Hello

I just remembered an ad for pistol parts several years ago. The message was something like "amazing things happen to steel at minus 250 centigrades", and the argument was that the deep-deep-freezing of steel would lead to a change in the metal, leading to a more homogenous and reliable structure. Albeit not historical in any way, a method of making a more homogenous metal structure would of course be desirable for sword-making, too. I wouldn't be surprised, though, if the idea of freezing steel is just a marketing trick with little or no actual effect.

Can anyone here with some experience in metallurgy say if deep-freezing really does anything with steel at all?

(and I added Angus' name in the title to possibly lure him to the thread, as I believe he would be among the more qualified people to know something about this :) )

Borger

I ran across this http://www.angelswords.com/cryogenic_processing.html not long ago. Of course I can't say for sure as I have no metallurgy experience, and I've never heard of these guys.

Well, I'm not qualified to speak on this, so naturally here I am posting... ;) I really know nothing about this other than what I've read, but it seems that the testing of cryo treated blades is so far in a state where it is hard to prove one way or another whether the freeze treatment works well on simple steels or not. There is a thread on this on Sword Forum currently, I think.

Now, it is proven that a lot of stainless steels gain from the cryogenic treatment because those steels often don't complete their transformation into martensite til getting way down below freezing (my statement is pretty general. As I said before, I don't know a lot about this, so general is the best I can present... :) )

I believe that Gus has mentioned looking into this stuff, so maybe he will comment...

The cryro-treatment of steels is a much miss-aligned and much miss-represented subject in general.

In any case, cryro will have an effect particularly on high-alloy steels that are prone to a condition called "retained austenite"... in simple terms the freeze will alleviate this by eliminating most of this "retained austenite" and turning it to martensite, which is what you want the steel's structure to be when it's hardened.

to a lesser degree cryro treatments will do the same thing with simple and low-alloy steels as well IF there is the retained austenite condition present... typically from a less-than-ideal quench condition or from a quench that is much slower and less thourough than it should be. If the low-alloy or simple steel has been heat-treated well it eliminates much or all of the benifit of the cryro treatment.

Myself and a few others have tested the whole thing alot in the past, the general opinion was that if it's needed, a maker should use it, but good HT practice could eliminate the need. I found no difference in the blades I tested with my usuall heat-treat regimen, so I don't use the process.

I have one of my blades coming back from Angel Sword, that's gone thru Daniel Watson's thermal treatment. I'm going to semi-finish it on its return, and do some minor testing vs a similar blade I kept here after heat treat, as a control blade. Within about three weeks, both blades will be going to Alabama, where they will meet up with one of Daniel Watson's blades. Then all three will go thru a test cutting regimen, and finally go thru a destruction testing regimen......

Don't know that, that'll tell you much, but that's a gonna happen. There's a thread on this on AxeForum...... been several weeks since any posting on it........

I don't do my own heat treating, but have been working with a local aerospace heat treater who has 15 years experience heat treating sword blade.

This subject came up over a year ago, and we hashed it out some over coffee and donuts. The end result was no change, because Jim {lead metallurgist} didn't think it would really do much........

Since then, a lot of their customers have required them to do more cryo treatment. There's a lot of verbal feedback, that this stuff is really helping the end product.

So in December, Jim wanted me to leave him a couple of blades for him to test. Blades that I didn't need for ongoing production needs. Not knowing what he planned, I made four.... two for control purposes..

The test was the deep freeze....... or cryo if you will. During the holidays, I broke one cryo blade, and one control blade, to see what difference things made. I finished and mounted the other two, for test cutting, and sword abuse purposes {slamming 55 gal barrels around}.

The results were interesting enough, that I'm doing it again with lighter blades. Control and cryo, to see what comes of it.

I may be testing 'til summer. Its not just if it makes things a bit better, does it make it enough better to justify the increased cost, which has to be passed on to the consumer.......

Randal could tell you that one cannot make any real conclusions from a small sample. Its too easy for some unforseen variable to sneak in and bite you on the ass........

I have been getting a good temper, and a very cost effective temper from the beginning. To make me change, things will have to be not only better, but cost effective.......

Where I'm not to willing at this juncture to discuss the apparent results publicly, I will tell you that there is an apparent difference that warrants more testing. But its incremental, not revolutionary......

Yeah, only a few test pieces won't tell much overall, Gus is right there. After a series of blades though, then you have something to go on.

I did over 30 blades when I had the liquid nitrogen available, and didn't get any gain at all on the stuff I heat-treated in my favorite method, and minimal imrovement with stuff conventionally oil-quenched and conventionally mar-quenched and air-cooled to harden. Minimal enough not to bother IMO. However, others have had bigger gains, and make it a part of thier regular process, and should really, if this is what's required to max-out.

I still think "most" of the marketing over cryrogenic treatments is hype, with the majority of "reasearch findings" being provided by the companies that do the cryro, and supply the equiptment.
But it will trip over that retained austenite, if it's there, no bones about that.

Good luck with the testing Gus, in any case. I find the testing/reasearch end of all of it a great deal of fun.