Thanks to Bill Smutz, Alex Topfer, Florian Bachler, Brunhard, Art, Rod H, Sach, Jinny Koh, Jon Duda, Cory Henderson, and UPKnife for becoming Knife Steeel Nerds Patreon supporters! And Michael Fitzgerald, Tim Marais, and Head VI for increasing their contributions. All of the experiments shown below are possible thanks to supporters.
Video
I also have a video that summarizes some of the information below while also showing how some of the experiments work. Lots of information is still specific to this article, however. I think they are complementary and you should watch/read both.
Background to this Article
I have a (relatively) short introduction before getting into the ratings with a few important things to put them into context. That way you can get into the steel ratings quickly. Most of the discussion of how the ratings were generated, various caveats and details, etc. are after the ratings. If you want to learn more than keep reading past the ratings.
I wrote an article about knife steel ratings available online in 2018, where I concluded that none of them were very good. At the end of the article I gave a list of reasons why I hadn’t made my own ratings chart, two big reasons were: 1) I didn’t yet have articles explaining what edge retention and toughness even is (this was early on in Knife Steel Nerds), 2) I didn’t have good experimental numbers on many steels. Both of those things are no longer an issue as I now have way too many articles and a book. And I’ve done a lot of experimental work on knife steels where I feel more confident in my own ratings. There are still a few things I don’t know but we have enough information to make educated guesses where data isn’t available. I reserve the right to change my ratings based on new information.
Toughness vs Edge Retention
Toughness is a measure of how much resistance a steel has to fracturing. In the context of a knife this would be chipped edges or broken knives. Edge retention is the ability of a knife to maintain cutting ability during cutting. I will be focusing on CATRA edge retention which measures abrasive wear of knives. I did a large study of different knives with identical sharpening and edge geometry. One important concept I want to hammer home is that there isn’t one property that is most important. Many steel ratings seem to over-emphasize edge retention. Or even if they try to be more open to importance of toughness, the good reputation of the high edge retention steels means that they get inflated toughness ratings along with it. Toughness and edge retention are generally opposing properties and it is difficult to improve both of them at the same time. Therefore I will be showing the ratings of the steels graphically in terms of toughness-edge retention balance, where steels that are high and to the right have the best combination, and you choose the steel based on the level of toughness or edge retention necessary for the knife. There is no such thing as a steel that is a “10” in both toughness and edge retention. Or even a 7 in both categories.
Importance of Edge Geometry
Another important caveat before we get to the ratings are that these are for the steel only. This does not predict which knife will cut longer or be more resistant to chipping. The reason is because sharpening and edge geometry will also greatly control properties. For example, see the chart below for how much edge retention can change with edge geometry for a single steel (in this case 154CM and CPM-154). Using 10 dps sharpening (20 degrees inclusive on the chart) leads to about 5x the edge retention of 25 dps.
Things are similar with resistance to chipping and edge deformation. A more obtuse edge angle is much more resistant to chipping than an acute edge. So setting edge geometry for the type of knife and intended use is very important. This is a major tradeoff between improved cutting ability and edge retention with an acute angle vs a strong and chip resistant edge with an obtuse angle. Below shows pictures of a 61 Rc knife that was impacted with a 3/16″ rod at different energy levels. The 25 dps sharpened knife saw almost no edge damage with 2 ft-lbs while a 15 dps edge saw a significant chip with only 0.3 ft-lbs and catastrophic chipping with 1.4 ft-lbs. These images are taken from my book Knife Engineering.
The Ratings
I’m going to give the ratings first and then give more explanation about how the ratings were created.
Carbon Steels and Low Alloy Tool Steels
These steels are typically used by forging bladesmiths, traditional folders, and some production fixed blades. Carbon steels are those that have primarily carbon added to them with some Mn or Si as well. Low Alloy tool steels have small alloy additions to increase “hardenability” so they harden more easily in oil rather than water. Water is a severe quenchant that can often lead to warping or cracking. Some of these steels also have vanadium (CruForgeV) or tungsten (Blue Super, V-Toku2, 1.2519) for increased wear resistance. In general, higher carbon steels have higher edge retention but lower toughness. The maximum edge retention available in this group is not particularly high because most of the wear resistance comes from iron carbide, also called cementite, which is the softest of the different carbide types. On the positive side, they are very easy to forge and grind.
8670 and 5160 are good choices for large knives that need very high toughness. 52100 and CruForgeV are good for general purpose knives. Blue Super and 1.2562 have higher edge retention but relatively low toughness. ApexUltra is a steel that we are working on that had excellent properties in small batch production (50 lbs). I’m looking forward to seeing if it does as well in full production.
Carbon and Low Alloy Tool Steel Ratings
High Alloy Tool Steels and High Speed Steels
High alloy tool steels are designed to be air hardening, so they can be cooled even slower than the oil hardening steels found above. This is good for ease in heat treating in large batches and for even cooling that greatly reduces warping and size changes. High Speed steels are a subset that have significant additions of Mo and/or W that makes them resist softening when they are used for machining operations. The big difference in properties vs the low alloy steels, however, are the harder carbides that are found in these steels. Vanadium carbides are among the hardest that form in steel, and chromium carbides are in between iron carbide and vanadium carbide. Steels with very high vanadium content like Vanadis 8, CPM-10V, K390, CPM-15V, etc. have extremely high edge retention. Maxamet and Rex 121 are so extreme in terms of wear resistance and edge retention that I rated them higher than 10 because otherwise it throws off the ratings for everything else. Powder metallurgy steels with low vanadium content like CPM-1V and Z-Tuff/CD#1 have extremely high toughness. The best steels with balanced properties include 4V/Vanadis4E, CPM-CruWear, and CPM-M4. My favorites of the high edge retention group are Vanadis 8 and CPM-10V.
High Alloy Tool Steel and High Speed Steel Ratings
Stainless Steels
Stainless steels are another subset of high alloy tool steels that have enough chromium in them to have stainless levels of corrosion resistance. You can’t look at only the chromium content of the steel to know the level of corrosion resistance. For example, D2 has enough chromium to be stainless (~12%) but its high carbon means that too much chromium carbide is formed to leave enough chromium for stainless levels of corrosion resistance. MagnaCut has the lowest chromium of any of the below steels but all of its chromium is in solution (no chromium carbide) and the fact that it has no chromium carbide also gives it the maximum level of corrosion resistance for a given amount of chromium. Also Mo additions improve corrosion resistance for a given amount of chromium.
As with high alloy tool steels, the amount of vanadium can be a shortcut to predicting the general level of wear resistance and edge retention. CPM-S90V is my favorite in the high edge retention category because of its decent toughness. S110V has improved corrosion resistance at the cost of some toughness compared to S90V. AEB-L and 14C28N are the best in the high toughness group. LC200N has similar properties to those two but with saltwater levels of corrosion resistance. The main downside is the steel is more difficult to heat treat and can’t go harder than about 60 or perhaps 61 Rc. The most balanced is CPM-MagnaCut which is in an area all by itself on the chart. The steel was developed to be free from chromium carbides which gives it properties similar to balanced non-stainless tool steels like CPM-4V and CPM-CruWear. Vanax gives up some toughness and hardness vs MagnaCut for saltwater levels of corrosion resistance. It also tops out around 60-61 Rc like LC200N and needs relatively careful heat treating to even be that hard. But it would be my recommendation for applications requiring extreme corrosion resistance.
Stainless Steel Ratings
Composition of Steels
I have the average composition of the steels rated above (plus some extras) so you can see what the different names refer to. There is an acceptable range for every element so this doesn’t mean that 1084 will always have exactly 0.84% carbon. Not every element is shown in the charts. For example, the Si space is blank for several of the carbon steels because they have a relatively wide acceptable range, not because the element isn’t added. And Mn and Si isn’t shown at all for the high alloy steels, even though those elements are added to all of them. This is to keep the focus on the elements that are making the biggest difference.
I actually don’t recommend that enthusiasts spend all that much time analyzing the exact composition of different steels and trying to guess their properties. Even metallurgists can have a difficult time estimating properties just based on the elements. There are so many interactions between them that predictions are difficult without modeling software. In general, higher carbon and higher vanadium steels have higher wear resistance and edge retention but lower toughness. And steels with at least 10% chromium are probably stainless, except for several important exceptions like D2 and ZDP-189.
Carbon Steel Compositions
Low Alloy Steel Compositions
Composition of High Alloy Tool Steels
Composition of High Speed Steels
Stainless Steel Compositions
Edge Retention
You can read about my CATRA edge retention testing in this article. Each steel was tested with a knife that was produced just for the test, and then sharpened the same way for each test (15 dps 400 grit CBN sharpening). A few steels have been added since such as MagnaCut and M398. I also added a few more steels in this study. The studies confirmed that the primary controlling factors are hardness of the steel, volume of carbides, and hardness of the carbides. The highest edge retention steel was Rex 121 which was at 70 Rc in combination with lots of high hardness vanadium carbides. We can predict edge retention of a steel within a relatively narrow band based on hardness and carbide volume. We should be suspicious of anyone who is claiming very high edge retention with a steel at low hardness and a small amount of carbide. The chart below has dotted lines which indicate the average effect of hardness for any given steel. So you can estimate how much a change in hardness would affect edge retention by following the slope of those lines.
And below shows a chart of carbide hardness, the equation we created to predict edge retention based on edge angle, hardness, and carbide volumes, and then the chart showing the good correlation:
TCC (mm) = -157 + 15.8*Hardness (Rc) – 17.8*EdgeAngle(°) + 11.2*CrC(%) + 14.6*CrVC(%) + 26.2*MC(%) + 9.5*M6C(%) + 20.9*MN(%) + 19.4*CrN(%)
Toughness
With toughness it is a bit harder to link to only one article as I don’t really have a summary of all of the toughness testing that we have done. Mostly it has been presented piecemeal with all of the studies that we have done on optimizing heat treatments of different steels like CPM-CruWear, AEB-L, 52100, etc. We use a subsize, unnotched chapy test with 2.5 x 10 x 55 mm dimensions. Each test is done with 3 or more specimens to get a good average. Below shows charts summarizing tests of different steels for the major categories discussed so far, low alloy steels, high alloy non-stainless steels, and stainless steels. In general, the more carbide the steel has and the larger the carbides the lower is the toughness. The hardness of the carbides does not matter much unlike with edge retention. There are a few other complicating factors such as carbon in solution and plate martensite, especially in low alloy steels such as described in this article.
Toughness vs Edge Retention
In some previous articles I have shown the balance between my toughness and edge retention measurements such as in the following chart, where the high alloy non-stainless are in orange and the blue are stainless:
However, one issue with these charts are that difference in toughness is that a linear scale for toughness is a bit misleading for visualizing practical toughness differences. If you look at the chart you may notice that at high toughness levels if you increase edge retention by only a relatively small amount you get very big drops in toughness. For example, increasing edge retention from Z-Tuff to 3V (100 mm in the CATRA test) led to a drop in over 10 ft-lbs, a similar drop is seen by going from 3V to CPM-CruWear. But then if you look at an increase of 100 mm in the CATRA test from Maxamet to Rex 121 the toughness only drops 1-2 ft-lbs. However, the relative difference in toughness between these different examples are similar. When we plot toughness vs edge retention on a log scale instead we get a straight line that is a better visualization of toughness differences. This is the basis on which I do the ratings rather than a linear scale.
Importance of Carbides
In all of the cases above, properties are greatly controlled by carbides. For high wear resistance and edge retention you want a large amount of hard carbides. And for high toughness you want little or no carbide. So the major tradeoff is in how much carbide you want in the steel for edge retention without dropping toughness too much for the intended knife and user. Steels with only vanadium carbides have the best balance of properties because the hardness of carbide matters for edge retention but doesn’t for toughness. So hard vanadium carbides means you get more edge retention for a given amount of carbide. You can see micrographs of different knife steels to compare their carbides in this article. Below I have shown the difference in carbide volume between AEB-L, CPM-10V, and Rex 121 to get an idea of how much more carbide there is in the high edge retention steels.
AEB-L – 6% chromium carbide
CPM-10V – 17% vanadium carbide
Rex 121 – 23.5% vanadium carbide, 4% molybdenum/tungsten carbide (M6C)
Conventional Ingot vs Powder Metallurgy Carbide Structure
Powder metallurgy is a technology designed to maintain a small carbide size. Read more about how it works here. It is most useful for steels with large amounts of carbide but also helps to be able to add certain carbide types. Vanadium carbides are very large with conventional production of steels but are very small with powder metallurgy. With conventional steels this limited vanadium additions to about 4-5%, and this was greatly expanded when powder metallurgy was developed. The biggest change that is seen with powder metallurgy in measured properties is in regards to toughness. Below shows a comparison of carbide structure between D2 and CPM-D2, and then toughness measurements between the conventional and PM versions of CruWear, D2, and 154CM.
D2 – conventionally produced ingot steel
CPM-D2 – powder metallurgy D2
With steels that have a small amount of carbide the size of the carbides can be kept small through processing (see the AEB-L micrograph earlier in the article). Most low alloy tool steels and carbon steels also have fine carbide structures without powder metallurgy processing. Therefore powder metallurgy is not necessary for certain steels, or could even be slightly detrimental. As wear resistance is increased the differences between conventional and powder metallurgy steels become greater.
Corrosion Resistance
I test corrosion resistance of steels by heat treating 1 x 1.5 inch coupons, finishing to about 400 grit, and then spraying with water. A mirror finish is the best at resisting corrosion and a rough finish means rust and corrosion is more likely. Distilled water can separate steels that are stainless vs those that are not. This showed that XHP and ZDP-189 have significantly lower corrosion resistance than other stainless steels. 1% saltwater will separate between other stainless steels. And only Vanax and LC200N have been free from corrosion with a 3.5% saltwater solution, though MagnaCut was close. Read about my tests in this article. Below shows the results of MagnaCut testing vs other steels where it is labeled as “New Steel.”
Corrosion is not just about cosmetics and rusting, however, but can also affect edge performance. I did a test with knives in 440A (stainless), D2 (high alloy steel with some corrosion resistance), and 1095 (no corrosion resistance). I dipped each in lemon juice and left in open air and tested after 30, 100, and 300 minutes, dipping in lemon juice again each time. There was significant sharpness loss with 1095, almost none with 440A, and D2 was in between.
Hardness vs Rating
For the steels that I rated I give them a single rating rather than a range based on different heat treatments that can be performed. In general, steels “look” worse as you go up in hardness because the toughness is reduced by more than the edge retention is increased. So for most steels they are given a rating at around 59-62 Rc, apart from a few steels that are never used at that hardness. I have a few examples below for steels that I have ranges of hardness tested for both toughness and edge retention. You can see that 64 Rc AEB-L has both lower toughness and edge retention than 61 Rc MagnaCut, so I feel that in general you get a better sense of where the steels fit with a single point. Plus the charts get messier, and I don’t always have data for a wide range of hardness values.
While higher hardness does lead to improved edge retention the bigger reason to have higher hardness is for resisting edge deformation. This is especially important for chopping knives and for knives with thin edges for enhanced cutting ability and edge retention. For example, below is a video comparing a 1095 ESEE knife at 55-57 Rc and a MagnaCut knife at 62.5 Rc, both with the same edge angle. Both knives were chopped through a nail. The ESEE had significant edge damage while the MagnaCut knife did not. This was not necessarily because of superior toughness but because of the superior strength of the MagnaCut from higher hardness. The very good toughness of MagnaCut meant that it didn’t chip despite this relatively high hardness and the difficulty of the test.
Heat Treatment vs Rating
Many steel ratings articles pay lip service to the importance of heat treatment without providing examples. The ratings I have are for an “optimal” heat treatment. By that I don’t mean that a better heat treatment is not possible, but that major mistakes in heat treating are avoided. It is certainly possible for a knifemaker or heat treating company to do a heat treatment that will have suboptimal properties. I have an article that lists off the major mistakes often made in heat treating.
Austenitizing is the process where the steel is heated to high temperature prior to quenching (rapid cooling) to harden the steel. If the steel is overheated in austenitizing, very large reductions in toughness are possible. See the chart below showing 52100 steel that was overaustenitized (unintentionally) by a knifemaker that sent me specimens for toughness testing. Using controlled furnace heat treating resulted in toughness around 23-28 ft-lbs at 61-62 Rc, while the knifemaker heat treated specimens were 7 ft-lbs or below.
Another common heat treating choice that is not even categorized as a “mistake” is tempering in the high temperature regime (~1000F) rather than the low temperature regime (~400F). After the steel is quenched it is reheated to a lower temperature to increase toughness and decrease hardness. Steel softens as tempering temperature increases, but certain steels see an increase in hardness in a certain higher temperature range such as shown below for high speed steels that are designed for this type of tempering:
This high temperature tempering can be done for several reasons, such as better resistance to overheating during grinding, or because a coating will be applied to the knife that requires a high temperature. However, in our testing there is a reduction in toughness by using the high temperature range rather than the low temperature range, such as was found with CPM-CruWear (Z-Wear) or CPM-10V. The 10V specimens tempered at 1000F were 4-5 ft-lbs while the specimens tempered at 4-500F were 7-8 ft-lbs.
Perhaps a bigger issue with the upper temper is for stainless steels, as there is a significant reduction in corrosion resistance by tempering at 1000F instead of 400F. The bump in hardness comes from precipitation of fine carbides in the steel, which include chromium carbides. The steel loses some of the chromium in solution for corrosion resistance to form these fine carbides for hardness. This can turn the ultra corrosion resistant LC200N or Vanax into a “normal” stainless steel that will rust with only 1% saltwater. Below shows Vanax tempered at 400F on the left and 1000F on the right after 1% saltwater for 24 hours:
There are many other ways in which knife steel performance can be reduced through heat treatment but I can’t cover them all in this article so hopefully these illustrative examples will be enough.
Corrosion Resistance vs Hardness
Typically an increase in corrosion resistance means a reduction in potential hardness for a given steel. This was described in this article on Vanax heat treating. Non-stainless steels can be heat treated to 66 Rc or even higher depending on the particular steel. Stainless steels usually top out around 64 Rc and may require careful heat treating to get there. The ultra high corrosion resistance steels Vanax or LC200N max out around 60-61 Rc instead. A cryo treatment and close temperature control is necessary to achieve those hardness levels. The majority of knives target 63 Rc or below so this limitation of stainless steels does not always come into play but can be an important factor for certain knives targeting high performance and thin edges. Below shows approximate maximum hardness vs stainless rating for several stainless knife steels. This is about comparing steels to each other rather than a limitation of an individual steel. In other words, heat treating a steel to its maximum hardness does not necessarily mean reduced corrosion resistance.
Cost of Steels
The biggest factor for cost of knife steel is whether it is produced with conventional ingot technology or powder metallurgy. However, there are other factors. Some steel companies charge more than others. Some steels are more difficult to manufacture for the steel company or have more expensive alloying elements so the cost is increased. Importing steel from Europe to the USA, or vice versa, generally increases the cost. Steel produced in China is generally less expensive. Poor availability may effectively increase cost of steel. In many cases the cost of working with the steel for the knife companies is more significant than the cost of the steel itself. In a pocket knife the total amount of steel is rather small. However, high wear resistance means that abrasives are used up more rapidly, more careful grinding is necessary to avoid overheating, finishing and polishing is much more time consuming, etc. High toughness steels can be produced without powder metallurgy and also have low wear resistance for lower manufacturing costs. High wear resistance steels are more expensive to buy and to process, especially since many require powder metallurgy. You can read an article I wrote on budget steels here.
Ease in Sharpening
I have not provided a rating for ease in sharpening. Generally this is “code” for difficulty in abrading away steel. In that case the difficulty in sharpening would be the inverse of the edge retention rating. In other words, Rex 121 would be the most difficult to sharpen and 5160 and 8670 would be the easiest. However, even in this case there is the complicating factor of carbide and abrasive hardness. Aluminum oxide is used in most common sharpening stones and it is softer than vanadium carbide, which makes sharpening high vanadium steels more difficult. Diamond and CBN stones make sharpening those steels easier. However, I would argue that pure material removal is usually not the limiting step for ease in sharpening. Deburring of edges often takes even longer than removing material to produce the edge. Softer steel usually forms larger burrs and they are more difficult to deburr. Steels that are improperly heat treated have excess retained austenite which makes them extremely difficult to deburr. Oftentimes steels that are reported to be “difficult” to sharpen are in fact improperly heat treated and challenging to deburr.
Summary and Conclusions
Steel ratings are not about “ranking” steels in terms of what is better than another, but understanding the different balances such as toughness vs edge retention. Other factors that can be added in are corrosion resistance, hardness, and cost. There is no single category that means that a steel is more “premium” or “better” than another. Heat treatment and edge geometry can mean more for knife performance than the specific steel used in the knife. The best scenario is when the steel, heat treatment, and geometry are selected for the knife and the use. You can read more about these factors in my book Knife Engineering.
Thanks! Question. The stainless steel rating. Is this at the same hardness?
Vg10 and cpms45vn same toughness at same hardness ?
Thanks!
Approximately the same hardness, yes. Around 61 Rc usually.
Thank you for the accurate data.
I always thought VG10 to be way more chippy/less tough compared cpms45vn. In reality hardly difference.
Quite an eyeopener!
I noticed that too! I appreciate my old VG-10 Delica and Endura even more now! Haha
Thanks Larrin,
It was your original article on ratings that brought me to knifesteel nerds so it’s great to see your results put back into a form that will no doubt be distributed \ plagiarized widely, hopefully leading to more rational thought and better understanding by the knife consuming public (not that the misleading marketing will go away).
Still looking forward to magnacut making it into high volume production and use.
Extra kudos for your mathmatical steel composition to edge holding model – that’s really impressive work.
Larrin, thank you for this. It confirms what I always suspected and what anyone could have figured out by reading the technical data. Old time 8670, 5160 (known to ignoramuses as 51shitty) and 52100 are excellent choices and arguably better choices than 80crv2. I’m not hating on 80crv2 , I’ve used it. I like it. It is an excellent steel that in the right hands has proven to produce high performing blades. But a few overly vocal forgers were making claims about it that clearly were not true especially when comparing it to 5160. Goes to show that science not marketing or conjecture is what determines a good steel, 51shitty? HA!
Interesting. I have a Winkler Knives Recon model in 5160 steel and even though the knife model is ok, the steel is shit. It rusts like nothing I’ve seen before and it dull just by looking at it. Yes it’s very easy to sharpen but it doesn’t hold an edge at all. I couldn’t find much on 5160 steel and from a knife makers point of view if you are saying you’re the preferred supplier of special ops than I don’t understand this choice in knife steel. Sure if you don’t want stainless steel fine, but there are plenty other carbon steels out there much better than 5160.
5160 is a good carbon steel. Like many other steels it is all dependent on the heat treatment. I like using L6 that is differentially heat treated. A hard edge with a springy spine. 5160 is a selling point for some manufacturers as though it was magic somehow. Then they do not harden it properly hoping to avoid having the blade breaking. I have alot of knives and I’m still surprised at how low the Rc is on some blades.
Yeah, that’s the problem. Usually made too soft despite it being tougher than most steels at that given hardness due to no plate martensite. Harder yet tougher means the thing just doesn’t deform. Using it as a prybar isn’t even a bad example. If it’s too soft it just bends permanently instead of taking more force and putting it into the object, but too hard and it snaps. Most make this steel too soft because it’ll still be extremely toughat 60+HRC Instead of 55, where bending becomes your main mode of damage over anything else.
Coming from a former teams guy and contrary to Steven Seagull in Under Siege, operators rarely if ever use their knives against another human being. We have fire arms for that and they work great. Nor do we spend all day cutting hemp rope. I used mine more as pry bar or even a shovel at times. The point is a vast majority operators favored toughness, ease of sharpening and of course cost vastly above edge retention. My knives were abused and misused constantly, but there was always a chance it would be needed to save my life so it had to be super tough and easy to sharpen in the field. That’s where Winkler gets it right. He makes knives based on the end users needs and not based on the needs of a majority of people who have never relied on a knife as a life saving tool. It’s almost a right of passage amongst the special operations communities to be gifted or save up enough money to buy a Winkler. I own 2 myself and I love them. The first one was gifted to me by my dad who was also former frogman. I carried it with me on ever deployment, every operation hence forth and it never let me down. I loved it so much that when I started making civilian money I decided to buy another. That is why Winkler Knives are number one in special operations. I’m not trying to be snarky, but it seems these days everyone gets too hung up on steel and forget that the steel is a very small factor in what makes a knife good. Hopefully this helps shine another light on things.
I would suggest adding a second axis to the ratings charts that show the data values that the 0-10 ratings are based on (unnotched charpy impact energy, 1% saltwater , Total cards cut, etc.).
I would also suggest adding a hardness rating to the ratings tables that currently include toughness, edge retention, and corrosion resistance ratings.
So all my 8CR13mov knives don’t suck?
8cr13mov if proper slicing geometry it’s good budget steel if you don’t rust it and no prying or screwing it’s ok cutting steel
The main problem with 8Cr13MoV is the inconsistency. The Chinese steels with designations of 9Cr and 10Cr have seemed to have gotten quite a bit better, but any of the 7 or 8Cr steels seem to be all over the place with hardness. A Knife with 8Cr13MoV can be all but indistinguishable from another knife with the same steel in terms of edge holding and toughness.
I think 8Cr gets a bad reputation because of the Chinese manufacturers. They had very bad reputation for now knowing how to heat treat. The steel manufacturers tended to be much less sophisticated than European or American producers. The name brand Chinese stuff seems to be ok nowdays.
Based upon all the numbers mentioned, maybe an average of all numbers put together to give a hierarchy of steels and then leave it up to the reader to determine what numbers correspond with the type of cutting they need a knife for.’
Spoiler, it’s MagnaCut. ;P
Was intended to be the best jack of all trades I idea steel and it ended up being it. Then there’s just options for tough steel or edge retention steel, where AEB-L, and maybe s90v for those. Then there’s most cheap.. 5160, 8CrMoV, 12c27, etc.
Thank you for such a great article! Very much appreciate you.
Hi Larrin, thanks so much for writing this blog and putting so much reliable information into such an accessible form.
I have a couple questions, not directly related to this specific post, that I wanted to ask publically so that others could find your responses as well, so here seemed as good a place as any.
1. Do “honing” steels as used on kitchen knives actually do anything useful? The claim is that they align the blade’s edge, pushing any slightly rolled over bits back into place and thus preserving the cutting ability of the knife for longer. I’ve not seen these used on non-kitchen knives, though, and it seems that if they had real utility they would be used in other knives as well – although perhaps on the thinner edges of kitchen knives they are more effective than they would be elsewhere? Or, is this perhaps a historically useful practice that made sense on softer/less tough steels, but would make less sense on some newer steels that can be used at higher hardness and thus higher edge stability?
2. I’m a woodworker and I’m interested in making better performing plane irons and chisels. Most vintage tool blades seem to have been made of 1084/1095 or similar, presumably at some <60 Rc hardness that gave the required toughness, and the rules of thumb for sharpening angles are based on those assumptions. You showed some pictures in this article of the effect on what we might call "effective toughness" of thinner edge angles vs thicker edges in the same steel at the same hardness. Is there some way we might predict the relative "effective toughness" of different steels at different hardness and at different edge angles? For instance, if a 35° edge in 1095 steel at 58 Rc provides appropriate toughness for planing hardwood, what edge angle in, say, AEB-L at 62 Rc might give us a comparable effective toughness?
Thanks again for everything you're doing, it's a tremendous resource.
Jeff I worked at a company that heat treated D2 (1.55% C) planer blades for a company that built wood working equipment for commercial shops. I was the heat treater, but after HT to only 58-59 hardness the blades went to the surface grinders for finishing and I remember them going into the packing boxes with mirror polished edges. Low Carbon steels like AEB-L won’t hold up to wood cutting even though it can hit 64 hard, it just doesn’t have enough Carbon. D2 at 58 hard will cut much more rope than AEB-L at 62.
Now that is power planer blades, but the principle stands, less carbon and alloy isn’t the best for wood working and I’d use a steel like 26C3 (1.25% C .30%Cr) for my hand tools and temper them to around 62 hard and use the best angle for wood shaving, not the best angle for cutting rope.
Alpha Knife Supply sells 26C3 btw.
I think this website is aimed at dispelling these kinds of assertions.
“Low Carbon steels like AEB-L won’t hold up to wood cutting even though it can hit 64 hard, it just doesn’t have enough Carbon.”
my understanding is that wood is not a particularly abrasive material and a plane is more of a push cut action than a slicing action so I would have though edge stability and sharpness is more important than edge retention meaning ABE-L should work pretty well. Although it should be noted that there doesn’t seem to be a need for the stainlessness on a wood working tool.
They made planer blades out D2 for its edge retention. D2 will go through a lot more rope at 58-59 hard than AEB-L will at 64 hard.
Also many hardwoods will dull planer blades just because they’re more dense. Not every wood is soft pine.
I forgot, I got the higher carbon steels will have higher edge retention from this website. Also D2 is not stainless as at least 5% of its chromium is tied up in carbides where it doesn’t help prevent corrosion. Having 1.5% Carbon does that.
Hi Jimmie, thanks for your comments. I’m not sure they answer my question, though, and some of your points don’t seem to jive with the info here on Larrin’s site. D2 has a relatively high amount of carbon in its composition (1.55%), more than twice as much as AEB-L (0.68%), but most of that carbon goes into making chromium carbides instead of into solution in the steel matrix, leaving D2 with only ~0.5% C in solution and very large carbides that are good for wear resistance but bad for toughness. So you’re right that a D2 blade will cut more CATRA cards than an AEB-L blade *when they’re both sharpened to the same angle* – but AEB-L has much better toughness and can therefore handle being sharpened to a more acute angle without chipping, and a more acute angle is more important to continuing cutting ability than wear resistance is. So we get back to my original question: if a D2 planer blade at 58 Rc and the associated level of toughness will perform acceptably with a 30° sharpening angle, is there some way to extrapolate at what sharpening angle another steel with higher toughness might perform equally well? If I made some plane irons from AEB-L at 63 Rc (where it’s still tougher than 1095 at 59-60 Rc, the standard vintage steel in plane irons), could I drop my sharpening angle from 30-35° to 25°? 20°? and get better and longer-lasting performance?
You said “wood is not a particularly abrasive material” and in absolute terms that is very true. However, many kinds of wood are REALLY tough and very hard on blades. I used to work for a company that did reclaimed old growth lumber (swamp cedar, old growth pine and oak beams, etc) and we went through planer blades twice as fast as the cabinetry shop next door (turns out the neighbors like it when you put all the loud businesses together and far away), which mostly cut fresh cherry, oak, maple, hickory etc. That says to me there’s a measurable abrasive quality to wood for sure. That old pine in particular is some crazy hard stuff.
I can also say from personal experience that marine grade plywood will chaw up your saw blade and battery a lot quicker than standard plywood, but that probably says more about the glue that was used than the wood. Anyway, astute comment, but edge retention does mean a lot in woodworking.
1.4116 got a 2.5 for toughness and edge retention where as 420HC got a 9 for toughness and a 2.5 for edge retention. What makes 1.4116 such a bad performer in regards to toughness on par with ultra high carbide steel like S125V? and why would anyone want to use it when 420HC looks so much better for a simple stainless steel option.
The 1.4116 I tested has large carbides in it which is presumably the reason for low measured toughness: https://knifesteelnerds.com/2019/05/26/new-micrographs-of-42-knife-steels/
It’s possible that there are steel manufacturers with better processing which would lead to an even carbide distribution but I can’t say that without seeing it for myself.
thanks that’s interesting. does 1.4116 deserve the title of title of ultimate trash steel? Looks like there is no reason to us it over 420HC. Also I notice 1095 looks like another underperformer as there doesn’t look to be any reason to use it over 5160 which I can’t imagine is any more expensive than 1095. Would be great if some manufactures changed their steels based on this information.
and yet millons of knives are being made out of 1.4116 (aisi 420mov?) worldwide, even the chinese have an equivalent (8cr13mov). at least it has some vanadium over the 420hc.
most knives are being made out of these and other “mediocre” steels like 14c28n, 420j2, 425m. its like with cars, most of them are not a corvette or a porsche. you can easily buy a $500 knive made out of 14c28n, which has nothing in it besides cr and a trace of ni.
im led to believe tha the melting procedure is more important with these steels than the exact composition.
Funny calling 14C28N “mediocre” as it is an outstanding steel, regarding its toughness-per-edge-retention, very good corrosion resistance.
It is rather mediocre in edge retention alone, and cheap thanks to its classic, non-PM process.
I would love to see a retest of this steel in the future, it’s hard to believe a low carbon steel can be so brittle like that, despite being similar to 8CrMoV. Also thank you for your contribution to this knife study space, Roman.
I also have meat cleaver 1,4116 ,58RC that I order and was looking up if it’s a good steel or did waist money and need to return it
Hello LARRIN, do you have a Rough estimate on when ApexUltra (as well as more Magnacut) will become available?
Thanks in advance.
Thank you for putting this together, incredibly useful!
What about K390? Toughness 3, Edge Ret 8, Cor Res 4?
Also how did you arrive at the edge retention & toughness numbers for 8cr13mov and for BD1N toughness?
great work, larrin. the following is not a critique, just a few thoughts to maybe put the relationships into a wider perspective and point to additional “dimensions”.
1) the cvn number is just that, a number. while its a very intuitive method and a simple way to e.g. compare different heat treats of the same component, it lacks a theoretical foundation and its not clear how to relate it to the real world. what does a cvn of 40 v.s 20 mean? can you strike twice as fast with the knife? how much more can you bend/pry with it? we dont know. the more complex fracture toughness at least lets you make some estimates in this sence. whats even more disturbing is that cvn and fracture toughness sometimes (often?) show very different and even inversed behaviour (e.g. in relation to hardness).
2) you do not go into the sharpening in much detail. i understand the samples were treated in the same way. first there might have been some annealing going on (even if its was a microscopic level) and the steels might have reacted differently. second it might be of importance which way you sharpened because if against the edge the steels might have reacted differently to the contamination remaining on the edge. third and most important is what happened to the burr. a burr might have developped on some of the steels and not on others, it might have ben reduced or even removed by the process. edge retention can vary by several orders of magnitude depending on what happens to the burr.
3) catra is (as far as i know) the only “accredited” (iso/en) testing method. nevertheles its importand to keep in mind what exactly is going on there (abrasive plastic media, loss of most of cutting ability during the first few strokes etc.). as you mentioned catra indicates the edge angle as being by far the most important variable.
and yet millons of knives are being made out of 1.4116 (aisi 420mov?) worldwide, even the chinese have an equivalent (8cr13mov). at least it has some vanadium over the 420hc.
most knives are being made out of these and other “mediocre” steels like 14c28n, 420j2, 425m. its like with cars, most of them are not a corvette or a porsche. you can easily buy a $500 knive made out of 14c28n, which has nothing in it besides cr and a trace of ni.
im led to believe tha the melting procedure is more important with these steels than the exact composition.
I forgot, I got the higher carbon steels will have higher edge retention from this website. Also D2 is not stainless as at least 5% of its chromium is tied up in carbides where it doesn’t help prevent corrosion. Having 1.5% Carbon does that.
I see tables that compare Toughness,Edge Retention,Corrosion Resistance.
There are also hardness/toughness and hardness/TCC charts….but no tables backing this charts.
I’m a layman trying to understand what makes the best steel for my use. It would be really useful to have the raw data that backs the charts that you produce. In particular, I really care about the toughness / hardness part.
I have a question about the chart
https://i0.wp.com/knifesteelnerds.com/wp-content/uploads/2021/10/stainless-toughness-10-19-21.jpg?w=757&ssl=1
There’s a green triangle at about RC 60.5 and toughness over 40.
There’s also a line of green triangles a bit below that.
And a label: AEB-L.
I would think that the label applies to either the line or the outlier, but probably not both unless the outlier is a measurement error.
But which? No idea.
So…could you please clarify which steel is the outlier and which is the line>
It applies to both of course, hence why there isn’t a separate label. They were two different tests (different batch of steel, different person heat treating, etc). The value being slightly different doesn’t mean it’s an outlier or measurement error.
I see, thanks.
Dr. Thomas you spoke of using a different media for cutting test and I have some extra veg tan leather and was wondering what are the parameters of the leather you need?
I made most of my leather knives from O1v (O1 with .20V) that I hold at 1475 for 15 mins and quench in 120-130 F AAA oil and Kevin Cashen is where those parameters came from btw. Anyway, buff up the O1v and it cuts leather easily.
Is that regression line (or other trend line?) in the correct place for the stainless-toughness-edge-retention graphic? How could it be? The line is only in the neighborhood of 5 of the datapoints. I’d think that line would be significantly to the left, more in the data swarm. What is pulling that line high and to the right?
It’s not a regression line, it is just a line through the best steels.
Ah, now it makes sense. Thanks Larrin!
Hi Larrin – Your estimate of 420HC’s corrosion resistance is different here than in your October, 2019 post on corrosion resistance testing: https://knifesteelnerds.com/2019/10/14/corrosion-resistance-testing/
There you said 7.6 for 420HC. Here it’s 8. Did you change the estimate based on more testing? (I think the 420HC estimate in that post was based on simulation or computer modeling, since you didn’t spray testing any of the 400 series.)
You also reported 8.6 for 440A in that post, compared to 8.5 in this post. That’s a tiny difference, but in combination with the 420HC disparity, it conceals a full point difference between 420HC and 440A: 7.6 vs. 8.6. That’s a pretty large difference in two budget steels that are often compared to each other. Is 440A really that much better than 420HC, or have you found a narrower gap?
I measured corrosion resistance of a slightly lower carbon 420 here: https://knifesteelnerds.com/2020/03/02/cpm-spy27-experiments-toughness-corrosion-resistance-and-more/
It had better than expected corrosion resistance due to the lack of chromium carbides, a behavior also seen in MagnaCut. 440A has more chromium in solution along with a small addition of Mo, but has significant amounts of carbide so the two are an interesting comparison. As to a difference between 8.6 and 8.5, all of the ratings here are rounded to the nearest 0.5 because better than that probably shows false precision.
I can’t seem to match steel to the SS data points on the toughness/tcc graph. It shows 3 stainless steels from 750-800tcc but the edge retention graph only has 1 SS in that range, S90v.
The values are normalized to 61 Rc.
Ah ok that wasn’t mentioned. Why does Maxamet and Rex 121 stay the same tcc but Zmax drops and 15v goes from below 900 to over?
You’re right I had to check my spreadsheet. The edge retention numbers are normalized to the hardness of the closest toughness test. Sorry about the misinformation.
I just want to thank you for all the work you do for the community and the world at large. There’s still a lot of misinformation being pushed by “influencers” especially in knife steel rankings. Even people that are aware of your work still do knife rankings and pass them off as steel rankings.
Hi Larrin,
On the spreadsheet, you’ve grouped AUS-8 and 8Cr13MoV. A quick check shows the compositions of these steels are nearly identical, so based on that I’d expect them to perform similarly (differences in heat treat and blade geometry aside). One argument I see consistently leveled against 8Cr13MoV compared to AUS-8 is that of the consistency of the composition. In real life, would you expect any presumed increase in deviation from the specified formula, as well as the effects of said deviation, to negatively impact the performance of 8Cr13MoV to any truly noticeable degree? Or is this an argument that tends to be rooted more in the presumption that “Japanese steel > Chinese steel” than any practical difference in reality?
Thanks.
There are a few aspects to your question, I think. One is certainly anti-China bias, as you pointed out. Another is that 8Cr13MoV is a “generic” name for a specific composition while AUS-8 is a name of a product by a specific company. Different companies can vary some between each other making the same product, while a single company is going to be more consistent. However, it is not really known how many different companies are making 8Cr13MoV (or at least I don’t know), it could be that it is one manufacturer that is dominating the market. But yes, I would assume that the general performance would still be relatively similar between them without evidence to the contrary.
I have two quick questions:
1. What would you rate the toughness of CPM-D2. I was guessing 5.5 based on your rating of CPM-154. Is that accurate?
2. I think you wrote an article a bit ago on CTS-XHP and concluded that like D2 and ZDP-189 it wasn’t really stainless (although stainless is a somewhat arbitrary line). If that’s true why do you include it in the stainless steel category?
I know that one does not normally make knife blades of titanium, but I gather that Ti is extremely corrosion resistant, used for saltwater applications, etc. Any idea where it would be on the hardness and toughness scales?
Also, what kind of steel is used for utility knives? I mean the box cutter type, with the replaceable trapezoidal blades. Lately I’ve been edc’ing one of those instead of a nice folder. When the blade gets messed up I just replace it. Thanks.
1. The hardenable grade of titanium (Beta C Titanium) reaches up to 45 or so rc. This is a bit of a guess because I can’t find un-notched Charpy data on it. But I think it would have much higher toughness than any of the steels on the chart.
2. I believe they are made of simple carbon steel
Hi Larrin – You’ve occasionally mentioned cryo treatment in your posts, including here with LC200N. It would be great if you wrote a basic rundown of cryo treatment of knife steels, what’s involved, the effects, interactions with other treatments like tempers, alloys that benefit the most, etc. I see very little about cryo outside of journal articles, and I wonder which knifemakers use it.
PESR would be an interesting topic too (also tied to LC200N).
He’s already done a three part series on cryogenic treatment:
https://knifesteelnerds.com/2018/12/03/cryogenic-part1/
https://knifesteelnerds.com/2018/12/10/cryogenic-processing-of-steel-part-2/
https://knifesteelnerds.com/2018/12/17/cryogenic-processing-of-steel-part-3/
Oh, that’s great, thanks. I guess that was before I started reading.
Does that mean that companies like Tops, Kabar and ESEE would be better off using 420HC instead of 1095 on their fixed blades?
Probably, yeah. This is why buck hasn’t changed their choice of basic steel for so long. People hate on that steel but few do is good heat treatment on it like Buck Bos’s heat treat. Regular people use their EDC knives hard, even prying and such, so the toughness at usable hardness is why they stick to it.
Why wouldn’t it be possible to make a damascus steel out of (say) AEB-L and s90V, or wouldn’t that gain the best of both?
It isn’t impossible, but contrast may not be very good and the austenitizing temperatures of the two steels aren’t very compatible.
I would love to see a Tungsten-Carbide blade (like Sandrin is using) and how it compares for Edge Retention, Toughness and Corrosion Resistance – especially how it compares to s90v.
just recently the idea occured tome to sharpen a planer blade like a knife and check out how it performs. the problem is in the innumerable combinations of grades, grains sizes and coatings available. then you have zirconia and diamond coated blades.
Thanks for the Article Larrin,
I would like to see the rating and performance on test of the Chinese Steels, that some people use to say its cheap garbage, like 3Cr13MoV, 4Cr13, 4Cr13Mo, 4Cr14MoV, 5Cr15MoV, 6Cr13MoV, 7Cr17MoV, 8Cr13MoV, 9Cr13MoVCo, 9Cr18MoV, 9Cr19MoV, and the 14cr14MovNB to see if they are similar, worse or better than the steels that they copy…i believe we gonna have some good unexpected results
Yes, please!
I especially appreciate the geometry/edge retention/toughness comparison with photos. It would be interesting to try to develop a conversation between /geometry/edge retention/toughness, so we could say e.g.: knife a with a toughness of 5 and an angle of 20 degrees will perform as well in edge retention as knife b with a toughness of 3 and an angle of 15 degrees.
Then we could say, e.g.: at a given toughness, magncut will have better edge retention in real life applications than s90v if it has optimal geometry (or maybe it wouldn’t, just an example).
I guess the question is whether toughness increases faster than edge retention decreases. it seems like all the pieces are in place to develop an algorithm for this.
imo o lot depends on how the blade is sharpened. there seems to be an optimal procedure for every alloy (provided its heat treated to industial standards). also the angle is by far the most important factor in catra testing, so such results might be irrelevant.
Sorry, most of my previous comment was borderline word salad. To reiterate the clearer part, I wonder if toughness increases faster than edge retention decreases as an edge gets thicker. I am just grasping at straws here, but from the data you shared, it seems like toughness does increase faster than edge retention decreases: it is harder to get a very high edge retention knife that will still be somewhat tough compared to a very tough knife that will still hold an edge ok.
Pretty interesting that regrinding a knife you already have can seemingly take its performance to that of significantly better steels. Rather than upgrade from D2 to M4 or S30V just drop the angle from 40 degrees to 30 degrees. Most production knives are more than thick enough at the edge to accommodate a regrind to significantly improve performance, and it’s a lot cheaper than buying a new knife a lot of the time.
Knife Grinders Australia has done some tests on this and even the cheap knives in mystery steel improves drastically. They actually concluded that a lot of super-steels don’t benefit much at holding a super-sharp edge much longer than simple steels, but hold a working edge for much longer. They also devised a method to measure edge stability for edge rolling resistance, the other half of edge retention that catra doesn’t measure. Their results though, showed that for de-boning, at least, that for basic steels you can get away with 12 degrees per side, powder steels were actually similar, and D2 was lower at 15dps thanks to large carbides and more brittleness. Higher or lower angles for three steels reduces edge retention in the real use case. Pretty fascinating stuff.
The defacto standard for edges being 20-25 degrees on cheap knives lowered the performance by 3x over what the optimized angle did.
Would love to see where S7 sits on the Corrosion/Edge/Toughness meter.
Spyderco announced Native 5 Salt with magnacut, but I saw test of magnacut with salt water and it grows corrosion…so Salt with magnacut could be a flop…
Spyderco has their own salt spray test setup to determine the corrosion resistance and they determined that MagnaCut is sufficiently corrosion resistant for their salt series of knives. My test is for comparing different steels, not necessarily for a “go/no go” test for saltwater applications.
They may also modify the heat treatment for maximum dissolved chromium and get away with slightly lower numbers for toughness and hardness, since it’s got plenty of both to spare. I’m not sure how much more you can get with a modified heat treatment, but I’ve heard some interesting claims about alternative D2 heat treatments to make it almost stainless. I worry about the integrity of that steel, though.
Is there a reason SG2/R2 are not included in the lineup, despite being one of the most popular ones?
Look for “Super Gold 2”
found nothing
It’s in alphabetical order. I believe in you.
How would n680 compare to m690? Is it similar but worse or better at one of the 3 things?
I was just comparing AEB-L and 14c28n to decide which steel to get for my next knife project and although 14c28n seems to be a bit more abrasion resistant, my primary goal is toughness and edge stability. I was wondering if the 14c28n sample was also prequenched like the AEB-L toughness samples? -> Maybe prequenched 14c28n could be a little tougher than AEB-L?…
Thanks in advance, Simon
The 14C28N was not prequenched.
For hard use everyday cutting in a packing company, Everything from fome, cardboard, tape, thick plastics, And plastic wrap that is against metal. Keeping in mind that I have a well rounded Set of sharpening skills. What would be the best deal to use I currently alternate between 20CV S35vn and D2. Recommendations are welcome
If you are cutting against metal I would maybe try K390 in a Spyderco or an S110V knife if you need stainless. I have a Spyderco K390 knife and I cut leather with it as it is only .090 thick and I seldom have to strop it on 1 micron diamond compound on leather. You need a hard medium to sharpen it like diamond or boride. Here is the article by Larrin on 48 steels. https://knifesteelnerds.com/2020/05/01/testing-the-edge-retention-of-48-knife-steels/
Unfortunately it all comes down to marketing on everybody involved: Industry, knifemakers, users. I personally don`t care about “stainless” (sic!), intended use will give you all the answers. False treatment and geometry upheld by “Made in USA” is like buying 8Cr from China (except late A.G) … My personal experience tops with Vanadis 4E, CPM-M4, RWL-34 and the likes. YMMV…
Marco, BSc Chem
Hi there,
I have two quick questions,
1. Among Vancron SuperClean, Agomi #1 and Shirogami #1, Which one tends to have finer grain size and Sharper edge?
2. Is Vancron SuperClean a good choice for a chef knife?
Vancron has a very fine microstructure so it would be tough to beat. Though the volume of carbonitrides in the steel is relatively high. Vancron would work well in a kitchen knife.
Could you please compare it to Shirogami #1 and Agomi #1, I didn’t find anything in terms of grain size ragarding thoese steels on the Internert.
I love reading through all the data you’ve gathered and making note of all the trends (I’m a physical organic chemist). I’ve seen more talk and some articles regarding the use of AI to come up with new potential drug molecules, polymeric materials, etc. Are you familiar with anything similar on the metallurgy/knife steel side of things?
There is buzz out there but I haven’t seen anything solid yet in the world of steel.
Have you tested K390 sufficiently to be able to rate it? I like it in the Seki City Spydercos, but I would like to know what ratings you would give it.
It’s in the same class as Vanadis 8 and 10V. I tested its edge wear resistance but not it’s toughness yet. It’s probably in between Vanadis 8 and 10V.
I’m writing a book about choosing a knife for EDC.
I was struggling to simplify all the Rockwell/Young’s Modulus stuff for readers when I came across your site. I’d like to quote some of your toughness, edge retention and corrosion resistance for balanced midfield steels, including yours, in some data tables. They’ll be fully attributed to you with website and Patreon links, obviously. Are you okay with that?
If you want to check the quality of my work, just search for “The EDC Bible” on Amazon. Obviously I’ll let you check the manuscript prior to publication. In fact I’d be delighted to have your experience checking my thinking!
Sounds good
Cool! Thank you. Should have a first draft by the end of next week. Can you contact me via my email address so I can send you a copy in PDF and epub.
Any thoughts how Sleipner might fare in the ratings? What carbon/tool steel would you choose for a survival knife if a PM steel was too expensive? I was thinking maybe Sleipner or A2 would be best if a PM steel was out. Actually, I’d be thinking 14C28N, but I want to leave stainless out.
I haven’t tested Sleipner yet. Uddeholm lists it as somewhat worse in toughness than A2 but somewhat better in wear resistance. So presumably, wear resistance would be in the 3.5-4 range and toughness in the 5.5-6 range.
Is that cpm-D2 or just normal D2
Larrin, I think you’ve got the tradeoffs oversimplified. The category you call “Edge Retention” isn’t that at all, by your own article it is actually “Abrasion Resistance”. Haft of the Edge Retention parameter is impact resistance, which you don’t account for… at all.
This is why you’ve got S30V as more “edge retentive” in your charts than Magnacut, while Pete has Magnacut as between M390 and K390 in actual, true, “edge retention”, that is a combination of “abrasion resistance” from the sisal rope, and “impact resistance” from striking the wood cutting board on each cut.
Essentially your charts showing “Edge Retention” are not showing how long a knife can retain its edge in real life cutting where there is an impact after the cutting medium is breached. Your “Edge Retention” isn’t.
He’s just using the same language the knife community uses. The knife community misuses the term “edge retention” when what they usually actually mean is abrasive resistance, which has been adjusted to “slicing edge retention” in these materials to reduce confusion. In reality edge failure aka chipping isn’t retention either, and neither is corroding your fine edge to oblivion after 30 seconds of contact with lemon juice like you might see with some basic carbon steels. Edge retention is complex and multi factorial which makes it difficult to talk about comprehensively. When you’re doing empirical testing, which is a foreign concept to many in the knife community, you want to isolate and limit the variables. If you want a better idea of how things work out “in the real world” you need to look at more than just the CATRA test results, also compare the results to the standardized test they use to measure toughness ie impact resistance which is called Charpy. That data is included in this article as well. The data in the site is just generalized guidelines for things, what makes it valuable is that it’s based on empirical evidence which is controlled for variables. What Pete does in his video, while it’s cool and fun and a decedent general guideline to that specific blade he happens to be testing, could hardly if at all be considered a test of blade steels. There are too many variables involved to suggest his videos are tests of blade steels but rather of those particular blades and their ability to achieve that particular task.
Exactly.
The issue with Larry’s view is edge retention cutting what and at what force. The variability is almost infinite. Edge retention is not a finite term it’s subjective. Slicing tomatoes on what cutting board compound or cutting this or that weighted rope etc. Before long it will start to look like “Forged in Fire” testing
No testing protocol can ever be all encompassing covering all variability. This is by far the most consistent and standardized testing protocol I have seen that is open to public viewing.
A good point. Edge stability (hardness+toughness) plus carbide wear resistance is what determines overall edge retention is the real world. Edge stability might be even more important because it lets you get away with much thinner bevels. D2 maxes out at 15dps for maximum retention on the charpy whereas other steels max out at 12dps or even less, and obviously catra will be better at fine angles as well. It would be very interesting if Larrin could add a charpy to his testing suite. Knife Grinders Australia has done some testing with a charpy which is very enlightening and compliments catra very well – it might be the smoking gun as to why magnacut and cru-wear are so highly rated in real world use for edge retention.
Im just trying to figure out the best steels for a bushcraft blade and a game blade. One for food prep from hunt to feast, and the other for wood prep tasks
Hey man, just wondering, I think the S35VN is off? You have it listed as 4% vanadium which confused me because I believe it’s 3% according the other sources.
I didn’t see 1075 on the charts??
I recommend looking at the similar 1084.
1075 is up front in carbon steel composition
What about maraging steel, from C250-C350? Very expensive, but ignoring that, is it a very good steel?
For the toughness v edge retention graphs, are they relative to each other between steel types (carbon & low alloy v. high alloy v. stainless). E.g., does 14C28N have similar toughness as 3V (both 9), and does S60V have similar edge retention as Vanadis 8 (both 7)? Or, should these properties only be compared within the same steel type graph?
This is excellent information, Larrin – thank you so much for sharing!
The are directly comparable
This is a broad and encyclopedic post, thank you.
I am stuck wondering why anyone uses 1095 for anything. It seems like its poor edge retention and zero corrosion resistance are balanced out by – very average toughness? Why would anyone use 1095 for a working knife? (This makes me think Ontario’s late move to 1075 is quite logical.)
Also, it seems like 420HC is very under-rated except by Buck, and that 14c28n deserves even more attention for its solid properties at low-medium cost.
Larrin, I’m really curious if you see any use case where 1095 truly makes sense, or if it’s just thoroughly obsolete and used for nostalgia reasons?
I’ll try an answer. On one hand are a zillion variables for knives, on the other, the knife you have in your hand and if it works and if you like it. Also, knife use falls very broadly into two categories, first, those that get a lot of routine daily use, like cutting cardboard, & etc. And second, occasional use, as with hunting, woodcraft, & etc. But for me, where the rubber meets the road lies in the ease of sharpening.
With daily use comes the need for routine sharpening. In occasional use, while it’s nice if the knife remains sharp while in use, it also will need to be sharpened, and maybe in the field. All decent knives start out sharp; the question then being, can I sharpen it? And will it stay sharp for a reasonable amount of time/use? 1095, 440C, and 420HC, yes to all three. And yes to 1075, 1084 and so forth. Lot’s more to be said, but I’ll stop with this: that to sharpen a lot of the more advanced, “better,” steels, our online knife reviewers and influencers often have and use very expensive sharpening tools.
I don’t think you adequately answered why 1095 is still used over the better 1084, but I will say this much: great heat treated 1095 will be leaps and bounds better than most knives. It seems that it would do better at much harder treatments where the toughness goes down much slower than 1084 where they more or less meet up. So for people making kitchen knives at 64 rockwell in 1095, it’s plenty fine. I do think 52100 is a better choice there, though. I’m a big believer in the edge stability over maximum carbide super-steels, though I think they overlap with a happy medium in the magnacut range, at least if heat treated well.
Hey,
I was wondering if you have done any tests on the AR-RPM9 steel found in the “budget” CJRB knives and how it compares to other knife steels.
Thanks in advance
I haven’t done any tests on it. I do have a Patreon article a while back where I talked about the composition.
My friend please help me, this will be my first knife to start in this big world
i want it for bushcraft used, so i so that the steel 14c28n is a very good option, but also the CPM 154, if you can choose, wich steel you will decide for full tang propuse?
thanks
First, you want a knife that you can sharpen. Second, you do not want to spend a lot of money – save that for later. Third, a blade of modest size. Then, fixed blade or folding? For fixed, a Buck 102 or a Buck 113 is a good start. And their 420HC steel is perfectly good and you can sharpen it. Also research puukko knives at Lamnia.com. The Scandinavians know a thing or two about knives. Finally, get it into your head exactly what you are going to be using your knife for (and how often and how much) – and a knife that is too big is a misery. For a steel, 1095 meets all of these requirements. And there are similar steels, do your research. But most important, if you cannot sharpen it, it becomes useless.
1095 doesn’t seem to be amazing. It’s good enough, though, with a good heat treatment. Super steels aren’t very hard to sharpen if you use an abrasive harder than the carbides, like diamond of CBN. That being said, for a knife, a good heat treatment, good handle, good grind, and such trump using some super steel. I’d rather have a knife of well heat treated 1095 with freezer cryo and 2x 2hr tempering cycles than a knife made of supersteel that someone tried to heat treat in a forge by eye, and then tempered it with a torch to a yellow straw oxide – all without decarb protection.
LT, which steel do you believe is the best for a straight razor? O1? ApexUltra? something else?
Awesome article and thank you very much for doing this work. I would’ve liked to see edge retention testing with knives sharpened to a high degree of sharpness, say around 8K. I don’t think very many knife enthusiasts sharpen their knives at only 400 grit.
Hi,
Very interesting. But something I don’t get.
There is a knife made by wildsteer: the wing tactic, which is made of X50CrMoV15. I read this is comparable to 1.4116.
According to your data it has low toughness and low edge retention, both 2,5. Its only good characteristic is its corrosion resistance.
The thing is if you look at video’s on YouTube about the wing tactic, they stabb through cars, pry car doors open, there is even a clip where they hammer the knife into a tree and then attach the winch of a heavy jeep onto it, which got stuck in the mud but could pull itself free!
How is this possible if the toughness is so low compared to other steels?
That seems possible because at the reported high thickness of that knife, almost any steel would work. With a blade of “3/16 inch blade thickness at the tip and 5/16 inch near handle” they designed a sharpened prybar. They designed their tool very well for their intended purposes (stabbing, prying, hammering, winching), by realizing which parameter was most important to reach that goal: thickness, and not steel type.
What can you say about 14c28n vs. N690? What would be better, overall?
It’s hard to find people talking about this 2 steels at a same time. It looks like one steel is the number one enemie for people who likes the other steel, in a way that in can’t even be mentioned.
Are these two steel at the same level?
N690 has higher wear resistance but 14C28N has much higher toughness. I would pick 14C28N if it were me, and if I wanted higher wear resistance I would use a PM steel.
14C28N in a production line knife is typically heat treated too soft and doesn’t hold an edge well at all. Civivi used to HT their 14C knives at Rc 60-62, but changed to Rc 58-60. It needs to be up around 62.
N690 is the Bohler equivalent of VG10 and holds a decent edge much better compared to a factory made 14C28N. Now if a custom knife maker is making the 14C at Rc 62+ hard I might be tempted to buy it IF it isn’t too expensive. Tougher doesn’t make much difference if you make one cut through cardboard and see shiny dull spots on your edge, welcome to budget steels. I’ve owned both steels and no longer use the 14C28N knives, I gave them away. I have had two VG10 knives, both Spyderco and use them. I also gave my granddaughter a knife, Pink, made of N690 and she uses it often, says she didn’t know how she got by without a pocket knife before and she has yet to ask me to sharpen it.
this is good to know. i was wondering as well. i probably will end up sticking 14c28n though. while i see where you’re coming at im personally the type of irresponsible knife user that has found himself having to use his knife as a pry bar to break down various things or to hack into tough materials and the last thing i’d want in those situations is to snap the blade or have it shatter in my face. even as far as edge damage goes i much prefer a rolled edge over a chipped edge. thanks again for the info
This article has rapidly become my knife testament, so much so, it’s been a permanently open tab in several browsers for many months now and I refer to it almost daily. Absolutely magnificently detailed with almost every piece of necessary information.
Many thanks Larrin for putting this together.
Hello,
I would like to know, if there is a formula or equation to compare steels with different toughness / edge retention. For example if there is a steel with toughness 10, edge retention 5 and one with toughness 1 and edge retention 6, I would assume, that the first steel is far better then the second, because you should be able to sharpen a knife with the first steel to a much more delicate edge and get a better edge retention while still remain a higher toughness.
So is there perhaps a formula like “you loose one toughness per 2° smaller sharpening angle and win x edge retention per 2° smaller sharpening angle”?
Best regards
Martin
So I have been thinking about this for a while but couldn’t find much. If you have 2 steels only differing in carbon content, like 1045 and 1095, when they are at the same hardness, will there be a measurable difference in edge retention?
It kind of looks like the only factor for the plain carbon steels is hardness not actual carbon content. I often have seen this discussed, 1045 is tougher but does not keep an edge as well, but what if they are at the same hardness?
Looking at 1084vs1095 there is a toughness difference, but on the CARTA-graph all the carbon steels look to be on a neat line correlating with hardness.
Also is there maybe a list with numbers for the CARTA results? Personally I find the graph a bit too loaded now and also like nice, crisp numbers.
Problem with CATRA and carbon steels is that sand like used in the test media is harder than iron carbides, which isn’t a whole lot harder than the fully hardened steel out of the quench. So the steel hardness matters a lot more in those steels. Go for less carbon hardened harder if you want a usably tough but decent fine edge holding knife. Toughness doesn’t mean much when the knife is so soft the apex mushrooms instead of chips no matter what.
What I found: There is a theorethical difference, more carbon, more carbides, better wear resistance, but you’ll likely not feel much if anything. Also different sources say different things about coorrosion resistance, some say higher carbon have a slightly better corrosion resistance, others say it’s worse. What is for sure is that harder equals less corrosion resistance, that’s the only point I can 100% say is true.
There is one pretty noticeable difference between 1045 and 1065, the 1045 takes a set a lot easier than the 1065 at the same hardness, same seems true for 1065 vs 1075 with 1075 being much more resistant to bending at similar HRC levels.
Great work there, just one question:
how about sk-5 found in cold steel’s srk knives ?
I could not find it on this page…
It is equivalent to 1084
Hey, great article. Is the raw data available to download anywhere by chance?
VERY useful , so a good cpm s35vn steel is pretty much the most well rounded right behind Magnacut.
This is a fascinating subject. I only started paying attention to knife steel about 5 years ago. At first, it was easy to get caught up into the “better, best” of knife steel. But it didn’t take long to realize that, as with almost everything, it’s not about better or best, but about which compromise works well for a particular use. Your website helps clarify this even more. With my favorite knives, the blade steel is only a small part of what makes them favorites.
I’m happy to help!
Thank you! Your publications and posts are excellent, a long needed demystifying source on this topic.
Didn’t know what article to put this under so why not here? Your day job is working with structural steel in vehicles, I would be interested in an article that goes over a structural steel for fun put through your tests, and maybe talk about the differences when it comes to strength and hardness and toughness that comes from these steels. Just would be a neat wildcard article if you’ve got not a huge plate full of more important steels to document.
Structural steels are a different category, I work on automotive sheet steels. The problem with trying to do something about automotive steels is I may have to go through the legal department of the company I work for. Maybe I can figure something out we will see.
Thanks for all the wonderful articles about metallurgy and knife steel either way!
You’re the biggest pillar of knowledge on the web about these things, devoid of hearsay.
You do a great job explaining them, which is why I could see you explaining what makes a knife steel different from other types of very different property steels interesting
oddball things like nickel martensite in maraging and hybrid steel, and highly austenitic (not stainless) steels, and the like. The biggest head scratcher was reading of lower yield strength right out of the quench versus after tempering in your HRC article, but can’t figure out why, beyond carbon precipitation strengthening changing the balance between the two. Would a spring temper aim to be at the peak of this point?
Either way, I’ll read and enjoy pretty much any article topic you want to write about.
Where would Aus10 land for toughness and edge retention? Seems to go under the radar but perform decently. I’m also curious why Aus-8 has higher toughness than say 440A.
AUS-8 has lower chromium than 440A so the microstructure is finer
Thanks! I’m a data scientist with a knife collecting problem, so this quantitative analysis is fascinating.
Love your work Larrin.
1. Can you put in layman’s terms why a knife can have better edge retention at 12 DPS vs. 25 DPS ? It seems counter intuitive. Perhaps it is because of more carbide surface exposure at 12 DPS.
2. I have 2 Magnacut Meglio kitchen chef knives and love them. I sharpen with Wicked Edge 100 thru 3000 grit and strop with 4 and 2 micron juice. I recently got the BESS Industrial and can get consistent measurements. I am just a homeowner/engineer whose use case is just in the kitchen and I’m looking to improve edge retention. I sharpened 1 at 16 DPS and the other at 20 DPS and was able to get around 130 BESS on each which made me think 20 DPS should have better retention because of “more apex mass”. Then I read your article and I am confused. What do you think and what DPS should I use on Magnacut in the kitchen ?
Not Larrin, but here’s my 5c in the mean time:
Dulling on the lower angle causes a less wide dull spot plus less wedging due to the bevel being less wide makes lower angles have better cutting ability and edge retention – if the steel can hold the angle that is. Of course if a steel is too soft or brittle the lower angle will roll/chip and dull too quickly.
On what angle you should put: That isn’t easy to say for sure since not everyone uses a knife the same way. Some can get away with 12°, others will damage the blade badly at that angle, it depends what you cut and how you cut (like when someone tends to shove food around edge side down, you need higher angles). Best to experiment, go down to whatever degrees and if it gets damaged (chips or rolling), go up a few degrees until you feel safe. I hit my knives on a piece of hard wood, hard enough but not a full swing. If it does’t get dinged by that, it can do what I need it to.
This is such a thorough and informative breakdown of knife steels! It’s great to see the ratings based on actual data instead of just popular opinion. Do you think there are any emerging steel types that could rival the top performers in toughness or edge retention in the near future?
A coworker liked working leaf springs many if not most are 5160. He’d buy cheap butterfly knives in TJ
(Illegal in just about every US state) and replace the Pakistani SS blade with the 5160 for better sharpening and edge retention so he said. He had some way of checking to see if it were 5160 which might not have been entirely reliable but he claimed the tempering and heat treating wouldn’t vary for leaf springs. If I’m carrying a knife on the trolley at night it’s a big legal Kershaw. Sandvik blades are an option on some Kershaws, btw.
I just bought chef knife of 14C28N based on my impression of Sandvik bladed Kershaws and surfing through this metallurgy assessment has me happy with myself for a good choice although I haven’t sliced a thing with it yet.