What a Good Heat Treatment Can and Cannot Do

Larrin

Larrin

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Larrin said:
An article about how heat treatment affects knife properties. Including 9 ways to perform a “bad” heat treatment, how hardness affects properties, the important variables within good heat treatments, and how steel and edge geometry affect knife performance compared with heat treatment. https://knifesteelnerds.com/2019/07/01/what-a-good-heat-treatment-can-and-cannot-do/
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I totally agree. I’ve had to shift my views a bit over the last couple of years with the testing. Heat treat is still the most important part of knife making, but good heat treat will never make D2 as tough as 8670, and 8670 will never be as wear resistant as D2, assuming the heat treat wasn’t botched. There are improvements to be had with tweaks for knife specific heat treats, to keep
carbides small, and with high hardness for fine edge stability, but you are still not going to break the laws of physics.
 
Larrin, at first I wondered why an article like this wasn't your first article when you started this blog, but (whether by design or chance) I now see why coming out at this point is better, brilliant even. There are so many variables and considerations to take into account when speaking "in general" about heat treating, that the writer inevitably has to assume some level of knowledge on the reader's part, or ignore some factors or variables that would require more time and space to address than necessary.

But now that you have a library of articles that go into specific detail on a number of those variables, you can afford to generalize and then say "look here for more in depth information."

I don't know if that was your intent from the start or not but either way, well done.
 
kuraki said:
Larrin, at first I wondered why an article like this wasn't your first article when you started this blog, but (whether by design or chance) I now see why coming out at this point is better, brilliant even. There are so many variables and considerations to take into account when speaking "in general" about heat treating, that the writer inevitably has to assume some level of knowledge on the reader's part, or ignore some factors or variables that would require more time and space to address than necessary.

But now that you have a library of articles that go into specific detail on a number of those variables, you can afford to generalize and then say "look here for more in depth information."

I don't know if that was your intent from the start or not but either way, well done.
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Some by design, some by happenstance. I was frustrated in early articles because it seemed like every paragraph I got to a point where I said, "Well I can't say anything about that without 3000 more words." It felt like I was limited with what I could write about unless I had articles covering the background. So at the beginning I tried to stick with basic, single concepts (what are grains, what is austenitizing, what is tempering, etc.) so that everything could be covered in a single article. And then expanding the more general topics I could write about as more concepts had been covered. I'm now finally getting to the point where a lot of background has been written about and I don't have to explain everything. Unfortunately, no one clicks on the links within the article so I need to be careful about making sure the article stands alone to some extent.
 
Larrin said:
Some by design, some by happenstance. I was frustrated in early articles because it seemed like every paragraph I got to a point where I said, "Well I can't say anything about that without 3000 more words." It felt like I was limited with what I could write about unless I had articles covering the background. So at the beginning I tried to stick with basic, single concepts (what are grains, what is austenitizing, what is tempering, etc.) so that everything could be covered in a single article. And then expanding the more general topics I could write about as more concepts had been covered. I'm now finally getting to the point where a lot of background has been written about and I don't have to explain everything. Unfortunately, no one clicks on the links within the article so I need to be careful about making sure the article stands alone to some extent.
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It's super cool that you attach links in your articles. If it ever turns into a textbook your students will be grateful. A lot of us are reading every article from start to finish and if we have questions will re read the other article later. I do find it very helpful that you do include some background because it helps to recall the earlier learned concepts. Unlike in a classroom we are a pretty engaged group but without a daily discussion of technical terms they tend to get a little lost so those extra few sentences really help out.
 
Really great article. I need to read it all again! But this proves, when someone claims their heat treat makes their knives perform miracles, self sharpen, or whatever nonsense, is false. I’m sure there can be improvements with any alloy, but only slight improvements. As long as everything is controlled and consistent, the results will be good. And much better then factories can consistently reproduce!
Of course we hear claims, from certain companies, that have the best heat treat, that no one can possibly match. With larrins research, things are being proven different! Thanks Larrin!
 
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rodriguez7 said:
Really great article. I need to read it all again! But this proves, when someone claims their heat treat makes their knives perform miracles, self sharpen, or whatever nonsense, is false. I’m sure there can be improvements with any alloy, but only slight improvements. As long as everything is controlled and consistent, the results will be good. And much better then factories can consistently reproduce!
Of course we here claims, of certain companies, that have the best heat treat, that no one can possibly match. With larrins research, things are being proven different! Thanks Larrin!
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Personally I would love it if someone could show vastly improved properties from heat treating. But it's unlikely.
 
Great article Larrin. This is great stuff. Especially with the info about the low alloy steel being more picky with heat treatment.
 
rodriguez7 said:
Really great article. I need to read it all again! But this proves, when someone claims their heat treat makes their knives perform miracles, self sharpen, or whatever nonsense, is false. I’m sure there can be improvements with any alloy, but only slight improvements. As long as everything is controlled and consistent, the results will be good. And much better then factories can consistently reproduce!
Of course we hear claims, from certain companies, that have the best heat treat, that no one can possibly match. With larrins research, things are being proven different! Thanks Larrin!
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Very well said! Those guys claiming their heat treatment is the best make me laugh out loud and make me run away from their products, even if it’s nice stuff. The very best guys at heat treating are Metallurgists, like Roman Landes and Fredrik Haakonsen, and I never heard one of them saying their heat treatment is the best (even if it is, both are PhD Metallurgists, like Larrin, and both have access to state of the art equipment). They just say it’s adequate for that steel.
 
Now I know, with a lot of time and effort, you can optimize and tailor a heat treat for your uses! Like, honestly, if I could use only two steels for rest of my knife making life, I would choose Ztuff, and vanadis 4e. With both of those steels, you can custom suit the heat treat to whatever you need, skinners, choppers, chefs knives, you name it! Run hard, run soft, high temper low temper. The options are many. Optimizing is key, dialing in an austenizing temp, finding the correct tempering temperature, and optimal hardness for your uses!
I’ve still yet to find a need for 10v steel, or something with insane wear resistance! And this is coming from someone who hunts big game, and butchers animals year round. For my uses, I can use a medium alloy steel, and dial in a heat treat, with proper edge geometry, and skin out and quarter an entire elk without a touch up. At least with v4e. I’m still testing ztuff! Time will tell. Hopefully in September, I’ll test ztuff on a bull elk!
 
Good article. Agree that most of us use the best heat treatment we have found to use for our knives. New makers must keep detailed notes on how they heat treat and find some way to check hardness. Once you have found the best results for a certain steel, that should be the recipe every time you use that steel. thanks for taking the time to write and post.
the old sailor
 
Larrin said:
Personally I would love it if someone could show vastly improved properties from heat treating. But it's unlikely.
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All you need to do is read the articles by a well known cowboy knifemaker from Montana. He claims to make steel three times as hard and many times tougher by his HT. Unfortunately, the testing done by some PhD that he claims will prove it never have appeared.
 
Stacy E. Apelt - Bladesmith said:
All you need to do is read the articles by a well known cowboy knifemaker from Montana. He claims to make steel three times as hard and many times tougher by his HT. Unfortunately, the testing done by some PhD that he claims will prove it never have appeared.
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I though he was in Wyoming. There must be more than one. :)
 
All heat treatment does is get you as close to ideal material properties as possible. When we worked with our steels to establish property baselines we used ideal samples that were heat treated using as high as quench rates and as accurate of times as possible. In the real world, equipment, material geometry and size, and normal fluctuations in materials heat to heat have a profound affect on the outcome. We are lucky with blades as the thin cross section gives a great quench rate compared to really thick sections where you have to estimate how much extra time to add so the soak is all the way through. In my opinion, follow the guidelines established by the manufacturer and more importantly be consistent. I remember having a discussion with an un-named individual on why mountain lion fat is better for quenching than bear fat. Shows you not all oil based quench medias are the same. :D
 
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