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nitride treatment

 
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  #8  
Old 02-20-2011, 07:36 PM
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Re: nitride treatment

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Originally Posted by bsl135 View Post
I'm interested in this process as well.

Gary, what's the difference between nitride and melonite?

Joel Kendrick (sp?) is the guy I talked to about it and plan to have do mine. Here's the article I read about it:
Melonite Surface Treatment for Barrels, Bolts, and Actions Daily Bulletin

-Bryan
I don't actually know a lot about that process, but gather it's really a coating (maybe like TIN). There's been a good bit of discussion about it on Benchrest Central. The thing that bothers me about nitride is the 900 degrees of heat, and I never seen anybody attemp anything in stainless steel. Plus (with some grades of steel) I've seen as much as .0009" shrinkage, and almost the same in growth with other alloys. Now I've had some barrels in the past that I wish I could shrink about .0005", but I also know that when the parent metal shrinks, it shrinks all the way around. Thus opening up the bore. Then there is a warpage issue from not being able to suspend it correctly. I'll probably be sending him a barrel this year (a Savage 6/250AI barrel). If you just want to try nitride, be sure to spec gas treatment!
gary
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  #9  
Old 02-20-2011, 07:43 PM
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Re: nitride treatment

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Originally Posted by Trickymissfit View Post
I don't actually know a lot about that process, but gather it's really a coating (maybe like TIN). There's been a good bit of discussion about it on Benchrest Central. The thing that bothers me about nitride is the 900 degrees of heat, and I never seen anybody attemp anything in stainless steel. Plus (with some grades of steel) I've seen as much as .0009" shrinkage, and almost the same in growth with other alloys. Now I've had some barrels in the past that I wish I could shrink about .0005", but I also know that when the parent metal shrinks, it shrinks all the way around. Thus opening up the bore. Then there is a warpage issue from not being able to suspend it correctly. I'll probably be sending him a barrel this year (a Savage 6/250AI barrel). If you just want to try nitride, be sure to spec gas treatment!
gary
The salt bath nitride process is not a coating. It's an ionization, molecular change of the surface of the metal. It reaches 1100-1200 degrees.
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  #10  
Old 02-20-2011, 07:54 PM
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Re: nitride treatment

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Originally Posted by ZEEK View Post
In my present position as an Engineering Manager, I've spec'ed in nitriding on a number of different applications. There are several different nitriding processes, the three I'm most familiar with are: salt bath(or liquid) nitriding, gas nitriding, and ion(or plasma) nitriding. All three do the exact same thing, the diffuse nitrogen ions into the surface of the metal so that iron nitride (Fe3N or Fe4N) can form, either of which are extremely hard. Before doing nitriding it's important to understand the heat treat history of the metal being case hardened. The nitriding process temperture can be as high as 1100 1200 degrees F, if your metal's tempering temperature was lower than the nitiding process temperature, then the steel's mechnical properties will be reduced as a result of being exposed to the the higher nitriding temperature.

PS
Melonite is a salt bath nitriding process
Now I'm quite familure with liquid salt, but never put the two together! How does one deal with the 1460 degree temps? As well as warpage? I've not done any liquid salt work since the mid 1970's, and I'm sure some things have changed over the years (you don't see it used very much anymore)

There is another form of liquid nitride treatment that actually injects cracked amonia into the furnace (temps escape me). I did my race hemi cranks that way a zillion years ago. Parts come out a sooty black, and the case might be .0075" deep at best. I've aslo done plasma a little bit (very small parts), but not very much. Most of what I did was with gas at 900 degrees. Process was slow, but quality was excellent (usually carborized & hardened 8620 or 4000 series C/H that had been prehardened)

Tell us a little more about this process as it's new to me. And is it or is it not a granular penetration? Also how deep of a case are you working for?
gary
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  #11  
Old 02-20-2011, 09:05 PM
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Re: nitride treatment

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Originally Posted by MontanaRifleman View Post

There is supposed to be an increase in velocity which is another bonus. How much seems to be sketchy, but thread poster claimed 200 fps, 3250 to 3450 in his 19" 300 RUM barrel.

This is really great if it's real!

As I understand it, with the same loading, pressure would decrease markedly & velocity would decrease some.

Due to the reduced friction & related chamber pressures you can increase your loading to more than regain what velocity was lost (so long as the shells will ONLY be used in this , and hence the increased velocity possible (so long as there is adequate case capacity).

With factory ammunition I would expect a velocity decrease.
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  #12  
Old 02-20-2011, 09:19 PM
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Re: nitride treatment

Do not do it without the expressed permission and guidance of the barrel manufacturer.

They must specify the exact barrel material used, temperature etc and approve the exact process with the company doing the treatement.

Failure to do this will void the barrel warranty and may be dangerous as the wrong heat treatement can change the barrel strength.
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  #13  
Old 02-20-2011, 10:13 PM
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Re: nitride treatment

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Quote:
Originally Posted by Buano View Post
As I understand it, with the same loading, pressure would decrease markedly & velocity would decrease some.

Due to the reduced friction & related chamber pressures you can increase your loading to more than regain what velocity was lost (so long as the shells will ONLY be used in this , and hence the increased velocity possible (so long as there is adequate case capacity).

With factory ammunition I would expect a velocity decrease.
Yes, I understand this and thanks. I will shoot low level break-in rounds through it to remove any rough spots, then have it treated. Once treated, I will work up my loads.

From my reading on the subject, the more used the barrel is, the more risk of accuracy loss. I plan to only do this in new and broke-in barrels.

Quote:
Quote:
Originally Posted by Topshot View Post
Do not do it without the expressed permission and guidance of the barrel manufacturer.

They must specify the exact barrel material used, temperature etc and approve the exact process with the company doing the treatement.

Failure to do this will void the barrel warranty and may be dangerous as the wrong heat treatement can change the barrel strength.
The barrel maker (Broughton) was actually the first one I broachd the subject with. He had no problems with it and his customers have had about 50 of them done so far.

To the best of my knowledge, on the research I've done so far, most, if not all actions and barrels made these days will not be affected by this heat treatment other than metal stress relief which might cause some "movement". Custom barrels are stress relieved my the makers and should not be greatly affected.
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  #14  
Old 02-21-2011, 03:52 PM
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Re: nitride treatment

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Originally Posted by MontanaRifleman View Post
From my reading on the subject, the more used the barrel is, the more risk of accuracy loss. I plan to only do this in new and broke-in barrels.

This makes no sense to me unless there has been significant throat erosion & the smoother surface keeps the rifling from grabbing the bullet. If that's the case, the barrel was toast already.

Even if the barrel has been shot a lot, this treatment should slow the future wear down considerably & keep it shooting well longer. If a "well used" rifle is dismantled & reassembled, that might introduce accuracy issues but that would not be caused by the metal treatment, just by disassembly & reassembly.


Only question I have is whether a barreled action can be treated as one piece or whether it must be dismantled completely prior to treatment. I would love to get a couple of bright stainless rifles treated as this would dull the stainless glare, and make the rifles more wear resistant. If this could be done without removing barrel from action my costs would be lower.
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