For those of you that follow the “Toyota Truck and 4Runner Talk” threads. You may have seen the thread on some new birfield that are supposed to be “unbreakable”. These birfields come with a lifetime guaranty.

Well the discussion got very heated, and though some of us were trying to keep the discussion focused on the science, the thread got a little savory…

So now I come to the 4x4 community as a whole, in trying to determine if cryogenic tempering works, and if people have tryed it. Please try to keep the discussion of unbreakable birfields to a min.

For thoughts that do not know about the process…

The deep cryogenic tempering process uses cryogenic temperatures (-300 degrees F) to transform the soft carbon (austenite) into a smaller and stronger carbon molecule (martensite). This makes the surface of the metal less porous, so there is more surface area to wear. When the process is complete, the metal is less brittle, stronger and much more durable than before. Tools can be Cryo'd when new or dull. Cryo'd tools are actually easier to resharpen because 50% less material is removed each time, so the tool can be resharpened twice as many times. If the tool is resharpened after being Cryo'd, it will cut much longer.

It is clamed that this process will…
· increases abrasive wear resistance.
· requires only one permanent treatment.
· creates a denser molecular structure. The result is a larger contact surface area that reduces friction, heat and wear.
· changes the equipment's entire structure, not just the surface. Subsequent refinishing operations or re-grinds do not affect permanent improvements.
· eliminates thermal shock through a dry, computer controlled process.
· transforms almost all soft retained austenite to hard martensite.
· forms microfine carbide fillers to enhance large carbide structures
· increases durability or wear life.
· decreases residual stresses in tool steels.
· decreases brittleness.
· increases tensile strength, toughness and stability coupled with the release of internal stresses.

Andy thoughts?

for drivetrain components, it seems to be a waste of time. I had 44 shafts cryo'd a few years ago and when they broke they shattered rather than just breaking into a few pieces like "normal" Didn't seem any tougher than normal. JMUO!

Im a police officer not a metalurgist but I can say that all of the NASCAR teams use cryo treated components such as rotors , axles , etc they say it will increase the wear resistance almost 25% and they wouldnt use it if it did not work:smokin: :smokin:

the high end pistol business went to cryo a few years back. the main problem was wear on the hammer and sears. they used to be shot after about 10k rounds. now they seem to last forever. they are very hard as in the rockwell 55 to 60 range. but that has been the case in point for a while. i don't think its near as good as you stated in the write up on it. i mean it sounds to good to be true. as for the toys, it shouldn't take very long to see how they hold up time will tell. and knowing this bunch it wont take long.

who gives a rats ass about wear resistance, when it's not wear that causes axles to explode. nascar using the process for rotors is swell, maybe it's cool for gears and such, just not axles and ujoints IMO. But if the money is burning a hole...:eek:

Originally posted by Aggro
for drivetrain components, it seems to be a waste of time. I had 44 shafts cryo'd a few years ago and when they broke they shattered rather than just breaking into a few pieces like "normal" Didn't seem any tougher than normal. JMUO!

Bob had some Cryo'd 60 front shafts as well, and snapped em

Originally posted by 84xtracab
The deep cryogenic tempering process uses cryogenic temperatures (-300 degrees F) to transform the soft carbon (austenite) into a smaller and stronger carbon molecule (martensite). This makes the surface of the metal less porous, so there is more surface area to wear. When the process is complete, the metal is less brittle, stronger and much more durable than before.

Andy thoughts?


Uh your wrong (not rrying to be a jack ass) but that is not cryogenic treating. Austinite is a high temp. phase of metals, simply getting a good fast quench is all that is required to form martensite. Martensite has a needle like structure which creates a lot of stress raisers. Martensite is strong but very brittle and often crackes because it is so brittle. Martensite has many lattic strain which make it very strong but brittle. You then take martensite and temper it and then you have tempered martensite. tempering it releaves the some of the latice stress which makes the material a lot more ductile and also very tough. Tempered martensite has very small round particles of carbon it it (much smaller thatn the needles in martensite) because they are round and small teh structure is tough and ductile and still very strong.

Why you should believe me:
In my materials engineering class we took several peices of steel and made martensite, tempered martensite, and pearlite(standard crystal structure) Then we tested to see how hard they were, how much "spring back" they had when bent and their yield strenght. The the tempered 1090 steel (tempered martensite) had 60% spring bakc and high strenght while the martensite had no spring back (because it imediatly broke) although it was very hard to break.

Hope this helps. (i will get more info about cryogenic treating from my professor and post it here at 3:00 today)

Originally posted by Aggro
who gives a rats ass about wear resistance, when it's not wear that causes axles to explode. nascar using the process for rotors is swell, maybe it's cool for gears and such, just not axles and ujoints IMO. But if the money is burning a hole...:eek:

I think wear resistance plays a big part. Unless you grossly underestimated your drivetrain you usually don't break the first trip out on a new set of axles. It takes a little while of continually putting that stress....the axles become weaker over time and eventually snap. WIll the cyro hardening thing help here?? I don't know.

RRaker:
Thanks for the reply, and look forward to your follow-up post.

Aggro:
You are right about wear. In the case of the Birfield, strength is the issue.

toymaniac:
I think Aggro meant wear, as in to loose material.
Birfields don't really loose material - say like a rotor.
But they do loose strength ie ‘wear down’ if that is what you meant.

All:
Here are some questions in my mind:

Is there a process that can be preformed on a birfield AFTER is has passed the tempering process of the factory to increase strength?

If so, does this same process derogate another attribute of the metal to compensate for the increased strength (ie trade off)?

I don't know what kind of steel they make birfields out of (let me know if you know) but tempered martensite is about as strong and ductile and tough as you are going to get (that i have heard of and i am no expert) anything else you do to gain strength you will sacrifice ductility which would be a really bad thing in the case of a birfield. Seems like if they were any more brittle it would be a huge problem.

Originally posted by RRaker
I don't know what kind of steel they make birfields out of (let me know if you know) but tempered martensite is about as strong and ductile and tough as you are going to get (that i have heard of and i am no expert) anything else you do to gain strength you will sacrifice ductility which would be a really bad thing in the case of a birfield. Seems like if they were any more brittle it would be a huge problem.

Yea.....MATE 210-215, I remeber those days. Get Heidersback on the case................come on guys, look up an iron carbon phase diagram.

snake oil....... i am not a metealurgist either but i have asked one and his opinion was that it was hocus pocus. lots of racing teams use the process and nobody can demonstate that it adds any strength, but then again nobody can demonstarte that it doesn't.

Originally posted by camo
snake oil....... i am not a metealurgist either but i have asked one and his opinion was that it was hocus pocus. lots of racing teams use the process and nobody can demonstate that it adds any strength, but then again nobody can demonstarte that it doesn't.


Heat treating like i duscussed makes a very big difference.

I have some access to the -300 freezers here at work, and there is a guy I know that sticks all his knives in one for a couple of hours, and they do hold their edge and sharpen easier, he even claims that a pair of panty hose will last longer if frozen for a few hours in one of thse freezers,

so what is the process, they throw the thing in the freezer for a while and pull it out? if thats all, some one bring me an axle, and we'll try it, then go break the thing.

regarding stress build-up: The shafts I had cryo'd were new spicer blanks and broke after two trips. I usually ran 20+ year old junk yard take-outs and resplined them, but I stepped up for the new stuff for a fair test. ie not cryo'ing a take-out that was potentially stressed previously, thereby swaying the results of the cryo'd axle testing.:D

The new super-birfs aren't just cyro'd. They're also getting heat treated to reduce brittleness, I forget all the details, they were posted recently. I'd go search it out but I need to get some work done and I'm lazy :flipoff2:

Don't go and through axles in a -300 freezer. That will cause thermal shock and they will shatter just like the terminator in T2. The cryo process is very calculated and take minimum or 18 hours on up depending on what it is and mostly how thick. I have done a fair amount of research into this because I am planning on starting a buisness in this field. In simple terms what it does is finish the heat treating process. When something is heat treated they let it cool and then send it out the door but at room temp the process wasn't done. So by slowly bringing the temp down to -300 it let all the molecules arrange in proper order so they arn't in clumps so to speak. This also lets the marinsite move up to the surface and therefor make a very durable surface. So does this make a better axle I have no idea but I doub't it hurts. What I do think it would help is an axle that has been turning one way for years and then is cut down and used the other direction. I think the process would realy help to alieve the built up stress. What this does help dramaticly is wear surfaces like rings, ring & pinions, end mills, drill bits, and such.

Originally posted by Brent Orton
he even claims that a pair of panty hose will last longer if frozen for a few hours in one of thse freezers,

Now why would he know this ? :rainbow:

Why do they reinforce the crotch anyway, I have a hard enough time gaining access as it is !

Wish I had something constructive to contribute, but I am enjoying the discussion!

Originally posted by orbitcat


Now why would he know this ? :rainbow:

Why do they reinforce the crotch anyway, I have a hard enough time gaining access as it is !

Wish I had something constructive to contribute, but I am enjoying the discussion!
This is one of the handout things they do to show you it does something. Another they do is hand out treated disposable razors that last about 10X longer. I don't think he is :rainbow: and was doing his own pantyhose but it is funny to think about.

Originally posted by 84xtracab

It is clamed that this process will…
· creates a denser molecular structure. The result is a larger contact surface area that reduces friction, heat and wear.


I have always wondered how cryo treating can make the molecules "denser" without effecting the overall size of parts. I ask because as far as I know you can cryo treat gun barrels, axle shafts and the like and then stick them right back in where they came from. You aren't adding material, so if it gets denser than the physical dimensions have to be affects.

Anyone know the answer to this one?

so here is a quote from the tech article.

"When I returned home, I called Mr. Long and asked him what makes his Super birfields hold up so well. He replied “heat treat”. He told me that a stock birfield was heat-treated to a 65 Rockwell hardness (that is as hard as a file). He explained that he re-heat treats the inner cages to soften them and then he has them cryogenic hardened. Cryogenic hardening is done by dipping the part in liquid nitrogen and freezing it to -300 degrees. He also re-heat treats the outer shell and at a certain temperature, he stick welds the outer ring on with a “special rod”. All of this produces a “Super birfield”. These birfields have been tested on a special machine and were able to withstand 10,000 pounds of torque at a 30 degree angle without breaking. Pretty impressive I must say."

How does this "re-heat to soften" step effect the cryo process?

Originally posted by orbitcat


Now why would he know this ? :rainbow:

Why do they reinforce the crotch anyway, I have a hard enough time gaining access as it is !

Wish I had something constructive to contribute, but I am enjoying the discussion!

this qoute combined with the picture under "orbicat's" username was hilarious....i think I hurt myself when I fell out my chair with laughter...:D

Originally posted by 66CJdean
Don't go and through axles in a -300 freezer. That will cause thermal shock and they will shatter just like the terminator in T2. The cryo process is very calculated and take minimum or 18 hours on up depending on what it is and mostly how thick. When something is heat treated they let it cool and then send it out the door but at room temp the process wasn't done. So by slowly bringing the temp down to -300 it let all the molecules arrange in proper order so they arn't in clumps so to speak. This also lets the marinsite move up to the surface and therefor make a very durable surface.

Molecules in steel don't rearange themselves at room temp much less -300 degrees. That is why for tempering you have to heat them back up to 500 deg. As far as martensite "moving to the surface" martensite is a term for the structure of teh entire thing. If you want a martensitic surface you case harden (like gears).

I talked to my proffessor and she had no idea why any one would do this. She found it baffling. She said she is going to talk to other proffessors and look up more info. (btw she has a doctorate in materials engineering)

you get proper arrangement of molecules in pearlite which is air cooled slowly.

more to come wed/thurs

some guy had them in his rear 44........................ they broke...

Originally posted by Dirty Harry


I have always wondered how cryo treating can make the molecules "denser" without effecting the overall size of parts. I ask because as far as I know you can cryo treat gun barrels, axle shafts and the like and then stick them right back in where they came from. You aren't adding material, so if it gets denser than the physical dimensions have to be affects.

Anyone know the answer to this one?

I was a Materials Engineering student for a few years and don't know the answer to this question, however, I will take a stab at it. It may be because the the materials do change dimensions but they change so little that the parts are still within their original tollerences. The molecules become denser because of the cold (cold contracts) and then in a way the piece is cold worked thus changing the crystal stucture (more compact). This is only a guess.

So, could this process be aimed at a set of ball joints. I've got a couple of designs for unbreakable steering knuckles, but I need to figure out how to keep the ball joints in one piece.

Easy

Last time I looked into it the process also de-stress'd the parts which makes their tolerance for *pain* much more (since they aren't in it to begin with).

Personally I like the idea and process. I've seen it work more times than I've seen it fail.

Just keep in mind that it does its best work on things that wearout.

Just a guess, but it seems that you take an axle temper it and then cryo dip it and this would give you an axle that has the same wear resistance but is less brittle.

Originally posted by Air Bag
Just a guess, but it seems that you take an axle temper it and then cryo dip it and this would give you an axle that has the same wear resistance but is less brittle.

AB, I am not really following you on this one...how about harden the axle, temper the axle, cryo the axle = more wear resistance, more brittleness (denser crystal structure on the outside). Just a guess. If I have time i'll break out the books.

Here is the deal with cryo treating steel. 99% it is a hoax people are making money selling snake oil. However there are a few cases where it is beneficial. The only time it is beneficial is in martensitic steels that have retained austinite. Basically most of the steels that are heat treated are of this type. They heat the steel up above 1700 degrees and then they quench it in water or oil. When the steel is hot it is in the austinite form and if it is cooled quickly enough it forms martensite. If it cools too slowly it forms bayinite. this is where the hardenability of the alloy comes into play with different alloys you have to cool it at different rates to form martensite, the TTT diagrams come into play here, but anyway sometimes when you are near the limit or in some really high strength steels like airmet 100 not all of the austinite has converted to martensite. If this is the case putting the material in liquid nitrogen transforms that retained austinite to martensite. It makes sense to do this right after quenching and before tempering so you have a uniform tempered martensite microstructure. This is a real procedure there is an ASTM standard for it and everything.

Now the more legitamate cryo treating places claim that they take the retained austinite and transform it to martensite, and that this is good even after the tempering process has taken place. They argue that the volume change that takes place produces residual compressive stresses in the surface of the part which should give better fatigue life. Certainly if there was some retained austinite on the cutting edge of a razor blade or a wear surface this process would make it harder and more wear resistant, but ussually the retained austinite is near the middle of the part. They also claim that the process gives better dimensional stability at elevated temperatures. This would make sense and I know of a couple applications where it has been used in the aerospace industry for that purpose.

So on an axle shaft or transfer case output shaft that is induction hardened yes it actuall could help slightly in theory, but we are talking about gaining a few percent in strength. I have had offers to have it done for free, and I haven't accepted.

As far as panty hose and stuff goes, I am not a polymer scientist, but I work with some and they all think it is a joke.

Right on Gordon.........