nitride treatment

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by retiredcpo, Feb 20, 2011.

  1. retiredcpo

    retiredcpo Well-Known Member

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    Anyone have any experience with this treatment
    comments good or bad.
    Reccomnedations on who/where to have it done.
    trying to get prepared to rebarrel my 7mm remington mag.
    Thanks retiredcpo
     
  2. Trickymissfit

    Trickymissfit Well-Known Member

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    I've done a lot of it in my lifetime, but honestly I would not do a gun barrel. Melonite would be the route for me.
    gary
     

  3. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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  4. sinarms

    sinarms Well-Known Member

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    I am going to send out a barrel to a guy to have nitride coated. It will be in my 338 Sin chambering and I will test it side by side to a twin uncoated barrel.
     
  5. retiredcpo

    retiredcpo Well-Known Member

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    Gary
    What Bryan said! what is the differance?
    Do you know who does this ect
    Retiredcpo
     
  6. ZEEK

    ZEEK Member

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    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
     
  7. MontanaRifleman

    MontanaRifleman Well-Known Member

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    I've been talking about this in my 6.5-375 Ruger thread. I decided to go with a couple of Wildcat 375 Ruger builds in 30 cal and 6.5 after talking with my smith about the process. He seems impressed with it and is planning on doing one of his bore burnig rifles with it. This is the only reason I would consider doing a 6.5-375 Ruger.

    I did some googling on it today and found a number of threads from other forums and this video with the guy Bryan mentioned. 5000 rounds and his F-class rifle is still shooting 1/4 MOA.

    YouTube - Salt-Bath Nitriding for Rifle Barrels -- Joel Kendrick Interview

    Based on this development, if it's as good as it looks like it is, I'll be choosing higher velocity chamberings for future rifles.

    For a 7mm, I would go with the 375 Ruger or RUM for LR application.

    For a 25 Cal, I'm thinking of a WSM

    For a 6mm, I'm thinking of an -06 or WSM

    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!
     
  8. Trickymissfit

    Trickymissfit Well-Known Member

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    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
     
  9. MontanaRifleman

    MontanaRifleman Well-Known Member

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    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.
     
  10. Trickymissfit

    Trickymissfit Well-Known Member

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    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
     
  11. Buano

    Buano Well-Known Member

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    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 gun), and hence the increased velocity possible (so long as there is adequate case capacity).

    With factory ammunition I would expect a velocity decrease.
     
  12. Topshot

    Topshot Well-Known Member

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    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.
     
  13. MontanaRifleman

    MontanaRifleman Well-Known Member

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    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.

    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.
     
  14. Buano

    Buano Well-Known Member

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    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.