Cryo treating

[grizzled gizzard]

Is it possible to "over-cryo" a blade?

I use LN, and I've been of the mind that all of the final thermal cycles would be best finished with at least 3 hours in LN.

I triple quench, and triple temper, so that makes 6 cryo treatments per blade. I haven't had problems until my last batch of blades. I don't think that cryo was at fault, but wonder how you guys feel about it.

Thank you for your help.

 

[Stacy E. Apelt - Bladesmith]

Cryo converts RA and changes the carbides. It really can't be overdone.

However, If you are triple quenching, it probably isn't needed until the last quench - since you re-convert everything to austenite upon reheating above Ac1. Same goes for the second temper cycle after the last quench. There really isn't enough RA to convert.