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Cryo treated axles

CUJeeper

NAXJA Forum User
Ok so i am and engieering student and i am trying to get some extra credit. There was a question asked in my materials class about Cryo treating axles. What does that do to them. Make them stronger? Last longer? I figure this isn't really OEM stuff so i will post it here. So yeah if you guys could help that would be great. I have never heard of this before so anything will help.
 
You will find more information if you look it up in conjunction with rifle barrels, but I seem to recall that the benefits of Cryo treatment are twofold...

1) Similar to normalising, the cryo soak and return will make the grain structure more consistent, and return the grains to a more uniform "spheriod" shape after working (which typically elongates the grains of the metal.) Normalising is done because the more uniform grain structure presents a greater tolerance for working stresses.

2) Cryo treatment offers better dimensional stability under conditions of load and heat. This helps to prevent excess wear caused by shifting wear points due to expansion - the more so since axle shafts tend to be "selectively hardened." Look that one up under "case hardening," "carburizing," or "nitriding."

The next session of my Materials and Processes class is Thursday, I'll try to remember to ask there...

5-90
 
very good information...

from what i have learned (Materials selection class) , when these parts are heat treated, the austenitic phase converts to a much harder brittle phase(martensite, and some others depending on quench rate and alloying elements in the metal) some of the austenite still remains. as the metal cooled, it reaches the martensite start temperature (TTT diagram) and then continues to cool until it reaches the martensite finish temp. sometimes this finish temp is much below room temperature and the result is some retained austenite phase in the metal. During this process, if the temperature is forced to decrease enough(cryo) the phase transformation is complete.

like already mentioned, there are also benefits from stress relaxation within and among grain boundaries as well as the formation of very fine carbides.

what is interesting to note is that this is 1 step in the heat treatment process, so sending parts to be "cryo'd" wont help unless they fully normalize the metal and start over with a new heat treatment cycle. without them knowing the EXACT composition and history of the parts you send them, they can't perform a proper heat treatment.

One advantage of 4340 alloy is that it has the ability to be through-hardened, meaning that thicker sections can be hardened than a regular high-carbon steel where only a thin surface layer can be quench hardened.
 
I have had my rotors, solid steel, no composite, and drums done for my XJ, have not put them on yet but while I was dropping them off at the cryo place in orlando there were trucks there from almost all the NASCAR and CART teams dropping off and picking up just about the complete vehicle, disassembled and yes they were doing axle shafts also. Not to mention the musical instruments they were doing. Had several rifle and pistol barrels done and noted improved groupings with the 700PSS's, not so big an improvement with the .45 barrels for the Gold Cups. There are several sites out there that deal with this and give some pretty detailed information.
Will probably put the brake stuff on sometime in the next year when it comes time to do the brakes.
The treatment takes 4 - 5 days to complete.
 
I have personally seen the reliable life of valvesprings, connecting rods, cranks and tranny parts in Pro Stock bike motors increase dramatically because of cryo treatment with all else equal.
 
Yeah, i think the cryo treating would work for axles. But the only reason i think this is cause i saw on tv that a bunch of the tractor pull guys are treating most of their running gear. They were saying that non-treated parts that had a useable life of maybe 2 runs were lasting about 5-6 times longer if they were treated. just my .02$
 
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