Heat Treating Stainless?

smcfalls13

smcfalls13

Joined
Aug 5, 2005
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Is it possible to differentially temper stainless steel? I see it done quite often with carbon steels like 1095 and the like, but just wondered if it's possible to do something similar with 440C?

Or is it simply not feasible due to the higher temperatures required to heat treat stainless?
 
AFAIK it is not possible because of the high hardenability of stainless steels (which is because of high amount of chromium in SS)

But I am no expert, I can be wrong :)
 
Paul Bos knew a maker in San Diego that did just that on 440C and ATS34 years ago. The method was never divulged, to me anyway, except to say is was not worth the effort. Lots of labor involved for just cosmetic gain.

Another guy used to advertise in the back of Knifeword every month that he did it. He lived down near the coast in southernTexas.

I believe you get a better blade doing it conventionally, with a cryo treatment included.
 
I heat treat (oil quench) 440C using my forge, if you read the archives there was quite a bit of discussion about it a couple years ago.
I don't recommend as being the right way or the best way, only that it works for those who are inclined to break a lot of blades developing a method that works with their equipment.
Having broke a lot of test peices and tried alot of stuff along the way, I've had a few that behaved similar to a differentially treated blade. There was a definite hardening line (not visually, but you could tell when you bent the blade).
I don't think there is any benefit in doing this with a stainless steel. The blades I had that hardened this way generally had poor characteristics in both sections of the blade. The grain was much too coarse in the softer section making it break about as easily as the fully hardened section. The hardened section also lacked the strength of a normally heat treated blade. It would bend much easier and break with the same degree of flex.

Thats just what I've seen. Anyone out there is welcome to try it and post their results as well, I'm far from the expert on the subject.
 
Ok then, maybe I won't try it. :eek:

I don't have the extra materials to be breaking blades left and right. Might be safer to stick with 1095.

That saves me a lot of aggravation, and time, and money in wasted steel(not that is costs that much, but still).

Thanks gentlemen.
 
smcfalls13 said:
Ok then, maybe I won't try it. :eek:

I don't have the extra materials to be breaking blades left and right. Might be safer to stick with 1095.

That saves me a lot of aggravation, and time, and money in wasted steel(not that is costs that much, but still).

Thanks gentlemen.
Click to expand...


I know a knifemaker from Denmark and all this talk was going around about how bad stainless is, ad naseum. Well he took a standard 4" stainless drop point hunter from his bench, clamped it in the vise and tried to break it.

He's 6'5" or so and not thin. He couldn't bend it by hand. He then took a 4'(IIRC) metal tube placed over the handle to use as a cheater bar and really layed into it. It took quite an effort to get it to 45 degrees, before it cracked a litte.

What in the world kind of situation would you get into that your blade wouldn't stand up to without you being dust long before the blade failed?

The test above would have taken his weight easily on the knife without the slightest problems. What more do people want? Nuclear proof? Make knives and enjoy them, let others worry about unrealistic failure scenarios.

Stainless or regular tool steel, it's all good used within it's design boundaries.
 
I agree with Mike, and would add that you SHOULD break a test blade sometime that is made with stainless and heat treated properly. The last one I did was 440C , maybe 3" long(with a 3" tang), 1/2" wide at its widest, hollow ground and about 3/32" at the spine. I put the tip about 3/4" into the vice and I couldn't break it off with my bare hands. I'm a fairly good sized too, the amount of force it took to actually get it to break was unbeleivable.
That is one of the main things that stood out in the blades that seemed differentially hardened. The fully hardened section wasn't nearly as strong. And when you coupled that with coarse grain making the spine brittle, its a losing situation all the way around.
 
the guys are right it's not really worth the pain for no real gain, one thing is if you take ats 34 soft it will break anyway if bent to far .. so what will you gain??

BUT you can do it though,, in a few different ways,
1 you'll have to heat sink the part you want soft (or I should say cold sink it) with good heavy steel on both sides you want left soft with would be basically the flats..

2 is you heat treat the edge with heated very heavy steel conforming to the part of the blade you want to air quench you have to have enough mass to keep the blade up to temp for the soak time..

so you can see you'll have a time doing it these ways.
but 3 with 440c you can OA it to a point I've have some luck with doing it this way testing but it's a bit softer than doing it the right way in the oven :)

we did talk about this along time ago and one of the above #1 or #2 ways was told by Ed Fowler..I believe :confused:
 
I remember reading something several years ago when Paul Bos (I think) and some one else made a quench tank out of a pipe that had been opened up and ran water through it when partially dunking a stainless knife blade. They got a few to come out and show some degree of differentialy hardening but the failure rate between breakage and warped blades wasn't worth it. I'm satisfied with how much a stainless blade will 'hold' before failure.
 
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