
Originally Posted by
SomeOtherGuy
Daniel Defense is offering a CHF barrel with nitride treatment in the new 300BLK upper. AFAIK this is the first nitrided CHF rifle barrel on the market. (Glock and others have been doing nitrided CHF handgun barrels for years.)
From what I've read, and I am only an amateur:
1) properly done, the nitriding process is so hard and deep that hardness or wear resistance of the metal below the nitride layer becomes relatively less important;
2) a barrel that is made of good steel and treated with a good nitriding process will last so long that seeking additional life is almost irrelevant in a semiauto-only rifle;
2) the temperatures involved in typical salt bath nitriding may be high enough to counteract some or all of the benefit of work hardening from the CHF process.
Constructor and Rsilvers seem to know plenty about nitrided rifle barrels, hopefully one or both of them will chime in here.
A related question that I would like to know is this: given the apparent benefits of nitride treatment, why don't we see machinegun barrels using this approach? To my limited knowledge, most machinegun barrels are CHF and thickly chrome lined, or in a few cases lined with Stellite or other special alloys that have superior high temperature wear resistance. Does nitriding lose its benefits at higher temperatures?
My 2 cents:
I work as an applications engineer for a valve company. My work is mostly in critical process applications, many of which are high pressure/high temperature steam for turbines in power plants.
In one such application, we were using 316ss with a nitride-type overlay on the seats and gate of the valve. We began to experience valve leakage (failure). What we found was not that the nitride had failed, but rather that the 316 under the nitride layer was physically compromised through heat and galling. Thus, we made the switch to a harder (though less chemical/corrosion resistant) 410 stainless.
The point being that despite nitriding, the sub-material can be affected, particularly when heat is involved.
Now, these are valves with large surface areas. Not gun barrels, so Robert may have different experience.
Semper Paratus Certified AR15 Armorer
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