For all you cryo guys...

[subzali]

...UB

I was curious about cryoing so I asked my old metallurgy teacher what the science is behind it, and here's his response to my email.

"For most alloys cryo treatment will not change the structure of the metal and hence there will be no change in properties. There is a psychological affect like a medical placebo that seems to occur at times.

The one major exception is the cryogenic treatment of high carbon steels. In these steels there is often some retained austenite (normally a high temperature fcc phase). By cooling the steel this austenite can transform into martensite with a subsequent increase in strength (and wear resistance).

The stress relief that you colleagues are doing is more akin to a tempering heat treatment after quenching. This will increase the toughness of the steel which only a minor decrease in strength. The subsequent cryo treatment would then make fresh martensite in those regions that had been austenite, but will not change the bulk of the structure. This new martensite may add back a bit of strength to the component.

Be aware that this processing does not work with all steels and the only ones that I have seen industrially treated have been high Cr, high Mo steels for large rolls for rolling mills. The alloy composition of these steels is much higher than what is normally available for purchase from a steel warehouse."

 

[DaveInDenver]

Oh sure, what's next? Why SAE grade 8 isn't the end all, be all or maybe why sometimes the right tire isn't the widest, tallest one? Sheesh, can't the pointy head geeks just leave the ghetto engineers alone? Just simply by asking an expert you've found out that if properly heat treated, metallurgically-speaking, gears don't really need a band aid cryogenic treatment (if they benefit even at all). I mean you quote a Ph.D. who's only studied the subject his whole adult life, no reason to go around crowing about it. Anyway, when did the truth ever really deter anyone? You've obviously not been paying attention to politicians and professional athletes.

 

[RockRunner]

This will be interesting to follow, I have been thinking about getting some stuff done but wasn't sure. I think this thread will be my make it or break it decision, not to mention the cost factor.

 

[Uncle Ben]

I had a professor tell me that religion was only a way for people to gain a sense of strength from believing in something that wasn't real. So just because he doesn't believe should I follow?

You can continue to wheel with stock Birfields and 31's but if you decide to add a front locker and bigger tires you might want to start believing! But then again I guess you can learn like we had too! Suggestion....wear glove when replacing broken Birfields especially after a second or third one......the housing gets pretty none human knuckle friendly!

Cryogenic processing

The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. With a background in the heat treating industry, Busch founded a company in Detroit called CryoTech in 1966. Though CryoTech later merged with 300 Below to create the largest and oldest commercial cryogenics company in the world, they originally experimented with the possibility of increasing the life of metal tools to anywhere between 200%-400% of the original life expectancy using cryogenic tempering instead of heat treating. This evolved in the late 1990s into the treatment of other parts (that did more than just increase the life of a product) such as musical instruments or amplifier valves (improved sound quality), brass instruments (improved tonal characteristics), baseball bats (greater sweet spot), golf clubs (greater sweet spot), racing engines (greater performance under stress), firearms (less warping after continuous shooting), knives, razor blades, brake rotors and even pantyhose. The theory was based on how heat-treating metal works (the temperatures are lowered to room temperature from a high degree causing certain strength increases in the molecular structure to occur) and supposed that continuing the descent would allow for further strength increases. Using liquid nitrogen, CryoTech formulated the first early version of the cryogenic processor. Unfortunately for the newly-born industry, the results were unstable, as components sometimes experienced thermal shock when they were cooled too fast. Some components in early tests even shattered because of the ultra-low temperatures. In the late twentieth century, the field improved significantly with the rise of applied research, which coupled microprocessor based industrial controls to the cryogenic processor in order to create more stable results.

The Science of Deep Cryogenics

Deep cryogenics is the ultra low temperature processing of materials to enhance their desired metallurgical and structural properties. In our case, this is a temperature about -320°F, -196°C, or 77°K. These ultra cold temperatures are achieved using computer controls, a well-insulated treatment chamber and liquid nitrogen (LN2). Nitrogen is the gas that constitutes 78.03% of the air we breathe here on planet Earth. The liquid form, is the product of air separation, compression and liquefaction. What this boils down to is that our deep cryogenic systems are completely environmentally friendly and actually help reduce waste.
Cryogenics International's Deep Cryogenic Process.

Cryogenics International's patented, controlled deep cryogenic treatment system and process is capable of treating a wide variety of materials, such as ferrous and non-ferrous metals, metallic alloys, carbides, plastics (including nylon and Teflon) and ceramics. The entire process takes between 36 to 74 hours, depending on the weight and type of material being treated. Strict computer control and proper processing profiles assure that optimum results will be achieved with no dimensional changes or chance of thermal shock. This special process is not a surface treatment; it affects the entire mass of the tool or component being treated, making it stronger throughout. This means the process keeps working even after continued use and/or numerous sharpenings. The hardness of the material treated is unaffected, while its strength is increased.
What Does Deep Cryogenic Treating do?

These ultra-cold temperatures, below -310°F, will greatly increase the strength and wear life of all types of vehicle components, castings and cutting tools. In addition, other benefits include reduced maintenance, repairs and replacement of tools and components, reduced vibrations, rapid and more uniform heat dissipation, and improved conductivity. Cryogenics International's process is like an insurance policy for your tools and components.

Comparative microphotographs (1000x) of steel samples show the change in microstructure produced by the controlled deep cryogenic process. Uniform, more completely transformed microstructure and less retained austenite at right, is related to improvements in strength, stability and resistance to wear.

 

[subzali]

Hey Kev, I thought it looked like he was supporting the process! Aren't axles and Longfields and stuff made out of High Cr-Mo alloy steel? He said it helps for that application! I thought it was cool because I was skeptical at first, but it's not just blowing smoke!

And I don't know what to make of Dave's post, I'm just relaying info, not saying if he's right or not or whether I agree or not.

Sheesh...

 

[Red_Chili]

Kinda reminds me of that mosquito who bites a guy eating pizza with Tabasco...

 

[Uncle Ben]

Sorry Matt, I obviously didn't read much past the first couple lines. I seem to have a quick temper these days and I'm sorry. I guess the emotions of putting my oldest daughter on a plane tomorrow and sending her "down under" to study abroad for a year is hitting me harder than I thought.

 

[subzali]

No worries...I was just giving a fun poke in the first couple of lines, guess that's the problem with internet forums. Understand that the Christmas season is pretty stressful, and yes sending your daughter away to study has got to be hard too! See you tonight!

 

[DaveInDenver]

And I don't know what to make of Dave's post, I'm just relaying info, not saying if he's right or not or whether I agree or not.

Tongue in cheek my man, tongue in cheek. But, I've never asked any of my friends who are real life practicing metallurgists about the cryo process w.r.t. differentials or what-not, so I dunno. I went with plain old gears using the time honored (but admittedly maybe not ideal) in-situ oil quenched work hardening. But in general, I'd probably trust a guy who by training or practice knows he wants his alloy austenitic material to be martensitic and free of cementite during tempering. To that end, cryogenic treatment was one thing foundries have done for a while to get a better martensite transformation. I certainly don't think it's Rube science at all. Although, I think if the original manufacturers did good work, then it probably isn't necessary and probably shouldn't ideally gain you much. It's not a substitute for proper tempering techniques and only works marginally. Maybe if the original heat treating was poorly done, then it might do more. I simply don't know, but then again I'm just a goober. But in the case of Birfields, evidence seems to indicate that cryo'd parts do in fact have a longer life than ones not subjected to the process. I do think it's mostly marketing to do to brake rotors, I can't see the benefit really there. But I'm not at all saying cryogenic tempering is not a useful tool, I was just poking fun at ya.

 

[Hulk]

but then again I'm just a goober.

Dibs! I'm putting this in my signature.

 

[rover67]

we used to do brake rotors but stopped because we never noticed a difference.

makes sense after reading above.

 

[bskey]

Wow..... and I was seriously thinking to myself earlier today "I need to learn more about this Cryo stuff...." Ha! Thanks for the info... I'll be following this thread!

 

[Uncle Ben]

we used to do brake rotors but stopped because we never noticed a difference.

makes sense after reading above.

80's are notorious for warping rotors. I'm going on two full years now with cryod rotors and no pedal pulsing yet! I only got about 4 or 5 months on non-cryoed rotors previously. (I hate pulsing brakes) Since Bill started cryoing his biggest customers have been drag racers doing front rotors.

 

[rover67]

we did them for rotors on race cars for wear purposes.. maybe the place we were using wasn't doing them right... who knows..

 

[bskey]

Where can I get price info on this?

 

[Uncle Ben]

Where can I get price info on this?

mountainhighperformance.com Are great guys! I have a 20% off coupon here on my desk but if you tell them you are in Rising Sun and that Kevin mentioned the 20% discount coupon from Pat I bet they will honor it. (Bill and Pat are the only machinists there)

 

[bskey]

^^ great, thanks!