cyro

[v-6]

any one here do cyro. what stage are you suppose to have it in to have it done?
vern

 

[richard j]

the heat treat should be done at least

 

[Teknition]

You neglected to mention what steel you are using but I will assume its stainless (not a whole lot of benefit doing cryo simple carbon steels).

There are a few schools of thought when doing cryo. This is the way I do it.

Ramp to soak temp and hold, ramp up to austenize temp and hold, quench, let blade cool to room temp, cryo, temper x2.

Some will say you should do a snap temper between the quench and the first cryo to stress relieve the blade a bit to prevent cracking but I've never had any problems doing it the way I do and I think the maximum benefits from the cryo are attained without the snap temper.

Brad
www.AndersonKnives.ca

 

[Rob!]

What Brad said - I agree. I haven't seen anything that cryo hurts. I have seen that it has an effect (that I conside positive) on most complex steels.

Same process - austenize - quench - cryo - temper. I don't see cryo as any more violent than the quench. It takes maybe 30 seconds for the LN to stop boiling from room temperature blades - which I interpret to mean it take about 30 seconds to get close to matching temperature. Compare that rate to quenching from - whatever, to room temperature. WAY faster than cryo!

Rob!

 

[8PT]

This may not be the time or place to ask it, but I have a question concerning cryo treatment. I think this may be my first post on the forum so keep me straight. This has to do with 440C mainly in pre made blades and kits from a supplier. If a hunter that knew what a sharp good performing knife felt like was to pick up two identically style and built knives, one deep cryo treated (below -300 degree F.) and the other not, what and how much difference would he be able to tell between the two as far as cutting performance and edge holding/retention if he had several deer or hogs hanging to be skinned and dressed out? This is if the two blades were the same or within one point in hardness.

Thanks in advance for any help as I have been wondering about this for a while.


Thanks
Tommy

 

[kc custom]

I'm sure we will be going over this till hell freezes over. I can treat and rc 2 blades one froze and one not and get the same Rc out of both blades (usually within a half point)
I've seen some crazy things done to stainless blades and I absolutley believe in the freeze. I've heard numbers like 15 to 20%.
Ken

 

[mete]

Cryo will give you 1-2 HRc points harder. Cryo has to be part of the HT, not an add on process. A lot of variables here , type of steel and the details of the HT. Cryo does not perform miracles !

 

[Kevin R. Cashen]

What the heck, I said if mete can still bring himself to discuss this topic, I can hang my backside out there for a moment as well. It is a very complex topic that is how so many sliksters manage to market so effectively, there are so many areas to focus on and too many to be pinned down on. Let us also consider the effects it may have on the formation of interlathe precipitants by dealing with the austenite before a full temper? Tempered martensite embrittlement could be affected this way and thus account for the results of higher toughness. Folks who really know more about eta carbides than I also have pointed out that such secondary carbides can form over time on their own thus the cryo may simply be viewed as an accelerated aging process. Think of the ramifications of this when considering the control blade in any tests??

Once again, it is a very gray area and a very complex topic, answers held up as definitive should be viewed with the healthiest dose of skepticism. But in the end we do indeed know that stainless responds well to being frozen! And better yet we know why:thumbup:

 

[jdm61]

What the heck, I said if mete can still bring himself to discuss this topic, I can hang my backside out there for a moment as well. It is a very complex topic that is how so many sliksters manage to market so effectively, there are so many areas to focus on and too many to be pinned down on. Let us also consider the effects it may have on the formation of interlathe precipitants by dealing with the austenite before a full temper? Tempered martensite embrittlement could be affected this way and thus account for the results of higher toughness. Folks who really know more about eta carbides than I also have pointed out that such secondary carbides can form over time on their own thus the cryo may simply be viewed as an accelerated aging process. Think of the ramifications of this when considering the control blade in any tests??

Once again, it is a very gray area and a very complex topic, answers held up as definitive should be viewed with the healthiest dose of skepticism. But in the end we do indeed know that stainless responds well to being frozen! And better yet we know why:thumbup:

With stainless, does that have to do with martensite "stop" being low or room temp being too warm to tie up the maximum amount of chromium into carbides? Or C., none of the above?

 

[Kevin R. Cashen]

With stainless, does that have to do with martensite "stop" being low or room temp being too warm to tie up the maximum amount of chromium into carbides? Or C., none of the above?

Stainless has enough subtitutional alloy atoms distorting the matrix to give more resistance to the shear type deformation necessary to transform the austenite to martensite. This gives more stability to the austenite and makes lower temperatures necessary to kick it over, thus Mf (or M90+ if you prefer) can be lower than room temperature. It is obvious why freezing such an alloy is a good thing that yields results.