Blade Steel Rehardening

You're right because... you say so? That does not strike you as just the tiniest bit solipsistic?

Far be it from me to criticize the one percent of the one percent of self-proclaimed super-users out there, but this sounds to me like an unrealistic level of perceived performance gains -- like building a rifle so accurate that no human being can wield it steadily enough to get that marginal performance increase from it.

Let's stipulate that such gains are theoretically possible. Sending a bunch of knives off to somebody to be "rehardened" for free still sounds like ruining those knives for no good reason, to me.
No, I had others check the knife out also. I refuted your generalization, and I'm not proclaiming to be an expert. I tested the knife both before and after the re-heat treat. The performance gains were obvious, and *easily* verified - no theory required.

If you think it sounds too good to be true, then don't send in any of your knives. We all like to experiment, there's no harm in that. Certainly everyone who sends in a knife is aware that it might not work. And we all might learn something in the process.
 
Please point to me where I claimed to have discovered something they haven't? They heat treat AUS-8A (different from AUS-8, btw) for toughness and sharpenability, convenient as the industry moved away from oil-quenching steels and it would be too expensive to cryo treat right after the quench. AUS-8A can reach 61+ rc just fine, max hardness is 62 rc after tempering. And it's not brittle.

I'm sorry if I hit a nerve to cause you to be so angry. I am merely offering a service to my fellow steel enthusiasts, many of whom prefer hardness over impact toughness. It's all personal preference.

I suppose the only thing that puts me off on this thread is that it has been well established by Sal Glesser, AG Russel, and the tech support folks at Cold steel that there is no difference in composition between AUS8 and AUS8A.

If the poster is as well acquainted with these alloys as he claims, I would expect him to know that.

Of the blades I have tested from Spyderco (3), Benchmade (3), and Buck (4), KaBar(2) I have not found any that were below the published hardness spec. Since Gerber mostly doesn't publish specs, I can't say about them. YMMV.
 
I suppose the only thing that puts me off on this thread is that it has been well established by Sal Glesser, AG Russel, and the tech support folks at Cold steel that there is no difference in composition between AUS8 and AUS8A.

If the poster is as well acquainted with these alloys as he claims, I would expect him to know that.

Here's the compositions (yeah I know AUS-8A is usually listed as the one with .70-.75C):

http://www.knifemakersdatabase.com/...MD/KnifemakingBladeSteelCompositionChart.html

There are many AUS-8* steels, including an AUS-8W and so on. I could not find the composition for AUS-8W. I might be wrong, just going by the chart. I know Americans use AUS-8 and AUS-8A interchangeably, because the other two AUS-8* steels are only popular in Japan (and still rare).

And since when did I claim to be "well acquainted" with any alloy? I think you have been reading into my posts too deeply, where I may be coming off as arrogant in your mind. I may make a statement like "manufacturers are not heat treating Steel X for maximum performance" and you are reading that I think I am better than these manufacturers, when I am just stating an opinion.

You are clearly one of the more knowledgeable posters on this forum, yet all I've seen you post is pure nitpickyness. In the context of your posts in the past 3 months, you clearly have a subconcious agenda to discredit me. Which is fine if you hadn't joined in on the poo-pooing on this thread; I've been wrong many times before, and I get a chance to learn something new.

Of the blades I have tested from Spyderco (3), Benchmade (3), and Buck (4), KaBar(2) I have not found any that were below the published hardness spec. Since Gerber mostly doesn't publish specs, I can't say about them. YMMV.

How did they test out?

My impression from previous threads was that he was in fact a practicing engineer. Even if that were not the case, extraordinary claims (ie that the heat treating guidelines published by the companies that develop and manufacture the steels will not yield their stated results, if they are followed properly, which, by the way, isn't all THAT hard for someone with decent home shop) require extraordinary evidence, of which you have provided none.

Thanks. Well you are close...(Lucky Bob) my degree is in Chemistry and my background is working on anti-cancer drugs for Pfizer. It is somewhat related to metallurgy in that I can read metallurgy texts and understand the theory, since metallurgy is the chemistry of metals. This is still very much a learning experience for me.
 
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You're so kind, Cotdt.
I've always impressed with your inquiry into steel performance.

Let me ask one thing..
In theory steel phase transition between alpha and gamma is reversible but
I've heard it is not always true in case of higher alloyed steels.
They are heated to well above the critical point, which causes
some irreversible effect on steel, it that right?
If so, does this matter to what you are trying to do?

Well, to be honest I have nothing material-related detailed understandings,
I'm just a math and informatics bit. :D
 
You're so kind, Cotdt.
I've always impressed with your inquiry into steel performance.

Let me ask one thing..
In theory steel phase transition between alpha and gamma is reversible but
I've heard it is not always true in case of higher alloyed steels.
They are heated to well above the critical point, which causes
some irreversible effect on steel, it that right?
If so, does this matter to what you are trying to do?

Well, to be honest I have nothing material-related detailed understandings,
I'm just a math and informatics bit. :D

Yeah you're right, it matters, so some steels can't just be rehardened directly or you can get excessive grain growth. You have to anneal them first to "reset" the steel, then you can heat treat. I'm not sure to what extent the steels need to be annealed, but a full anneal can take over 20 hours. Fortunately they can be done in batches, as most high alloy steels start the anneal process at 1650F.

So basically, it's not an issue, I just take the 20 hours to anneal the steel first with my computer-controlled kiln. This is probably why rehardening is rarely done, it takes too long.
 
Thanks!
I think I understand it.
Annealing takes lots of time and energy, which is necessary to obtain
the matrix of smallest potential.
I also sometimes use annealing within my job, although it is nothing more than a
`simulated' one, and it also takes lots of computation.
 
When you don't provide a good argument other than it is your opinion, it is trolling when you repeatedly do it. Provide a good argument that has not been addressed in the thread. No one cares what your opinion is if you don't have a reason!

We have the ignorant government telling us what we can and can't do and what is good and bad in our every day life. We don't need your ignorant comments on what we should and shouldn't do. Keep them to yourself. Troll. That's MY opinion.


The basic flaw in your assumptions is that it is "trolling" to question the need or the advisability of this "free service." Nobody is claiming that the heat treatments offered by manufacturers are perfect. I simply can't see something like this provided for free by a private individual doing anything but ruining what was a perfectly good knife.

People are free to do any dumb thing they want with their knives, up to and including strapping on hockey masks and videotaping themselves stabbing cinder blocks and hammering the things to pieces -- but just because nobody's stopping you from doing it doesn't mean somebody shouldn't stick up their hand and say, "Hey, that... doesn't seem like a very good idea."

I don't care if the original poster is a traveling ninja rocket scientist with a degree in engineering from Miskatonic University -- this is still a really bad idea.
 
And since when did I claim to be "well acquainted" with any alloy? I think you have been reading into my posts too deeply, where I may be coming off as arrogant in your mind. I may make a statement like "manufacturers are not heat treating Steel X for maximum performance" and you are reading that I think I am better than these manufacturers, when I am just stating an opinion.

You are clearly one of the more knowledgeable posters on this forum, yet all I've seen you post is pure nitpickyness. In the context of your posts in the past 3 months, you clearly have a subconcious agenda to discredit me. Which is fine if you hadn't joined in on the poo-pooing on this thread; I've been wrong many times before, and I get a chance to learn something new.

codt - welcome to the world of internet educated "experts". With plenty of reading on different subjects, it allows them to pontificate freely on a multitude of subjects, even if they have only read about it.

I am a professional woodworker and have been for 35 years. You would be surprised how aggressive the garage worker is that fixes a kitchen drawer, builds a set of shelves or repairs a fence can be when expressing their opinion on the woodworking forums I participate in.

I wouldn't let it bother me if I was you. I am an inveterate experimenter, and teaching myself different aspects of my trade on my own has often been a quicker more rewarding experience than listening to the peanut gallery of experts that seem to be out there on any subject. When I was teaching myself cabinet finishing/refinishing, my backyard and shop looked like Dr. Frankenstein's lab because there were so many WIPs out there. I am a firm believer in hands on learning and applaud your efforts.

I am surprised too, that the recurring comment that seemed to bother some was that you were offering your service "free". I hate generosity, especially from an inquiring mind looking for potential volunteers. I am thinking now you should have karate chopped ( :D ) that earlier by charging fifty cents a blade. That would have cut the negatives down by about half.

I think everyone here knows there would be an implied loss if things went wrong. But for an knife that never lived up to specs, never performed as advertised, what does anyone have to lose? If I had not given my nephew the knives I had that would come apart to get to the blade (some were old pinned knives, some were fixed) then I would happily send you a knife.

BTW... I am still looking.

Do you have a method to test the blades before hand like a Rockwell tester, etc., and after or will you be relying on us to report back after treatment?

Robert
 
I suppose the only thing that puts me off on this thread is that it has been well established by Sal Glesser, AG Russel, and the tech support folks at Cold steel that there is no difference in composition between AUS8 and AUS8A.

Well, it's not that simple. While I was compiling Knife Steel charts I've stumbled on that problem too. Still researching, but here's what I found so far

For starters, AUS-8 is not Hitachi steel as Planterz and you believe, but an Aichi steel.

Aichi doesn't list AUS-8A. Which just adds to the confusion. They could've listed it as an alias, or as a separate one. Missing steel from the listing doesn't mean much as manufacturers not always list all of their steels on the websites.

Second, with all due respect to Sal Glesser, for you to assume that everyone should know what Sal Glesser said in 2001 and 1998 is a little far fetched. If you search outside of bladeforums you will find AUS-8A and AUS-8, both. While Aus8A might be incorrect and specs can be wrong too, it's just another source of information.

Next, in general when you research the steel, you perhaps do that on the internet... For AUS8 and AUS8A there are several sources listing them as different steels, and giving different chemical composition for both. Composition differs significantly. (AUS8A has ~0.20% more C, more Mn, more Ni.)

1) Knifemakers Steel Database

2) Glen E. Fryxell website - where he directly states the opposite - " (there is a variation on this alloy too, called AUS8A that contains 0.95% C, 14% Cr, 1.0% Mn, 1.0% Si, 0.50% Ni, 0.20% Mo, 0.15% V, 0.40% W, which should be harder and have better edge retention). "

3) Rather Large Knife char from Italy(?) also lists aus8 and aus8a differently, withthe same composition as the sources above.

4) Cedametal steel catalog or registry lists AUS-8 and AUS -8A separately. Sadly they don't provide compositions for free. I am trying to contact one of their reps to see if I can get the info I want or at least purchase their data at a reasonable price.
This one is interesting, because it's an international steel catalog.

5) I've asked about AUS8 / AUS8A steels Japanese knifemaker Watanabe, who believes those two are different steels, both from Aichi.
Now, even if he is wrong on that topic, I really doubt his forging, hardening and knifemaking skills will be any less :)

6) Keytometals which is even larger metal catalog doesn't list neither AUS8 nor AUS8A. I called their rep and asked about those steels. he was very surprised that there was a steel not in their listing, but promised to investigate and get back. Dunno if he will, but point is it's not as simple as you might think...

As of now, nobody really explained what's up with AUS8A with different composition. I can't exclude the possibility of bogus data, and then it being copied, but given the number of sources, there might be some merit to it. It is one thing to say people call AUS8 AUS8A, but when you have the same AUS8A listed with different compositions and AUS8 makers doesn't list t as an alias it's not very straightforward.
 
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So any questioning of the basic concept is "sarcastic trolling?"
Not at all, however, as you posted there was absolutely no "questioning" in that. It was a statement from you. Quite authoritative at that. OP unlike you has some background in the area, both theoretical and practical, yet he's not to assertive as you are.

There can be no legitimate questioning of the advisability of mucking about with the heat treatment of a perfectly functional knife?
:) There were no questions from you, except doomsday prophecies.

I'll say it again -- this seems like a very bad idea to me
You said it few times already, Once is ok, you warned us, thank you very much.
Repeated warnings of yours, are adding 0 value to this thread, and most likely indicate trolling.

And if his HT experiments work, then he contributes to knife enthusiasts and this forum more than U.
 
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It's pretty clear that he's not charging for the service because he is using this as a testbed and to get more data points on his process and the outcome. Anyone choosing to participate should be pretty well aware of that, and of course we all are. The HT may not work, at least as well as hoped, so he's doing us a favor by not charging for the electricity, gas, and fatigue on his materials while getting this worked out. I doubt anyone is going to send in a Lake or Moran to get the HT 'fixed'.

OTOH, we could just tell cotdt to buy bar stock of half a dozen different alloys, a KMG, several dozen belts, a few pounds of micarta, corby bolts, anaerobic adhesive, a blast cabinet, a drill press, etc etc etc, and make his own complete knives to then heat treat to various protocols, and send them out for free so people can test them. Or, he can do some production knives other people have paid for, are willing to risk, and can comment on first hand assessments of improvement/worsening in performance. Which one carries less individual financial risk and time investment?
 
For starters, AUS-8 is not Hitachi steel as Planterz and you believe, but an Aichi steel.

Gator,
Where did I say that AUS8 was made by Hitachi?

I think I agree with Phil. For an honest and open discussion, you do seem to be quite hostile. I did not consider my post hostile. Sorry if you took it to be so.

cotdt,
I posted most of my hardness results in the 2nd post of my thread on edge retention that you saw in the testing forum.
http://www.bladeforums.com/forums/showpost.php?p=6770827&postcount=2

I have tested two more Bucks in 420HC since that time, both measured 59.

And I tested what turned out to be another 440C Buck at 60.4.

I have tested one more KaBar, a regular Dozier at 57.
 
cotdt,
I posted most of my hardness results in the 2nd post of my thread on edge retention that you saw in the testing forum.
http://www.bladeforums.com/forums/showpost.php?p=6770827&postcount=2

I have tested two more Bucks in 420HC since that time, both measured 59.

And I tested what turned out to be another 440C Buck at 60.4.

I have tested one more KaBar, a regular Dozier at 57.

Thanks a lot! I missed that one and really appreciate it. I'm surprised by the 420HC result, Buck definitely does a premium heat treat on this one. The rest is expected. Interesting.

It's pretty clear that he's not charging for the service because he is using this as a testbed and to get more data points on his process and the outcome. Anyone choosing to participate should be pretty well aware of that, and of course we all are. The HT may not work, at least as well as hoped, so he's doing us a favor by not charging for the electricity, gas, and fatigue on his materials while getting this worked out. I doubt anyone is going to send in a Lake or Moran to get the HT 'fixed'.

OTOH, we could just tell cotdt to buy bar stock of half a dozen different alloys, a KMG, several dozen belts, a few pounds of micarta, corby bolts, anaerobic adhesive, a blast cabinet, a drill press, etc etc etc, and make his own complete knives to then heat treat to various protocols, and send them out for free so people can test them. Or, he can do some production knives other people have paid for, are willing to risk, and can comment on first hand assessments of improvement/worsening in performance. Which one carries less individual financial risk and time investment?

Great post. This is exactly right. I'm doing the rehardening professionally as if I was paid, but for many of the steels it is experimental. I've been sent some very expensive knives, for those I'm using only heat treats that I myself have tested extensively.

I am surprised too, that the recurring comment that seemed to bother some was that you were offering your service "free". I hate generosity, especially from an inquiring mind looking for potential volunteers. I am thinking now you should have karate chopped ( :D ) that earlier by charging fifty cents a blade. That would have cut the negatives down by about half.

Robert

Yeah good point. I'm suspicious of anything free as well. That said, I did require people to provide feedback on the results of the heat treat, so it's not completely free, just free from a money perspective.
 
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Gator,
Where did I say that AUS8 was made by Hitachi?
My apologies if that came out hostile, but I wrote mostly about my research results about those two, and I tried to explain why assuming or dismissing someone else's unrelated skill based on that wasn't worth it.

As for hitachi, actually Planterz and you posted pretty much next to each other, he classified it as Hitachi, you didn't comment, so I assumed you agreed. I figure i shouldn've assumed.

I did not consider my post hostile. Sorry if you took it to be so.
Me neither.
And I still disagree with Phil's approach to the whole thing in this thread.
 
And I still disagree with Phil's approach to the whole thing in this thread.

And I disagree with destroying perfectly functional knives because some random individual claims to be able to achieve speculative, marginal gains in performance by monkeying about with their heat treatment. But then, I don't claim to be a metallurgical genius who can sense that which no other knife owner or manufacturer can sense, nor have I conducted extensive tests in my home laboratory. I can't even claim to be an expert in metallurgy because I have work experience or a degree in an entirely different field. It's a crazy world, what with all the disagreement.
 
would you call Phil Wilson a random individual?
I have found that CPM 10V at 62 and CPM10V at 64 act like two different steels.
http://www.bladeforums.com/forums/showpost.php?p=6300095&postcount=96
The difference is that CPM 154 can be used harder and hardness equals edge holding in my experience with steels that don't have a percentage of vanadium carbides.
http://www.bladeforums.com/forums/showpost.php?p=4515850&postcount=7
One pt hardness can make a very big difference on some steels.
http://www.bladeforums.com/forums/showpost.php?p=4299959&postcount=15

If you would prefer, I can just link you to some data sheets that show the obvious; wear resistance improves as hardness increases.
 
Phil Wilson didn't start this thread.

Nobody is questioning the basic physics involved in heat-treating metal. Why is it so threatening and outrageous to consider the possiblity that the "service" being offered in this thread is nonetheless ill-advised? Why are those clinging so desperately to this idea so quick to resort to childish insults and hostility? And why is it, when these things are pointed out, that the only responses that can be offered in its defense are appeals to completely different authorities or mindless, unfounded shrieks of "troll, troll, troll" ...?

I don't see honest inquiry or a genuine interest in improving performance here -- I see an ardent need to be seen as engaged in such an activity, which isn't the same thing at all.
 
I think it's an interesting idea, but if the knife is ground thin (ie. an edge thickness of less than 0.050"), it could warp .... and that would not be good on a folder!! :eek:
 
Phil Wilson didn't start this thread.

No, someone who has received advisement from Phil Wilson, along with other knifemakers, started this thread. As well, you did not start posting in this thread with any concern for who was providing the service.

I don't understand this thread. There is nothing an individual can do to the heat treatment of a purchasezd blade except ruin it. This seems like a bizarre idea to me -- an unworkable solution desperately searching for a nonexistent problem to solve.

Nothing an individual can do except ruin it? I send a knife to Paul Bos, and he's going to ruin it? He's an individual.

Nobody is questioning the basic physics involved in heat-treating metal. Why is it so threatening and outrageous to consider the possiblity that the "service" being offered in this thread is nonetheless ill-advised?
Because this service, as provided by others, has been used several times prior.

So any questioning of the basic concept is "sarcastic trolling?" There can be no legitimate questioning of the advisability of mucking about with the heat treatment of a perfectly functional knife?

I'll say it again -- this seems like a very bad idea to me, and anyone who avails themselves of this free service is going to get exactly what they paid for.

Free knives are given away in a variety of fashions on this site constantly. I received one recently, and also offered one. Knifemakers have an annual event, people leave them behind when geocaching, they often post about carrying an extra to hand out to try to get others interested in knives. Since these knives are free, are they a bad idea? Should people not accept them for fear of faulty heat treat, missing screws, poison on the cutting edge?

By giving a knife away, a private individual does himself no tangible favors, just a sense of goodwill. With this offer, cotdt gets a chance to feel good, experiment, and if all goes well, set himself up to provide the service for a fee. He's taking a page from the drug dealers' manual ;)

The basic flaw in your assumptions is that it is "trolling" to question the need or the advisability of this "free service." Nobody is claiming that the heat treatments offered by manufacturers are perfect. I simply can't see something like this provided for free by a private individual doing anything but ruining what was a perfectly good knife.

People are free to do any dumb thing they want with their knives, up to and including strapping on hockey masks and videotaping themselves stabbing cinder blocks and hammering the things to pieces -- but just because nobody's stopping you from doing it doesn't mean somebody shouldn't stick up their hand and say, "Hey, that... doesn't seem like a very good idea."

I don't care if the original poster is a traveling ninja rocket scientist with a degree in engineering from Miskatonic University -- this is still a really bad idea.

You have yet to provide a reason why this is a bad idea. Just that you think it is... because it is free. What exactly is required to heat treat a knife blade? Can you point out what cotdt is necessarily missing to make this offered service sub-par? You are completely sure that this will ruin any knife, that much is clear. Why you are, is not. Of course, the basic notion of a new set of thermal cycles on the blade has been shown to be viable in this thread. It was shown several times, years ago.

And I disagree with destroying perfectly functional knives because some random individual claims to be able to achieve speculative, marginal gains in performance by monkeying about with their heat treatment. But then, I don't claim to be a metallurgical genius who can sense that which no other knife owner or manufacturer can sense, nor have I conducted extensive tests in my home laboratory. I can't even claim to be an expert in metallurgy because I have work experience or a degree in an entirely different field. It's a crazy world, what with all the disagreement.

Destroying? You do realize that many of the registered knifemakers posting here started as random individuals. Also, some people posting here appear to be random individuals, and then we find out they are established makers. There is no pedigree required to heat treat a knife. Some use a blowtorch and a bucket of used motor oil. Some use cooking oil, or a concoction made up of various chemicals. Some use industry specific oils, as from Parks or Houghton. Some use PID controllers, forges lined with ceramic fiber insulation, sealed with refractory coating, perhaps even a layer of ITC 2000 for additional heat reflection. Hell, I have that (at least some components remain after the hurricane), and I haven't sold a knife or offered to heat treat anyone's blades. I, being a random individual, have over a gig of pdfs, saved web pages, and other digital documents on heat treating and forging. I have the Heat Treater's Guide published by ASM, the Atlas of Isothermal Transformation & Cooling Transformation Diagrams, class notes/lecture material for steel metallurgy, Functions of the Alloying Elements in Steel by Bain, and Metallurgy of Steel for Bladesmiths and Others who Heat Treat and Forge Steel by Verhoeven. You can find most of the information needed to heat treat simple steels in a home built shop right here on Bladeforums. More complex steels can require higher temps and longer hold times, but do not require a graduate degree.

You're right because... you say so? That does not strike you as just the tiniest bit solipsistic?

Far be it from me to criticize the one percent of the one percent of self-proclaimed super-users out there, but this sounds to me like an unrealistic level of perceived performance gains -- like building a rifle so accurate that no human being can wield it steadily enough to get that marginal performance increase from it.

Let's stipulate that such gains are theoretically possible. Sending a bunch of knives off to somebody to be "rehardened" for free still sounds like ruining those knives for no good reason, to me.

There is no theory at this point. The gains are noticed in a task as mundane as cutting manila rope. It is like questioning the difference between 420HC and S90V. Why does one cut longer than the other? Why would a 1095 blade at 59 Rc cut longer than one at 55? These are not difficult questions, and they are not barely perceptible differences.

Why are those clinging so desperately to this idea so quick to resort to childish insults and hostility? And why is it, when these things are pointed out, that the only responses that can be offered in its defense are appeals to completely different authorities or mindless, unfounded shrieks of "troll, troll, troll" ...?

I don't see honest inquiry or a genuine interest in improving performance here -- I see an ardent need to be seen as engaged in such an activity, which isn't the same thing at all.
And what is the difference between actually testing for performance gains, and only being perceived as doing such? That people aren't being asked to pay?
 
Yeah I've done folders but I'm not sure what steel they use in the SAKs. If it's 420 I won't be able to do much, 440A I can get to 59 rc. I like your idea though, I've been wanting a high performance SAK myself for a while.

As far as my research has shown, it's presently Krupp 4116. Don't remember what that's equivalent to.
 
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