CPM 3V: High temper(1000°) vs low temper(400°) and sub zero quench

What is availability of cryo treatment in US?
Can you just call the place and arrange treatment for a few blades in "humane price"?
 
Remember that cryo is only part of the heat treat ,it's not something you can add later. If you're HT'ing a complex steel and don't have the equipment for precise time and temperature you best send it to a commercial HTer to do it.
 
mete said:
Remember that cryo is only part of the heat treat ,it's not something you can add later. If you're HT'ing a complex steel and don't have the equipment for precise time and temperature you best send it to a commercial HTer to do it.
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Off course. I just wonder if cryo is something to care about, or is it way beyond access, so it is not really worth pursuing the knowledge.
 
Cryo, as it applies to knives, is neither expensive nor complicated. But to be effective it needs to be performed relatively quickly after the quench before any major tempers because there is a relatively brief window of opportunity for it to be effective in this application.

There are places that will take your money and freeze your blades after-the-fact and they will tell you it is helping. And in reality it is making some measureable changes, but they don't add up to much. To my knowledge, after-the-fact cryo applied to a finished blade has never had any noticeable effect in cutlery.
 
We do a sub zero quench as part of the quench on certain steels..Its a dry ice and acetone bath that reachs about -104°..Its main purpose is to reduce RA, that's why we use it..RA reduction takes a temp of about -95° to work if Im not mistaken. Im looking for a dewar because I have access to LN but I haven't ran across the right one yet(i.e cheap enough) We buy dry ice forabout .99 cents per pound close to home. Its not expensive at all.
 
Nathan the Machinist said:
There are places that will take your money and freeze your blades after-the-fact and they will tell you it is helping. And in reality it is making some measureable changes, but they don't add up to much. To my knowledge, after-the-fact cryo applied to a finished blade has never had any noticeable effect in cutlery.
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Yeah, I know. I remember the graphs - preheat, heat, quench, temper, cryo, temper, temper as a single process.
But while sub-zero treatment is doable even at home, cryo is not. So I wonder if it is worth worrying about, or it is better to leave it for the future time, and now concentrate on other elements of HT.
 
idaho said:
Yeah, I know. I remember the graphs - preheat, heat, quench, temper, cryo, temper, temper as a single process.
But while sub-zero treatment is doable even at home, cryo is not. So I wonder if it is worth worrying about, or it is better to leave it for the future time, and now concentrate on other elements of HT.
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Cryo is very doable at home. In some places LN is both less expensive and more available than dry ice. You just need a dewar, which can be had used if you don't mind a bit of bull jizz...
 
I can buy LN less 10 minutes from my house and its cheap..I just need a "cheap" dewar..
 
international cryogenics i thinkm is where i got my brand new 20l with a big mouth (wanted it for taller kitchen knives) disadvantage of big mouth is faster evaportion. i make sure to have a batch ready to HT then go get itfilled so i can max out blades per fill. there are a few places that i can get my tank filled and cost is not too hateful
 
I was talking to the guys from Bohler-Uddeholm at Blade and notice that there charts indicated that the typical temperature of the dry ice and acetone or kerosene slurry looked liked it was about 20-30 degrees too warm for some of their steels like Elmax or M390. The rep said that I was reading the graphs correctly and that they had found that -120F was the minimum number for optimum benefit with those steels.
Kentucky said:
We do a sub zero quench as part of the quench on certain steels..Its a dry ice and acetone bath that reachs about -104°..Its main purpose is to reduce RA, that's why we use it..RA reduction takes a temp of about -95° to work if Im not mistaken. Im looking for a dewar because I have access to LN but I haven't ran across the right one yet(i.e cheap enough) We buy dry ice forabout .99 cents per pound close to home. Its not expensive at all.
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butcher_block said:
international cryogenics i thinkm is where i got my brand new 20l with a big mouth (wanted it for taller kitchen knives) disadvantage of big mouth is faster evaportion. i make sure to have a batch ready to HT then go get itfilled so i can max out blades per fill. there are a few places that i can get my tank filled and cost is not too hateful
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Butch, for people that who haven't looked into these things, we should probably mentioned that the different in evaporation rate on a 20 liter dewar mean that the "big mouth" one will only hold the LN for 2 months as apposed to 4, right? ;) That is still a lot better and probably cheaper than dry ice and a cooler once you get pat the extreme sticker shock of buying the dewar.
 
spec on web site i think said 45 days on my tank (20l big mouth) and a std 10l is 45-60 days (been a while since i lookd tho )
 
Just so you guys know I did this heat treat on a few knives now and Im very,very happy..I beat it through crossgrain wood, cut up a ridiculous pile of cardboard, make kindling and it would still slice paper now problem..Its still very,very tough with the low temper..Im completely satisfied.
 
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