cryno

[sabu386]

How do home HT'ers do the cryno part of heat treating? I feel sure that few knifemakers have the equipment that Paul Bos has but I get the feeling many of you ht complex steels with success or no one would be doing it.

 

[kc custom]

Dry ice and alcohol or acetone, or go to the local welders supply and buy liquid nitrogen.
Of course it would be really difficult to tell if a blade were cryoed or not right?
obviously knifemakers make knives for different reasons.
Ken

 

[SBuzek]

I use a nitrogen dewar, I have it filled at my local welding supply.Soak blades for at least 6 hours or overnite.
Or you can make a slurry out of dry ice and acetone and soak blades in it.

Stan

 

[Nathan the Machinist]

Of course it would be really difficult to tell if a blade were cryoed or not right?
obviously knifemakers make knives for different reasons.
Ken

For an alloy that benefits from cryo, if you cut with it, not only is it easy to tell if it received cryo, you can also tell if it was done as a part of the quench or after a temper. The first time I had Paul do D2 for me the edge stability wasn't right. Upon talking to him about it we finally figured out it was the snap temper he uses before cryo that I had stopped doing. He reprocessed those blades which corrected the problem.

You can have two geometrically identical blades that are both HRC 62, and put both of them through the same cut tests and one will perform like a champ and the one with RA will suffer edge roll and chipping that can be seen at an arm's length.

This isn't cryo hype, it is a fact based upon sound metallurgy and proven through my own experiences. Steel with an Mf of -100 will develop a lot of stabilized retained austenite if you don't go sub zero with it, and the timing is important.