test. Thank you for this article and keep up the good work!

  10. I was wondering that myself, especially since I think that my Sebenza’s blade performs better than any other knife with S35VN blade steel, including Spyderco, ZT, and Bark River. Between his heat treatment and grind, Reeve blades are the peak performance of S35VN, which I guess isn’t that surprising since he helped invent the stuff.

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