My company is envolved with hard chroming & nitriding stamping draw dies for the Automotive Stamping Industry. These are the dies that stamp out most of the sheet metal on vechiles.
In regards to surface treatements the major difference between hard chroming & nitriding is one is a coating "Hard Chrome", the other is a penetrant "Nitride".
In regards to Nitriding there are two different process's we use:
1.Nitriding which has a surface hardness of 58-62 RC.
2.Ion-Nitriding which has a surface hardness of 58-62 RC, but has a surface layer of what is called a White Layer which has ceramic qualities that aid's in it's lubricity.
Both process's are considered a high heat process, after Ion-Nitriding the dies have a very rough surface that needs to be stoned & polished before going back into the press.
The intial hardness of 58-62 RC for a Ion-Nitrided piece is only a few thousands deep, from there hardness will drop off. Basically what you have after Ion-Nitriding is a case hardening process with lubricity due to the ceramic qualities of the White Layer.
Dies will rust after treatment, most dies are cast iron or cast steel.
These stamping dies will see a tremendous amount of friction & heat due to the forming of sheet metal, more then any rifle barrel would see in normal shooting.
Both process's do quite well in that enviroment. I have seen dies with over a million hits before needing to be processed again.
I've often thought to Ion-Nitride my receivers & bolts, but to Ion-Nitride or Nitride my barrel to help with corrosion or enhance the life of my barrel would be a waste of time & money.
The chance of warpage would be too great. I've seen inserts that weigh over 50lbs that where Nitrided that had to be squared up again afterwards due to warpage from the high heat.
The only way I would surface treat a barrel bore is with a low heat process, but I just don't see the benefits versus the cost.

Whatever you say, InfoSponge. Only people who know what they are talking about is capable of "oversimplification". This discussion hasn't been broad and shouldn't be.

Now you back nitrocarburization into a blueing substitute as long as it does not affect bore durability...you don't seem to see it as a bore treatment anymore, are you finally convinced that durability of hard surface treatment IS dependent to material underneath? Please say yes so I can take a vacation.

Do show respect and be grateful to others' intellectual capability, without above response from other members, you will probably still have undue faith in the nitrocarburization for bore idea.....having a misunderstanding for indefinite amount of time in life, should upset the intellectually-keen type like you. True intellectuals challenge and destroy their own misunderstanding, not to carry it on and superimpose on others. Know how much you don't know.

If you propose an idea and want to make your statement strong : seek and provide hard evidence yourself, if one is unwilling to believe in others then he'll just have to be on his own.

I feel that I have learned little from you and that I am not obliged to make you believe anything more, I shoulda wisely retire from this conversation like Axel did. If you truely want to find out more, then like Axel said, find out yourself. That's all I want to say.

A spongeful of info,
can't absorb no more,
if it thinks it's full,
only after it is willing,
to give up those bad info,
will it siphon even more.

Pyrotek,

I'm sorry that you seem to take what I intended as a purely technical discussion as some sort of personal affront. You make take a vacation anytime you wish, and I will gladly retire from further correspondence with you on this subject.

Sounds like a job for Saeed, and his crew of experts!

Hasn't Blackstar made a business out of this? I believe they (at least at one time) offered a bore surface hardening process that was supposed to extend the accuracy life of a barrel.

Paul

To all of you nitriding proponents. I did a little research through the archives.

Steel - SAE 4140
Nitriding temperature: 950 F
Dissociation: 25%
Nitriding time: 50 hours
Core hardness: 25.6 Rc (avg)
Surface harness: 53.1 Rc (avg)
Effective case depth: 0.127 mm (0.005")

Steel - SAE 4140
Nitriding temperature: 950 F
Dissociation: 25%
Nitriding time: 50 hours
Core hardness: 35.2 Rc (avg)
Surface hardness: 61.4 Rc (avg)
Effective case depth: 0.356 mm (0.014")

Remember that all heat treatment and tempering MUST be completed before nitriding! Also, the tempering temperature used MUST BE GREATER than the nitriding temperature to maintain strutural integrity during nitriding. Rc 35 is about all the harder that 4140 can achieve and be tempered above the nitriding temperature.

Nitriding is a DAMNED expensive method for creating a wear resistant surface. Wear does not begin to be significantly affected until surface hardness approaches Rc57.

Nitride away, but at least you have been warned.

Infosponge, this is REAL data taken from REAL steel shafts. There is NO cyber world dreaming going on here!

FINAL NOTE. THE RC VALUES ARE CONVERTED FROM RN-15.

Axel

[ 04-28-2003, 21:03: Message edited by: Axel ]