Cryo treatment without LN??

[Daniel Rohde]

I want to be able to put my blades through a cryo treatment and right now liquid Nitrogen is unavailable. I have heard of some deep deep freezers that can do something like that(I think like two stage compressors or something) I'm just curious if I can either buy a freezer that can do that or how you could make one if at all possible. What are my options? I'd kind of like to be able to but blades in at -0*F
and have it go down to -300F over the next 6 hours or so...
DR...

 

[12345678910]

I don't think there is a -300F freezer, that's why they use LN


There are -70*C freezers, but they are not "cheap" or fast
It takes a few days to settle down to full coldness, so you run it steady


A new one would be $10,000 ish and a quick ebay tour shows the cheapest ones are $2,000 for a "broken used for parts or repair"




A used liquid nitrogen dewar is more or less $100 and you can get it filled.



the other option is a cooler with dry ice and acetone bath.
It's cheap, easy to get (welding shops sell it)
It's not nearly as cold as LN, but it's a good comprmise for some people.

 

[Bo T]

There are freezers that will go to -150 C. New, about $25000 US.

 

[jdm61]

Depending on what steel you plan to use, dry ice and a solvent you can get at Home Depot like kerosene, acetone or isopropyl alcohol might work for you. That will not work best for Elmax and some of the other really high alloy steels but it apparently will work on a lot of the theories ones that we typically use.

 

[Nic.]

This is just because I'm uneducated but intrigued...how does exposing the steel to such low temperatures help?

 

[jdm61]

It converts retained austenite to martensite. or perhaps more accurately, it allows the completion of the full transformation to martensite in steels that don't do that at normal temperature so that you avoid large percentages of retained austenite..

This is just because I'm uneducated but intrigued...how does exposing the steel to such low temperatures help?

 

[ron_m80]

For the Cryo treatment to work what is the target time for the blade to reach the target temperature?

 

[jdm61]

According to guys like Roman Landes, when doing it right out of the quench after the blade has cooled to room temp, it takes however long it takes to stabilize the blade at the low temp. Minutes. IIRC, Landes says that the actual final transformation happens in mere seconds which makes sense as yo are "finishing the quench" so to speak. . Long soaks at LN temps supposedly do other things as far as obscure types of carbides go, but you had better ask someone else about that.

For the Cryo treatment to work what is the target time for the blade to reach the target temperature?

 

[Kentucky]

We use dry ice/acetone. It gets down to about -106° that I know of( I checked with a thermocouple) Its not LN but will will complete the sub zero quench and take care of the RA in stainless steels like AEB-L,s35vn and other complex steels like cpm3v..Most folks get a measured 1-2 points of rc after sub zero quench or cryo..I think the temp has to be -95° to complete the martensitic transformation..Cryo supposedly has other benefits at longer soaks concerning carbides but I wont open that poop house door

 

[jdm61]

It varies with the steel. I was looking at the chart at their display at Blade a couple of years back and the guy from Bohler-Uddeholm confirmed what I thought i was seeing. Elmax and their even more complex PM super steels require like -120F which you cannot really get with dry ice. I think that this also applies to the crazy high alloy stuff from Crucible like S90V and S110V. On the other hand, I seem to recall that in addition to the steels you have listed, CTS-XHP also works okay with dry ice.

We use dry ice/acetone. It gets down to about -106° that I know of( I checked with a thermocouple) Its not LN but will will complete the sub zero quench and take care of the RA in stainless steels like AEB-L,s35vn and other complex steels like cpm3v..Most folks get a measured 1-2 points of rc after sub zero quench or cryo..I think the temp has to be -95° to complete the martensitic transformation..Cryo supposedly has other benefits at longer soaks concerning carbides but I wont open that poop house door

 

[Whiskey Papa]

Being a new guy knife maker, what the heck are all these fancy materials used for, I mean what happen to the good ole tool steels and 440 C? Dumb question I'm sure but what the heck............

 

[jdm61]

LOL. 440C would benefit from a little dip in the cold too.

Being a new guy knife maker, what the heck are all these fancy materials used for, I mean what happen to the good ole tool steels and 440 C? Dumb question I'm sure but what the heck............