Liquid nitrogen

After tempering an washing I always put them in a very cold freezer. Now given 25 dgrees is a f'r piece from -270, but I wanted to give the blade the best chance to avoid stresscracks.

FWIW I NEVER noticed a difference in performance frrm nearly-identical knives (and with my huge suply of L.N. I played alot), so I gave it up after a while. To each his own, but all my stock removal bladces have come back from Paul Bos as culling tools to stake one's life on, and my damascus and forged blades get differential HT, anyway.
 
John Frankl said:
I'm getting ready to purchase a dewar myself, but realize I'm not sure what to look for. On Ebay, these seem good:

http://cgi.ebay.com/Taylor-Wharton-...ryZ48731QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/Liquid-Nitrogen...ryZ48731QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Are these what I am looking for, or do I need something special/different?

Thanks,

John
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either should be good I'd go with the 36L just because it's bigger :D
I've adapted to mine as you will yours.. you can slow your warm-up with insulation. if you think you'll need to.

for me a small one does good because I'm not using it all the time so I don't have LN just floating back into the air..good luck on the Auction :)
 
Drag up Ed Fowler,he has a lot of experience on this matter on LN,52100 and the ensuing results. He has done the test work , time for the Master Smith to surface.

Be well
Floyd
 
Ok, sounds like a great idea! I'll try:

Mr. Fowler sir! Are you lurking on the forum? If so, several of us would love to have your expertise and opinions on the use of LN on 52100, and also 5160 is you didn't mind. Thanking y ou in advance, Robert Hensarling, Uvalde, Texas.
 
I just found your request.
From our experience with 52100, if LN treatment shows great improvement in your blade, it indicates an inadequate or inappropriate heat treat and you can make up the difference by working on your forging practices, thermal cycles and tempering and hardening.
When sharpening a LN treated 52100 blade it feels like a cadaver in my hands, and so far LN treated blades have not shown the toughness that one made right can demonstrate and not a significant improvement in cut.
Thanks for asking and take care.
 
thanks ED

feels like a cadaver in my hands,
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Ed why Is that? the amount of cold compared to the drop in heat from a quench is but a fraction of it.

this makes me think that some knives have made it to Antarctica I'm sure, and at -120 there, those knives would only be about 200 deg's different with out a cryo...sorry I'm thinking out loud, again :) ..
just wondering why you picked "cadaver" for the feeling?

so far LN treated blades have not shown the toughness that one made right can demonstrate and not a significant improvement in cut
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I agree ED,, for the high Carbons
LN treatment was designed
for the SS's mainly..but Still LN does help to a degree in many steels.. as said the closer you get the HT right, the less it will help on the majority of High carbons.

in other words if your HT is not up to par
the LN will help you more than the one that can HT and do it right.
 
52100 has a little retained austenite by design after good heat treatment. This gives the material a higher toughness than a fully transformed cryo'd 52100 blade. A2 and D2 act the same way. Cryo can give you optimum hardness but at the sacrifice of a little impact/chipping resistance.
 
I took some blades out of LN last night. Check the hardness most were the same as when they went in, but two were harder. Got me to thinking why, It can to me that all but 2 were tempered above 400 degrees and, the 2 were stress tempered at 300 degrees. Is this the way LN works? This is my first time using LN.
 
As I said before in this thread , tempering at 400F or above tends to stabilize the austenite against further conversion to martensite. So if you want max hardness stress temper at 300-350F before cryo.
 
Dan:
When we were working on our development of 52100, we got it to the point where Rex could find no mearurable amount of retained austenite in the hardened portion of the blades, that still holds true. To my hands blades that have been treated as carefully as we can have a (don't know the exact word) -- life like -- feel when you stone them. Cryo one and I just don't like the feel of the blade on my Norton fine India stone. I guess it goes back to toughness, the edge has a tendeancy to give up after fewer 180 degree flexes than those without the LN. They don't cut significantly better, it is usually a dead heat.
 
Ed Fowler said:
Dan:
When we were working on our development of 52100, we got it to the point where Rex could find no mearurable amount of retained austenite in the hardened portion of the blades, that still holds true. To my hands blades that have been treated as carefully as we can have a (don't know the exact word) -- life like -- feel when you stone them. Cryo one and I just don't like the feel of the blade on my Norton fine India stone. I guess it goes back to toughness, the edge has a tendeancy to give up after fewer 180 degree flexes than those without the LN. They don't cut significantly better, it is usually a dead heat.
Click to expand...

thanks ED
I have an Idea about a cause and a posable fix, but I'm going to leave it alone..that's a first for me right :)

Ed did you get my reply to you on the e-mail about the 5160?
 
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