I Tested the Edge Retention of 48 Steels

Larrin said:
Recently I was able to acquire a used CATRA machine, so I heat treated just about every knife steel I had, made 57 knives with the help of knifemaker Shawn Houston, and tested them all to see which cut the longest. For a few of the steels I did multiple heat treatments to look at a couple variables and to see the effect of hardness. I also compared edge retention and toughness to see which steels have the best balance of properties. https://knifesteelnerds.com/2020/05/01/testing-the-edge-retention-of-48-knife-steels/
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Congratulation for this job I appreciate your efforts trying to put some objective facts on this very traditionnal segment.

Of course I understand than is not possible for you to go more deeply on the metallurgical facts.
The questions are more on metallurgical facts: The influence of the processing is so much important than very few steel makers are able to controle the melting of these elements combinaison due to the attached cost, for this reason is very complicate to secure a good metallurgie along the year, I do not know very well the Carbone steel grades, but concerning the Martensitic range I know quite well.

The largest volume on this familly is used for razor blades, and medical cutter for bone or skin. You imagine than the major on theses fields have made alls kinds of tests and still today to select the best grades for their applications when you are producing millions and millions of blades each day and each one must be perfect at the end only two supplier around the world and not more than 3-4 grades with very specific application.
Same issues for large knifes producers who are producing millions of blades every years and want to keep the same quality over the year, in this case again the choice is very limited but more than the razor.

The main issue are: sizes and geometry of the Secondary Carbide, Density and homogeneity , and of course a min. of 13% of Chromium, the content in Carbone define the hardness with a risk of presence of Primary Carbide over 0,60%. And of course a good Retained Austenite balance of 15% this value is very complicate to verify (need of a magnetic balance together with a good expereince to use it)

When you use material not created to produce blades, you have a consequence the presence of Primary Carbide is not an issue because theses grades are created to produce massive stamping tools ( like the 440 series) The Primary Carbide are not an issue for this function but a catastrophy for a blade this is the reason why the blades produced with a 440 steel serie can be very hard but a low edge retention and very difficult to re-sharp and low ductility.

These are the few elements needed to produce a good blades, all's others elements are marginal on the performance? the most significative can ne presence of Nitrogen but not too much ( the Nitrogen can replace the Carbone with out sacrifice the corrosion résistance) and the addition of Molydenium to improve the corrosion resistance but not too much to avoid the destroy the balance of the others elements.

Compliment for your fantastic work, I understand how much this was hard and difficult to do.
 
This study makes me wonder why any knives are made from c100/1095/carbon5/50100b/etc. According to the charts it's quite litterly terrible at everything, with even 420 hc/Audi/8cr scoring significantly higher in every category.

I realize it's cheap and easy to heat treat but is the toughness and edge retention really that much worse than other low cost budget options? Obviously hugely anachdotal but my experience with it in very thin behind the edge still hard use Kabar Beckers (only 57hrc), opinel, and especially Morakniv has been quite positive. Would love to know more about this.
 
Kudos. Folks will reference that work for years.

I'd like to see something like that done with a large number of production knives from the industry leaders. Sort of like what Consumer Reports does, but better. The Forged In Fire tests are fun to watch but are only focused on two or three blades at a time, then changed for the next show.
 
Late to this party, I know.

This information is priceless. Hats off to you Sir, & all those who helped in this !

On to the obvious now. Price point. There are many schools of thought on this, to be sure. That's why America is so great. Choices !!!

Some people will want and be able to afford the super high end expensive "super steels." Good for them, I am truly happy for them. Seriously, I am.

Then there are those who simply can't afford or just don't want to spend that much on a knife that they beat the snot out of or may even possibly lose in the field one day.

Also, ease of resharpening is something to consider and varies greatly from user to user. Someone who can't sharpen very well may do better with a steel that holds its edge longer.

Then there are personal experiences. These vary GREATLY from person to person. I try to keep an open mind but some do not/will not. My personal example is: I broke 4 different knives while in the US Army. 3 were Army issue. IMHO, they were NOT even close to being abused. I chalked it up to a bad batch with bad heat treat, that made them super brittle. Some of the people who were there when I broke them said that they would NEVER own one of that brands knives because of that. I have purchased many of that brands knives since then and I love them & have purposely batoned them really hard, & have had zero failures. In fact some of those are some of my favorite knives.

In closing, I'd like to say that I am very happy with the "low end" steel knives that I own & there are many. I sure would feel a LOT WORSE if I broke a $1600 custom knife of high end steel vs a 1095 knife that would most likely be replaced by Manufacturer at no cost to me except maybe shipping. But that's just me. But I sure do like choices.
 
VorpelSword said:
Kudos. Folks will reference that work for years.

I'd like to see something like that done with a large number of production knives from the industry leaders. Sort of like what Consumer Reports does, but better. The Forged In Fire tests are fun to watch but are only focused on two or three blades at a time, then changed for the next show.
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factory knives are a difficult thing to nail down, especially if they don't actually spec steel and hardness.

I believe there's a guy on YT who at least returns the specs, and then you can find what the result of the specs would be vs. larrin's charts (by spec, I believe the guy XRFs knives and provides an actual hardness reading).
 
sixplymaple said:
I want a CPM 10V blade. Too bad they’re hard to come by…
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10v is an interesting idea - I kind if like XHP, but not as much as carbon steel (XHP makes a good kitchen knife, especially if ground thin). In theory, 10V/A11 should make a better knife, but

...oh, i forgot another reason (I grind chisels and knives on a contact wheel and platen freehand - XHP grinds about half as fast as plain carbon steel, which is plenty fast to make a kitchen knife quickly)..

...at any rate, 10V sounds like a great idea, but I would bet in production, the large amount of vanadium, especially with the whole knife at high hardness, would limit finish options. Machinability is listed at 10-15% of carbon steel (which is probably slightly different than wear, but I'd expect a kind of plain crude looking knife if done in 10V and affordably). The next question would be how reliably could get you get a production or small run maker to make sure the structure looks even and clean like the micrograph on larrin's site.

This came up on a woodworking forum in australia, though, as someone in australia is making plane irons out of 10V, they're not finished machine that well (compared to what the woodworking boutique industry is used to) and people are struggling to sharpen them (and getting bad advice to sharpen them with alumina stones whereas diamond stuff is cheap and plentiful - cheaper than most of the more finely graded alumina stones).
 
Larrin said:
Recently I was able to acquire a used CATRA machine, so I heat treated just about every knife steel I had, made 57 knives with the help of knifemaker Shawn Houston, and tested them all to see which cut the longest. For a few of the steels I did multiple heat treatments to look at a couple variables and to see the effect of hardness. I also compared edge retention and toughness to see which steels have the best balance of properties. https://knifesteelnerds.com/2020/05/01/testing-the-edge-retention-of-48-knife-steels/
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Holy shit. That was incredibly information dense, articulate, and well done. Thanks man!
 
Hey Larrin, I saw where in your testing of S110v that it was a little less wear resistant than s90v and you couldn't understand why, I think the reason might be because the cobalt in it actually reduces the amount carbide formed in the blade by making formation time longer. I know alot seem to miss that fact because the first thing they think of is well why would high speed steels use colbalt in them if it reduced wear resistance, but thing is that cobalt is for increasing red hardness so it stays more wear resistant at high temperatures during operation, in a highspeed application s110v would indeed outperform s90v but outside of that application it actually has less total carbides formed and therefore less wear resistance at room temperature.
 
Rockwelledge75 said:
Hey Larrin, I saw where in your testing of S110v that it was a little less wear resistant than s90v and you couldn't understand why, I think the reason might be because the cobalt in it actually reduces the amount carbide formed in the blade by making formation time longer. I know alot seem to miss that fact because the first thing they think of is well why would high speed steels use colbalt in them if it reduced wear resistance, but thing is that cobalt is for increasing red hardness so it stays more wear resistant at high temperatures during operation, in a highspeed application s110v would indeed outperform s90v but outside of that application it actually has less total carbides formed and therefore less wear resistance at room temperature.
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Cobalt affects the formation of tempering carbides, not the vast majority of the carbide that affects wear resistance. If anything it increases the amount of those. When it comes to tempering carbides it affects the size and distribution not so much the amount.
 
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Larrin said:
Cobalt affects the formation of tempering carbides, not the vast majority of the carbide that affects wear resistance. If anything it increases the amount of those. When it comes to tempering carbides it affects the size and distribution not so much the amount.
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Larrin - as one late to the game (of your site) I have to tell you thanks so very much. I had a site bookmarked that for yearsss I referenced as for my steels. I basically just took a cursory glance at what I wanted to see on your site and knew I hit the motherload. Again - much thanks!👍
 
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