3 quench vs. 3 normalization

Unless your forge is PID controlled, you are not holding or even nailing any of those temperatures. I have been told of a test, where several experienced bladesmiths took part in an experiment to see if temperature could be accurately judged by eye. The average variance was 200F (overshooting the mark). I've never seen actual documentation of the event but a few trusted individuals(who were present) have confirmed it to me.
 
I have a pyrometer in my forge. I don't trust my eye. I have the equipment to make the forge pid, as well as the parts to make a kiln. Without the pyrometer, I wouldn't use anything besides 1084. There is no way anyone could judge temp by eye.
 
OK I just did a test. I sharpened this blade (52100) before putting the handle on. It got sharper than my best O1 and 1095 blades, which were all sharper than the 1084 and 15n20, which were sharp enough to shave with. I'll see how edge retention is.
 
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Sharp is more relative to grain and carbide size, plus geometry of the edge, than to the acual type of steel.
 
I have been following this thread as I am interested in possibly using some of Aldo's 52100 for some kitchen knives (read stock removal). My question is as follows:

If person "A" does a triple quench and reaches Rc 67 prior to temper and person "B" only does one quench and reaches Rc 67 proir to quench, haven't they both gotten the maximum out of the steel that it has to offer?

I realize that there might be a difference in grain size, and it seems that the fewer heat excursions that the steel goes through the better chances I would nave of not growing the grain size.

Thanks,

Jeff
 
The Info is out there, read it and THINK... Choose your educated method and make knives. If you are happy with your test results get them in the hands of other people that are not biased and will give you honest feedback. There are makers that I look up to and even emulate that do some "less than scientific" procedures in their Normalizing and HT including Triple quenches, delayed tempers.... Whether they do it blindly following their mentor, superstition or because it came to them in a dream, doesn't really matter. You will have your believers and followers, you will also have those that think you are silly.

Science is awesome but so is mystical magic steel ;)
 
LRB said:
Sharp is more relative to grain and carbide size, plus geometry of the edge, than to the acual type of steel.
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I was worried re: the performance of the 52100 based on the reports of others in this thread that they couldn't get a good edge on the blades, and couldn't get good hardness numbers. This blade must have the finest grain and carbides of all the knives I have made so far.
 
Iwannashoot said:
I have been following this thread as I am interested in possibly using some of Aldo's 52100 for some kitchen knives (read stock removal). My question is as follows:

If person "A" does a triple quench and reaches Rc 67 prior to temper and person "B" only does one quench and reaches Rc 67 proir to quench, haven't they both gotten the maximum out of the steel that it has to offer?

I realize that there might be a difference in grain size, and it seems that the fewer heat excursions that the steel goes through the better chances I would nave of not growing the grain size.

Thanks,

Jeff
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grain growth is more related to temperature then it is time, so if you never go above critical temp you have a much less chance of growing grain. this is why testing your kiln and steel for the right temperature is the first thing you should do. what i mean by this is the critical temp for 52100 is 1525 but for most people you do not want to go above 1500 degrees F.

with 52100 you want the best results at the lowest temp possible.
 
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Ryan,

I keep reading your post over and over, and I think that maybe from your last statement you and I are on the same page, kinda. My thought and original question was that if you get the "maximum hardness" for a given alloy after quench; then no matter what way you got there then your knife will be the best that it can be as long as the geometry is right for the task at hand.

For the record I have done quite alot of searching, and so far I have not seen where anyone has actually done some comparision testing of the results of "method A vs method B"; either scientifically or thru performance testing. The subject has been discussed, but never actually brought to fruition.

Chad,

Thanks for your help, as I don't yet own a kiln I will be sending the blades in question out for HT. I'll use that info to select the appropriate HT vendor.

Jeff
 
Getting maximum hardness alone does not indicate a successful quench.

I agree with Ryan to a point...

If you heat your steel in a campfire and quench in mountain goat sweat... no problem. If your knives perform to your expectations, who am I to say it is not so? BUT to take it further and make it into a pseudoscience really strikes a nerve with me. (eg. Trying to assert that the campfire somehow increases carbon content and the uric acid in the goat sweat prevents that excess carbon from migrating to the grain boundaries). I've got no problem with performance claims. My beef often lies in the interpretation of the perceived results. If anything we do as knifemakers seems to defy metallurgical principle... it is probably a mistake on our part. Nothing we do in heat treat will turn science on its head.
 
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Iwannashoot said:
I have been following this thread as I am interested in possibly using some of Aldo's 52100 for some kitchen knives (read stock removal). My question is as follows:

If person "A" does a triple quench and reaches Rc 67 prior to temper and person "B" only does one quench and reaches Rc 67 proir to quench, haven't they both gotten the maximum out of the steel that it has to offer?



I realize that there might be a difference in grain size, and it seems that the fewer heat excursions that the steel goes through the better chances I would nave of not growing the grain size.

Thanks,

Jeff
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Jeff, thats exactly how I see it. If you reach full hardness with the proper grain size then you're good to go. All thats left is to draw/temper to the desired working hardness.
Send me an email or give me a call, I have an offer you may be interested in.
 
Rockwell hardness isn't all there is to it, especially with 52100.

IMHO, a lot of the off-shoot arguments that pop up in threads like this involve a lot more than "just" heat treating. Many times I see guys talking about how knife X outcut knife Z, so obviously knife X's heat treat was much better... but then you find out they were totally different blade styles with very different grinds. It's definitely not comparing apples to apples.

The more I learn about this stuff, the more I realize just how little I know.

I remember about 14 years ago, I was at the OKCA show and told Bob Kramer about how I had water quenched a 52100 blade and how awesome it cut and how fine the grain was when I broke it. Bob asked, "Why did you want to water quench 52100?" "IDK, to see if I could." "Well what was your heat source?" "A forge." "How hot were you running it?" ...........

I remember feeling frustrated that this well known Mastersmith, known for using 52100 in his kitchen knives... didn't seem really impressed by my awesome water quenching story and how it clearly showed what a bad ass bladesmith I was striving to be.

Now, if a 21 year old kid came up and told me about water quenching 52100, my first response would probably be, "So, um, why is it you want to water quench 52100?" ;)


I wonder what the mind-set of some of these folks will be in another 14 years....? ;) :)
 
Hardness alone is not everything but achieving full hardness IS a very important part of the equasion when trying to get the most from any steel. It is definitely a balance of several things that make a good knife. There are many ways to skin a cat and all that matters is that he ends up naked. LOL
 
You want to achive the highest rc with the lowest temp possible. But the set up process is important also you want a very uniform and fine grain structure to go along with your fully hardened blade. This is why 3 normalizations should be done.
 
Iwannashoot said:
I have been following this thread as I am interested in possibly using some of Aldo's 52100 for some kitchen knives (read stock removal). My question is as follows:

If person "A" does a triple quench and reaches Rc 67 prior to temper and person "B" only does one quench and reaches Rc 67 proir to quench, haven't they both gotten the maximum out of the steel that it has to offer?

I realize that there might be a difference in grain size, and it seems that the fewer heat excursions that the steel goes through the better chances I would nave of not growing the grain size.

Thanks,

Jeff
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It seems that there are two initial properties that bladesmiths strive for; hardness and toughness. Generally, they are inversely related to each other, as one gets better the other gets worse. To a point, as grain size decreases, toughness increases. So for identical knives, except for the grain size, tempered to the same hardness, the one with the finer grain will be tougher than the other(s). Different thermal treatments are purported to give better grain size and therefore better toughness at a given hardness. The amount of carbides present, their size and dispersion also has an effect.
 
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