Just another Cryo question

[DaveL]

How does one just add cryo to heat treat? Do you add nitrogen and how is that done? Do you find dry ice, which I am finding is not easy. What is a simple way?

[Doug Lester]

Dang, I haven't noticed up here, but where I used to live some of the grocery stores had it. I guess it kept the beer real cold. I've never tried it, I work with more simeple steels that don't benifit from cryo, but as I understand a bath of dry ice in acetone is used in place of a tank of liquiid nitrogen. It gives just one increased level of hardness. Just remember that hardness can be overdone and is not a plus in all applications.

Doug Lester

[Don Robinson]

Dave, if you can't find dry ice, I have a nitrogen canister I'll sell if you want it. I don't use it because I have to make a 50 mile round trip to the closest supplier.

I use dry ice.

Check with welding supply co's to find nitrogen.

The nitrogen canister costs less to fill than the dry ice, and will last around a week..

[DaveL]

I got interested in the nitrogen thing some time ago but like most things just could not get it together. you still have to find a source for the gas, right?

[Geno]

If you do alittle study on cryogenics, there are several ways to accomplish it.
No process is easy, and you can freeze your fingers right off.
Each steel requires a certain H/T, some recommend cryogenics.
Liquid Nitrogen brings it to -300' F, Co2 cools to -107'F.
A certain steel may use nitrogen for an hour, or CO2 for 12 hours, and more often than not, a deep freeze will keep them below 0'F, for 36 hours. All recieve the benefit.
Not every steel benefits from cryogenics.
Some respond accordingly to each process mentioned above, but results will vary and very few home shops COULD measure the difference.
Few steels require below CO2 temps of -107'F.
Nitrogen vessels are called dewers, CO2 canister with a "dip stick", to draw your own CO2,(dry ice), or a deep freeze for a couple of days.
Any of these are better than none, some just work better.
Check each steel recipe to find out if and what cryo is required.
Don't touch anything that cold with bare hands, PLEASE.
God bless,
Gene O.