Cryogenic tempering if tool steel links

Does anyone have any "back yard" how to links on this tempering method. I done a google search but that only yeilded places that sold the service, I
want to do it myself.
Thx Mat
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As I understand it, you drop it in LN or at least dry ice for up to a day immediately after quenching. Then draw the temper.
Or do I have that backwards?
Tim
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Its a little more complicated than that. The tool is not suppose to come in contact with the cryogenic fluid. It is a slow process (24 hrs or more) with slow ramps and soaks at key temperatures. What temps? Those are the trade secrets. I attended a seminar of a company that was trying to sell the service to improve the life of lead cutters on circuit board trimmers. Didn't buy into then, still not convinced its useful in real world applications.
My 2 cents
Jim Vrzal
Tim Williams wrote:

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Tim Williams wrote...

This isn't the way it's done in industry. Ideally, cryo tempering is done after the initial, normal temper cycles, and the part is again tempered normally afterward. Often, though, there is a big time delay between the first temper and the cryo because the processes can't be done in the same plant.
All the reputable facilities use long ramp times to reduce hazards to the parts and increase the effectiveness of the process. A typical cryo cycle involves a ramp down to the -300 to -320 F neighborhood over a 10-hour period, a 20-24-hour soak, ramp back to ambient over 15-20 hours, followed by two or three two-hour high-temperature temper cycles. (Boy, that's a mouthful.)
Jim
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Muy understanding is that the ramp back up is where the majority of the effect occurs. It's a slow steady process but quite effective for some alloys.

day
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