Cryogenic Treatment on low alloy steel

Oct 4, 1998
Hey did anybody read june Knives Illstrated Q&A about the Cryogenic Treatment? If you have what is your opinion?

I have got one hell of a arugment going on, at swordforum.

-Greg Johnson

I just discussed this topic with someone who does cryo treatment for knives and anything else. I don't know what the question is, but as I was told, it does improve both toughness and hardness in low alloy steels. However, I was also told that it improves performance on alloy or stainless steels but not as significantly. I was also told that it would not have any effect on the treatment that the steel previously got, including forging. How true this all is, I do not know since this comes from the source. Some say it makes absolutelly no difference.

Cryo? Well, I have yet to see any studies, let alone well conducted studies, showing any improvement.

Someone (I believe Mad Dog) summed it up this way: it is another imaginative way to separate the suckers from their money.

I think it is like EDM rifling. It was the rage a few years ago, and then it was found out not to be as accurate as traditional broached rifling. So Ed Brown has switched back from EDM to broached rifling.

Perhaps it worked years ago with low alloy tool steel, such as M2. With the new high alloy tool steels, which can contain much more vanadium than the traditional ingot steels, I doubt there would be any difference. M2 has about 2% V, which is about the most you can obtain with ingot steel. With CPM technology, you can get up to 15% vanadium. With that much vanadium carbide, I doubt that the change of a slight amount of remaining austenite to martensite will have much, if any, effect.

If anyone knows of data to the contrary, I would very much like to see it. Walt
Greg, the following is from CFI in Florida, for what it's worth:


"By extending the standard heat and quench cycles of conventional metallurgical practice to the cryogenic reaches of the temperature scale, certain desirable structural changes are induced in alloys commonly used in industrial applications. Controlled thermal cycling between +400ºF and -310ºF markedly improves the wear life of steel and cemented carbide tooling and wear parts. Cryogenic processing, performed after conventional heat treating, enhances tool life by three known mechanisms:
The conversion of significant amounts of retained austenite to martensite.
The formation of fine carbide particles.
The relief of residual stresses.

Steel cutting tools, cobalt & non cobalt-bearing HSS, uncoated or TiN or chrome coated: DRILLS - END MILLS - HOBS - BROACHES - REAMERS - TAPS - CHASERS - FORM TOOLS - SAWS - ROUTERS - PIERCING TOOLS - SLITTERS - KNIVES - etc.
Copper alloy resistance welding electrodes
Stress relieve ferrous and non-ferrous castings and forgings for enhanced dimensional stability and surface finish upon final machining.

The Benefits
Dramatically reduce consumption of perishable tooling. Treated tools typically yield two to five times the production of non-treated tools before regrinding is required.
Cryogenic treatment will result in the permanent volumetic enhancement of metal properties. Treated components may be ground after treatment and the benefits of treatment are retained.
Reduce the frequency and cost of tool regrinding. Worn treated tools require less material removal to restore a uniform cutting edge. Hence, treated tools may be reground more times before falling below minimum acceptable dimensions. This represents yet an additional cost savings.
Substantially reduce machine downtime attributable to tool replacement.
Reduce the scrap rate for machined forgings and castings by cryogenically treating prior to final machining for better stability and surface finish.
Cryogenic processing, enhancing the wear resistance of steel and cemented carbide, chromium or TiN coated tools and wear parts, and copper resistance welding electrodes;
Dimensionally stabilize metal optics and precision ground parts prior to final polishing/grinding to produce a superior surface finish;
Stress relieve forgings and casting to ensure dimensional stability during final machining;
Dimensionally stabilize nylon components;
Stress relieve metals for tear-free drawing."

For what it's worth. It would be nice to see some real world results from identical knives with identical steels.

I think you have it backwards Cobalt. Last year on the knife-list there was a big discussion about this, and Howard Clark stated that he doesn't believe cryo treatment does much good for low alloy steels, as long as the heat treatment is well controlled. He doesn't bother with it, since low-alloy steels are what he works, and his heat treating equipment is very accurate. He said he thought it might do some good on high alloy steels which tend to have a slower, and less reliable, conversion. He said he thinks the biggest proponents of cryo treatment are the companies that sell it.

There are a couple of guys that do a lot of work with high-alloy steels who highly recommend it for the steels they use, namely ATS-34, and they are Ernest Mayer of Black Cloud Knives and Larry Harley of Lonesome Pine Knives. Ernie says that he gets about a 25% improvement in the toughness and corrosion resistance of ATS-34 by cryo quenching. I have heard numbers as high as 45% increases for 440C, but a lot of that depends on how well the non-cryo treated blades were quenched.

thanks guys, I was trying to see what you thought of the article in the mag.
Not really what you thought on cryogenic treatment in general. I have been researching the subject for about 20 years now.
I think it works on all stuff not just High alloy metal.
In fact I hace some computer chips that I had cryogenic done on them and I could run them a lot faster.
They were pentium166. you know the 166 has a buse speed of 66mzh and you get 166 by multiply 66 by 2.5 it get 166. Well the cryogenic chip runs at 83 buse speed ot get a speed of 208 out of a 166 chip. And I tryed ot uver clock before the cryogenic it didn't work but after it worked great.

-Greg Johnson

I think Cobalt has it right.

If you are saying what Howard told you, then you are wrong. Howard is the one I am Talking to about this on a another forum.
And doesn't like cryogenic At ALL.
I do see the problem

-Greg Johnson

Greg, it wasn't Howard.

But my last statement is what applies the most. The proof is in the pudding. Until you make two exact knives, one cryo'd and the other, not, it is hard to say if the improvement is significant as well. This would have to be done on every steel to really get an idea of what's happening.

Doesn't this sound like another strengthening system, forging. Knife makers on this forum have stated that you do not get anything out of forging D-2, yet you get alot out of forging 1084. Same may apply to cryo for different steels.

Greg, what exactly is the discussion that you are having on the other forum?
Basically I say It helps he says not. But he did get very mad at me for saying I think he is wrong. I dodn't have all the data but I think it is worth ding on all blades. He doesn't think so. My reasoning is this even if I am wrong and it doesn't help it won't hurt plus it doesn't cost vey much. I have sent off blade to be done it cost me $5-10 blade.

Now Howard makes swords so it would cost a little more say $20-50 per blade buut his stuff cost $1200-whatever. I don't think Another $20-50 is going to hurt.

But Again did you read the Q&A in the June KI
He has some data I thought Howard would like to know. Like I said he just got mad.
I really don't want to say any more, we have decided to just drop it on the other forum.
And I don't want sombody tell him I am talking about him. I told him it was over.
If you really want to know go over Aand look.
I really shouldn't have started this thread, Iam just look for trouble :0
But thanks for the replay.

-Greg Johnson

Greg, I don't see the big deal in having this discussion. I think it's worth discussing. As long as everyone behaves and puts in facts, it's worth it.

My question and comment to you is, that I hope that the knives you sent have handles either pinned, rivetted, or screwed on, or no handles at all, because if they were epoxied on, chances are you will need to re-epoxy them on.

I was also told by a source that does cryo that it does not hurt the previous treat.
No it was some I heat treated myself. I didn't grind them a friend did but I heat treated them and finished them.
I can't grind very good YET but I will learn even if it kill me. But I sure hope it don't.

The reason I am worried is that Howard Got mad, So did I. But I think I had a good reason to get mad, but my opinion is biased and it could have been all my fault.

I don't want it to start over here. But thanks. I love to argue, that is the best way to learn new stuff.
Not that I am arguing with you.

-Greg Johnson

[This message has been edited by gregj62 (edited 19 April 1999).]
Hey, Greg, if you are finishing some knives maybe you can leave one as is without cryo and compare it to the cryo'd one. Edge holding, lateral strength would be good testing.

The reason I say this is because theory is one thing but actuall test results really provide insight.
Keep in mind the history of this topic with Howard. As I mentioned, he and a few other people have gone over this before. I think his reaction may have been a little bit of impatience due to that fact.

Howard's problem was with the argument that cryo helps ALL blades, ALL the time, when both he and Randal feel that they have proven to their own satisfaction that cryo doesn't help their blades with their steel and their heat treatment.

Randal keeps getting ignored when he states that one person can make two blades, quenched the same, cryo one, and the cryo treated blade may be better. But, that may be due to the fact that there was significant retained austenite in both blades before cryo. What Randal and Howard are saying is that if you heat treat the blades in a fashion that does not tend to result significant amounts of retained austenite, cryo treating them to reduce the retained austenite isn't going to do much good.

And, by the way, which is generally more inclined to have retained austenite, low-alloy steels, or high-alloy?

DAMN YOUR EYES, Harv. Here I thought I was getting the hang of this metallurgy thing, at least the basics, and then you toss out a simple question and I am mind boggled.

Austenite is a crystal formation of iron atoms, characterised by softness and not being magnetic, correct?

Martensite is a different crystalline arrangement of iron atoms, characterised by hardness, and being magnetic. Right?

Well, since the 'high alloy' steels tend to have more carbide formers, and keep the iron bound up in the carbide form, I think that less free iron would be available to alternate between austenite and martensite.

Am I right? Walt

So, am I right, Harv, or not? Walt

[This message has been edited by Walt Welch (edited 20 April 1999).]
Whoa, that's a little over my head Walt. I do not understand how the concentrations of carbide forming alloys effect the martinsitic transformation, except in the most general terms. There is this quotation from Howard Clark from the article on Cryogenics on

"The second possible thing that can happen is the change to martensite if there was retained austenite in the microstructure of the material. This is applicable to blades, but only if retained austenite is present. If the heat treating is done well, then there is no retained austenite present, i.e. no benefit to the cryogenic treatment. Retained austenite can be a problem with high alloy steels (stainless steels with high carbon are particularly susceptible, but still only if the heat treatment was not optimal in the first place). Low alloy and simple steels (likely what your kukri is made from a 10xx steel) are extremely unlikely to benefit from a cryogenic treatment, as they are unlikely to have any retained austenite to convert to martensite in the first place."

That supports my understanding of the benefits of cryogenics for knife blades, which is that it is of more benefit to high-alloy steels, which also tend to be air-hardening, than to low-alloy steels.


[This message has been edited by Steve Harvey (edited 20 April 1999).]

Oh, wait. On a second reading of your post I realize that you are correct about your characterizations of austenite and martensite.

What I don't know is exactly how the alloys effect the transformation speed and efficiency.

Even in a high-alloy steel, you've only got about fifteen to twenty percent alloys and one or two percent carbon mixed in with your Fe. If the blade is properly austenitized, all the elements should be fairly homogenously distributed, so 80% of the blade is still just plain old iron. My notion is of fairly thinly occuring carbides in a sea of Fe. Obviously the concentration of the carbon and alloys have a major effect on the austenite to martensite transformation, but for the most part, the Fe is just doing its thing without much contact with the other elements.

Maybe the 20% of alloys is by weight, and there is a much closer molar relationship between the alloys, iron, and carbon. Anybody got a periodic table?

Colbalt I have done that. but I can't be sure still, cause I am still learning and if you over heat it or under heat it during ant of the heat treat it will effect the out come.
But by my test the edge holding is about the same. but the toughness is improved.
But I am 100% sure of the results. Plus I was for the cryogenic treatment. And human nature as it is I might have changed the out come with knowing.
But I am sure enough that cryogenic works that I will do it unless I am proved it doesn't work.

-Greg Johnson

I thought the article on Cryo treatment in the June K.I. was very informative and self proving. That about sums it up for me.
Ed, I knew about the site but you really can't believe them, as they have a vested interest in proving it works and not that it don't work. I take it with a grain of salt

Oh and thanks RMLamey for the replay.

-Greg Johnson