Triple Quench ?

D

DLEEKNIVES

Joined
Jan 17, 2003
Messages
2
Hi everyone, been a machinist for 16 yrs making knives
stock removal,forging the last 2.lots of hunters here
in S.J. so skinners,gutters and bowies sell quick.
I've been surfing the forums lately and am a little lost on why
you would triple quench? My method I forge leaf springs,
normalize 2 or 3 times before quench,preheat oil to 125 degrees
go non-magnetic and edge quench.
clean up blade temper for 3 90 min cycles of 380 degrees in oven,
yellow to a light brown file bites on spine and skates off edge.
my blades hold a great edge and are springy no complaints yet.
what would the benifit be to the extra heats and quenches
I would think that would increase your chances for failure
warped blades,cracks undo stress.
how much better than right can it get?
Am I missing something?
Great site awesome info
any tips for the perfect finish for teak?
 
Although this may sound heresy to many, I feel your assumptions are correct. There may be some exceptions with a steel like 52100 in certain select situations. But for the most part, I feel you are firmly on track. Best of luck. Welcome to BFC.
 
Welcome to Blade Forums DL!
I've often wondered the same thing you just mentioned.
I've never heard of anyone heat treating stainless twice so why would someone heat treat carbon steel twice?
I'm not a smithy and don't work carbon steels much but it still doesn't make alot of sense. I've kinda wondered if it's so the maker can use the catchy phrase, "My blades are triple quenched tripled tempered", when he's offering them up for sale.
Man am I gonna catch it for that line! :eek:
 
Ed Fowler finds the triple quench makes for a superior blade, with several steels, including 440C, 5160, and 52100. After three, I believe the performance falls off, or the additional gains are marginal. He tests this sort of thing very thoroughly. One aspect I believe, is more complete conversion of the austenite to martensite.
 
From what I have heard/read, the triple quench or doing thermal cycles (fast air cooling) refines the grain size in the steel which would make a tougher blade. Smaller grain = stronger blage.

Depending on the temp you work at when forging, you can have grain growth. Anything above critical will allow the grain to grow. The more time above critical, the more grain growth. Big grain = weaker blade.

The above is what I know about simple carbon steels, I don't know anything about stainless. Well accept that it doesnt rust...:)
 
Laredo and RA are both correct. The triple quench makes a hiegher performance blade. i.e... it will make more cuts on a piece of hemp rope and flex to nintey degrees more times before the edge cracks.

according to data that we have collected it does this by creating smaller grain size and also by assuring that there is very little retained austenite in the steel. Propper forging and thermal cycles can be defeated by the long soaks needed to get complete transformation on a single quench, by promopting grain growth. The short time that a future blade is above criticle temp with the Fowler method is not long enough for grain growth to take place. And by repeating this proccess three times the amount of retained austenite is minimized.
 
Triple quenching wont give you better results than just normalizing a bunch. I could imagine some steel wont respond incredibly great to normalizing so people will use multiple quenching.
the grain size will effect the performance sure. But 2 blades of the same exact shape and size and final hardening and tempering, with the same grain size will perform the same. Even if one was triple quenched, and one just heavily normalized.
Its in the matter of "transformation points", which is kinda hard to explain but easy enough to understand.
If your getting grain growth from soaking for normalizing or quenching, your heating WAY too hot.
In truth you austenize steel, you get austenite. Think about it like that.
 
Thanks guys for all the great feedback.
When forging I stay well below critical temp in
the cherry red zone, I think it's called austenite
forging read about it in the complete bladesmith
by Jim Hrisoulas.It's suppose to produce a superior
blade by not allowing any grain growth.It is time
consuming drawing a three eigths to half inch leaf
spring down to three sixteens which is where I start
forming,can take 5 to 7 hrs of hammering.That's
why sat. and sun. are forge days.
The only time I go near critical temp, normalizing,
heat treat or when forming the tang(that's just
the scrap steel where the wood goes anyway)
as you've guessed I prefer full tang knives using
the blade as part of the guard.
To each his own.
Thanks for lettin me ramble and for the replys.
Don
 
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