Nitride Treated Barrels?

[bullseye]

this just keeps getting better,, i'm gonna order another one, while still on sale. looks like the ole blind sow did find an acorn.

[Mjolnir]

I am no longer in the auto industry so I no longer have [direct] access to their prodigious library and phenomenal subscriptions (both print and electronic) but I can make some phone calls to ex-fellow employees who are either still in R&D or Motorsports to try to obtain some more technical papers on nitrocarburization of ferrous and non-ferrous alloys referencing wear and corrosion resistance.

Suffice it to say, Gaston Glock got it right by using carbon steel and nitrocarburization (that's what "Tenifer" and "Tuftride" and "Melonite" are; they are merely tradenames for unique processes). ALL (USP-based) H&K pistols are treated likewise and can be found in the P30 Owner's Manual (or was it the P2000?). Same with Walther and FNHUSA pistols. With Glock, the barrel is treated. HK *may* be doing the same thing but obtaining the info from them is difficult to get. I assume they are doing the same or similar things as Glock is doing.

Sig Sauer has not hidden the fact that they employ nitrocarburization on their barrels but few gun persons are metallurgists and therefore there has not been a lot of conversation about it.

To clarify more about my comments about "since a bolt gun is not used like a carbine" previously, what I meant to say is that we're not trying to resist gas port erosion with the bolt gun (and probably not as much as one would think with a semi-auto precision rifle, either). With the precision rifle it's all about the throat and the last couple of inches from the muzzle. If nitrocarburization is more wear resistant than hard chrome which is better than bare metal it may very well be "an answer" - as opposed to being "the answer".

Persons who shoot better and more than I could state, "How many rounds do you send down range a year?" as well as rightfully declare, "Ten thousand rounds is a lot of rounds downrange and is more than 'good enough' for 99.99% of those behind the stock of a precision rifle. True, from my perspective.

But as an engineer I'd like for "everything" to "last a lifetime" and any technology that is readily available in one industry should be investigated and applied where proper to any and every other.

So for me it's cryogenically treated chromoly steel forgings, nitrocarburization and PVD coatings (like Tungsten DLC which has electroless Nickel substrate or Titanium Aluminum Nitride over electroless Nickel) on the exterior. I'm not aware of anyone doing this and there are plenty of barrel makers who would take issue with one or all of my "recommendations". To be honest, the vast majority of owners would NOT recognize a difference with these technologies as they don't shoot enough to stress their equipment. But if they could have that technology for, say, $120 more I'm certain that a fair number (likely all on this website and others like it) would spring the coin. I sure as Hell would.

[Mjolnir]

Here is an example of the type of papers available IFF (if and only if) you have access to subscription databases. This one is from Elsevier.:


Department of Materials and Metallurgical Engineering, Dongeui University San 24 Gaya-dong Busanjin-gu Busan 614–714, Korea

Received 15 August 2006. Available online 7 May 2008.

Abstract

Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of AISI 4140 steel. Plasma nitrocarburizing was conducted for 3 h at 570 °C in the nitrogen, hydrogen and methane atmosphere to produce the -Fe2–3 (N, C) phase. It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of -phase, with a small proportion of γ'-Fe4 (N, C) phase. The thickness of the compound layer was about 10 μm and the diffusion layer was about 300 μm in thickness, respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at a constant temperature of 500 °C for 1 h. The very thin magnetite (Fe3O4) layer 1–2 μm in thickness on top of the compound layer was obtained by plasma post oxidation. It was confirmed that the corrosion characteristics of the nitrocarburized compound layer can be further improved by the application of the superficial magnetite layer.

Key words: plasma nitrocarburizing; post oxidation; -Fe2–3(N, C); γ'-Fe4(N, C); Fe3O4

[khc3]

Is this process pretty easy to "get right," or does it require some level of expertise/experience?

Can it be done incorrectly or insufficiently?

In other words, is any "nitride" treatment likely as good as any other?

[Thomas M-4]

With salt bath nitrocarburization there is "no need" for the cold hammer forging - or stainless steel barrels.

Why?

No need for the several million dollar tooling though one can make a barrel per minute with CHF process at or near final dimensions. Besides, cut rifling produces a more accurate rifle and grooving with the least amount of stresses.

One can treat stainless steel but it actually loses corrosion resistance from this process and it won't be as hard as the chromoly steel (nor as tough for 416) and it's slightly more difficult to machine - surface speed is less so it's cut at a slower rate.

With the tougher, less expensive steel with less internal stresses (and cheaper tooling) I can then use ferritic nitrocarburization to make the surface nearly impervious to corrosion and the chamber, land and grooves should be tougher than hard chrome without the issues of geometric anomalies and flaking.

Look at H&K, Sig Sauer, Glock, Walther and FNHUSA - all carbon steel; and S&W for martensitic stainless steel. In Europe, several use the process (I believe) - and they also use different (read "better") alloys like 9310.

I was told by Accuracy International at SHOT 2006 that they nitrocarburize their barrels. I'm told they hold their accuracy for "well over 15,000 rounds." I don't own one so I cannot give you firsthand results.

I have experimental results comparing ferritic nitrocarburization, Tungsten DLC and hard chrome somewhere in storage. I'll try to ferret it out.

I am assuming that the DSA barrel is 4140. Assuming that nitride treated barrels out last chrome lining why would DSA put a superior treatment on a inferior barrel steel? Seems like 1 step forward another step back. Assuming it is 4140 steel.
If H&K, Sig Sauer, Glock, Walther use better alloys why would DSA use 4140 steel in there barrels?

The price of $175 is really low price for a quality AR barrel BCM lists for $259 not factoring in what you get with HPT/MP testing Which would have the longest service life?

[Mjolnir]

I am assuming that the DSA barrel is 4140. Assuming that nitride treated barrels out last chrome lining why would DSA put a superior treatment on a inferior barrel steel? Seems like 1 step forward another step back. Assuming it is 4140 steel.
If H&K, Sig Sauer, Glock, Walther use better alloys why would DSA use 4140 steel in there barrels?

The price of $175 is really low price for a quality AR barrel BCM lists for $259 not factoring in what you get with HPT/MP testing Which would have the longest service life?

I'm not sure what the DSA barrel is composed of but let's assume it is AISI 4140 (a good assumption, btw). The cost of steel is rising and the more "exotic" alloys are much more expensive than say 4140. A lot of it has to do with economies of scale. There is more usages of 4140 (NOT a cheap or poor alloy) than, say, 9310. Besides if its the stiffness (controlled to a large extent by geometry) and interior surface condition it's less expensive to use 4140 over a generally tougher alloy which may have higher costs associated with it and may have different (read "more expensive") requirements for machining. In other words it's machinability may not be as conducive to what is being used now. Everything is a compromise.

I think the pistol barrel makers are *all* (more or less) using 4140 or it's EUro equivalent.

I'm not sure I understand which are you comparing for longer usable life. Are you asking about different alloys or different barrel lining methods?

Keep in mind that throat erosion ends your accuracy long before the rest of the barrel - minus the last three inches, perhaps - on a rifle barrel. Both will lead to a degradation in precision.

[Mjolnir]

I found that I DO have an account with Science Direct/Elsevier so I do have some articles related to nitrocarburization and W DLC to share with anyone who is interested.

[Abraxas]

I found that I DO have an account with Science Direct/Elsevier so I do have some articles related to nitrocarburization and W DLC to share with anyone who is interested.

I absolutely would be interested

[MikeCLeonard]

So is Ferritic Nitrocarburizing the same process as Tenifer and Melonite?

Also, these are just surface treatments and do not impart any black color to metal surfaces correct?

[variablebinary]

Is this process pretty easy to "get right," or does it require some level of expertise/experience?

Can it be done incorrectly or insufficiently?

In other words, is any "nitride" treatment likely as good as any other?

According to Robinson Armament, yeah, it's a science not everyone gets right

They just had some XCR Barrels nitride treated and the barrel extension was weakened, so they are trying a different vendor with more firearms experience

About 80% of the M96 was nitride treated so they have some experience in this area