Ranking the Steel Ranking Articles

Note: I now have a steel ratings article of my own, read it here: Knife Steels Rated by a Metallurgist

Intro

Thanks to Stacy Apelt for becoming a Knife Steel Nerds Patreon supporter! Based on a poll of Knife Steel Nerds Patreon voting members, we have decided to purchase a small impact tester for knife edges. This will allow us to study the effects of steel, heat treatment, edge geometry, sharpness, etc. on chipping and rolling of edges.

If you do a google search (like I have) for “knife steel” you come up with a lot of articles that describe, rate, and/or rank various popular knife steels. I can see how these would be popular articles for budding knife enthusiasts as it can be overwhelming to figure out what to look for in a knife purchase. With all of these incomprehensible designations like 20CV, M390, 204P, XHP, S30V, etc. who can possibly know which to pick? I’m particularly interested in the articles where they are confident enough in their knowledge of steel to give ratings to different properties of steels. The available datasheets from the steel manufacturers are often missing information on specific toughness, wear resistance, or corrosion resistance tests and when they do have them the tests are typically not comparable between the manufacturers. So the ratings that are generated by those writing these articles are basing them on their own experience, the reputation of each steel, what limited information is available from the steel manufacturers, and how they feel that morning.

So I did a couple google searches, opened all of the articles in the first 2 or 3 pages, and kept each that had ratings for blade steels.  I narrowed down the list to 5 articles that I will be commenting on. I will be criticizing their descriptions of steels and steel properties as well as the ratings that they provide. Some will seem like nitpicking but I have tried to keep my analysis to relatively objective things and to avoid things I think are simply poorly explained. Even where I criticize the articles that does not necessarily mean that I think the author is clueless, or that none of the articles are worth reading, or that they don’t regularly call their mothers like good boys should.

Evaluating Steels

To understand how I know the approximate properties of different knife steels, you have to read my articles on what controls different knife properties. It is a bit difficult to summarize within this article which already requires many words to evaluate the different rankings. Here are links to learn about a few of them:

Edge Retention of Knife Steels Part 1 and Part 2

I don’t have a full article comparing the toughness of different steels to each other. Here is an article about how chipping of edges happens to understand the mechanisms that occur and so how we evaluate different steels based on those mechanisms. And here is an article where I took micrographs of 42 knife steels which has the most up-to-date toughness charts developed for this website.

Corrosion resistance of knife steels

The Ultimate Guide to Choosing the Best Knife Steel for Top Blades – TrekWarrior.com

This article is written by someone known only as “Huston” and he is quite confident in his article if the title is any indication. I would personally be more careful before calling any of my articles the “ultimate” anything but I suppose we can give him the benefit of the doubt and say that the title is for clickbait purposes and not necessarily how he feels about his own steel knowledge.

Huston begins his article with a relatively meaningless introduction that seems to be for the purpose of linking to his other articles on which knives to buy:

“Knives are one of the most versatile tools that someone can have on their person for any day-to-day projects. They are especially critical in survival situations.

In fact, there has probably never been a time where you were relieved to not have your knife on you.”

I had to read that second sentence a couple times before I figured out what he was saying but I have to disagree. I am relatively frequently relieved that I remembered to not bring a knife with me every time I visit an airport or a theme park with metal detectors. Fortunately I have not encountered any survival situations at either location thus far.

Defining Steel Properties

He then defines a few properties such as “Holding an edge – After sharpening, how well does the blade stay sharp.”

It’s nice of him to mention that the knife should be sharp before we see if it holds an edge, as it seems less useful to define how well it holds a dull edge. Perhaps it would be good to mention what type of cutting he means when he says that the blade may not “stay sharp.”

“Wear Resistance – How long the blade remains usable and resists chipping and other abrasions.”

Chipping is normally considered part of toughness rather than wear resistance. Also it’s not clear how this is different than “holding an edge.” And what does he mean by “remained usable”? I would say if it’s not broken it remains usable. I’m not sure that has much to do with wear resistance.

“Toughness – How much energy the blade can absorb before fracturing. Too much toughness can lead to a blade easily warped.”

No, toughness has nothing to do with a blade easily warping.

Elements

He next defines the effect of different alloying elements in steel. I don’t really like these kinds of explanations. They have the appearance of providing useful information but really doesn’t tell a consumer very much. For example, he says as anyone does in these kinds of articles that higher carbon means higher hardness. However, how much harder is S110V with 2.8% carbon than 1075 with 0.75%? The answer is that S110V doesn’t get harder than 1075 because it has to do with how much carbon is in solution during the high temperature hardening/austenitizing treatment and must be balanced with all of the other elements in the steel. How can a knife consumer determine that by looking at the steel composition? They can’t. I won’t nitpick much else other than he says that manganese improves wear resistance which it really doesn’t.

The Ratings

Now for the actual ratings which I assume is what most people are looking for when they click on one of these articles. Another point where it looks like more information is being provided to the reader but may or may not be useful is the inclusion of a property like “wear resistance.” The effect of wear resistance on edge retention or ease of sharpening is nowhere defined in the article so it mostly serves to pad out the chart. I won’t say that every single rating is wrong in these articles. Someone who has been around knives a little while and learned a thing or two can see that S90V has higher wear resistance than 420. And while I might rate something an “8” out of 10 while someone else gives it a “7” one might argue that it is perhaps not a meaningful difference. However, there are still easy things to point out in most of these, first here are the ratings themselves:

1050 gets a “1” for corrosion resistance while 1075 and 1060 get a “0” which he says is “because of the lower carbon content,” which wouldn’t make any difference in a steel with no chromium. 440A and 7Cr17, despite being the same thing, get very different ratings, particularly in corrosion resistance where 440A is given a “7” and 7Cr17 is given a “3”. VG-10 is given the same rating as Elmax for edge retention and a higher score for edge retention and wear resistance than S30V; VG-10 is a step below in wear resistance from those steels. S30V is given the lowest rating for toughness, which seems like a stretch. 1.4034 stainless steel is essentially a 420HC made in Germany but is given the highest score for toughness of “7” a full 2 points higher than 420HC, and higher than the high toughness steels 5160 and 1050. 440C gets a higher rating than 440A for corrosion resistance despite the fact that 440A has better corrosion resistance because less chromium is tied up in carbides in 440A. M390 gets a higher score than Elmax for toughness even though Elmax is tougher.

That seems like enough examples of poor ratings of steel. There are some ratings that I don’t disagree with but a novice can’t tell which are questionable.

Knife Blade Materials – by KnifeCenter.com

The anonymous author starts by giving properties of steel, which are mostly fine though I would write them differently. Except for “initial sharpness” which is not a steel property. And defining ductility as “ability to flex or bend without fracturing” is misleading. He next lists the effect of different elements which as I explained above I’m not a big fan of. He has another good example of how these can be misleading with the description of vanadium as promoting “fine grains.” That is true; small vanadium additions are made to some steels to help “pin” grain boundaries and reduce grain growth. However, the high vanadium additions (>1%) in many knife steels are made for wear resistance and that is not explained in the article. Also, a person new to steel terms doesn’t know what having “fine grains” means in a knife. 

Next the descriptions of steels are taken directly from Buck Knives and Cold Steel. At least he says that he took them from those sources rather than claiming them as his own. His ratings appear to also be taken from an older chart from Buck Knives which has only a few steels. Because the chart is small and has few steels there isn’t much to criticize. The most obvious strange thing in the ratings is that 420HC is listed as having better corrosion resistance than 420 for some reason:

Knife Steels – BladeReviews.com

This article has a much less pretentious title and was written by Dan Jackson. I like some of the writing better in this article than the previous two. He at least mentions the effect of edge geometry. Unfortunately he doesn’t define most of the properties that he is ranking, so I’m not sure if the “edge retention” rating incorporates hardness or toughness or primarily wear resistance, etc. I also like that he doesn’t define the effect of different elements on steel but he does link to a page that does so, so hopefully no one clicks on that. Here are the ratings:

Analysis of the Ratings

The most questionable ratings in this chart are perhaps corrosion resistance. For example, A2 and 3V, non-stainless tool steels, get the same score of “3” out of 5 as CPM-154 and VG-10 which are stainless steels and obviously are superior in terms of corrosion resistance. D2 and M4 do get a lower score of “2” though I would argue that 1095 should get a “1” or “0” rather than the same “2” as D2 and M4. The edge retention of 3V is too high at 4.5 out of 5 whereas D2 gets only a “3” despite the two getting a similar result in Bohler-Uddeholm CATRA testing [1]. And 3V gets a lower result in CATRA testing than Elmax, S30V, or S35VN which are given a lower “4” rating [1]. ZDP-189 gets a toughness rating of “3,” the same as S30V and VG-10 despite the very high hardness and carbide volume of ZDP-189. The datasheet for ZDP-189 shows that it has very low toughness [2]. AUS-8 gets a toughness rating of “4” where 8Cr13MoV gets a “3” despite the two being similar steels. I would rate the toughness of VG-10 higher than 440C despite Dan’s ratings, and would probably score M390 a notch below where Dan has it based on its high carbide volume [3] and my own testing [4]. I’m not sure why M390 has such a good reputation for toughness. Must be the effective “3rd Generation Microclean” advertising.

Guide to the Best Knife Steel – KnifeInformer.com

This article was written by Matt Davidson of Knife Informer. He begins the article by saying, “In choosing the best pocket knife you should pay particular attention to the type of steel used in the blade.  Steel is really the essence of the blade and primarily responsible for how the knife performs.” I think edge geometry and design is primarily responsible for how the knife performs not the steel, but maybe Matt is using hyperbole since this particular article is on steel.

Definitions

He defines wear resistance in terms of both abrasive wear and adhesive wear but it’s not clear to me how that is useful to the novice that needs an article to introduce different topics. He defines edge retention in terms of wear resistance and hardness so that is the basis upon which I will analyze his rankings. He also defines toughness but does not rate toughness of any of the steels. He finishes out the article by describing Maxamet and CruWear but says that Maxamet is Carpenter’s answer to S110V. It really isn’t, as Maxamet is a high speed steel designed to be a carbide replacement for better toughness but retaining much of the hot hardness, and is not stainless. He doesn’t list the effect of different elements (yay!) but does link to an article that does (boo!).

Ratings

Matt gives an “edge retention” rating which is reportedly based on wear resistance and hardness though almost all of the ratings correlate with his wear resistance rating. The exception is D2 which gets a relatively high edge retention score (higher than S30V) despite a low wear resistance rating of 4 (compared to 6 for S30V). He gives a higher edge retention score to 14C28N than 13C26 even though the steels are very similar other than corrosion resistance. S110V gets only a “6” for corrosion resistance despite the steel being designed for high corrosion resistance. 440A gets a very average corrosion resistance rating of 5.5 despite its very good corrosion resistance. I’m not sure where the hardness ratings came from as most of these steels can be heat treated to a wide range of hardness values. It is true that a steel like 420 does have a limited maximum hardness but for most of the others it is a matter of choice. Elmax is given a hardness of 62 despite that being close to the maximum it can reach with typical heat treating. D2 is given a hardness rating of 62 Rc despite 60 Rc being much more common. So I don’t know if the number is supposed to be based on maximum achievable hardness or typical hardness in production knives.

The ratings above are perhaps the best of those analyzed so far though he was helped by the fact that he did not rate toughness; that is a “tough” one to rate using commonly available information. I’m not a fan of how he lists the steels in groups from “ultra premium” down to “low end” which is only in terms of edge retention. There are different steels for different purposes but I don’t like to think of steels in those terms. Will the last article I look at be the best of all?

A Comprehensive Guide to the Best Knife Steels – ThePocketKnifeGuy.com

Another rather pretentious article title but we have to bait those clicks, I suppose. This article was put together by “The Pocket Knife Guy” but I couldn’t find anything about him other than his name is Matt. I normally want to know a little more about a person that calls himself THE pocket knife guy. He starts the article with some meaningless stuff about our destiny and the iron age and promises “answers to all of your questions about the best knife steel!”

He gives some strange explanations for the microstructure of steel: “When steel is viewed at a high magnification, it becomes obvious that it has a grain structure similar to grains of sand. The smaller the crystals are, the tougher and stronger the steel with be, and the better it will hold an edge. So while adding chromium to steel increases corrosion resistance, it also increases the size of its crystals.”

I’ve never thought that steel looked like grains of sand. It does have grains, yes, but it does not have a sandy or grainy appearance. It is true that smaller grains means higher toughness and strength. Then he takes a left turn and says that chromium “increases the size of its crystals” which is not true. He then says that “Stainless steels are stronger than plain steels, but they are not as tough.” It is actually somewhat difficult to make a stainless steels that is as strong/hard as a simple carbon steel. Stainless steels cannot be said to be “stronger” in any kind of general way.

He also says what the different elements do to a steel (oh no….) and it does not go particularly well. He says that, “during forging, Cr and Mo form hard, double-carbide, bonds which help to improve hardenability, wear resistance, and corrosion resistance.” I don’t know what double carbide bonds are but I know that carbides are not a positive for corrosion resistance. He says that vanadium helps produce a fine grain structure which is true enough in small doses. However, he also says that, “Many people report that they are able to get knives using steels that contain vanadium such as CPM S30V sharper than they can non-Vanadium steels such as ATS-34.” I’m not sure I’ve heard anyone report that before, as the hard vanadium carbides typically make sharpening more difficult. He says that manganese “[i]ncreases toughness and hardenability in non-stainless steels and helps to produce a fine, dense, grain structure in stainless steels by reducing the size of the Carbides.” It does not improve toughness or reduce the size of the carbides, and he doubles down on this later in the article by saying “A blades toughness is generally determined by the steel’s Manganese content,” which it certainly is not. In defining wear resistance he says that “the amount, type and, distribution of carbides within the steel are what determines its wear resistance,” which I point out because it is a true statement that I found.

Many of the descriptions of the steel types are questionable as well, such as

“D2 – An American made, but less expensive version of CPM S30V.”

D2 is made worldwide and cannot be called a “version of CPM S30V” particularly because it is nearly 100 years older.

“420HC is a somewhat less expensive American-made stainless alternative to 440C. While it is similar in composition to 440C, it neither withstands impact as well nor, does it take and hold as fine an edge and, it is not as corrosion resistant.”

420HC is not necessarily made in America and is not similar in composition to 440C, as 440C has much higher carbon and chromium. Nothing about 420HC makes it less tough or corrosion resistant than 440C.

“VG-1 is a less expensive Japanese stainless steel somewhat similar to 420HC but which is mostly used by Cold Steel on knives that require a tough blade steel composition.”

VG-1 is not similar to 420HC as VG-1 has double the carbon.

“Elmax – A third generation Austrian, powder-metal stainless steel that is noted for its fine carbide distribution with extremely low inclusion content.”

Elmax is made in Sweden.

“O-1 is an ideal steel for edged weapons and tools because it is known for its ability to be differentially heat treated.”

O1 is not well known for being differentially heat treated, as it has relatively high “hardenability” which is a measure of how quickly it has to be quenched to achieve full hardness. Typically low hardenability steels are best for differential heat treatments because the edge can be quenched so it is hard while the spine is left to air cool to be soft.

“1095 – When quenched, it produces a near saturated lathe Martensite with no excess carbides; avoiding the brittleness associated with higher carbon materials. This steel is particularly well suited to applications where strength and impact resistance are valued above all other considerations and will produce blades of nearly legendary toughness.”

I thought this statement looked familiar and indeed it does because I found the same thing written about 1055 in the Cold Steel-written portion of the KnifeCenter article above. So not only is the information on lathe (sic) martensite, “no excess carbides,” and “legendary toughness” plagiarized but it’s also about the wrong steel. Plagiarized all the way down to misspelling lath.

He has some very pretty charts summarizing the ratings of all of the steels, which I have reproduced below:

If you compare the ratings above with those from the Knife Informer ratings you will notice that they are nearly identical. I did some sleuthing and found that the Knife Informer article was online first. I confirmed with Matt Davidson from Knife Informer that he did not give permission for his ratings to be used. Therefore I will not analyze these ratings as I already did so.

With steel element explanations and steel type descriptions that are straight up wrong, plagiarism from Cold Steel (that was assigned to the wrong steel), and plagiarized ratings I can’t recommend this article at all. The Pocket Knife Guy probably doesn’t call his mother either. I haven’t provided a link to his article because I don’t think anyone should read it. 

Ranking the Rankings

I will be using completely objective criteria for rating the various steel rating articles, just like the authors of the steel rating articles. I have rated their articles based on my own experiences, steel datasheets, and how I feel this morning. I even used gradients for my bars. Here are the ratings:

Knife Steel Nerd Steel Ratings

Why is there no page for steel ratings on this website? How can I criticize others’ attempts without providing my own? There are a few reasons:

• There are a few articles I want to write first. I don’t have any articles on how to determine steel toughness and edge retention, for example. I don’t want to have ratings with no accompanying explanation for how the scores were determined.
• There are some ratings I don’t know. The solution of the authors above is just to fill in numbers where they don’t know them. I don’t like doing that.
• I don’t like reducing things down to a single numerical rating when some properties are more complex.
• I write long, detailed articles that only true nerds read. Not make charts where people look at them without understanding anything behind it. I prefer to learn and educate.
• I’m not trying to sell knives or create clickbait.
• I will probably make one eventually. Probably. Maybe. It’s possible. I’ll think about it.

Update 6/20/2019: While I haven’t made a steel rating article, I did write an article about how to choose steels, and provided recommendations for the best steels within certain categories. Read the article here.

Update 10/29/2021: I now have a steel rating article! Knife Steels Rated by a Metallurgist

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[1] This Bohler-Uddeholm CATRA data is no longer available on the bucorp website. I have attached it here: Bohler-Uddeholm CATRA Data.

[2] http://www.discipleofdesign.com/knives/ZDP189_eng.pdf

[3] Gornik, Christian, and Jochen Perko. “Comprehensive wear study on powder metallurgical steels for the plastics industry, especially injection moulding machines.” In Materials science forum, vol. 534, pp. 657-660. Trans Tech Publications, 2007.

[4] https://knifesteelnerds.com/2018/06/04/toughness-testing-cru-wear-z-wear/