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Cryogenics on rifle barrels
- Thread starter Ldoll
- Start date
Al Thompson
Staff Alumnus
Personally, the jury is sort of out on this issue. I have one rifle that was frozen and it seems to validate the concept. (as far as cleaning anyway) I understand that Krieger freezes theirs and a couple of guys (Bruce Dow for one) feel that it works with blued steel but not stainless. My biggest problem with the process is that I can't verify that the rifle was "really" frozen. The other problem is that most of my guns are SS.
Giz
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"I don't make enough money to buy cheap stuff" - Mark Manning
Giz
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"I don't make enough money to buy cheap stuff" - Mark Manning
I had a new barrel made up for my 22-250 a few years back.Had it cryo'd right away so have no before and after stories.It does seem to clean easily after 100 or so shots.It is my truck gun and usually lays on floor.I didn't do the bolt as I wasn't sure what the treatment would do to springs.
I had the barrel on my Win. M70 Westerner (.223) done and it no longer liked its favorite load. Before I could develop a new one I found a Rem. 700 VLS in .223 so the Winchester is a goner. I haven't fired the Rem. yet but I did encounter some reloading difficulties. See Handloading section if interested.
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Gale McMillan
Member In Memoriam
It seems that every time I finish a chapter in my book someone makes a post on my material.. I just finished this subject yesterday. I tried a controlled test in 1984 on cryo treated barrels. It was on S/S match Bench Rest barrels and it was for accuracy only. Results were negative. It did not help. A couple of years ago Lazzeroni did a comprehensive accuracy and wear test. The conclusion was accuracy negative but some improvement to wear. Before he did a release on the study he did the complete study again. This time the results were the exact opposite as the first test and the control barrel lasted longer. Conclusion Save your money!!!
hksigwalther
New member
Well, having seen this question here a couple of times I had decided to ask my former boss of any benefits of cryo-treatment. (His degrees up to PhD are in metallurgy, UConn):
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Hey Ron,
.
.
.
The heat treatment industry differentiates between cold treatment (-84°C) and cryogenic treatment (-190°C...liquid nitrogen
temperatures). The purpose of these treatments is to convert retained austenite to martensite. Austenite is a face-centered
cubic phase of steel which forms during solidification or heat treatment above 740°C. Martensite is a body-centered cubic
phase of steel which forms when austenite is quenched. However, some of the austenite doesn't get converted to martensite
during the quench, and is called retained austenite. Martensite is the desired phase in tool steels; the presence of
retained austenite can cause excessive wear, undesirable residual stresses, and cracks. Austenite is thermodynamically
unstable at room temperature, but the kinetics are slow; it would probably take a few hundred years to change. Cold
treatment and cryogenic treatment will accelerate the phase transformation to a few hours or a day.
Cold treatment of tool steels is pretty widely accepted in the metallurgical community---it works, and we know why.
Cryogenic treatment of tool steels has been under debate for years, mostly because the mechanism is not completely
understood. Some believe that the lower temperature produces a more complete phase transformation to martensite; others
believe that submicroscopic carbides form, reducing internal stresses. There is evidence that wear resistance of cryogenic
treated parts is better than cold treated parts; the degree of improvement depends on the alloy. I don't know if cracking
resistance improvement over cold treated parts has been documented.
That's a long-winded answer to a short question. Yes, cold treatment works. No, I'm not sure if cryogenic treatment is
worth the extra money. If you want more details, let me know. Good luck!
Barry
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So...what I gather from what he had written was some evidence suggests cryo does have, at most, a very slight benefit but whether if it is cost effective is up to the user.
- Ron V.
[This message has been edited by hksigwalther (edited January 24, 2000).]
__
Hey Ron,
.
.
.
The heat treatment industry differentiates between cold treatment (-84°C) and cryogenic treatment (-190°C...liquid nitrogen
temperatures). The purpose of these treatments is to convert retained austenite to martensite. Austenite is a face-centered
cubic phase of steel which forms during solidification or heat treatment above 740°C. Martensite is a body-centered cubic
phase of steel which forms when austenite is quenched. However, some of the austenite doesn't get converted to martensite
during the quench, and is called retained austenite. Martensite is the desired phase in tool steels; the presence of
retained austenite can cause excessive wear, undesirable residual stresses, and cracks. Austenite is thermodynamically
unstable at room temperature, but the kinetics are slow; it would probably take a few hundred years to change. Cold
treatment and cryogenic treatment will accelerate the phase transformation to a few hours or a day.
Cold treatment of tool steels is pretty widely accepted in the metallurgical community---it works, and we know why.
Cryogenic treatment of tool steels has been under debate for years, mostly because the mechanism is not completely
understood. Some believe that the lower temperature produces a more complete phase transformation to martensite; others
believe that submicroscopic carbides form, reducing internal stresses. There is evidence that wear resistance of cryogenic
treated parts is better than cold treated parts; the degree of improvement depends on the alloy. I don't know if cracking
resistance improvement over cold treated parts has been documented.
That's a long-winded answer to a short question. Yes, cold treatment works. No, I'm not sure if cryogenic treatment is
worth the extra money. If you want more details, let me know. Good luck!
Barry
__
So...what I gather from what he had written was some evidence suggests cryo does have, at most, a very slight benefit but whether if it is cost effective is up to the user.
- Ron V.
[This message has been edited by hksigwalther (edited January 24, 2000).]
Art Eatman
Staff in Memoriam
Based upon the posts above, it seems a fair summary might be 1) There is a bit slower rate of wear in cryogenically treated barrels. Easier cleaning means smoother surface; smoother surface means slower rate of wear. How much slower? I don't know. 2) It could be beneficial if the barrel has some problem with residual stress, created during the machining process. If a barrel for whatever reason does not have stress-related problems, there would be little or no benefit.
Since most barrels "wear out" from flame erosion in the throat, the gain in rate of wear of the barrel in general does not seem significant.
It seems to me that this could be part of a lengthy process in "perfect accuracy", but only a part.
FWIW, Art
Since most barrels "wear out" from flame erosion in the throat, the gain in rate of wear of the barrel in general does not seem significant.
It seems to me that this could be part of a lengthy process in "perfect accuracy", but only a part.
FWIW, Art