I was chatting with a machinist at work and he was thumbing through a cryogenics book. He brought up that the book lays out for you how to cryogenically treat your own parts at home with dry ice. He said that the dry ice is no where near as cold as liquid nitrogen, but its easier to get your hands on and will show improvement (for people like me that cant justify the expense of the real thing but would love to have something better than ‘stock’).

Here is the procedure he laid out for me.
- take a Styrofoam cooler
- line it with painters plastic
- place parts inside it
- fill with kerosene, alcohol, or any other liquid that wont freeze
- drop a bunch of dry ice inside
- close the lid and let it sit until the liquid is back to room temp
- pull (metal) parts out and place in the oven @ ~ 400 degrees
- after an hour or so, turn off the oven and with the oven door still closed, let the parts cool slowly.

Now in the above procedure I specify if the parts are metal proceed with the tempering process. He showed me in the book where they do the same process (minus tempering) with various plastics and show positive results. One of the most dramatic of which is a set of golf ***** that they treated and showed a 125 yard average gain. The built a hitting rig and all that to take the human element out of it….

Has any one herd of this or have tried it?
If so what are the results?

I am thinking of testing this out with a set of drill bits.
- buy 6 bits all the same brand type and size
- take some 1” thick hardened steel
- using a drill press see how many holes can be drilled in a designated time interval or until failure with the 3 untreated bits.
- use this method to treat the last 3
- repeat the same test at the same speed, same material, and compare.

That and Im going to do a set of golf ***** (any thing to help my game a little!!)

 

You should certainly get more use from your short irons if this all works as advertised. Your tee shots should now put you on the greens on those pesky 400 yard par 4s.

FWIW, most high speed steels used in cutting tools like drill bits have probably already had the deepfreeze and temper process done to them during manufacturing. Give the drills a break. Use pre-heat treated 4140/4142 at Rc 26-32 for your test. You can buy a piece at www.mcmaster.com.

Let us know how the 400 F temper works on aluminum.

Jon

 

yeah I had thought of the issue you pointed out with he drill bits so that’s why i was going to go down to harbor freight and get some cheep-o junk made in china.

we have some T-1 tank steel here at the shop. i was going to grab a chunk of that to use.

any thing im missing here about the aluminum? I may have misunderstood what he said but I was fairly sure he mentioned to do the heat treatment with aluminum as you would the steel... I haven’t had any classes on material science or any thing so I have no clue when it comes to this, just what I was told to do by him.

Im just curious if any one has tried this, and if it worked?

 

Actually 400F should not do anything to the aluminum. I must have been thinking of 400C. We cure powdercoating @ 400F.

If I were doing your drilling test, I would also use a good HSS drill (not from Harbor Freight) and a TiN coated HSS drill as benchmarks.

Have fun.

Jon

 

yeah true.
I have a feeling that no matter how well I will do this the Hss drills will blow it away. I just want to see if there is any improvement. then again your right a bench mark on the upper end would be nice.

 

My gut says that the procedure you layed out won't cool enough to do a damn thing to most metals. I don't think the co2 has enough latent heat of vaporization to cool the liquids to a useful degree, and the cooling will happen at a much faster rate than a real cryo treatment. The normal procedure involves hours of carefully controlled cool down and back to ambient temps. That being said, there is no substitute for real world testing, so the only thing you have to lose is a few dollars and some time.

 

dry ice is not cold enough.

Need Liquid Nitrogen, to cool a container of isopentane. Lower the part in the isopentane ie approx -270C, for 30 sec.

THEN the cooling will only penetrate less then 1 mm on each side. SO unless your part is 2mm thick or less, Cryo treatment does not work.

 

i disagree here..
Yes dry ice will never cool it enough to get the same results. But I believe it will cool it enough to gain significant results over non treated metal.

Also if you are only cooling the item for 30 seconds it wont penetrate the metal fully so it will have to soak for longer.

I will take a second look at that book and get a name and author so I can hopefully find excerpts online.

 

Dipping the parts in a cold solution for 30 seconds doesn't even remotely accomplish the point of cryo treatment. Useful cryo processes do not thermally "shock" the parts at all. It is a VERY gradual temperature differential. IF it was as you described, then of course it wouldn't work.

 

if cryo treateements dont work then why do some tranny sponsers here advertise that service on their builds?

 

i dont think cyro treatment not working is the question here.

 

I seem to remember my high school days in advanced chemistry we did a class project involving freezing stuff to very cold temps. but we used glass instead of metal and then heated it to a high temp in a standard oven...anyway the outcome give the glass a tempered effect and also made harder to break, I'm guessing that it is possible in a very small chance to process metal in this way but its going to be difficult to eliminate as many variables as possible...it is all very interesting though!

its like heating up metal to its melting point and them rapidly cooling it maing it stonger right?

 

To make money on an easy to do process

30 secs or 24 or 48 or 100 hours, there is no difference in penetration. The so called cold tempered can not penetrate more then 1 mm from the cooling liguid. SO 2 mm max for penetration.

We have done some extensive test of cryotreated brake rotors. We found cryo rotors crack sooner then normal

Be very careful on some of those so called expert articals or books. Most of them can not be verified in per review engineering journals

 

The brake rotor is not a good comparo to this your talking failure to heat cycles.The op just wants to make something more stress resistant.

 

What's your source for this info?
I assume that by "cold temper" you're referring to some assumed thermal shock. Rest assured, the part WILL get cold through and through if it's left in the cold environment.

The primary mechanism whereby cryo treatment works in the iron-carbon system (steel) is completion of the phase transformation from austenite to martensite. This transformation is not complete if the quench is stopped at room temperature. Cryo treatment is therefore only a continuation of the initial quench used in the original heat treatment.

CO2 method should have SOME effect, just not as much as a complete treatment to a colder temperature. You also have to be sure that you have enough CO2 in the cooler to keep your parts cold long enough to fully "treat" them.

What kind of parts are you eventually looking at doing? Parts with stringent surface finish requirements (like gears, crankshafts, etc), may NOT be a good idea to treat without subsequent machining operations. The austenite and martensite lattices have slightly different densities. When the phase transformation is run to completion, the volumes of the austenite pockets will change. Since the initial finishing operations were done with these pockets in place, the change in volume will cause the surface to become "lumpy" even if only at a microscopic level.

 

Listen closely to this^^^. You may not understand it all, but it is pretty much correct. No critique of the content, but everyting I am familar with is right on in the post. I work in the real world of metal parts design, machining, and heat treating. BTW, "Heat" is relative, especially if you use K instead of F or C.

As in most things in nature, there is no magic bullet, but there are many things that can help at least a little. Sometimes the cost/benefit is there, sometimes it isn't. Mother Nature is one tough broad and a practicing physicist. You can't mess with her.

Jon

 

I read use ice chest with dry ice. Make sure parts are clean. Handle parts with attached wire only. Leave in dry ice 24 hours then remove using wire attached then lay on padded blanket (vary gently) & let the warm to room temp. Finished no heat involved. Most parts like tranny shafts are already tempered this improves on that. You can't have oil or grease on the parts or handle except by mechanic wire.

 

K, instead of F or C REALLY puts things into perspective.

 

I'm too lazy to go and pull my textbook and play with the requisite cooling rate; but I'm going to ballpark it and say you won't notice a difference in practice. It's primarily for surface wear properties, that's why i've got various bits on my car cryo'd. The strength, depends on a whole boatload of factors.


Oh ya, I call BS on the depth of 2mm, unless you mean that the immediate volume of effect is only 2mm depth, then for all intents and purposes it's merely a "thick surface." Then I can allow for 2mm surface hardening effect zone. (for conventional metals anyhow).
If not:
It's dependent upon cooling rate and temperature diffusion through the material. How else would amorphous metal be made? The "surface" is indeed hardened if it's the requisite steel, and there are also effects to be observed beyond the surface.
Also to consider is Chvorinov's Rule and how it can be modeled for "beyond the solidification" i.e. If a part will solidify, you must consider the atomic level differentiation of cooling rates from the outer surface to the inner surface. With enough time; the innermost part will reach the cold temperature. Simply applying the time to solidification, with mental respect to the diffusion of temperatures. Since temperature information is transmitted at the vac. speed of light, it will continue to seep into the depths of the metal for infinium. <--- information diffusion (sorry, fuzzy logic'ing some physics concepts and mech. engr. concepts together; hoping it came out right)

We're not talking about surface hardening via additives, that's an entirely different set of mechanics. <- Atom diffusion

I can make a conventional steel rotor crack just as fast as a cryo'd rotor... so moot point there. I personally run conventional, as I'm not going to waste an hour or so worth of driving to drop off and pick up some stuff that won't last me more than 5 hours, but I do know from my experience that various energy field related parts are cryo-treated as it's quite a functional process and they've shown that conventional parts have typically failed in comparison.



The process itself is divided into these presumed two realms:
1) Precipitation by incomplete prior quenching, only works on steels, steels must contain some austenite, yatta yatta
2) Physical deformation (as things get cooler, they typically shrink; metals do; blah blah blah... object at infinium near abs. zero will be at it's smallest physical size ever) I like this one because it can in theory introduce chaos to the crystalline structure and increase strength.

 

Any thing sizable that we should worry about when doing precision parts, or are we talking only 1 or 2 thousandths on a connecting rod??
I see that they do transmission parts and ring and pinions all the time without re-machining them so it cant be too much.