Cryogenic treatment at home?

s500yards

s500yards

Joined
Jan 6, 2009
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Does anybody know of any cryogenic units available for home use? I did a brief search and not much came up. Maybe I'm not looking in the right places, or maybe the idea is obsurd in the first place. Either way, this is just my curiosity and any information would be great. Thanks all! And have a good week
 
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Cryo is -300 F which you get from liquid nitrogen . You need LN2, an insulated dewar to keep it in, and a blade to freeze ! Temper after freezing.
 
yep just get a LN tank and get it filled when you need it the sub0 coolers are a waste for even a full time maker like me
 
Liquid Nitrogen (LN2) Dewars can be found on an auction site....they are not inexpensive however if you keep an eye open you can find one in decent used shape. Beware of small neck openings on small volume units!!
 
mete said:
Cryo is -300 F which you get from liquid nitrogen . You need LN2, an insulated dewar to keep it in, and a blade to freeze ! Temper after freezing.
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You NEVER need to good lower than -80°C (about -100°F) There is no benefit to goo deeper.

I was most likely wrong
 
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Idaho, there is sub-zero quench which is -100 F. This reduces the amount of retained austenite.
Then there is cryogenic cooling which is -300 F This further reduces retained austenite and creates the precipitation of "eta carbides " , small carbides in the matrix. This is for maximum performance only for complex steels .
 
I was under the impression that certain steels required certain temperatures. if you were to only use the LN 2, would you not be subjected to using only that one temperature? that being negative 300 degrees.
 
We never had a blade complain - they were too happy to get out of the cold.
 
s500yards said:
I was under the impression that certain steels required certain temperatures. if you were to only use the LN 2, would you not be subjected to using only that one temperature? that being negative 300 degrees.
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Different steels are often tempered (heated and softened) to different temperatures, depending desired results.
 
the benefits of sub 0 from -100 to -300 have been debated but it seems that so long as the steel benefits from any true sub 0 cryo "quench" then as long as it does not fail during the "quench " then its ok or better yet improved the RA or ETA carbides when done to -300

simple steels have shown no reall benefits
 
mete said:
Idaho, there is sub-zero quench which is -100 F. This reduces the amount of retained austenite.
Then there is cryogenic cooling which is -300 F This further reduces retained austenite and creates the precipitation of "eta carbides " , small carbides in the matrix. This is for maximum performance only for complex steels .
Click to expand...

Ok, MAYBE if we can find some superalloyed steels where Mf is under -80°C, although I do not remember any. And even if they are, -80°C would probably get us from 15%RA to 4%RA or 2%RA, no need fight more.
And for eta-carbides - they mostly preciate when steel is tempered under 200°C. And they dissolve if you temper steel higher - they are transformed into cementite.
And most superalloys require high temperature multiple temper. So byebye eta-carbides :D
 
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many knife makers including myself use heat treats that are not to the std. on the data sheet due to the sheet might be for making the steel right for a punch die and not a knife

alot of testing gets done to tweek steels not made for knives into good knife steels with a good HT. most of the high temp tempering is done for the size change aspect and to get rid or RA if you get rid of the RA with -300 then why temper at 1000f.

edit to add that LN is easer for me to keep at the shop then dry ice and those -100 collers are not cheap and they use a bunch of elect.
 
It occurs to me that threads like this demonstrate there are several ways to approach any challenge.

SCIENCE: Following what is known and proven, and disregarding what is unknown or unproven in order to achieve clear and predictable results.

ART: Combining methods and techniques in ways that are not fully documented or proven in order to achieve results that are inexplicably (for now at least) positive.

CRAFT: Utilizing methods that have proven, through experience, to be effective at generating pleasing results, whether or not they can be explained.

MAGIC: Utilizing techniques that have no scientific basis in the hopes of achieving results that cannot be explained.
 
idaho said:
Ok, MAYBE if we can find some superalloyed steels where Mf is under -80°C, although I do not remember any. And even if they are, -80°C would probably get us from 15%RA to 4%RA or 2%RA, no need fight more.
And for eta-carbides - they mostly preciate when steel is tempered under 200°C. And they dissolve if you temper steel higher - they are transformed into cementite.
And most superalloys require high temperature multiple temper. So byebye eta-carbides :D
Click to expand...

The lower Mf occur for the hypereutectoid steels. So 1095 will benefit from cold treatment -100 F if you want to reduce RA. D2 seems to be the poster child for cryogenic treatment. There is an increase in carbide formation at -300 F. These carbides do not go away when the blade is tempered at 400 F or higher.
 
I won't argue about the eta carbides , I don't have any D2/K110 cryo treatment papers on hand, you might be very right. :D
 
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Don't worry about confusion over cryo .It took me a long time to find the facts. We even had people who worked for cryo companies who made many claims but couldn't tell us WHY !! I still don't know why things change for other metals
To be precise , at -300 there is a re-arrangement of atoms and that small movement permits the carbides to form on tempering ! So the eta carbides form at 400 F. BTW I get custom knives tempered at 400 F because I want those properties not the 1100 F properties.
 
Yeah, I'm trying to promote 400F tempering in Poland too.
But most books and papers are talking about epsilon carbides mostly.
Eta carbides are quite new area to discover.

And like allways - if one gets great result it is not know if it was because he implemented new solution, or he just got everything else without a single mistake :D
 
while here is alot of backyard engineering going on in here we do liike to make sure that some science is interjected
 
Is there much consensus on When, How Often, and for what Length of Time you should cryogenically freeze the steel?

I normally work with 52100, and I've read that it is one of the most reactive steels to cryogenic treatment. As in, a 24 hour soak will convert every grain to martensite. I'm only saying that I've read this.

Are there other Real benefits, such as reducing stress?

Mete, you seem quite knowledgeable about cryogenics. When you say "temper after cryo treatment", do you mean one cryo treatment after hardening, then 2 or 3 normal tempers, or cryo between tempers, ending on a temper?

I assume the most important would be cryo after hardening. Is that correct?

How much cryo, and when, is enough for simple steel (52100)?

IMHO, cryo seems to make a big difference in rigidity. In other words, it seems to make the blade stronger, but sacrifices toughness.

I'm not a big fan of being able to bend knives back and forth, but I don't mind a blade that can flex 90*. I've had dramatic catastrophic failure at about 90*. Not like cracking the blade, more like the blade kind of shatters, and usually a chunk of blade goes flying at high speed.

Upon examination of the failed blade, the grain seems invisibly small, and the steel looks like broken glass.

Thank you for sharing on this topic. I've had these questions for quite some time.
 
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