# I Tested the Edge Retention of 48 Steels



## Larrin (May 1, 2020)

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. Testing the Edge Retention of 48 Knife Steels - Knife Steel Nerds


----------



## rob (May 1, 2020)

Thanks Larkin. Jeepers, this test would of been a huge amount of work.


----------



## MontezumaBoy (May 1, 2020)

Excellent Larrin - I am always impressed with the thoroughness of your work plus I really enjoy your writing style that keeps me informed & entertained throughout. Very very cool ... a tremendous effort (as always)!


----------



## inferno (May 1, 2020)

really surprised by the minimal difference between blue super and 1095


----------



## Barmoley (May 1, 2020)

Many surprises and excellent work. The surprises is why this work is so important, good to have some solid data to make better decisions.


----------



## inferno (May 1, 2020)

i see you said that the machine could take other media. I think it could be interesting to test steels similar to the most common japanese, like 1095 instead of white and some steel similar to blue2 and the blue super and test them with different media like the one you suggested, rope and cardboard. or maybe even some rubbery foamy plastic, or cotton/hemp/jute cloth.

i get the feeling that there actually is a difference in "edge retention" at home (with food) with blue vs white. could be minor though.

sure that edge retention might not be just abrasive wear but could be minor rolling/chipping etc etc but for the end user the result is the same, the knife feels dull.


----------



## Ruso (May 1, 2020)

Acidity of food contributes to the edge degradation. Hence blue holds edge better in food prep than white.

Great work as usual Larrin!


----------



## inferno (May 1, 2020)

but i think the blues are so low alloyed it might not make a difference vs white regarding corrosion resistance. could be wrong though.


----------



## Eloh (May 1, 2020)

Yeah, cool work, i cant say that these figures reflect my experience with kitchen knives at all though. Aeb L with more Edge retention than 1.2562? 

too many variables to get useful results for kitchen knives i guess, still interesting though.


----------



## HRC_64 (May 1, 2020)

inferno said:


> but i think the blues are so low alloyed it might not make a difference vs white regarding corrosion resistance. could be wrong though.



Hitachi recommends using blue for kitchen knives. White steels are only recommended for tools (like chisels). Presumably the difference is that tools never see water or acids, whereas everyday reality in the kitchen is full of both.


----------



## Bert2368 (May 1, 2020)

That is an amazing piece of work.

As others, I would love to see similar tests run with non abrasive impregnated materials more similar to clean veges and/or boneless meat- but the required time and test media volumes for those higher wear resistant steels could be an issue... What could the test medium be?

I finally became a patreon supporter after skimming through this.


----------



## Hz_zzzzzz (May 1, 2020)

inferno said:


> but i think the blues are so low alloyed it might not make a difference vs white regarding corrosion resistance. could be wrong though.


I do notice huge difference between white 2 and blue 2/1/super in cutting tomatoes. The blues cut multiple times more tomatoes than white 2 and I've got 4 knives in white 2 so far given its popularity and they all perform similarly for acidic produce.


----------



## HRC_64 (May 1, 2020)

HT appears critical to performance for AEBL, and a good HT really delivers...


----------



## Larrin (May 1, 2020)

Bert2368 said:


> That is an amazing piece of work.
> 
> As others, I would love to see similar tests run with non abrasive impregnated materials more similar to clean veges and/or boneless meat- but the required time and test media volumes for those higher wear resistant steels could be an issue... What could the test medium be?
> 
> I finally became a patreon supporter after skimming through this.


I bought some rope that fits the machine a couple days ago. I plan on testing a limited number of the knives to look for differences.


----------



## tostadas (May 1, 2020)

Amazing work! Cant wait to see more


----------



## inferno (May 1, 2020)

Larrin said:


> I bought some rope that fits the machine a couple days ago. I plan on testing a limited number of the knives to look for differences.



i got an idea. when doing these lesser abrasive materials well all know it can ages to see any results at all.

most people will not run the knives duller than a certain point. they just pull out the stones when the knives starts feeling dull.
so my idea is this. and i think it reflects how people actually use the knives. 

sharpen up to maybe 3-4-5k. cut 1 or 2 stacks of regular copy paper/hemp cloth/hemp rope, then test the sharpness with your bess tester.


----------



## Panamapeet (May 1, 2020)

Could you maybe elaborate on your ability to heat treat each steel to bring out its maximum potential, and the relevance of this study considering those abilities?


----------



## Larrin (May 1, 2020)

Panamapeet said:


> Could you maybe elaborate on your ability to heat treat each steel to bring out its maximum potential, and the relevance of this study considering those abilities?


I have a PhD thesis about heat treating and a job where I optimize the heat treatment of steel. I have done several heat treating studies on different knife steels that are published to the website. There is a section of this article about the effects of heat treatment on the cutting behavior.


----------



## Panamapeet (May 1, 2020)

Larrin said:


> I have a PhD thesis about heat treating and a job where I optimize the heat treatment of steel. I have done several heat treating studies on different knife steels that are published to the website. There is a section of this article about the effects of heat treatment on the cutting behavior.


That’s all very impressive! However, how do we know that you have practiced what you know? I don’t mean to be a party pooper, but all this study confirms is that the specific pieces of steel you have tested give these results...


----------



## Ruso (May 1, 2020)

I am somewhat surprised with 440C performance especially at the lower hardness. I would say it will be at the bottom of the chart. :/


----------



## inferno (May 1, 2020)

Ruso said:


> I am somewhat surprised with 440C performance especially at the lower hardness. I would say it will be at the bottom of the chart. :/



you should check out the vg10... the most hated steel on the forum.
i kinda like it though.


----------



## RDalman (May 1, 2020)

Kudos for the work, awesome. 
Not that it takes away anything or makes any difference here necessarily for this catra test, I was struck that across the board the heat treats I prefer on steels in the study that I use in knives are very different from the ones you used.


----------



## Ruso (May 1, 2020)

inferno said:


> you should check out the vg10... the most hated steel on the forum.
> i kinda like it though.



While it was somewhat unexpected the result of VG10 tbh but it did not surprise me as much as 440C


----------



## Barmoley (May 1, 2020)

Panamapeet said:


> That’s all very impressive! However, how do we know that you have practiced what you know? I don’t mean to be a party pooper, but all this study confirms is that the specific pieces of steel you have tested give these results...


So what you are saying is that no study or comparison can ever be done because you will always deal with specific pieces of steel that give specific results? The heat treat data is in the article.


----------



## Larrin (May 1, 2020)

RDalman said:


> Kudos for the work, awesome.
> Not that it takes away anything or makes any difference here necessarily for this catra test, I was struck that across the board the heat treats I prefer on steels in the study that I use in knives are very different from the ones you used.


If you give me some examples along with your heat treatment I can tell you the thought process and what differences might arise.


----------



## RDalman (May 1, 2020)

Larrin said:


> If you give me some examples along with your heat treatment I can tell you the thought process and what differences might arise.


I'm sorry that's not a discussion I want to have. I believe we might have different preferences and that's all fine.


----------



## inferno (May 1, 2020)

Ruso said:


> While it was somewhat unexpected the result of VG10 tbh but it did not surprise me as much as 440C



i think 440c got a bad reputation because people have ran it too soft, like 50-55hrc. or that that it has quite coarse carbides and supposedly, "cant be sharpened to a fine edge". d2 has very big carbides too. but i took my yoshikane skd santoku to 12k, no problem there really. it got truly scary sharp. 
and according to internet lore i shouldn't have been able to do that. "theory" and practice seems to differ i guess.

and its probably just like all other steels. if you do it properly, it will be good. at least good enough for most people and uses.


----------



## Larrin (May 1, 2020)

There’s nothing wrong with 440C, it tested about as expected for edge retention.


----------



## M1k3 (May 1, 2020)

Great article! I'm surprised by some of the results. Like 1095/52100 being close to blue super/1.2562. And A2 being so close to them.


----------



## inferno (May 1, 2020)

M1k3 said:


> Great article! I'm surprised by some of the results. Like 1095/52100 being close to blue super/1.2562. And A2 being so close to them those.



i think the machine runs the stuff way past what most people on this forums would call dull and resharpen.


----------



## RDalman (May 1, 2020)

Larrin said:


> If you give me some examples along with your heat treatment I can tell you the thought process and what differences might arise.



Ok I came to think of one I don´t use, cpm m4. Why did you austenize it so low, and do the high temper you usually advice against? The hardness and catra result I think is very low, if you would have ran it much higher, like much much higher aus and got it to 65-67 hrc rangethe same temper, I believe it would have performed drastically different.


----------



## McMan (May 1, 2020)

Any post that begins "I tested the edge retention of 48 steels" is bound to be good...
Thanks, Larrin!


----------



## Larrin (May 1, 2020)

RDalman said:


> Ok I came to think of one I don´t use, cpm m4. Why did you austenize it so low, and do the high temper you usually advice against? The hardness and catra result I think is very low, if you would have ran it much higher, like much much higher aus and got it to 65-67 hrc rangethe same temper, I believe it would have performed drastically different.


The high temper was used because a low temper requires that I have heat treated a range of specimens and know the approximate hardness that will result. The datasheets only provide information for high temperature tempering. A lower temperature austenitizing was used to get a hardness in the target 61-62 Rc range. CPM-M4 knives historically are run anywhere from 60-65 Rc depending on the intended use. CPM-M4 unlike some other high speed steels gains quite a bit of toughness when heat treated to the low 60's making it more versatile. A higher hardness would of course result in higher edge retention. This is why I included the dotted lines with the predicted effect of hardness so that values can be extrapolated with varying hardness. Not a perfect comparison, of course, but it allows easier visualization.


----------



## Larrin (May 1, 2020)

inferno said:


> i think the machine runs the stuff way past what most people on this forums would call dull and resharpen.


And that is your hypothesis as to why some of the low carbide steels did worse than high carbide steels?


----------



## inferno (May 1, 2020)

Larrin said:


> And that is your hypothesis as to why some of the low carbide steels did worse than high carbide steels?



no, its my hypothesis as to why some of the simple carbon steels performed so similar. like blue super and 1095


----------



## Bert2368 (May 1, 2020)

Having USED knives and woodworking tools made with at least 8 of the steels tested, I am most struck by several of the LOWER edge durability steels having been ones I liked and found rather effective in use. We are blessed with some pretty damn awesome tool steel these days.


----------



## inferno (May 1, 2020)

Larrin you write in your article . *The CATRA test results in extremely dull edges, you can run your finger along the edges with no fear of being cut.*

and i guess this is beyond where most people would resharpen. i never let any knife get so dull i cant actually cut myself with it. i resharpen it when i feel its not cutting well anymore. subjectively. and for any number of reasons obviously.

it would be cool to see some test with a media that was less destructive and you simply put the blades on the bess tester afterwards, then you can see how dull they got after 1 or 2 or whatever x cycles. i think this would be more accurate for kitchen knives.

the alternative would be to measure how much force is required to cut the stuff at a certain amount of cardstock into the cycle. and then you need more sensors. probably expensive ones. and it might even be impossible to do. i dont know.


----------



## RDalman (May 1, 2020)

Larrin said:


> The high temper was used because a low temper requires that I have heat treated a range of specimens and know the approximate hardness that will result. The datasheets only provide information for high temperature tempering. A lower temperature austenitizing was used to get a hardness in the target 61-62 Rc range. CPM-M4 knives historically are run anywhere from 60-65 Rc depending on the intended use. CPM-M4 unlike some other high speed steels gains quite a bit of toughness when heat treated to the low 60's making it more versatile. A higher hardness would of course result in higher edge retention. This is why I included the dotted lines with the predicted effect of hardness so that values can be extrapolated with varying hardness. Not a perfect comparison, of course, but it allows easier visualization.


comparing the dotted lines with the curves of steels you have heat treated more samples of, not one follows the dotted prediction by the looks.


----------



## ExistentialHero (May 1, 2020)

Really interesting work, and a tremendous write-up--thanks!

I'm also interested in how non-silicate test media would affect the results, since kitchen knives generally don't encounter that much abrasion. If you could rig up your tester with a webcam and convert it to use carrots, we could automate a lot of other threads on this forum...


----------



## M1k3 (May 1, 2020)

ExistentialHero said:


> Really interesting work, and a tremendous write-up--thanks!
> 
> I'm also interested in how non-silicate test media would affect the results, since kitchen knifes generally don't encounter that much abrasion. If you could rig up your tester with a webcam and convert it to use carrots, we could automate a lot of other threads on this forum...



CATRA Edge Retention Tester: CiderBear X Daveb Edition


----------



## RDalman (May 1, 2020)

ExistentialHero said:


> Really interesting work, and a tremendous write-up--thanks!
> 
> I'm also interested in how non-silicate test media would affect the results, since kitchen knifes generally don't encounter that much abrasion. If you could rig up your tester with a webcam and convert it to use carrots, we could automate a lot of other threads on this forum...


Everybody liked that, esp DaveB


----------



## inferno (May 1, 2020)

ExistentialHero said:


> Really interesting work, and a tremendous write-up--thanks!
> 
> I'm also interested in how non-silicate test media would affect the results, since kitchen knifes generally don't encounter that much abrasion. If you could rig up your tester with a webcam and convert it to use carrots, we could automate a lot of other threads on this forum...



we could also have a betting pool which steel will cut the most carrots and onions and such.


----------



## Larrin (May 1, 2020)

RDalman said:


> comparing the dotted lines with the curves of steels you have heat treated more samples of, not one follows the dotted prediction by the looks.


I would be happy to test a sample of CPM-M4 at higher hardness if you want to make one.


----------



## Ruso (May 1, 2020)

*moc* (Meters Of Carrots) new Si unit for edge retrntion measurments


----------



## Deadboxhero (May 1, 2020)

Panamapeet said:


> That’s all very impressive! However, how do we know that you have practiced what you know? I don’t mean to be a party pooper, but all this study confirms is that the specific pieces of steel you have tested give these results...


Based off this logic, we would assume 1095 would outcut rex121 in controlled cut testing if it had magic heat treatment but that's not how that works. Heat treat can trade off features with strength and toughness and higher hardness does boost the resistance to wear but the chemistry is what decides what Carbides are formed at a range of volumes. And it is the carbide types and volumes that are boosting the softer HRC steels over the the harder HRC steels you see on the graph. You can't heattreat 1095 to have 30% carbide volume and tempered hardness at 70hrc it doesn't have the chemistry for making those structures.

Larrin is not a knife maker but he also works with knowledgeable knife makers that also share their experiences with him just as he shares his PhD knowledge with us.


----------



## boomchakabowwow (May 1, 2020)

I have a Buck 112 that rides permanently in my hunting pack. I don’t remember sharpening it. Maybe right before last turkey season. It’s really sharp. Really sharp. Boring as white bread, but I like it. 440 steel.


----------



## Jimboss (May 1, 2020)

Great article, really comprehensive and well-written/presented! Will definitely be using this a future resource, thanks Larrin.


----------



## Gregmega (May 2, 2020)

Panamapeet said:


> That’s all very impressive! However, how do we know that you have practiced what you know? I don’t mean to be a party pooper, but all this study confirms is that the specific pieces of steel you have tested give these results...


Ol’ Peter Party Pooper.


----------



## Gregmega (May 2, 2020)

inferno said:


> we could also have a betting pool which steel will cut the most carrots and onions and such.


Maybe it could finally settle the horizontal onion cut debate once and for all


----------



## Eloh (May 2, 2020)

Despite the fact that i find the experimental setup a bit limited in its significance for kitchen knife use for several reasons, it would imo get more interesting if you could build upon what you have, and indeed cooperate with more knifemakers to test some of their favourite ht procedures (could be anonymous). Because i know that some of these protocols go straight against what certain makers, with a great reputation for heat treating certain steels, would advise to do. (can dm you specifics if interested)
Still, great work and effort!


----------



## Ruso (May 2, 2020)

@Larrin what CBN stone do you use?


----------



## Larrin (May 2, 2020)

Ruso said:


> @Larrin what CBN stone do you use?











Poltava Premium Metallic CBN Stone [6" x 1"]


Metallic CBN Sharpening Stones from Poltava Diamond Tools are used for sharpening knives using guided knife sharpeners (Hapstone, TSPROF, and other Edge Pro-compatible sharpening systems). CBN (Cubic Boron Nitride) is the second-hardest material after diamond. Metal bonded CBN stones utilize...




www.gritomatic.com


----------



## Larrin (May 2, 2020)

For those who are interested in learning about what separates good, bad, and ”super” heat treatments I recommend this article: What a Good Heat Treatment Can and Cannot Do - Knife Steel Nerds


----------



## Codered (May 2, 2020)

Very good article. However most of the steels listed there are more utility knife centered and not for kitchen knives. Interestingly SG2 a powder steel which is staineless and easy to sharpen seems to be the best choice for kitchen knives. 
The high alloy ones (supersteels with lots of Chrome and Vanadium carbides) although have better edge retention, would probably eat through the whetstones to sharpen not to mention thin.


----------



## LostHighway (May 2, 2020)

Thanks for yet another really interesting read. As several other people have noted it might be interesting to rerun the test with media that is not quite as abrasive, whether that be rope, non-silica impregnated paper or something else. Maybe dipping the edge in a mild acid solution, perhaps 4.5 pH, letting it sit for ten or fifteen minutes and then running the test might alter the relative results? A benefit to the true stainless steels seems like a given but I'd be curious to learn if the small amounts of CR and/or Ni in steels like A2, 52100 or 1.2519 offer any edge retention benefit under these conditions relative to simpler alloys like Shirogami 2 or 1095. pH 4.5 is roughly that of a fresh tomato, but higher (less acidic) than many other fruits while lower than potatoes. onions, and cucumbers (all around 5.5).


----------



## Eloh (May 2, 2020)

i guess that link was partly directed at me, so ...
" Metallurgists spend a lot of time optimizing heat treatments and it is unlikely that a random knifemaker has taken things beyond standard research. "

how many metallurgists spend any time on optimzing ht for a steel that nobody uses anymore (aside from knifemakers) for a specific application the steel was not devleloped for (kitchen knives) with virtually no real money in it  
well, i guess for some steels the only ones doing any research are in fact knifemakers, and i know that there are knifemakers who actually work with metallurgists to optimze heat treatments, and i know they would strongly advise against some of your ht protocols.

but anyway...cheers


----------



## RDalman (May 2, 2020)

Eloh said:


> i guess that link was partly directed at me, so ...
> " Metallurgists spend a lot of time optimizing heat treatments and it is unlikely that a random knifemaker has taken things beyond standard research. "
> 
> how many metallurgists spend any time on optimzing ht for a steel that nobody uses anymore (aside from knifemakers) for a specific application the steel was not devleloped for (kitchen knives) with virtually no real money in it
> ...


Often some folks want to follow what they call steel-manufacturers datasheets. What they are, or contain sometimes, is just recommendations for heat treatments, on some form of sample they might show what to expect. Sometimes these work well foe knives, and often not ime.


----------



## Bert2368 (May 2, 2020)

1: Knife making is a niche material use. There are a FEW kinds of tool steels I know of, plus some damascus, monosteel and pre laminated stock developed and made expressly for our favorite tool, the knife. Naturally, manufacturers of a steel developed for, say, punch press dies, roller bearings or truck springs will have processing recomendations developed in that light. It is unlikely one guy with a day job has had free time to personally experiment with making knives and optimizing heat treating for 40+ materials. YOU PEOPLE, collectively pretty much have. 

2: Larin did a huge project because he is way into your favorite application- and you don't have to pay a dime to see the results. Should you thank him or complain about some of the details?

3: The methods chosen to treat the test pieces and data taken certainly were not perfectly in line with what dozens of makers have learned by experience. They are a nice big pile of (Free! Open source!!!) data, perhaps best viewed as a community resource to suggest FURTHER INQUIRY. 

4: If your results vary, as many indicate? Kibitzing and complaining that he should have done what you do (and possibly also not wanting to publicly state what your techniques are as you consider that to be proprietary info?) is not constructive. A better response might be to contact Larin, ask if he wants to work on it, and if so, start fabricating test samples conforming to his physical specs, heat treat under your conception of optimum for kitchen or other knife uses and send them to Larin for testing.

5: Larin does this for a day job. I like my day job, but I don't do it for free anymore (although I did for 10 years while I learned the craft). Don't look the gift horse in the teeth, give it a tasty apple and say "good horsey!"


----------



## Barmoley (May 2, 2020)

I think the main point of the heat treat article is that even though there are many ways to majorly screw up a heat treat and ruin the steel, once you get a good results improving on them is marginal. Once the heat treat is good there is only so much you can do with improving it. The steel chemistry is the limiting factor of what a perfect heat treatment can do. You will not be able to make 1095 as wear resistant as Rex 121 or as tough as AEB-L, or to become stainless. So unless you are saying that the steel samples in the test were just ruined, improving on Larrin's heat treat might buy you marginal improvement, but it will not significantly alter what your steel of choice is capable of and how it stacks up against other steels. Once you have good heat treat the only ways to drastically change what the knife is capable of is to change geometry or the steel or both. 

For you guys that seem to be upset that your favorite steels didn't do as well as you expected, it is not personal. Larrin has done an amazing job with his articles and this last huge study. It is ok to discuss results and disagree on methodology, but it would be even better to also help with money or by sending test blades in, if you truelly want to see your steel of choice be tested at its best. Larrin has been asking for knife samples for a while, the parameters are known. Very few people actually helped and did most of the work for this study, yet everyone has an opinion on what's wrong with the study.


----------



## The Edge (May 2, 2020)

I can't begin to thank you enough for the time and energy you've expended on these tests Larrin. The transparency, of these tests, gives me even more information than I have, even though I've been running my own tests for 5 years. 

I'm a bit in shock that people think this data is irrelevant, or doesn't compare to the real world, when obviously there's a direct correlation. Before questioning you, I would question why my own experience doesn't match (i.e. - knives from different makers, different geometries, improper heat treats).

What I really get from this, is that steel, heat treatment, and geometry all play their own roles in edge retention.


----------



## Deadboxhero (May 2, 2020)

Codered said:


> Very good article. However most of the steels listed there are more utility knife centered and not for kitchen knives. Interestingly SG2 a powder steel which is staineless and easy to sharpen seems to be the best choice for kitchen knives.
> The high alloy ones (supersteels with lots of Chrome and Vanadium carbides) although have better edge retention, would probably eat through the whetstones to sharpen not to mention thin.


They make diamond/CBN bonded stones that behave more like water stones with resin and Vitrified bonds.

They have been around for 5 years now.
@JBroida


----------



## M1k3 (May 2, 2020)

All this heat treated steel and no knives for us?  Useless test!







Joking. Larrin and everyone that helped him did a great job. Way better than I would of been able to of done. And I'm still checking out the article.


----------



## inferno (May 2, 2020)

i demand to know how katos, shigefusas and TF's are HT:ed. I demand it!


----------



## M1k3 (May 2, 2020)

inferno said:


> i demand to know how katos, shigefusas and TF's are HT:ed. I demand it!


Heat, quench and temper? Or maybe he just beats the metal with unicorn bones until the edge is hard enough to be chippy?


----------



## WildBoar (May 2, 2020)

Larrin, great stuff! I think we will all benefit from your generosity. While results may be in debate to a certain extent, it is a great foundation.


----------



## M1k3 (May 2, 2020)

We, this forum, aren't the only audience for Larrin. Probably not even his target audience. So we should be appreciative of his work. And give him constructive criticism, advice or even give him a hand if you can.


----------



## inferno (May 2, 2020)

M1k3 said:


> Heat, quench and temper? Or maybe he just beats the metal with unicorn bones until the edge is hard enough to be chippy?



yes of course.
just wanted to point out that NO or almost no makers publish how they HT the steel. hell some dont even tell you what steel they use.


----------



## Codered (May 2, 2020)

I think everyone appreciated the research even the guys who commented. I believe that it's natural to debate and question ideeas. It prooves thought process and active synapses. If we all agree all the time it means there is no base for new ideeas or questions. Had Einstein not question the classical laws of physics would we have the theory of relativity?
And the questions were quite good. Meaning that it might be a good ideea to take each steel to its highest supported HRC and test how many cuts it can perform. I mean same steel at 65 HRc will have better edge retention than 61 hrc ( while more brittle). Let people debate because it's healthy it's not criticism ( no one said the study was stupid) it was just points for improvement.


----------



## Corradobrit1 (May 2, 2020)

TF and Kato quench in water, mizu-style


----------



## McMan (May 2, 2020)

inferno said:


> yes of course.
> just wanted to point out that NO or almost no makers publish how they HT the steel. hell some dont even tell you what steel they use.


Off the top of my head, I can think of one maker that has a *D*efinitively *T*horough knowledge about optimal HT for a variety of the steels Larrin mentions... Maybe he and Larrin have talked?


----------



## inferno (May 2, 2020)

i think you're missing the point. what i meant is that the HT procedures are usually secret. no makers publish their HT specs. so why should Dalman be forced to do that?


----------



## McMan (May 2, 2020)

inferno said:


> i think you're missing the point. what i meant is that the HT procedures are usually secret. no makers publish their HT specs. so why should Dalman be forced to do that?


No. But I was probably too indirect. Just look at what I bolded.

Edit--Of course I agree. It's absurd to ask that Larrin ask a variety of different makers known for their HT recipes for their recipes and then duplicate these recipes and then publish them.


----------



## bryan03 (May 2, 2020)

the interest of a study is precisely to be able to discuss it, to question certain results.
it is written but probably not frozen. (?)
and here, there are points which are clearly debatable.


----------



## M1k3 (May 2, 2020)

Then debate away. Just don't be all "test flawed. I/so and so, can do better. Not going to do anything other than type words."


----------



## Ruso (May 2, 2020)

inferno said:


> i think you're missing the point. what i meant is that the HT procedures are usually secret. no makers publish their HT specs. so why should Dalman be forced to do that?


DT is not Dalman but Devin Thomas - and because I am “your father”.


----------



## bryan03 (May 2, 2020)

For The moment I only have questions : 
why cryo for all steel ? i know nothing about SS but 1.2519 ? 1.2442 ? super blue ?
Why austenize 2442 and 2519 at 800 and the other 830 ?
why temper 149 and the other 200° ?
10 and 15 minute soaking, what thickness at edge before quench ?
no big deal here but all the differences in the process make huge difference in the knife »performance« .


----------



## inferno (May 2, 2020)

Ruso said:


> DT is not Dalman but Devin Thomas - and because I am “your father”.



i know.


----------



## holdmyphone (May 2, 2020)

This is an amazing article. I like that you threw in the graph showing toughness as well. Anecdotally, I think your results make sense with my kitchen knife experience in some ways. I have always thought my VG-10 knife had surprisingly good edge retention, but it definitely shows visible damage to the edge far more than my White #2 or Blue #2 knives.

Perhaps the takeaway here is not that we should buy all the ZDP-189 knives, but that we place a greater value on toughness and ease of sharpening than we think we do.


----------



## Ruso (May 2, 2020)

inferno said:


> i know.


Sorry, I misunderstood your comment since it was after DT post.

I got the impression that the idea is not to get the “secret sauce” of the HT, but that Dalman (Just as an example) could create a blank to Larrin specs and HT it the way he does it. Then this blank could be tested and compared to the current data. I think it would super awesome if many makers would do it and we got a data with S30V vanilla, s30v Spyderco, s30v Benchmade etc


----------



## HRC_64 (May 2, 2020)

I think complaining about CATRA testing is really mis-placed. In order to get any test standard to be useful, there has to be a basic or baseline that still forces variance over the correct range.

IF we stick XYZ in this machine you need to force measurable variance (repeatable, measurable, scaled etc) in a specific way: ie quickly, consistently, with realized range easy to measure etc.

The special test medium is almost surely designed to solve some problem related to this.

If you recall back when ATK did chef knives they tried to dull the knives nd could't actually do it. They resorted to CUTTING ON GLASS or something stupid to "force variance" in an accceptable window of time to get results they could talk about.

That being said, it would be interesting to devise an "acid resistance" protocol,
and see if one can empirically validate /dimensionalize variance along that axis.

That is to say, without altering the CATRA setup, to maybe "dope" the blades with acid exposure and then run them thru the test. 

The practical problems here is you might need to find/validate the correct chemicals and correct proportions and timings etc. That could be complex/expensive/hassle so the fact this wasn't done isn't a flaw, its maybe better thought of as possible next steps or extensions of the analysis.

Anyways, thanks OP for the test/results/writeup...
and the many commenters on this thread

Its a good discussion


----------



## M1k3 (May 2, 2020)

HRC_64 said:


> I think complaining about CATRA testing is really mis-placed. In order to get any test standard to be useful, there has to be a basic or baseline that still forces variance over the correct range.
> 
> IF we stick XYZ in this machine you need to force measurable variance (repeatable, measurable, scaled etc) in a specific way: ie quickly, consistently, with realized range easy to measure etc.
> 
> ...



You're right, party pooper. Still would like to see an automated carrot cut test, for science and all.


----------



## Larrin (May 2, 2020)

M1k3 said:


> You're right, party pooper. Still would like to see an automated carrot cut test, for science and all.

















Sharpness vs Cutting Ability - Knife Steel Nerds


Thanks to Matthew Berry for becoming a Knife Steel Nerds Patreon supporter! CATRA, Sharpness, and Cutting Ability I got several good comments on the article about CATRA edge retention testing regarding sharpness and cutting ability. The edges tested with more acute angles (20° edge is more acute...




knifesteelnerds.com


----------



## DevinT (May 2, 2020)

This wasn’t a study of heat treating like some of you are trying to make it in to.

Wear resistance is controlled mostly by carbides and hardness which is controlled by the chemical composition of the steel. Most of these test coupons were heat treated using the standard recommended heat treatments or something that would fit the test better.

There needs to be some follow up testing to determine if we can get some separation with optimum heat treats.

This was some very good testing but I’m afraid some of you lack the intelligence to learn anything from it.

I highly recommend that those of you with the biggest mouths do your own testing and then let us sit back and criticize your work.

Hoss


----------



## Gregmega (May 2, 2020)

Lolz.


----------



## Gregmega (May 2, 2020)

Bert2368 said:


> 1: Knife making is a niche material use. There are a FEW kinds of tool steels I know of, plus some damascus, monosteel and pre laminated stock developed and made expressly for our favorite tool, the knife. Naturally, manufacturers of a steel developed for, say, punch press dies, roller bearings or truck springs will have processing recomendations developed in that light. It is unlikely one guy with a day job has had free time to personally experiment with making knives and optimizing heat treating for 40+ materials. YOU PEOPLE, collectively pretty much have.
> 
> 2: Larin did a huge project because he is way into your favorite application- and you don't have to pay a dime to see the results. Should you thank him or complain about some of the details?
> 
> ...


Well I’ve enjoyed this.


----------



## Deadboxhero (May 2, 2020)

How much is "drastically different?"
What are your expectations?
Any predictions? 




RDalman said:


> Ok I came to think of one I don´t use, cpm m4. Why did you austenize it so low, and do the high temper you usually advice against? The hardness and catra result I think is very low, if you would have ran it much higher, like much much higher aus and got it to 65-67 hrc rangethe same temper, I believe it would have performed drastically different.


----------



## RDalman (May 3, 2020)

Deadboxhero said:


> How much is "drastically different?"
> What are your expectations?
> Any predictions?


I have no experience with catra testing just heat treat experiments what I feel works well with the kitchen knives I make. And since I don't want to contribute that maybe I should have just cut off my post at kudos for the awesome work, which I do feel. I just wanted to note I thought the heat treats was a little odd for many steels. This was my original reply in the thread:
"Kudos for the work, awesome.
Not that it takes away anything or makes any difference here necessarily for this catra test, I was struck that across the board the heat treats I prefer on steels in the study that I use in knives are very different from the ones you used."


----------



## Deadboxhero (May 3, 2020)

No big deal Robin, thanks for sharing, I was just curious, and the words "drastically different" in your other post caught my eye.










RDalman said:


> I have no experience with catra testing just heat treat experiments what I feel works well with the kitchen knives I make. And since I don't want to contribute that maybe I should have just cut off my post at kudos for the awesome work, which I do feel. I just wanted to note I thought the heat treats was a little odd for many steels. This was my original reply in the thread:
> "Kudos for the work, awesome.
> Not that it takes away anything or makes any difference here necessarily for this catra test, I was struck that across the board the heat treats I prefer on steels in the study that I use in knives are very different from the ones you used."


----------



## milkbaby (May 3, 2020)

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. Testing the Edge Retention of 48 Knife Steels - Knife Steel Nerds



Really excellent study and report @Larrin ! Thank you!

One thing that I would've liked to see but understand it makes the graphs cluttered is for all three CATRA measurements to be plotted. It would be interesting to see the spread in measurement values. It's not entirely clear the procedure followed between the three measurements; was the same knife was resharpened between the measurements? Was the thickness behind the edge checked between tests and after resharpening and no significant increase was seen? Or does your other testing of cutting edge angles show that thickness behind the edge is negligible in the CATRA slicing test?

It's really cool to see some measurable values from standardized testing like this, regardless of the quibbles some people may have. May be of more interest over at Bladeforums shop talk since there is more discussion of steels with respect to knife usage. KKF has a very Japanese knife-centric audience, and for Japanese kitchen cutlery, it's very unlikely many of the favored makers/bladesmiths/shops will expand their steel offerings outside the steels they are used to forging or using especially considering how little spread in the CATRA values are seen between the low alloy carbon steels typically used.


----------



## lemeneid (May 4, 2020)

So who wants to donate a Denka, Kato, Fujiyama etc to @Larrin for testing


----------



## Jimboss (May 4, 2020)

lemeneid said:


> So who wants to donate a Denka, Kato, Fujiyama etc to @Larrin for testing


I assume this is somewhat tongue in cheek but wouldn't testing individual knives give results that are not comparable to the previous results due to introduction of many different variables associated with each specific knife? I agree it would be great to have tests done to compare individual knife makes to each other for different metrics, but in terms of gathering data for analysis about steel type this doesn't seem that useful.


----------



## _THS_ (May 4, 2020)

DevinT said:


> This wasn’t a study of heat treating like some of you are trying to make it in to.
> 
> Wear resistance is controlled mostly by carbides and hardness which is controlled by the chemical composition of the steel. Most of these test coupons were heat treated using the standard recommended heat treatments or something that would fit the test better.
> 
> ...


Would be much better for the test itself to be discussed and clarified instead of being putted on a stand to be untouchable. If someone have a doubt on why some steels are hardened in a way, why not explain it instead of saying we lack the intelligence for understanding? You're taking a scientific test religiously, wich is plainly wrong


----------



## Bolek (May 4, 2020)

If my understanding is correct we need big carbides for edge retention but small ones to have a sharp edge.


----------



## Larrin (May 4, 2020)

_THS_ said:


> Would be much better for the test itself to be discussed and clarified instead of being putted on a stand to be untouchable. If someone have a doubt on why some steels are hardened in a way, why not explain it instead of saying we lack the intelligence for understanding? You're taking a scientific test religiously, wich is plainly wrong


Constructive criticism and discussion are always appreciated. Sometimes what happens is instead there is anger, ridicule, dismissive statements, or “arguing” rather than discussion. In my experience, once an internet discussion has taken a negative turn further productive discussion becomes very difficult, and further negativity is more likely to result. Sometimes the negativity is very obvious to some people (see pushback from some people in this thread about the attitude of some other commenters) while appearing harmless to others. Studies show that when “trolling” comments have appeared in an online discussion, more such comments are more likely to follow. See: Anyone Can Become a Troll

For me personally, when I feel that questions are presented only to win an argument rather than to discuss I would rather avoid further discussion altogether rather than try to “save the thread” because the win-loss record on such attempts is very poor. Sometimes this also requires ignoring questions from people who are more well-meaning because it provides more fodder for the trolls. Once I have given in to my baser instincts and start arguing with the critics, I only add fuel to the fire and diminish my own reputation. Perhaps some of those times I mis-perceived the intentions of the person driving me to argue. Regardless, leaving a conversation is a better avenue, at least for me. Sometimes criticism, even from trolls, may provide food for thought or lead to experiments to see whether experimental assumptions are accurate or if results may be different with certain variables. Even when that is the case, arguing about it in a negative tone is not productive.


----------



## The Edge (May 4, 2020)

_THS_ said:


> Would be much better for the test itself to be discussed and clarified instead of being putted on a stand to be untouchable. If someone have a doubt on why some steels are hardened in a way, why not explain it instead of saying we lack the intelligence for understanding? You're taking a scientific test religiously, wich is plainly wrong



What about his experiment is in question? I gather you want to know why he heat treated the steel the way he did, but is that even a valid question. The fact is, he told you how he shaped the pieces, the tolerances, the heat treating recipe for each steel he used, the method of how he tested, and finally the results. If this brings up more questions like, "I wonder how this steel would perform heat treated a different way." Then I think this experiment did its job. 

I, in no way, think this was meant to be a table of results that showed the absolute best capability in each steel. Instead we have a baseline that we can use to compare future values. Larrin took a great amount of time and money to give us raw data. We know more by having it. Does it answer all your questions? Nope. But if your interest is peaked, please stop questioning him, rather than thinking of new experiments that can start filling in some of the holes.


----------



## esoo (May 4, 2020)

For a *free* resource, that article is beyond belief, as is much of Larrin's site for those of us that are non-knife makers.

When designing a test, decisions needed to be made - like how to heat treat the steel. Those choices may seem arbitrary, but they needed to be made to make the test move along. Could Larrin have chosen a different procedure for each steel? Yes. Could those other procedures have ended up with better edge retention? Possibly. 

But in the same mind that Dalman isn't going to release his preferred heat treats to Larrin, is Larrin going to give out all his best heat treat knowledge in a free paper? I think not.

You want to find the best heat treat for a steel for edge retention? Pay Larrin (or someone else) to do the work.

In the meantime, he's given us a resource that is great for discussion. Is it what we all want - the comprehensive guide of edge retention from every smith's heat treat of every steel? No. But since we paid zero, I'm pretty damn impressed with what I got.


----------



## _THS_ (May 4, 2020)

The Edge said:


> What about his experiment is in question? I gather you want to know why he heat treated the steel the way he did, but is that even a valid question. The fact is, he told you how he shaped the pieces, the tolerances, the heat treating recipe for each steel he used, the method of how he tested, and finally the results. If this brings up more questions like, "I wonder how this steel would perform heat treated a different way." Then I think this experiment did its job.
> 
> I, in no way, think this was meant to be a table of results that showed the absolute best capability in each steel. Instead we have a baseline that we can use to compare future values. Larrin took a great amount of time and money to give us raw data. We know more by having it. Does it answer all your questions? Nope. But if your interest is peaked, please stop questioning him, rather than thinking of new experiments that can start filling in some of the holes.


I wouldn't be able to discuss whether the OP is right or not on his heat treatment as I have no idea whatsoever on the topic, but once you separated some sterile trolling from the serious questions, you can notice that 2 quite famous and renowned makers had the same question: why some steels have been treated that, apparently or at least for them, weird or unusual way. Now, if the OP has no intention in explaining here, that's understandable, but other people asserting that you either agree or you're not intelligent enough is quite annoying since as far as I can tell, the article try to be as scientific as possible. Now, having said my knowledge of metallurgy isn't great, my question is: is it the best choice to heat treat all steels at the same hardness, even knowing some can perform arguably better at different hardness?


----------



## Bert2368 (May 4, 2020)

Question for Larin:

Could you ballpark what an asking price might be if you, in your professional capacity, were to test a single heat treat sample provided to you under the regime used here?

Not fabricating/heat treating the test piece. Work to include sharpening a sample to the spec used in previous testing, running it through the card stock test (testing 3X as for the listed samples?), collecting the data and providing documentation.

I do understand why many would not care to disclose their heat treat procedures and that some would not care to publicize their results from such tests. But I suspect, for their own information, many who are driven to pursue the craft still would want to know how their results stacked up.

In the case some experienced, competent people ARE willing to disclose HT procedure and agreed to open publication of results, be they good, bad or indistinguishable- Are you willing to continue this experiment and release such data gratis? To what extent COULD you continue the testing without your wife taking a sledge hammer to the machine...


----------



## Larrin (May 4, 2020)

Bert2368 said:


> Question for Larin:
> 
> Could you ballpark what an asking price might be if you, in your professional capacity, were to test a single heat treat sample provided to you under the regime used here?
> 
> ...


I'm still considering costs of testing. It will be $50 or less but I haven't decided how much less. 

Knifemakers who do not disclose the heat treatment will not have their knives tested at this time as my interest is in research and not as being a testing service. The CATRA company tests knives for $75 or so for them.


----------



## Bert2368 (May 4, 2020)

Sorry, was editing my question while you replied.


----------



## Ruso (May 4, 2020)

@Larrin I might not see it, but I could not find results for xhp. Is it under different name or it was not tested? If the latter, what is your ballpark prediction for XHP?


----------



## Larrin (May 4, 2020)

Ruso said:


> @Larrin I might not see it, but I could not find results for xhp. Is it under different name or it was not tested? If the latter, what is your ballpark prediction for XHP?


An XHP blank was produced but warped in heat treatment and the warp was missed until it was already ruined. It is on the list to be tested later. It would be expected to be around 540mm at 61 Rc.


----------



## DevinT (May 4, 2020)

I apologize for being so offensive.

@RDalman and @bryan03 are highly respected knife makers who make excellent knives.

I don’t think this is the best test for simple carbon and low alloy steels because it uses far too aggressive media. We need to devise a better test for all of the most popular kitchen knife steels.

I think I’ll build a rope cutting machine so that we can tease out some of the better heat treatments.

In order to find the optimum heat treat and working hardness of a steel, the test would be nearly as big as this one but only involve one alloy. It would require working with several smiths/knife makers.

Heat treating is the most mysterious part of a knife because you can’t see it and it is very hard to measure, there are too many variables.

Even if we did thousands of tests with thousands of alloys with thousands of different heat treatments from thousands of accomplished knife makers, we would never come to any conclusion.

Peace out,

Hoss


----------



## esoo (May 4, 2020)

DevinT said:


> I think I’ll build a rope cutting machine so that we can tease out some of the better heat treatments.



Take that rope and soak it in different pH solutions to figure out how acidity of the product being cut affects edge retention. 

It really is a never ending pit of testing....


----------



## Deadboxhero (May 4, 2020)

Those makers were also asked if they 
would like to share their thoughts on heat treatment in detail. They declined, but gave kudos.

So, it's not an open, two-way discussion or even anything to debate.
So, it's not something YOU should be hung up on.

Hardness does increase the wear resistance but it doesn't change the types of Carbide particles that have different hardnesses inside the the steel. 
The hardest carbide (Vanadium carbide) is fixed to the steels ingredients.

So heat treatment cannot add elements to the steel.

You can read in the article that 15V cut more than zdp189 despite the zdp189 being harder.

Why?

The answers are in that article, I highly recommend you giving it another read if you have already.







_THS_ said:


> I wouldn't be able to discuss whether the OP is right or not on his heat treatment as I have no idea whatsoever on the topic, but once you separated some sterile trolling from the serious questions, you can notice that 2 quite famous and renowned makers had the same question: why some steels have been treated that, apparently or at least for them, weird or unusual way. Now, if the OP has no intention in explaining here, that's understandable, but other people asserting that you either agree or you're not intelligent enough is quite annoying since as far as I can tell, the article try to be as scientific as possible. Now, having said my knowledge of metallurgy isn't great, my question is: is it the best choice to heat treat all steels at the same hardness, even knowing some can perform arguably better at different hardness?


----------



## bryan03 (May 4, 2020)

Deadboxhero said:


> Those makers were also asked if they
> would like to share their thoughts on heat treatment in detail. They declined, but gave kudos.



?

i do not Understand the way this Thread is taking...


all tests on knife’s steel is interesting, and i think it’s legitimate to ask questions, if it’s posted publicly, and Mostly if some points seems unusual with our practices. you are talking about science , it’s not a dogma .

i do not have a PhD , i only have few low alloy steel blades quenched by myself , so i do not wonder everything ( to be honest, nothing with PM steel or thing like that, by lack of interest ) , but i think It’s enought to no been called troll.


----------



## Larrin (May 4, 2020)

bryan03 said:


> For The moment I only have questions :
> why cryo for all steel ? i know nothing about SS but 1.2519 ? 1.2442 ? super blue ?


Cryo was performed for all steels to keep the heat treatment process consistent across all steels. It is common for knifemakers working with low alloy steel to claim that those steels do not "benefit" from cryo in some way or that cryo has no effect on them. This is of course false and based on a misunderstanding of what cryo does (and doesn't do) and how it works. I have several articles on cryo where you can learn more. If I hadn't used cryo on the low alloy steel then I would be fielding questions about why I didn't use it and whether that affected the low scores of the low alloy steels. 


> Why austenize 2442 and 2519 at 800 and the other 830 ?


The higher chromium content of 1.2519 means higher austenitizing temperatures are necessary for a similar amount of carbon in solution. You can read more in the following articles: 








History and Properties of 52100 Steel - Knife Steel Nerds


A history of 52100, where it came from and how it has been used in knives. And all about the effect of the chromium addition on final properties.




knifesteelnerds.com












How to Heat Treat 52100 - Knife Steel Nerds


Toughness experiments with 52100 steel have resulted in a recommendation for achieving the optimal hardness-toughness balance with this steel.




knifesteelnerds.com












Ranking Toughness of Forging Knife Steels - Knife Steel Nerds


Toughness measurements of a range of popular steels used by forging bladesmiths, and an explanation for what makes one better than another.




knifesteelnerds.com






> why temper 149 and the other 200° ?


To achieve the desired hardness. Since 1.2442 and 1.2519 ended up within 0.3 Rc it appears I was successful.


> 10 and 15 minute soaking, what thickness at edge before quench ?


Again because of chromium content.


----------



## DevinT (May 4, 2020)

I had forgotten how good those articles are. It was good for me to reread them.

Hoss


----------



## Kippington (May 4, 2020)

Cheers Larrin, for all the work gone into all the detailed and concise information you've put out for free. I continue to learn more with each new article, and this one was a doozy.
I personally find it difficult to think of any additional questions*, as you've covered everything I can think of in previous heat treating articles already.

Also, my personal experience with many of the steels in your study have echoed your results, which is nice because thanks to you I can now slot the untried steels into the picture with ease, plus my confirmation bias is brimming with pride! 

Thanks again!

* Did you quench in the light of a blood moon?


----------



## Luftmensch (May 5, 2020)

Well done! I know how long it can take to do labour intensive experiments. What a gift to the collection of freely available knowledge.



Larrin said:


> Constructive criticism and discussion are always appreciated.



With regards to the low-alloy steels, I can try :



DevinT said:


> I don’t think this is the best test for simple carbon and low alloy steels because it uses far too aggressive media. We need to devise a better test for all of the most popular kitchen knife steels.



I don't have a feel for how sensitive CATRA testing is. I am just taking the data for granted. From @Larrin's comment in the article, i assume testing variation is low (e.g. +/- 5mm TCC??):



> Each knife was tested three times on the CATRA edge retention tester and the results averaged. When one of the tests looked substantially different than the other two I performed a fourth test as a tiebreaker. In general the results between re-tests were pretty consistent but there were cases when an individual test would be worse than the others.



As a sanity check, one thing you guys could do, with the low-alloy steel data, is analyse the variance of the results. If you take the measurements for each low-alloy steel and subtract their mean, you would have a collection of zero-centred measurements. Now if you take the standard deviation across all this zero-centred data, you will get some idea of variation in the testing.

If the variation for the low-alloy steel data is super low (e.g. 1mm TCC), you can probably trust the 'ranking' of steels (even if this isn't the point). A more sensitive test would be unnecessary, unless you want to stretch the scale.

If the variation is something like 10mm TCC, the general trend will be correct but you might not want to trust the exact 'ranking' for similar results. For example, A2 and O1 are well separated - it is likely that A2 has something like 20% better edge retention. On the other-hand, 1.2519 and 1095 are very close. In this (variation) scenario, all you could confidently say is that they perform about the same and the ranking _may_ not be correct (the very slight advantage to 1.2519). If you wanted more precision, you may want to devise a more sensitive test.



Other rambling thoughts:



> I may try to use rope or cardboard in the CATRA machine in the future to test this further.



I'd be interested in plain cardboard (it is a cheap and easy test material). Again... I don't have a feel for how CATRA testing scales. Would plain cardboard increase the TCC 100x? 10x? I suspect it is less than 10? That might 'stretch the scale' for the low-alloy steels.

If it is easy to exchange the steel cylinder at the top of the machine, you could also consider lowering the cutting force.


All in all... nice work


----------



## Luftmensch (May 5, 2020)

milkbaby said:


> It's really cool to see some measurable values from standardized testing like this, regardless of the quibbles some people may have. May be of more interest over at Bladeforums shop talk since there is more discussion of steels with respect to knife usage. KKF has a very Japanese knife-centric audience, and for Japanese kitchen cutlery, it's very unlikely many of the favored makers/bladesmiths/shops will expand their steel offerings outside the steels they are used to forging or using especially considering how little spread in the CATRA values are seen between the low alloy carbon steels typically used.



Yeah... just to make it explicit to readers here... The fact that @Larrin makes insightful posts here doesn't mean his immediate interest is kitchen knives. Larrin participates in (at least):

BladeForums.com
Spyderco Forums
r/knives
So he is likely to have a broader view on what use-cases various steels might face; at least, compared to the general standards of kitchen cutlery!


----------



## Larrin (May 5, 2020)

I like kitchen knives the best. But some of my kitchen knife readers are lacking in imagination when it comes to what is relevant for kitchen knives. Or at least that is my conclusion when they say that certain steels or topics are not relevant to kitchen knives. I worked very hard to obtain certain Japanese produced steels that almost no one uses in the USA, for example. But not everything will be about kitchen knives.


----------



## Kippington (May 5, 2020)

It's almost like kitchen knives are related to other cutting tools...


----------



## RDalman (May 5, 2020)

I will say it without imagination. My opinion is that using that catra chart as comparison for choosing steel alloy for kitchen knives is a potentially misleading route. Many of the heat treatments used I have had very poor experience with. And I think the cutting media is problematic as a reference to kitchen knives.


----------



## Larrin (May 5, 2020)

RDalman said:


> I will say it without imagination. My opinion is that using that catra chart as comparison for choosing steel alloy for kitchen knives is a potentially misleading route. Many of the heat treatments used I have had very poor experience with. And I think the cutting media is problematic as a reference to kitchen knives.


Relying on anecdotal experience is very dangerous when it comes to learning broader principles about how the world works.


----------



## RDalman (May 5, 2020)

Larrin said:


> Relying on anecdotal experience is very dangerous when it comes to learning broader principles about how the world works.


Enough of the arrogance for me. Peace out.


----------



## Larrin (May 5, 2020)

RDalman said:


> Enough of the arrogance for me. Peace out.











Definition of IRONY


the use of words to express something other than and especially the opposite of the literal meaning; a usually humorous or sardonic literary style or form characterized by irony; an ironic expression or utterance… See the full definition




www.merriam-webster.com


----------



## madelinez (May 5, 2020)

Edit: Not relevant


----------



## DevinT (May 5, 2020)

RDalman said:


> I will say it without imagination. My opinion is that using that catra chart as comparison for choosing steel alloy for kitchen knives is a potentially misleading route. Many of the heat treatments used I have had very poor experience with. And I think the cutting media is problematic as a reference to kitchen knives.


You should make test coupons from the steels that you’ve seen the most improvement with your advanced heat treat. Even with the aggressive media being cut/tested, there will be a separation from the standard heat treat. Then we can find out how much of a measurable difference there is.

Hoss


----------



## Iggy (May 5, 2020)

@DevinT @Larrin

Ok... I think every material scientist (btw... am one by myself... polymers and composites, 8 years of experience, worked at a material science institute here in Germany before going to the industry, multiple publications and leading international R&D projects in the field of material development) will agree, that standardized test procedures are one of the key aspects when doing material analysis for comparison (of course besides other factors like a statistically approach the control of defined influence parameters).

But... and I think here lies the key, were you and some of the knife makers here (as well as myself that said) differ...

The use/load case is one of the, may be THE most significant aspect in material testing. The question is... are CATRA or rope cutting tests simulating the real life load cases that occur when using a kitchen knife? For an Outdoorblade or heavy duty folder, that is mostly used for cardboard cutting or wood etc.... maybe, yes.

For kitchen knives? I really doubt it...

In my opinion, kitchen knives are mostly loaded with an impact and bending/shear load case, f.e. in combination with corrosion. The CATRA test (as well as rope cutting when you pull/push cut) is not sufficient to simulate these load cases. This is why the results "from the experience of the real world" and your CATRA based results seem to differ quite a bit.

Maybe it would be more suitable (and scientifically more "clean") to simulate the load cases, that occur in kitchen knives, and test and compare them before transferring results from another only remotely connected test scenario to kitchen knives. Don't you think?

With FEM simulation etc., you could for example simulate the critical load cases with different cutting techniques (f.e. chopping with straight impact on the board or rock chop with a certain amount of orthogonal force etc.). For most of these cases, standardized test methods exist.

Right now, I find the hypothesis to transfer CATRA results to kitchen knives quite (let's say) uncertain and not really "scientific" to be honest.
Would look forward to see how the results of the tests mentioned above would differ.

All the best,
Simon


----------



## DevinT (May 5, 2020)

Iggy said:


> @DevinT @Larrin
> 
> Ok... I think every material scientist (btw... am one by myself... polymers and composites, 8 years of experience, worked at a material science institute here in Germany before going to the industry, multiple publications and leading international R&D projects in the field of material development) will agree, that standardized test procedures are one of the key aspects when doing material analysis for comparison (of course besides other factors like a statistically approach the control of defined influence parameters).
> 
> ...


This wasn’t a test designed for kitchen knives or kitchen knife steels. It was posted here because Larrin is a member of this forum.

Hoss


----------



## Larrin (May 5, 2020)

Iggy said:


> @DevinT @Larrin
> 
> Ok... I think every material scientist (btw... am one by myself... polymers and composites, 8 years of experience, worked at a material science institute here in Germany before going to the industry, multiple publications and leading international R&D projects in the field of material development) will agree, that standardized test procedures are one of the key aspects when doing material analysis for comparison (of course besides other factors like a statistically approach the control of defined influence parameters).
> 
> ...


There are many cases where knife edge wear does not predict performance. If the knife is failing due to chipping or rolling, for example, then sharpness loss is not due to wear as in the CATRA test. In those cases the edge angle must be increased so that we can have a more stable and predictable loss of sharpness to wear. It would certainly be excellent if an FEM expert were willing to team up and make more simulations of different edge geometries that would be a fun project. It is not so simple to make predictions using those simulations, however. Every edge geometry and user leads to different stresses. At the same time, claiming that a test does not make any predictions about knife behavior is just as uncertain and unscientific. I know that it makes good predictions about some types of cutting because I have already done the comparisons. Can CATRA predict Rope Cutting Performance? - Knife Steel Nerds


----------



## Iggy (May 5, 2020)

@DevinT Ok, I got the impression when reading through this thread, that the CATRA results are used to create some verdicts on steels of kitchen knives. If not, then sorry, I got the wrong impression...

@Larrin Of course, for such simulation, you would have to rely on a defined and constant edge geometry. Of course, when you have a first reference, you could expand the scope of the analysis using a design of experiments approach for example. Unfortunately, I'm no FEM expert myself, that's the field of another department. But I think this could be an interesting approach.

"At the same time, claiming that a test does not make any predictions about knife behavior is just as uncertain and unscientific "

I tend to differ. I was claiming that a test, designed to evaluate wear resistance could not lead to a reliable hypothesis for the material behavior for other (and of course combined) load cases (as statet before). Of course, if you compare two tests for simple wear resistance (CATRA and rope cutting), you are getting similar results. But what happens for example, when you compare the results of the CATRA with impact and/or bending tests?

Again.. I think the problem is... you are basing your hypothesis (or what people reading this thread seem to gain from it) on wear resistance tests and basically my point is, that I don't agree, that wear resistance is the key factor for edge retention in kitchen knives. Based first of all on reflecting on the load cases from a technological point of view but also based on assumption by having used hundreds of high end kitchen knives over the last couple of years and getting differing impressions on some of the steels... but that's another topic and I would not want to make some hypothesis' about steels for kitchen knives based on my own use, because, as you said correctly, there are a lot of influence parameters.

But long story short... the analysis (incl. comparison tests) you show are primarily for wear resistance. Maybe try to get some comparisons with other testing techniques for impact and/or lateral stress.

I think this would result in a far more "complete" picture and more reliable hypothesis'

Best,
Iggy


----------



## LostHighway (May 5, 2020)

Iggy said:


> @DevinT @Larrin
> 
> Ok... I think every material scientist (btw... am one by myself... polymers and composites, 8 years of experience, worked at a material science institute here in Germany before going to the industry, multiple publications and leading international R&D projects in the field of material development) will agree, that standardized test procedures are one of the key aspects when doing material analysis for comparison (of course besides other factors like a statistically approach the control of defined influence parameters).
> 
> ...



I think you make some legitimate points. However, IME real world research also operates within budgetary constraints. Larrin isn't getting paid for this and although he has some Patreon support this is shoestring budget research. A million dollar budget ideal study of kitchen knife edge retention that no one other than the funders and researchers can access is not something I wish for. I may have my own quibbles vis-a-vis some Platonic ideal but I'm *extremely* grateful for the work he has done and his openness in freely publishing it. I think some of the criticism in this thread is not about anything inherent in what he has presented but rather with somewhat adventitious interpretations the reader has brought to bear.


----------



## Larrin (May 5, 2020)

Iggy said:


> @DevinT Ok, I got the impression when reading through this thread, that the CATRA results are used to create some verdicts on steels of kitchen knives. If not, then sorry, I got the wrong impression...
> 
> @Larrin Of course, for such simulation, you would have to rely on a defined and constant edge geometry. Of course, when you have a first reference, you could expand the scope of the analysis using a design of experiments approach for example. Unfortunately, I'm no FEM expert myself, that's the field of another department. But I think this could be an interesting approach.
> 
> ...


Of course bending and impact tests are in no way predicted by a CATRA test. Which is why I test toughness and strength separately. Just because I post the result of one type of test doesn't mean that I am saying it predicts all behavior. I don't know why I would ever imply something so foolhardy. 

Where I see wear resistance showing up in "real world' knife usage are the many members of kitchen knife forums who repeatedly claim that their SG2/R2 or ZDP-189 knives cut longer than other steels like VG-10 or White Steel. If wear resistance is not a factor than White Steel should cut just as long or longer than SG2.


----------



## Iggy (May 5, 2020)

Larrin said:


> Of course bending and impact tests are in no way predicted by a CATRA test. Which is why I test toughness and strength separately. Just because I post the result of one type of test doesn't mean that I am saying it predicts all behavior. I don't know why I would ever imply something so foolhardy.



Ok, as said... I got the impression by reading through this thread, that a lot of the readers seem to get exactly this impression and transferring your results directly on the suitability of such steels for kitchen knives (also derived from discsussion from other forums as well)... and it was important for me, that no false results are obtained by the readers.
Maybe it's just me, that I got this impression and again, if I'm wrong, I apologize...



> Where I see wear resistance showing up in "real world' knife usage are the many members of kitchen knife forums who repeatedly claim that their SG2/R2 or ZDP-189 knives cut longer than other steels like VG-10 or White Steel. If wear resistance is not a factor than White Steel should cut just as long or longer than SG2.



Ok, then I will say that, depending on heat treat (of course there are good and bad) I had PM-steel in SG2/R2 knives that lost what I would call "sharpness" way faster then some of my knives made with simple carbon steels such as SC145 or 1.2008 (White 1, too) 
But that's exactly the point... this is just personal experience and also strongly depending on the individual HT of the specific knives in question and this has IMHO no really significance for the scientific evaluation of the edge retention of knives.

For that, the first step would be to derive a test catalog of different load cases to test. Wear resistance is one of them, no question. But there are others to test and compare first in order to derive any conclusions of edge retention of knives for different use cases.

As said in my last post... of course there are use cases for knives, which are reflected quite nicely with these tests (rope cutting, I would expect cardbord cutting also etc.).
Then there are other use cases, where the more realistic load case would be a straight impact on a wooden board. Then there are use cases, which will result in lateral force on the edge or quasi static pressure or dynamic loading to a fatigue failure... etc... etc.

I think you have the chance here to derive a "catalog" for suitable knife steels for different tasks, if you also reflect on the other load cases as well as combinations and correlations between them.


Iggy


----------



## Iggy (May 5, 2020)

@Larrin Just one question... comparing with your results, how would you judge the results of Global?



https://knifesteelnerds.com/wp-content/uploads/2019/04/CATRA%E2%80%99s-Report-_-GLOBALGLOBAL-small.pdf



Because it seems that they got some significant differing results betweens similar (or identical) steels and because I think this would make quite a good example of knives (GLOBAL) that seem to get quite good results in the CATRA tests, but have (from personal experience) significantly lower edge retention than some of the other knives (f.e. made from VG10) on their list.

I mean, I think most of us here used quite a few of the knives on their list and I would doubt that anyone would say, that Globals are a good example of high edge retention.

Thanks in advance

Best,
Iggy


----------



## DevinT (May 5, 2020)

Who has a Global knife that we can test to see if the results can be duplicated?

Hoss


----------



## Deadboxhero (May 5, 2020)

RDalman said:


> Many of the heat treatments used I have had very poor experience with.





Tell us more, join the discussion. Without more information everyone reading has no idea what that means.

Don't be so shy.


----------



## Barmoley (May 5, 2020)

Larrin said:


> Of course bending and impact tests are in no way predicted by a CATRA test. Which is why I test toughness and strength separately. Just because I post the result of one type of test doesn't mean that I am saying it predicts all behavior. I don't know why I would ever imply something so foolhardy.
> 
> Where I see wear resistance showing up in "real world' knife usage are the many members of kitchen knife forums who repeatedly claim that their SG2/R2 or ZDP-189 knives cut longer than other steels like VG-10 or White Steel. If wear resistance is not a factor than White Steel should cut just as long or longer than SG2.



I think this is the crux of the issue. For some reason some readers took this study and article as "what are the best steels to use for kitchen knives". No one claimed this. Many steels were compared for wear resistance. Wear resistance has high correlation with slicing edge holding, but still no one is claiming best for kitchen knives. Combining this study with toughness tests and strength numbers one can pick the steel that would work best for his application. What is wrong with that? Why are people upset? We all know some steels seem to last longer than others in kitchen knives, more wear resistant steels tend to last longer, but if your edge is bending or chipping then you have other issues and more wear resistance is not what you care about. Clearly good kitchen knives can be made out of all sorts of steels because there is so much more that defines a good kitchen knife. Take the study for what it is, use the results to make your conclusions and in combination with other results pick your steel. Don't imply that the article said something it didn't. Arguing with the results of this study by saying, "oh but my white 2 knife outcuts my vg10 knife" is great and all, but what does this have to do with vg10 being more wear resistant than white 2? I can guarantee that if anyone read all the articles that Larrin published he would have a much better understanding of steels, metallurgy, heat treats, etc. As a bonus it would help to pick the best steel for many applications, I think that's the point of what all of this is about, to educate knife enthusiasts about the material that their tools are made out. I know that my Z-wear, vanadis 23, m390, cpm-m4, HAP40 knives cut longer than my blue, white, 1095 knives. In a big part thanks to Larrin I know why, doesn't mean I am going to throw away all of my other knives. A good knife is a good knife regardless of the steel, but it is nice to be educated and not just blindly go with what the maker tells me. You don't buy slow, medium or fast cars after all......or at least I don't.


----------



## DevinT (May 5, 2020)

There might be a conflict of interest for a company to buy their own machine and do their own testing and show superiority of the knives they make.

Knife testing is different than steel testing.

Hoss


----------



## milkbaby (May 5, 2020)

Barmoley said:


> I think this is the crux of the issue. For some reason some readers took this study and article as "what are the best steels to use for kitchen knives". No one claimed this. Many steels were compared for wear resistance. Wear resistance has high correlation with slicing edge holding, but still no one is claiming best for kitchen knives. Combining this study with toughness tests and strength numbers one can pick the steel that would work best for his application. What is wrong with that?



Well stated, worth repeating by quoting...


----------



## Bert2368 (May 5, 2020)

I am pleasantly surprised that no one has mentioned Nazism or Hitler in this thread yet (Ooops! Bert just RUINED EVERYTHING!!!).

Also, happy that this thread brought back to activity some "lurkers" who I have learned worthwhile things from, thank you all.

------

About Globals and CATRA test results?

Anecdotally, GF has a block full of Globals which I sharpen. I have used those knives going on 20 years now... If I am going to seriously prep and cut a lot of stuff, I bring my own knives with me because I KNOW how much longer White #2, Blue Super, VG 10, Japanese proprietary semi stainless and S35VN from "adequate" knife makers will stay sharp, that is, long enough not to annoy me...

I also know from experience that if I leave those knives around for others to use, I will need to be repairing the edges after. And possibly cleaning the blood from kitchen floor they left behind on the way to the emergency room.

If serious about wanting to get a Global for repeating CATRA testing? Where would it have to be sent, will it need to be modified (other than being given the spec sharpening used on other samples) and could it be sent back to provider after? Or would it be a "sacrificial" knife?

(Edit) Yes, I could provide one- Especially if I get it back afterwards. Because, they actually DO work OK for limited duty use and I'm not doing much business this year so far...


----------



## Eloh (May 5, 2020)

Well, that would be my main complaint (or to be positive....recommendation): if you publish something like this on a kitchen knife forum, you should clarify what these results can actually teach us about kitchen knife use and what they can not.


----------



## M1k3 (May 5, 2020)

Results: General trend is more carbides (especially vanadium), results in more cuts made. 

Ability to slam against a cutting board, knock into bones or rust resistance is another article.


----------



## Barmoley (May 5, 2020)

Eloh said:


> Well, that would be my main complaint (or to be positive....recommendation): if you publish something like this on a kitchen knife forum, you should clarify what these results can actually teach us about kitchen knife use and what they can not.


Honest question; do we really need a disclaimer like that? A link to a study and an article was made, you follow or don't, read and make your own conclusions. Do we need to be treated like children and told, "here's this study, but don't take it to mean that I am suggesting anything about kitchen knives". I don't know, maybe we need something like that judging by the reaction of the forum..... Strange times, for a change bladeforums is reacting more civilized about this than this forum, very strange and unusual.


----------



## TSF415 (May 5, 2020)

I need a beer. Does anyone else need a beer?


----------



## M1k3 (May 5, 2020)

TSF415 said:


> I need a beer. Does anyone else need a beer?



Yes! I'm going 7 years of needing one!











I don't drink alcohol anymore


----------



## TSF415 (May 5, 2020)

M1k3 said:


> Yes! I'm going 7 years of needing one!
> 
> 
> 
> ...



Not a problem. Your next root beer is on me. Non fermented. Treat yourself too, get that real cane sugar not corn syrup.


----------



## Ruso (May 5, 2020)

Barmoley said:


> ...
> Strange times, for a change bladeforums is reacting more civilized about this than this forum, very strange and unusual.


My thought exactly when I was reading comments on bladeforum and thinking about what was posted here. Strange times indeed. 
Quarantine must be weighting more on kitchen knife folks


----------



## soigne_west (May 5, 2020)

M1k3 said:


> Yes! I'm going 7 years of needing one!
> I don't drink alcohol anymore



Three for me.


----------



## DevinT (May 5, 2020)

There should have been a warning in the title stating some of the content might be offensive to sensitive viewers.

Hoss


----------



## M1k3 (May 5, 2020)

DevinT said:


> There should have been a warning in the title stating some of the content might be offensive to sensitive viewers.
> 
> Hoss



Rated M
For mature audiences only.
May contain incomplete steel participation, heat treatment combinations and HRC data points. These tests were performed with a limited budget and time frame.

Or something...


----------



## Bert2368 (May 5, 2020)

This thread not approved for use in Belgium, contains drama.


----------



## Boynutman (May 5, 2020)

I guess all testing and research (in any field) answers questions and provides insight, and at the same time raises even more questions for the curious of mind.

Thanks Larrin for all the awesome work!


----------



## WildBoar (May 5, 2020)

DevinT said:


> There should have been a warning in the title stating some of the content might be offensive to sensitive viewers.
> 
> Hoss


No sheet! (wrote some more and then deleted).

Any research is useful, and this body of work by Larrin provides a lot of good info. It is yet another building block in the knowledge base of knife steels.


----------



## inferno (May 5, 2020)

hey guys i kinda made a blueprint for how to increase the scientificness of the catra machine, its just a rough sketch so far but it looks promising. patents pending...

basically you have a hopper with onions (probably with automatic pallet changing), that is feeding an ABB robot arm, which is feeding the catra machine.
the onions are weighed and counted while being fed into the catra.

i imagine it would look something similar to this.

problem??


----------



## MontezumaBoy (May 5, 2020)

If we are going to be all scientific about it - I have to insist for any of the "data" to be treated as "accurate" that the onions use must be genetically identical, grown in the same soil under environmentally controlled conditions. Further they must be pulled up when at identical weights (corrected for all/any gravitational changes), have exactly the same water content (within 0.0001% or less) and the sorted by the same robot prior to being loaded into the on site hopper all within a time frame that is required to be reasonably the same - say differing by no more that +/- 0.00000001 seconds or so ... Thx


----------



## inferno (May 5, 2020)

yeah well i guess i kinda said what/how i wanted tested.

there is a guy on youtube that is bess testing blades he has sharpened. and it doesn't take really much to get a much higher value when doing this.
a blade maybe goes from 50 to 150g on the tester after like 10 cuts in cardboard. i dont have a bess tester so i dont know where i would say a blade is dull.
but i'm guessing the 3-400g range or so.

and what happens after this or how long any blade can stay at the lets say "the 400g level dullness" is not really interesting to me for kitchen knives.
whats really interesting for me personally is how long does it take for a blade to go from 50 to 300or so g. just guessing these figures but you get the point.

..........

for folders its probably different. maybe you are out in the desert shooting some kinds of dangerous animals all day long and drinking their blood, and you suddenly you have to chop up a 500 year old cactus and a bunch of humvee tires. or whatever the F people generally do. and then it would be cool to have a steel that can do this for the absolute longest amount of time. because you have to go back to your secret navy seal base to sharpen the knives.

---------

i at least think the bess testers and using maybe regular copy paper in the catra could be interesting (and cheap). maybe 2-10 cycles/stacks or how much paper it now takes to make 1095 feel "not sharp" anymore. that amount of paper stacks cut could be the baseline. then measure the sharpness with the bess. and then measure higher alloyed steels after the same amount of paper cut.

-------------

i like the guy from the cedric and ada outdoors chan on youtube. he test knives that he has sharpened by cutting rope and then when the blades dont reliably cut paper anymore (they start tearing), then its over.

the variable there and its a very big variable is that he is testing production knives. not steels.

-----------

but to be honest i dont know if edge retention is all that important to me at all anymore. i just pull out a glass stone and sharpen the blade if it feels dull. 2-3 minutes. done. all kitchen knives i own stay sharp for a long enough time for me to think its good enough. well except 1. my fiskars chefs with 1.4116 @52 hrc  it sucks ass.

so for me its more important how long my knives can keep that fresh of the stone sharpness. you know when its new and super sharp. yeah thats what i want to maximize. now thats interesting. so far it seems its basically a draw between all steels i own here. go figure.


----------



## HRC_64 (May 5, 2020)

This gets us back to something discussed earlier...which is calibration of the testing setup.

his is why you have caliper and micrometer in addition to ruler and yardstick...same idea.

KKF is heavily biased towards pure carbons and AEBL (low carbide steels) for various reasons, but mostly because of ease of "refresh" sharpening to 'ultimate sharp'.

Any test that is demanding of the steel like this one is going to lump all those steels together and make them look like "losers", which people's ego gets caught up in their "team" not winning.

Its like expecting a sprinter and a marathoner to be competitive at "Running", and crying about your jamaican sprinter (specialized at 10 seconds) not winning the NYC marathon (2hrs race).

Only fools have such expectations. Its not the race organizer's problem than the sport of "running" has more than one measure of success.


----------



## HRC_64 (May 5, 2020)

Its worth also looking back here to AEBL--A steel not really "lknown" for its edge retention...

According to this test, however, the best AEBL can be differentiated from the worst with the existing setup. A key question is this because good aeble is really good, or if the bad aebl is just really bad?

And can we get this kind of variance in other low-carbide steels (stainless or not) just from heat treat? Expecially blue/blue super etc one would think maybe could be separated form white, just like o1 seems to underperform 1095.


----------



## inferno (May 5, 2020)

i'm guessing there is no incorrectly HTed steels in this test. probably all of them were HTed better/more suitable than all big brands HT them.


----------



## DevinT (May 5, 2020)

Heat treating takes a big jump from a poor heat treat to a good heat treat. There is a smaller jump from a good heat treat to a superior heat treat.

Hoss


----------



## inferno (May 5, 2020)

HRC_64 said:


> Any test that is demanding of the steel like this one is going to lump all those steels together and make them look like "losers", which people's ego gets caught up in their "team" not winning.



i dont think most people actually care that "their favorite steels" ranked low. almost all people on here know god damn well these low alloyed steels basically suck for abrasive resistance. 

and i actually dont think people have steels that is like their "favorite team". i have favorite knives. and its usually knives i have put my own handles on.

my own favorite steels, and they probably all suck in this test is: blue2, aus8 and vg10. because they have have a good balance of properties. and i get those properties when i buy almost any off the shelf knife. no magic needed. i have never tried a bad blue 2 knife. they are all good.

the only real supersteels imo is blue2 and mac's aus-8  but i'm probably alone thinking that. and i dont care because _for me_ these are the best tradeoffs.


----------



## sudsy9977 (May 5, 2020)

Larrin, i don’t pretend to understand everything you write but I do appreciate all your hard work. Is the paper used for the test standardized in some way? Couldn’t you get a “bad batch”. Did anything from the test surprise you at all? Also does the machine cut straight up and down ? Just curious. Thanks for any answers. And thanks again for your work. I know it took a long time. And it’s never easy when your wife is angry!


----------



## RDalman (May 6, 2020)

I want to apologize I havent taken the time to explain myself better. I do applaud all the work and found the experiment and it's findings really interesting. But also feel like Iggy was pointing out, it might not be great as using for relevancy for kitchen knives edge retention. I did react to the chosen heat treatments, because I believe other, or more optimized heat treatment temperatures would show exponential curves in this catra test, like the aeb-l does. And also I would venture to believe many steels are at a low level of catra performance comparing it to itself with a harder heat treat. If that is the case (that many steels are tested at what might be bottom range of a exponential chart-curve hardness wise) the study could have looked different I would believe.
Still, I found the study interesting! 
Since I don't want to contribute I should maybe not have said anything, but then this is a discussion board, and like Bryan mentioned, studies/experiments should really stand to be discussed. 

For my heat treatments I don't think I do anything special really. I just don't share exact temps I have come to use for a couple of reasons. One is I don't want to give alot of work away to be copied or potentially misused/misreferenced. And also, I don't want to open for being critiqued by people who might have the opinion, or be invested in the opinion, that using some temperature or the other would be very bad theoretically. For me as a knifemaker it's best to just have it like that, that if customers enjoy the knives I make performance, that's what matters.


----------



## gregfisk (May 6, 2020)

I spent many years on an audio forum. Any time someone posted a listening test of any kind you knew the thread was destined for quarantine. No matter how good of a double blind test was done if someone’s own equipment lost the test the test was flawed. 

I’m a very new knife maker and don’t really know anything about steel but I’m guessing the same thing is in some ways happening here. If someones favorite steel didn’t do well or it doesn’t compare favorably to their own beliefs the test is flawed in some way. I’m wondering, does the medium you’re cutting through really make a difference on the edge retention of different steels? It seems to me it shouldn’t matter what you’re cutting through when determining edge retention, what matters is how many times it takes to get through it. Other than the the huge variable of heat treating each steel to its best state this test seems to be very informative of edge retention of different steels.

One question for Larrin, I’m curious why 15n20 wasn’t included in this test? I didn’t think it was that obscure of a steel?


----------



## DevinT (May 6, 2020)

Predicted wear resistance of 15N20 would be close to 8670, maybe a little less. 

Hoss


----------



## gregfisk (May 6, 2020)

DevinT said:


> Predicted wear resistance of 15N20 would be close to 8670, maybe a little less.
> 
> Hoss


Thank you very much.


----------



## inferno (May 6, 2020)

15n20 can be hardened to much higher than 60 hrc though, so you might get another 10% on this test while doing that. you can get 62-64 after temper if you want.

i'm guessing the reason it wasn't tested it that there was no real confirmed virgin 15n20 to test. i can get it here in sweden as 3mm plates but this might not be the case in the US. its probably not.

one thing i reacted on is that uddeholm caldie is about as "good" as 1095 in this test but in practical reality it would be on the order of, most likely 3-10x, as durable and long lasting as a blade steel made out of 1095. at high hardness.

we used to make shearing knives out of caldie @ 61-62hrc for a plant that used it as "knives" to chop rebar. because this was the steel that lasted the longest. i think we re-machined them every 2 weeks or so. 1095 would have lasted maybe 2-10 seconds in this environment. so it is what it is.


----------



## Deadboxhero (May 6, 2020)

RDalman said:


> I did react to the chosen heat treatments, because I believe other, or more optimized heat treatment temperatures would show exponential curves in this catra test, like the aeb-l does.



57 blades were completed in total, more blades can always be created and added to see more data.



RDalman said:


> I don't want to open for being critiqued by people who might have the opinion, or be invested in the opinion, that using some temperature or the other would be very bad theoretically.


 

Yes, all the heat treatment is shared openly in the study for science and is open to scrutiny from all people of any background.

It is a complex subject. Scrutiny in some cases may be due to a misunderstanding of how some features work. 



RDalman said:


> I don't want to contribute I should maybe not have said anything, but then this is a discussion board, and like Bryan mentioned, studies/experiments should really stand to be discussed.


Scrutiny without constructive feedback or wanting to help isn't very helpful.

Discussion works best if information is shared.


----------



## Barmoley (May 6, 2020)

inferno said:


> one thing i reacted on is that uddeholm caldie is about as "good" as 1095 in this test but in practical reality it would be on the order of, most likely 3-10x, as durable and long lasting as a blade steel made out of 1095. at high hardness.
> 
> we used to make shearing knives out of caldie @ 61-62hrc for a plant that used it as "knives" to chop rebar. because this was the steel that lasted the longest. i think we re-machined them every 2 weeks or so. 1095 would have lasted maybe 2-10 seconds in this environment. so it is what it is.



This is a very good example of why studies like this are very useful and important. Taking your anecdotal evidence as an example. You don't really know if 1095 would last 2-10 seconds in your example or if caldie would last 3-10 times as long, a huge range by the way, but let's say you are right and it lasts 5 times as long. Well, wear resistance of caldie in this test is similar to 1095, but it so happens that at the same hardness it is about 5 times as tough as 1095. Could it be that in your application with "knives" to chop rebar, low toughness and not wear resistance is what causes failures? I don't know but looking at results of different testing that was done you could probably arrive at an explanation and pick the steel that would work best for you. Take A8Mod as another steel that is used in chipper blades, it too is not very wear resistant, but also very tough and it is used in a similar application, so wear resistance is probably not the main failure mode in such applications. If you wanted a steel that would give you similar toughness, but was also more wear resistant you would go for CPM-3V for example, cost not being an issue. So you can see how useful this and other studies are to make good decisions of steel choice for different applications.

Disclamer: Everything said in the above example is just a thought experiment, it has nothing to do with reality of chipper or rebar blades and definitely has nothing to do with kitchen knives or how steels relate to them. no claims of CPM-3V being superior to A8Mod for chipper or any other blades should be taken or inferred.


----------



## Larrin (May 6, 2020)

Rapid failure vs 2 weeks would be an indication of chipping or deformation.


----------



## inferno (May 6, 2020)

yeah it was just an approximation. but i guess caldie (and maybe even calmax) would be at the very top (with 3v) of the "carbon" steel hill when talking practical longevity of an edge, talking all regular types of "wear" combined kinda, both for folders and kitchen knives. it might not be very far ahead of some of other steels but they probably would come out ahead. thats what i'm guessing at least.

i'd buy a max hardened 3v kitchen blade in a heartbeat if i could. but now im probably forced to make it myself instead


----------



## Barmoley (May 6, 2020)

You can buy a Z-Wear kitchen knife at around 63 that will give you the practical longevity you are looking for with max hardness 3v, just saying.....

This is unrelated to this discussion


----------



## Larrin (May 6, 2020)

According to the Crucible datasheets the toughness of 3V starts to fall off around 62 Rc. For 62+ Rc CPM CruWear might be a better choice. Pushing a “tough” steel to higher hardness levels doesn’t always work out well If it’s not optimized for higher hardness.


----------



## Kippington (May 6, 2020)

Human nature.. It's funny how we want take a well thought out product and try to adapt it to something outside of the roll it was designed for, even while other products already exist to fill that roll.
I bet some of the metallurgists look at how bladesmiths (in general) are choosing and treating their steels, and see this:









Step aside blade steel, move over ball-bearing steel... Now I want to make a knife out of a high quality *injection moulding die*. Specifically one made from CPM-15V, obviously tempered lower than advised (duh).
Thanks guys... 


Crucible Mold and Tool Steels for Plastics


----------



## inferno (May 9, 2020)

Barmoley said:


> You can buy a Z-Wear kitchen knife at around 63 that will give you the practical longevity you are looking for with max hardness 3v, just saying.....
> 
> This is unrelated to this discussion



cool!


----------



## inferno (May 9, 2020)

Larrin said:


> According to the Crucible datasheets the toughness of 3V starts to fall off around 62 Rc. For 62+ Rc CPM CruWear might be a better choice. Pushing a “tough” steel to higher hardness levels doesn’t always work out well If it’s not optimized for higher hardness.



of course you are right, the steels are made/optimized for a certain hardness range. and outside the design range there might be better options.

but if we look at most of the common japanese steels, SS or carbon they are pretty much all in the 10ft-lb range or less in your tests. so even at this "low" toughness usually its enough for most people. but if one could double that toughness and still have good hardness, well, i think this is a good way to go to increase "overall performance". because chipping is very common with high hardness kitchen knives. no matter what steel. if they are thin enough they probably will chip out sooner or later in my experience.

------------

btw a bit OT, i think i'm done with 1095 for my moras at work. 

in sweden mora knives are multitools, its the most essential tool for any worker.
i usually do everything you are not supposed to do with a knife. hundreds of times a day. and have been for the last 20 years.

i scrape rust/paint/dirt/concrete/grease, deburr parts, chisel burrs away from hardened parts, general chiseling on steel, bend/pry stuff apart, puncture thinner materials (with a hammer), chop heavy duty shipping straps, clean surfaces, etc etc. but i also do maybe 5% actual cutting with it, opening boxes and such. and it still needs to be able to cut cardboard, tape and plastic bags at the end of the day.

i used to like the mora robust (because it has a bit shorter and a bit thicker blade than usual) but it would simply dull within a day or 2. and it usually chipped out. especially when chiseling stuff.

but now i have basically switched over to the orange/black companion stainless (12c27), and it chips out way less and i only have to sharpen it once a week. and it still opens the boxes. win-win.
------------

its usually thought that stainless is brittle and carbon is tough, but i find it to be the exact opposite most of the time.


----------



## inferno (May 9, 2020)

Kippington said:


> Human nature.. It's funny how we want take a well thought out product and try to adapt it to something outside of the roll it was designed for, even while other products already exist to fill that roll.
> I bet some of the metallurgists look at how bladesmiths (in general) are choosing and treating their steels, and see this:
> 
> 
> ...



hehehe i'm gussing its gonna be fun forging that out to a knife shape


----------



## Kippington (May 9, 2020)

inferno said:


> its usually thought that stainless is brittle and carbon is tough, but i find it to be the exact opposite most of the time.


----------



## Deadboxhero (Jan 12, 2021)

I thought it would be fun to show the cutting geometry the catra blades before I sharpen them.



Next batch of testing should be exciting.

Have some heavy hitters like Maxamet, also some lesser known steels like T15 and Rex 76.

Also some fan favorites like Rex45 (hap40) and XHP as well as the new SPY27 steel from Spyderco that's is stacking up to be a real SG2 killer.


----------



## DavidPF (Jan 23, 2021)

inferno said:


> *The CATRA test results in extremely dull edges, you can run your finger along the edges with no fear of being cut.*
> 
> ... i never let any knife get so dull i cant actually cut myself with it. i resharpen it when i feel its not cutting well anymore.
> 
> (followed by some specific suggestions)


Outside of whether those specific suggestions you went on to make are the best solutions (because I have no way of knowing if they would be), superficially it makes sense to me that in a dulling test, knife users are only interested in the part of the test that mimics our experience - the part from "fresh edge" to "subjectively seems like it needs sharpening". After a certain level of dullness, then regardless of technical terms I'd start to think of the remainder of the test as merely testing abrasion resistance rather than ability to hold an edge - because in knife user terms, that edge was already gone. 

There may really be a useful number lurking here to be found, perhaps something like "Subjectively, how many microns is too wide to qualify as an edge, and might therefore signal the end of a test?"


----------



## Barmoley (Jan 23, 2021)

Wear resistance is highly correlated to slicing edge holding. The curves of loss of cutting ability for different wear steels have similar slopes, so it doesn’t really matter at what point you stop the test. Relationship among steels will be similar. This is well explained here Which Steel Has the Best Edge Retention? Part 2 - Knife Steel Nerds follow the links for more.


----------



## Larrin (Jan 23, 2021)

When you run the test all the way to dull, you can analyze the data at any point you want. There is a cutting ability curve for every cut in the test. There isn't a difference in steel ranking if you stop at some subjective earlier point, however. There is just more scatter earlier in the test because it is more dependent on variability in sharpening.


----------



## Neofolis (Jan 23, 2021)

You know how they say a picture is worth a thousand words. I had hoped the nice pictures wouldn't make my head hurt as much as the text. Maybe reading at gone 2:30am wasn't the best choice. It seems like choosing Blue Super for my latest knife acquisition may also not have been the best choice.


----------



## Barmoley (Jan 23, 2021)

Neofolis said:


> It seems like choosing Blue Super for my latest knife acquisition may also not have been the best choice.



Why not, when heat treated well blue super makes an excellent kitchen knife.


----------



## ModRQC (Jan 23, 2021)

Relax... Blue Super is fine for kitchen use.


----------



## Neofolis (Jan 23, 2021)

ModRQC said:


> Relax... Blue Super is fine for kitchen use.


I'm sure it is and it's definitely a huge upgrade over what I was using previously, I was just surprised to see it do poorly in this test. Unless, of course, it didn't do poorly and I was having even more difficulty understanding than I thought.


----------



## Larrin (Jan 23, 2021)

Blue Super is a good choice for higher wear resistance low alloy steel (for forging). Low alloy steels don’t have particularly high wear resistance but Blue Super is among the highest in its category.


----------



## ModRQC (Jan 23, 2021)

@Neofolis what is your AS?


----------



## Neofolis (Jan 24, 2021)

It's a Kato 240 Nashiji Gyuto.


----------



## ModRQC (Jan 24, 2021)

What’s your kind of use with it? Those are pretty thin so if even just somewhat sharp you don’t have to use much force. If you’re in the push/pull cutting ballpark you’ll benefit from keeness of the steel and thin edge, without so much wearing it out as you’d slicing against a hard medium - cutting surface that is. If you’re into rock chopping, baillonnette and the likes, then you’ll have to resharpen often but still less than a good deal of carbon steels if you just give it a more conservative edge angle. More worrying is toughness, but Kato doesn’t work the extremes of hardness, so adopt same thinking as if a lot of slicing against cutting surface occur: keep it thin but edge rather conservative. You might not have to sharpen as often as with a lot of slicing neither, but this would sure be unremarkable in home use.


----------



## Neofolis (Jan 24, 2021)

It needed sharpening when I got it and my whetstones still haven't arrived yet. I tend to push cut more than rocking or slicing, but I do rocking cuts, if I'm finely mincing things. I'm using it on Teak edge grain and I know Teak dulls knives faster than some materials. To be honest, I'm not overly bothered by edge retention at the moment, because I need plenty of sharpening practice.


----------



## Jason183 (Jan 24, 2021)

Neofolis said:


> It's a Kato 240 Nashiji Gyuto.


Liked other said a good heat treated AS can have 66HRC, I used to have Kato AS too, it was around 62-63, still not bad around that price point, it is a great Vegetable cutter, this is what it can do when it get sharp, hand made( Kato AS) VS machine peeler on white Radish


----------



## Deadboxhero (Jan 24, 2021)

Everything in this batch is complete and has been sent to Dr Larrin for CATRA edge Retention Testing.

Including a New CPM stainless grade that Larrin designed that's quite intriguing.
I'm excited to see the results.


[YouTube]


----------



## DavidPF (Jan 24, 2021)

Neofolis said:


> You know how they say a picture is worth a thousand words. I had hoped the nice pictures wouldn't make my head hurt as much as the text. Maybe reading at gone 2:30am wasn't the best choice. It seems like choosing Blue Super for my latest knife acquisition may also not have been the best choice.


You are still going to have to sharpen any knife. What you need is a knife that will go a reasonable number of uses before needing to be sharpened again, instead of having to sharpen it five times a day or something ridiculous like that. Your new knife is _definitely_ going to allow you a reasonable not-difficult sharpening routine. It doesn't have to be the highest rated, it just needs to be in the "good knife zone" of the ratings and not the "crap knife zone". Hand-made knives need steel that allows for hand-made processes.

You *did* make a good choice. Sleep well knowing that.


----------



## M1k3 (Jan 24, 2021)

Neofolis said:


> It needed sharpening when I got it and my whetstones still haven't arrived yet. I tend to push cut more than rocking or slicing, but I do rocking cuts, if I'm finely mincing things. I'm using it on Teak edge grain and I know Teak dulls knives faster than some materials. To be honest, I'm not overly bothered by edge retention at the moment, because I need plenty of sharpening practice.


Don't stress over the cutting board. I regularly use poly cutting boards. Last night I was lazy and cut on a paper plate on my stone counter. And you know what happened? I ate dinner and the world kept turning. Oh and the knife didn't disintegrate.


----------



## captaincaed (Jan 24, 2021)

Neofolis said:


> You know how they say a picture is worth a thousand words. I had hoped the nice pictures wouldn't make my head hurt as much as the text. Maybe reading at gone 2:30am wasn't the best choice. It seems like choosing Blue Super for my latest knife acquisition may also not have been the best choice.


Having had, sharpened and sold a fair number of high alloy and PM knives...lower alloy can be a lot easier to live with long term. It can be a real chore to sharpen and maintain steels with high wear resistance over time. Also, you can have one of each! Best of both worlds.


----------



## captaincaed (Jan 24, 2021)

@Larrin will you be adding these new coupons' results to your previous article, or will you write a new one? Don't want to miss out.


----------



## Larrin (Jan 24, 2021)

captaincaed said:


> @Larrin will you be adding these new coupons' results to your previous article, or will you write a new one? Don't want to miss out.


Probably a new one. If I add it to an old one I will probably put at the top of a new article that it was updated.


----------



## captaincaed (Jan 24, 2021)

Also, if @Deadboxhero (BBB) is ever interested in writing a bit about completely deburring an edge as coarse as 400 grit, I'd be interested in reading and absorbing that. I feel like I can do pretty well, but that's some next level action. Curious if he thinks a jig is necessary.


----------



## ModRQC (Jan 24, 2021)

M1k3 said:


> Don't stress over the cutting board. I regularly use poly cutting boards. Last night I was lazy and cut on a paper plate on my stone counter. And you know what happened? I ate dinner and the world kept turning. Oh and the knife didn't disintegrate.



We want visual proof - defended to reglue the knife dust and photoshop.


----------



## Neofolis (Jan 24, 2021)

M1k3 said:


> Don't stress over the cutting board. I regularly use poly cutting boards. Last night I was lazy and cut on a paper plate on my stone counter. And you know what happened? I ate dinner and the world kept turning. Oh and the knife didn't disintegrate.


It's fine, I don't really stress about anything or maybe I just don't have anything to stress about.


----------



## DavidPF (Jan 24, 2021)

Neofolis said:


> It needed sharpening when I got it and my whetstones still haven't arrived yet. I tend to push cut more than rocking or slicing, but I do rocking cuts, if I'm finely mincing things. I'm using it on Teak edge grain and I know Teak dulls knives faster than some materials. To be honest, I'm not overly bothered by edge retention at the moment, because I need plenty of sharpening practice.


Teak might not be the most perfect, but at least it's wood and you can use it. Stone, glass, and metal are bad cutting board materials - teak is really OK when you have it, just if someone is shopping for a new board and could easily choose something else then they probably should. Definitely not something to waste time/energy/money over when you already have one.


----------



## Neofolis (Jan 24, 2021)

DavidPF said:


> Teak might not be the most perfect, but at least it's wood and you can use it. Stone, glass, and metal are bad cutting board materials - teak is really OK when you have it, just if someone is shopping for a new board and could easily choose something else then they probably should. Definitely not something to waste time/energy/money over when you already have one.


My research on cutting boards was basically watch the YouTube video by America's Test Kitchen, then buy the cutting board they say. Like you say, it's an acceptable option, just not what I would choose if I was buying it now.


----------

