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Freezer "Cryo" treatment for Carbon steels


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No, I don't have a liquid nitrogen tank, but I do have a regular freezer. Would I see any benefit from sticking carbon steel blades into the freezer for 24 hours after heat treatment? I'm assuming even those 30-40 degrees of difference would assist the formation of martensite from retained austenite left over at room temperature.

 

If I were to put blades into the freezer after heat treat, would I risk cracking if they went from 1) quench to 2) room temp to 3) freezer?

I'm thinking it would be safer to go from quench to a stress relief cycle in the tempering oven, say 300F for 1 hour, before placing the blades in the freezer. I haven't been able to find much info about how a LN cryo cycle is done. It seems risky to take as-quenched steel down to -300F, but as I said I haven't found detailed information about the process.

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I use the freezer. My procedure is quench, check with a file, into the freezer, sometime the next day temper in a kitchen oven, out to room temp, temper again.

Does it add anything? I don't know, I don't have the equipment to test but I figure it may help and since I haven't lost any blades doing it this way it probably doesn't hurt.

 

ron

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I would temper your blade after hardening, it will reduce your risk of cracking. Stick it in the freezer if you choose, but most benefits from cryo come at much colder temperatures. There is much debate over the benefits of cryo treatment and I believe we have already had a thread discussing it.

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