Cryogenic heat treating?
Before I ask for some input, please let me explain what I am talking about. I have designed tools and products requiring special heat-treating through cryogenic freezing. The companies I provided the work for requested this material treatment. The process is basically like traditional heat-treating, but you freeze the material to an extremely low temperature and then warm it back up. I do not have a whole lot of experience with using this process other than in some special manufacturing tooling or helping two local S.C.C.A. race car teams try this procedure on their disk brake rotors. They have experienced significant increased wear on there rotors approximately 175% of normal use. This is a generic way of saying they lasted an extra 3 weeks extended beyond the typical 4 weeks during there race season. Cost of this process is just a little more expensive then typical heat-treating. What I have been told theoretically happens is that when you "super freeze" the steel, the molecules "pull" together and align to a "pure state of existence”. To put it in my words, "It purifies the material, and helps reduce grain flaws in the steel. I think it basically de-stresses the steel". I am under the impression that this process does not surface or caseharden the material. It creates uniformity throughout the material. This should improve the wear of the material.
If anyone has more information or has different information, or has any experience with this process, I would be glad to here about it. The thought also occurred to me that this could be an option for prolonging machine way life. This thought comes from my recent research for a company to regrind my lathe ways.
As always I am forever grateful for everyone’s input! Thanks!!!
Cryo-treating is used extensively in knifemaking and gunsmithing to increase barrel life and to help a knife maintain an edge for a greatly extended period. It seems to help in the final conversion of the steel into martinsite (small fine grain).
Here is a chat site where I'm sure that you could get more complete information and sources.
Cyro is the way to go!
Hope this helps.
[This message has been edited by Bob Sigmon (edited 11-02-2001).]
There are many theories as to what is actually happening when materials are brought well below the thermal domain of liquid Nitrogen. The most plausible is as Bob has stated the creation of finer grain carbides and a fine, dense crystal structure. This is what happens with heat treating and it is generally accepted that cryogenic freezing is an extension of the quenching operation.
Maybe we need to invent steels that are quenched from high temperatures to the extreme lows near 0* Kelvin. It would be interesting to actually see what happens under these conditions. I have not heard of anyone attempting this (a terribly expensive experiment!).
As far as the "pure state" theory, I do not buy it. If that were true the folded Japanese sword steel would be the "Choice Material" as it is as close to a homogenous material as science (or art) can produce.
There is much debate as to if the cryogenic freezing has any tangible benefits as results can vary in like pieces. Did not help much, did I...
As far as the gun barrel business goes, I think it's all a bunch of sales hype. "The barrel has been 'cryo-treated'"! It's a fix where there wasn't a problem to begin with.
The most common use seems to be in carbide cutting tools, where stress-relief is a much bigger issue.
I have friend that shoot competitively and have notice a great reduction in throat erosion in cryo treated barrels. If you can get a few extra thousand shots out of a barrel, what the heck.
Just my opinion,
A friend and customer set up a cryo service in California. His explanation was it completed the migration of the carbon molecules to the center of the crystal structure. Hmm. Their best customers were the serious amature racers; they could get another race and a few more rpm out of their engines before rebuilding if cryo'd. They quit monkeying with gun parts pretty quick. When he was just setting up, I sent Norm some end mills, carbide inserts, etc. for testing his tanks. Left them in their plastic containers, which MELTED in the short heat cycle at the end of the process. I still chip one out of the blob from time to time, but can't quantify any cutting or longevity improvement for you. Except for the plastic encapsulation technique, that is. I DO like to cryo gun barrels, both chrome moly and stainless, before machining the shank and reaming the chamber, they turn, thread, and ream very smoothly. Again, can't attest to an improvement over non-treated; it would take two barrels from the same billet same action same fire rate, etc, and I'm lucky to get my shoes on the right hands in the morning.
Could be the same processes happening that happen after aircraft aluminum alloys are annealed. The metal hardens at room temperature without being worked, because of interactions of metals.
Dave; That has been done several years ago.
The material is mostly used in power transformers. Supposed to be more efficient in that use.