Proper heat treatment - how do you know?

JDRanger

JDRanger

Joined
Aug 14, 2017
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People routinely mention how certain knives have excellent heat treatment. How does one go about ascertaining whether or not a blade has been properly heat treated?

Sorry about the nub question but I had to admit to myself that I know my steels but don’t have any idea how to tell if a knife has been heat treated correctly. I just go by reputation and feedback I see on the forum.
 
I’ve had enough different knives and steel that I can tell a little bit by how they sharpen but I can tell better by how they cut and how much cutting before needing sharpened again.
A reputable knife manufacturer is going to have a certain percentage per batch that are tested to verify the hrc. Some test every knife but I don’t know how many companies do that. I would think and hope they are honest with their testing and methods because a bad reputation is bad business and they won’t be around for long. So I’ll take their word for it and I haven’t been suckered yet.
 
No need to apologize for the question-very valid.

More often than many would admit-you DON'T really "know". Often we're left to trust the manufacturer and their history. Often after a catastrophic failure THEN "bad heat treat" becomes the word of the moment. And it often IS, but maybe not always. Most folks are never going to use theirs that severely (and correctly so.) Short of life or death circumstances, I don't believe in abusing a knife but I want one that can be used in a very rugged and hardy fashion! :p

I recall a video Adam Francis (Equipped to Endure) did several years ago where he tested about 4 (?) blades for extreme cold weather use and batoning wood/firemaking/survival. One (that was made, advertised, and even NAMED for this very niche) failed miserably while one from another reputable maker that was NOT designed for this type task made it through fine.

(The company quickly contacted HIM and offered a replacement; translation: "Here-let us get this CHERRY PICKED one from production into your hands!") :)
 
JDRanger said:
People routinely mention how certain knives have excellent heat treatment. How does one go about ascertaining whether or not a blade has been properly heat treated?

Sorry about the nub question but I had to admit to myself that I know my steels but don’t have any idea how to tell if a knife has been heat treated correctly. I just go by reputation and feedback I see on the forum.
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Every now and then, even in super reputable companies comes a “lemon” and the sentence immediately used is “bad heat treatment”, as David From NC David From NC already explained. These heat treatment inconsistencies is because all companies (or 99% of companies) harden and/or temper in large batches, and heat is not the same in every place of a big furnace, not even in the super duper ultra high tech vacuum ones. Now, how can you be certain that your knife is well heat treated? First, buy from a reputable company that makes knives for your particular use and second, use your knives the way it suits you. No safe queens if you want to be 100% sure your knife was well heat treated for your purposes.
 
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The fastest and easiest way in my opinion to truly know is to use the knife. Some people will use a Rockwell tester which measures steel hardness to see if the hardness is matches the manufactures claims. If the Rockwell tester gives a very different rating than the manufacturer claimed it may be an indication of a bad heat treat. It can be a helpful tool if used correctly but testing error can occur. Also some blades will only have the cutting edge hardened with a softer spine so if tested in the wrong spot can give a false rating with a knife that would actually work fine. (usually its only high end custom knives that use that method) Others like some layered steels can have softer layers on the outside and a harder core so it is not a fool proof way, but can be a tool to help tell.
 
I would start by buying from a reputable custom maker or a popular knife company. At least you know you have a better chance out of the gate. Unless you get a knife tested you will never truly know.
 
As Monofletch Monofletch and A Alberta Ed said: buy from a reputable company and don’t worry about it.

Little anecdote about MANLY knives: I bought a Peak from them (and a Wasp) a year or so ago. The Wasp was in S90V and the Peak was D2. Several months after the fact, their US distributor contacted me and told me that the batch that I bought my Peak from had a bad heat treat (I couldn’t have told you and I was using the hell out of it). He verified my shipping address and a few days later I had a brand new Peak. I know that was the right thing for them to do, but it still speaks volumes about the integrity of the company. They’re excellent.
 
You learn with experience. Buy a few 420hc, 440C, Aus 8, etc. blade steel from different companies and use the heck of them. You will see performance differences with them.

Probably the best example is 420hc. Buck's steel is the best of the bunch and that is due to Paul Bos and his crew and their HT.
 
AntDog said:
Easy - Use the knife.

If it holds and edge and doesn’t chip out from being too brittle, it has a good heat treat. There’s no way to fake performance.
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I think it will ultimately be more of an impression. I think impressions fall more in the soft-medium-hard characterizations for blade hardness resulting from the heat treat. Even if the edge chips, it does not necessarily indicate a poor heat treat. So, buy from a reputable person/manufacturer and take your chances. After you use it a while, you will get an impression. I have one knife (fixed blade) that I know has a heat treat issue, but it was inexpensive and not worth worrying about.
 
You really don't until something doesn't work as expected. That experience could be anything from very obvious to hardly noticeable.

I'm finding myself tending more towards companies that have a better reputation for heat treat, including Cold Steel, Spyderco, and some smaller makers.
 
22-rimfire said:
I think it will ultimately be more of an impression. I think impressions fall more in the soft-medium-hard characterizations for blade hardness resulting from the heat treat. Even if the edge chips, it does not necessarily indicate a poor heat treat. So, buy from a reputable person/manufacturer and take your chances. After you use it a while, you will get an impression. I have one knife (fixed blade) that I know has a heat treat issue, but it was inexpensive and not worth worrying about.
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I can look at a tire and tell if it’s flat or not. I can also use a knife for a month or two and tell if it has a good or bad heat treatment.

Is that an “impression” that the tire is flat or that the knife has a good or bad heat treatment? You tell me. I think it’s more cut and dry than you think if it’s truly a bad heat treatment. The knife will either do what it’s supposed to, or it won’t.
 
Just don't chase "heat treatment" or "hardness" based off spurious information gleaned from Instagram or Facebook and you'll be ahead of the game.

Still too many people trying to win a pointless "Best Knife" contest with pics of their 200th EDC pocket dump.

Also avoid $300 beads, $300 hanks, $300 spinner tops, etc.
 
I've only ever actually had one bad one. It was an opinel no 6 Carbone. I do not believe it was actually hardened. Only knife I've ever owned I could not get sharp. Ok sharp but not sticky edge sharp and always had a wire edge I could not remove. Being that it is a basic carbon steel I actually read heat treated it. Removed the blade. Applied a layer of Turco. Heated to non magnetic and let cool for a normalize. Then heated to non magnetic again plus a bit and quenched in oil. Tempered 2x for an hour each at 325°. Now it gets sharp! Was a fun experiment
 
AntDog said:
I can look at a tire and tell if it’s flat or not. I can also use a knife for a month or two and tell if it has a good or bad heat treatment.

Is that an “impression” that the tire is flat or that the knife has a good or bad heat treatment? You tell me. I think it’s more cut and dry than you think if it’s truly a bad heat treatment. The knife will either do what it’s supposed to, or it won’t.
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For you perhaps, I'm not so sure of my impressions with knives. A flat tire is a bit of an extreme comparison. But a very slow leak might be more apt. I had a nail in a tire for I don't know how long.... since it is a newer vehicle it had the tire inflation warning light and it went on, probably after months of being there. The dealer actually found the issue as I had a warranty checkup and mentioned the light was on. They actually replaced the tire for free which surprised me. I think a honest knife manufacturer would do the same with some evidence.
 
Production knives have come a LOOOONG way. But when it comes to heat treat, this is where a custom knife maker wins. With the custom knife makers I use, they do their own heat treat in very small batches and have Rockwell testing machines.

that's not to say you can't get a good heat treat on a production knife...it's just easier to control the process on a custom. More expensive too...but hey.

I'm willing to bet the majority of knife guys really can't tell if the knife is properly heat treated (myself included). I would think that would require a knowledge that few collectors/users possess. In most cases, if the knife doesn't cut properly, I'll bet it has more to do with poor sharpening rather than an improper heat treat.
 
Ron Sabbagh said:
Production knives have come a LOOOONG way. But when it comes to heat treat, this is where a custom knife maker wins. With the custom knife makers I use, they do their own heat treat in very small batches and have Rockwell testing machines.

that's not to say you can't get a good heat treat on a production knife...it's just easier to control the process on a custom. More expensive too...but hey.

I'm willing to bet the majority of knife guys really can't tell if the knife is properly heat treated (myself included). I would think that would require a knowledge that few collectors/users possess. In most cases, if the knife doesn't cut properly, I'll bet it has more to do with poor sharpening rather than an improper heat treat.
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I’m sure I can tell. It hasn’t happened to me often, but I’ve had a couple of knives with bad heat treats. One bent and the other wouldn’t hold an edge at all. It was pretty easy to tell what was wrong.

For my part in this discussion, I’m not talking about nailing RC numbers right on the nose. I’m talking bad heat treat. You can tell definitively by using the knife if the heat treat is bad.
 
I loosely hold the bare blade in my fingertips and tap the tip against a hard wood table; and like a Country music song, I listen for the "twang"... :D
 
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