Cyro Combos?

David Loukides

David Loukides

Joined
Mar 17, 2006
Messages
1,363
Hi Guys,
I am going to do my first Cyro with Dry ice and Acetone on 440c and 154cm blades. What amount do you use of each for a batch of 5 knives:confused: What kind of container should you use:confused: and should you let the knives cool down after the oven temper befor the Cyro?????
Many Thanks
 
i let the blades get to room temp then i dunk in the Ln over night but you should be ok just filling a coller and letting them soak
 
When I was using dry ice and acetone, I used just a couple inches in the bottom of a small cooler. I was doing maybe 10 blades at a time. You just need the blades under the liquid all the way through the process. I added dry ice till it stopped 'boiling', indicating the acetone was about at temperature. I then just kept adding enough dry ice to keep it down there overnight. It worked fine and did give me a point or two over just plate quenching.

My problem was that the dry ice disappears too quick. If I have another blade to do a couple days later, it is all gone. 20Litres of liquid nitrogen lasts about a month and a half in the dewar even when used a few times. It's not better - just more convenient. (Especially since I have an hour and a half drive for either dry ice or LN.):(

Rob!
 
SOME COOLERS WILL DISSOLVE, especially styrofoams. Test first by rubbing a little acetone on and see if it melts or gets gooey. More than one idiot has poured acetone in a cooler without checking only to have it melt faster than pissin' on snow. Personally, I insulated a metal container.

Some people use kerosene instead of acetone to reduce the fire and health hazard.

Some people eliminate the acetone altogether and just make sure the blades are covered over/under with dry ice for the desired time. It gets down to the same temp and elminiates what is a very serious fire hazard.
 
DO NOT USE ACETONE!!!!!!!!!!!!!!!!!!!!!!!!!!

Use Kerosene instead. Much less dangerous, and, you'll get the same results. Line your cooler with a plastic garbage bag-the kerosene won't melt it.
 
ive read ethanol is the best (or at least an alcohol) you could reach -80°C or so iirc
 
hp2spare said:
My questions stands... is Sub-Zero quenching good for Carbon Steel too?
Click to expand...


it depends on what temperatures you will be tempering at i assume, and the hardening temperature and how much retained austenite you will have after the hardening. maybe someone else knows
 
hp2spare: No, not as much benefit for carbon steels as SS, because the alloying additions in SS lower the Mf temperature considerably, therefore there is more retained Austenite in SS after the initial quench.

However, there is enough benefit from cryo for any knife steel that I would recommend using cryo.
 
The higher the austenitizing temperature the more the retained austenite. Do not overheat !! You cannot remove all the RA when it has been overheated.
 
Thanks for all your Help Guys.:thumbup:
I now have the dry ice and I am on the start of the cyro.
I feel like the Guy selling the Dry ice was over charging me.:mad: It cost me $1.00 a pound for 30 lbs:eek:
Well live and learn.
 
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