Cyrogenics, more questions???

Many years ago Tim Zowada did some tests on I believe it was 1084 steel, I'm sure it was a 10XX steel. His results show higher breaking strength cryoing even simple steel.

I do mainly high Carbon steels; I do cryo many of the blades I make.

I have a question for Phil and others that might want to comment: Is this transformation process something that will happen over time without the cryo treatment? In '96 at the blade show a person handled an antique bowie and dropped it. The knife shattered and now the four pieces have a new owner.

Any comments? Thanks...Ed
 
Ed, yes retained austenite will transform over time even at low temperatures. The structure is un-stable and will attempt to convert. Some alloys will have stable austenite after heat treatment (D2 for example). Even stable austenite will convert but it takes the cryo to get the mechanism working. The tooling industry and cutting tool industries have used cryo as a stabilization technique for years. I've seen tooling punches and high speed tools grow and or crack on the shelf from room temperature austenite conversion.
 
Talking about digging up the dead !
Since the post was made things have changed , such as learning what is cryogenic cooling.
The mechanism of cryo is the formation of small carbides called "eta " . The cooling to that of LN tweeks the matrix permitting the formation of eta carbides on tempering !. The tempering is at 300 F. Different steels require different times at -300 F .6 to 8 hours should work for many of the blade steel.
Doing a typical 900 F Secondary Hardening at this point will destroy what you've just made !!!

So -300 F tweeks the matrix to give room for the eta carbides to form along with cohesion [strain of the matrix around the carbide ]. Carbides form during the 300F 'temper' .
It took me a long time to find this information !! and it removed lots of guessing !
 
You must log in or register to reply here.
Back
Top