Cryo Elmax?

V

verrocchio100

Joined
Aug 10, 2002
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For makers using Elmax; are you cryo-ing the blades at all or just HT?

Any performance difference between cryo and non-cryo blades?

Thx!
 
My more recent Elmax blades have been HT'd by Peters Heat Treating.They do
a (PROPER) cryo, and the difference between their cryo, and non-cryo processing
is marked.
 
Russ' point about PROPER cryo is a good one. I talked to the B-U USA rep at Blade and his chart said (and he confirmed) that you don't really get the full effect on Elmax until you get down around -120F, which is 20-30 degree COLDER than what you could typically expect from a dry ice/acetone Slurpee from what i can gather. You don't "need" -190C but you do need nitrogen.
 
Joe....Did the B-U rep state whether -120F was just for complete transformation,or
if there was more to it..?
Peters goes to -300F I beleive, and takes the temp down slowly.

(One recommended cooling rate is 1/2 Deg/min.))
 
Russ Andrews said:
Joe....Did the B-U rep state whether -120F was just for complete transformation,or
if there was more to it..?
Peters goes to -300F I beleive, and takes the temp down slowly.

(One recommended cooling rate is 1/2 Deg/min.))
Click to expand...
Russ, I recall that the -120F or -85C was for complete RA transformation. if you read the specs, you will see that a number of the European high alloy steels call for a cold treatment in that mid 80's range, so you wold be running inot the same issue as you do with Elmax. I think that most places go down to -300F/-196C because that is the temp of LN2. I was looking at some Union Carbide style dewars on line and they say that at the liquid's surface, you get the -196C which is like -320F and even in the unfilled airspace right up by the neck, you will still see temps of like -190C . The -300F is around -185C, so those are temps that you could see in a large "chamber" perhaps without dipping the blade into the liquid.
My understanding of the argument re the weird things that small carbides do at those "true cryo" temps is nil, but everything that I have read says that it can't hurt, but THAT process is the one that requires the overnight soak. IIRC, according to Roman Landes, conversion of RA to martensite is almost instantaneous once you het the right temp.
Obviously, the dry ice trick works quite well for some of the simpler stainless steels and probably helps with the more complex ones. i have run across people who don't do cryo on crazy high alloy stuff like S90V, but if I am going to spend that kind of cash on raw materials, I am not inclined to skimp. I think this is especially true with a steel like Elmax which is known for being one of the tougher PM super stainless steels. it doesn't make sense to me to use it if you arenet' going to tackle that mortal enemy of toughness, RA.
 
Joe. My understanding is similar. My curiousity too, is in when the eta carbides start/stop forming,
and if that happens at the same temps and at the same rate in all high alloy steels........Too bad Roman's book
isn't available in English....
 
Russ, Roman gave a pretty good Reader's Digest Condensed version of some of the work he did for his thesis over on Kevin's forum a while back. It was in response to a question for the Matthews boys about a problem they were having with some 3V. Good reading.
Russ Andrews said:
Joe. My understanding is similar. My curiousity too, is in when the eta carbides start/stop forming,
and if that happens at the same temps and at the same rate in all high alloy steels........Too bad Roman's book
isn't available in English....
Click to expand...
 
Great info there fellas, thanks!

Okay, how about cryoing CTS XHP?

Is there any general guideline to which metals respond "better" to cryo than others?

Powdered vs cast?

Or does elemental make up dictate how well a metal reacts?

All else being equal with proper HT?
 
the alloy can make all the difference due to the fact that alloy mix shifts the MS and MF points. also how high a temp. you need to quench from and how that works on the RA conversions. you see it more with powdered steels but thats cause the powder prosses allows for much higher alloy content then std. cast smelts
i am one of the guys that cryo jsut about everything sept for simple steels (hey i have the tank of LN here ayhow so less it cracks the blade what can it hurt ) while i dont have any micro graphs of my XHP with cold or withought i am loving it for extra fine edge forming and holding
 
Cryogenic treatment can effectively carry out the metal internal crystal structure refinement, better crystals in wear resistance
 
What I have read recently says that CTS-XHP may not be nearly as temperamental re super tight HT parameters as some of the other PM steels like 3V or some of the Bohler-Uddeholm stuff
 
hktamiya said:
Cryogenic treatment can effectively carry out the metal internal crystal structure refinement, better crystals in wear resistance
Click to expand...
actually, I think that cryo appears to contribute more to properties like higher hardness, better toughness and better edge stability. The hardness will give better abrasion resistance obviously.
 
As I know the under-zero treatment can make the steel harder about 1-2HRC,and decrease the retained austenite ,it's good for the strength of the knife.
 
i talked to Brad Stallsmith at Peters extensively about cryo on ALL steels. he said that every steel will benefit from a cryo cycle. i am planning on some experiments in my own shop to see what i cant gain with a 24 hour dry ice cycle. I am limited to dry ice because the only distributor of LN in my area will not deliver small quantity's and they are too far away for me to go get it
 
more of a complete MS transformation... is the one off the top of my head. i am more concerned with the performance aspect so say i do the subzero quench and i gain 30 cuts of a rope before it gets dull. will i introduce that into my HT recipe? that would be a negative LOL im looking for a more marked increase in performance thats why i need to do some testing
 
Agreed Lon!

I too am interested in what real world advantage cryo gives.

Elemental/chemical transformation is fine and dandy on paper.

I am more curious about the steel's corrosion resistance, impact resistance, how easy it is to touch up the edge in the field and how well an edge holds a true workable edge before I have to resharpen on the bench.
 
A maybe dumb question, but.
Would there be a reason to do a cryo to an existing knife (Spyderco Mule 17) thats been reprofiled?
Can it hurt anything other than my wallet?
 
verrocchio100 said:
Agreed Lon!

I too am interested in what real world advantage cryo gives.

Elemental/chemical transformation is fine and dandy on paper.

I am more curious about the steel's corrosion resistance, impact resistance, how easy it is to touch up the edge in the field and how well an edge holds a true workable edge before I have to resharpen on the bench.
Click to expand...
You may find that the way you mess with corrosion resistance is to look at low temperature tempering. Less RA is always going to give better toughness.
 
Not entirely stuck on corrosion resistance but what I don't want to happen is too diminish the steels inherent corrosion resistance.

Not to hijack my own thread but Butch can you please elaborate your experiences with XHP?

Thx!
 
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