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.
I Tested the Edge Retention of 48 Steels
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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.
Larrin
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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
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And that is your hypothesis as to why some of the low carbide steels did worse than high carbide steels?
inferno
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no, its my hypothesis as to why some of the simple carbon steels performed so similar. like blue super and 1095
Bert2368
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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
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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.
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.
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.
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...
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...
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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
Everybody liked that, esp DaveBReally 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...
inferno
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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
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I would be happy to test a sample of CPM-M4 at higher hardness if you want to make one.
Deadboxhero
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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.
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boomchakabowwow
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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.
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Gregmega
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Ol’ Peter Party Pooper.
Gregmega
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Maybe it could finally settle the horizontal onion cut debate once and for all
Eloh
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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!
Still, great work and effort!
Larrin
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Larrin
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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
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.
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.
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
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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
" 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
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.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
Bert2368
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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!"
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!"
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.
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.
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.
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.
