i did a search i didn't find anything so....

Can someone give me a detailed explanation of what Cryo treament is, how it works, and what the results are?

or point me to where i can find one?

from the way I hear people talk about, it seems to be a magically form of heat treatment (but actually going to cooler temps?) that people seem to think improves stiffness, ultimate tensile strength, yield strength and toughness (which I know is impossible)

i have a BSME and went through two in depth Materials Science courses, covering heat treatment of steels extensively and never heard of anything resembling the cryo treatment automotive people speak of, so it seems like BS to me, but I would be happy to be proven wrong if this process exists and has been proven to work

 

http://www.efunda.com/processe...c.cfm

 

interesting, thanks

it still sounds like it isnt a "cure-all" for any alloy

since it would probably be difficult to determine the exact alloy of an engine component, it would be impossible to determine the proper heat treat cycle since it depends on carbon content

 

But each manufacturer that uses it knows what alloy and can control the amount of carbon in the material if they choose. Its up to them to do the R&D on it, but in general it makes for a better parts, and of course increase the cost due to added quality.

 

Right, I agree. I would put more faith in the process if the mfg did the work

but the reason i bring it up is because i keep hearing people talk about tearing apart their motor and cryo treating critical parts to improve strength. which seems impossible since they probably dont have access to the exact alloy information

 

you could simply treat the most carbon rich material in the alloy being treated. Cater to the highest common denominator so the other metals in said alloy would fall in the the "no residual austenite" category in the process.

Or maybe that's just my take.

 

check out this diagram...

http://www.gowelding.com/met/carbon.htm

Carbon percentage is on the x-axis and temperature is on the Y-axis. This is just part of the complex phase diagram for plain carbon steel, once other alloying elements get thrown in the mix it becomes much more complicated.

An alloy should have uniform carbon distribution (unless it has had some sort of surface treatment) so you cant just treat part of the alloy, its all or nothing (with the exception of surface hardening)

 

I think you may have missed what I was saying. I wasnt saying treat only one part of the alloy, im saying this:

If you find the alloy is made of 2 metals, metal A has a low carbon percentage, metal B has a high carbon percentage you are able to then treat it as if its wholey made from metal B. This will effectivly take car of the lowe carbon metal that does not need such a low temp as well as metal B that needs the -300 process

Unless you meant that metal has uniform carbon BEFORE you treat it (mentioned alloy doesnt have a metal A or B, but a combination of both yeilding carbon metal C) then the whole idea goes out the window.

 

yeah we aren't really on the same page i guess

i cant think of a case where you would have two distinct alloys combined in one part (this would be a disaster because of different thermal expansion coefficients, stiffnesses, etc)

the only case that comes to mind is a thermostat, where you want the metal to bend and curve drastically under small temp changes

 

I was thinking of chromoly rings and tri-metal honda bearings

 

hmmm...

well i know "chromoly" is the laymans term for 4340 steel (i think thats the common number), which is just carbon steel alloyed with a decent percentage of Chromium and Molybednum (sp?) which im sure has its own particular phase diagram, and heat treatment cycles

i'm not familiar with "tri-metal" bearings, although i am curious? are you talking about ball bearings or bushing style bearings?

 

I was talking about the rod bearings, truthfully. I beleive ACL uses dual metals in thier bearings, too. Thats as far as I know on that subject, but id like to know more.

The rings aren't 100% chromoly, either. Chromoly lasts a long time when used in pistons rings, but is notoriously hard to seat unless mixed with another metal (ask a 60's engine builder for more on the ring seating epidemic)