View Full Version : Cryo available


knightsteel
12-21-2002, 01:58 PM
Cryo offered
Angel Sword Forge has opened its cryogenics treatment facilities commercially. We can handle lengths up to 48 inches.

Daniel Watson

Jerry Hossom
12-22-2002, 12:41 PM
Do you do post cryo tempering also? Crucible Steel recommends at least one tempering after cryo.

knightsteel
12-22-2002, 01:09 PM
We typically do a computer controlled descent to -300F, no thermal shock, then a controlled re-ascent and temper to +300F. We like to do a second temper as well.

Daniel

Jerry Hossom
12-22-2002, 01:18 PM
How about high alloy steels that might temper as high as 950F?

This might be a great resource for those lacking cryo facilities. They can do a single temper right after hardening, then send it off to you for cryo and final temper(s). They have to do at least one temper after hardening of course, at least with high alloy steels anyway.

knightsteel
12-22-2002, 08:48 PM
Most of the info I have read suggests cryo between hardening and tempering for maximum benefit.

Our cryo unit itself does the temper to +300F. We have a separate unit for higher temperatures.

Daniel

Jerry Hossom
12-22-2002, 09:05 PM
I agree about the cryo then tempering, IF it is done immediately out of the hardening oven. The important thing is to always temper after cryo, regardless. Paul Bos frequently does what he calls a snap tempering anyway, just a short cycle to begin drawing the steel, allowing more time for the cryo to begin. It's not usually done in different cities though... :)

knightsteel
12-22-2002, 09:06 PM
Oops! I forgot to mention that from now until the end of March, the first piece any knifemaker sends me for cyro will be free (except shipping). :D

Daniel

http://www.angelsword.com/

knightsteel
12-22-2002, 09:38 PM
A snap temper certainly would relieve some of the stress, but is likely to also convert some of the residual austentite to bainite and so gain less martensite in the cryo. It might be a trade off.

What kind of temp and hold on the snap?

Daniel

Jerry Hossom
12-22-2002, 09:38 PM
BTW, you make beautiful swords. Nice website.

Jerry Hossom
12-22-2002, 09:49 PM
I don't really know the cycles Paul uses. I send him my iron, he sends back steel. It works. I've had one of my Rc61 CPM-3V blades bent 90 degrees, back and forth four times before it broke, and that was with a BIG man leaning all his weight on it to get it to bend that far.

knightsteel
12-22-2002, 10:07 PM
Thanks for the comment on the website. The Avatar TechnoWootz has been extremely popular. I hope to be able to offer it as bar stock soon.

Daniel

knightsteel
12-22-2002, 10:13 PM
Impressive. Any idea of about how much bend and return to true you're getting with that?

Daniel

Jerry Hossom
12-22-2002, 10:18 PM
The first bend left about a 15-20 degree set.

I'd be interested in your wootz when you have it ready.

knightsteel
12-22-2002, 10:20 PM
Length and thickness of blade?

knightsteel
12-22-2002, 10:22 PM
Oops I had better clarify that I was asking about your bend test.

Daniel

Jerry Hossom
12-22-2002, 10:28 PM
As I remember the blade was 9". Thickness was likely about 5/32" or slightly more. 3V comes in odd sizes, but that's about what I use for a knife that length and style - single edge fighter.

John Frankl
12-24-2002, 02:52 AM
Daniel,

This is interesting. How would a snap temper produce bainite? From all I know, steel must be austenitized and then be held for some time slightly above martensite start to produce bainite.

Thanks,

John

knightsteel
12-24-2002, 10:37 AM
After the initial quench to room temperature there is retained austentite. Cryo would convert this to martensite. Reheating (even snap tempering) will relieve some of the internal stress. But it could induce some of the austentite to convert to bainite.

This isn't really a bad thing, but for most applications it's probably not be as good as getting more martensite. However we are dealing with fairly small percentages, depending on the amount of retained austentite after the quench.

I was looking at micro-photos of one of my steels last week and was surprised to see more bainite than I expected in just a normal oil quench and temper.

Daniel

John Frankl
12-25-2002, 07:41 PM
Thanks Daniel. I'm not sure what steel(s) you're using, so this discussion remains somewhat hypothetical. But, from what I have read, retained austenite transforms to lower bainite under the following two conditions: (1) a tempering temperature between 450-700F, which is much higher than most snap tempers (and even most full tempers); and (2) when retained austenite has not already been transformed to martensite by cryogenic treatment. In theory, again, I would think your blades meet neither of the above two conditions. Of course, theory often breaks down in the real world. Any ideas why you are getting bainite when the theory books say you should not?

John

knightsteel
12-25-2002, 10:35 PM
There are still a lot of unknowns about steels.

The temperatures which you are using are for a straight carbon steel. Most alloying elements lower both the martensitic finish temp and the bainite temp. Supposedly lower bainite can form as cold as 125C !!!

Those particular samples had not been cryo processed. So it was probably #2 of the mentioned possibilities. The steel had been tempered to 300F for 30 min.

Daniel

dogman
12-25-2002, 11:07 PM
Please post as soon as you start making bar stock available. I am definitely interested.