Thread: Another dumb question- Cryo Treatment

Cryotreatment is best applied to high alloy steels, meaning stainless in the common tongue. There is spurious evidence (at best) that this process works on low alloy steels, meaning high carbon steels when they have been properly heat treated in the first place.

The low temperature cycle is meant to convert retained austenite into martensite. Austenite is less tough and more prone to fracture and is less desirable as one of the crystalline components. The optimum time for freezing a blade is in the quench. I would suggest that to be a very dramatic experience for the ordinary blade crafter.

Given that most folks would quench in air/oil/water or other preparation and then complete the freezing cycle, there is the possibility the interruption may induce changes that are not accounted for. There was a wonderful segment of this process on the Discovery/History channel about how the steel strips for Bic type razors were made. The strip is coming out of the induction heater at a yellow color and in less than a half inch straight into a quenching system cooled by liquid nitrogen. It's moving pretty fast too.

After the freezing cycle, the steel MUST be tempered to convert the fresh martensite into tempered martensite. Ref: John Verhoeven Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel. It should be of interest that Dr. Verhoeven does not mention the cryo treatment of high carbon steels anywhere in the chapter about them, but does discuss cryo treatment in the chapter on stainless materials.

It will not likely hurt a high carbon blade that has been properly heat treated. There is the risk that the preparation for heat treatment was off a little and the cold shock could induce a significant risk of stress or fracture too. But, there will be nothing gained in the steel and the only measured change will be in the pocket of the liquid nitrogen supplier and provider of equipment, or your heart if the blade breaks.

Interestingly enough, the very people who are publishing the research that this is a process that everyone should do are the one's who have an interest in selling you the equipment. I call that a conflict of interest. It calls into question the validity and reliability of their conclusions.

If an owner-maker wants to do this to their blades, no problem with me, it's their business. I like processes that leave fewer questions to answer than I started with.

See here: and root around a little. This has been discussed before.

http://straightrazorpalace.com/razor...h-doing-2.html