View Full Version : Barrel Treatments (nitride/CL)
Senior Bigg
04-18-12, 14:12
I am not an expert if any of my information is incorrect please correct me. I do not have any impending NEED/WANT to do anything to my rifle this is purely an inquisitive post based off my interest on this topic.
From what I have read I feel I have a good understanding of what CHF barrels are, how they are made and some benefits offer (like removal of kinks or density inconsistencies in the metal and a longer overall barrel life). From what I understand CHF consistently gives accurate shots for a longer duration despite the barrel getting hotter. My interest is in how the barrels are treated. From what I have come across it seems like one can either choose a CHF with chrome lining or a non-CHF with Nitride.
Chrome lining: Although chrome lining hampers accuracy to a certain degree it makes the barrel last longer because one would have to “go through” or wear out the chrome before getting to the steel. Once this happens the inside of the barrels may have imperfections leading additional lose in accuracy (I don’t know the round count it would take for this to happen). The thicker the lining the longer it will take to wear down. The most wear occurs in the throat and the edges of the lands within the barrel. Chrome lining adds to the barrels dimensions. Having said that, the harder the steel is underneath the chrome the longer it will take for the chrome wear.
Nitride: Doesn’t add anything to the dimensions of the barrels because it’s a surface treatment. The surface metal of the barrels is changed making it harder than chrome lining and more wear resistant. It’s more corrosion resistant; it keeps the accuracy of the barrel (unlike chrome lining) and gives the barrel a longer life.
I read a post by someone with this statement and I thought it was interesting: “Putting Nitride on a non-CHF barrel is like taking one step forward and one step back.” If Nitride is “better” than chrome why wouldn’t manufactures make Nitride CHF barrels?
I take it that a non-CHF barrel would wear out faster without chrome - but if a CHF chrome lined is it still advantageous to the shooter since the barrel is already made for longer life?
Is my information correct? If not where have I gone wrong? I would love to hear what you guys think, pros/cons and what your experiences have been.
Is my information correct? If not where have I gone wrong? I would love to hear what you guys think, pros/cons and what your experiences have been.
Actually, and this is just my take, but you are mixing things that are only slightly related.
CHF is a method of forming a barrel. It makes for a harder, more durable barrel, compared to a regular CMV steel or stainless barrel.
The next thing you mentioned is chrome-lining or nitride treatment. Both of these are treatments that can be added to a barrel, CHF or not, to increase barrel life and reduce corrosion. Nitride (or Melonite as S&W calls it) is fairly new, and many folks have not gotten used to it. You can expect to see it used more as time goes by. Newer S&W ARs are using 1:8 melonite treated non-CHF barrels. Chrome-lining has been around in ARs since the mid 60s, so everyone is familiar with it. The thing you don't want is a non-CHF barrel with no treatment. There are actually quite a few barrels sold that are just CMV steel (Chrome-moly Vanadium, no relation to chrome-lining,) with no treatment. Likewise, it seems silly to use both barrel treatments, trying to nitride treat a chrome-lined barrel.
An Undocumented Worker
04-18-12, 17:17
There are people out there in the process of getting some CHF barrels manufactured specifically to be nitride treated. Unfortunately the manufacturers capable of doing this are also very busy manufacturing existing products and still not able to keep up with demand.
Give it time.
If I may add, if a nitride treatment to a chrome lined barrel seems silly, how about chrome lining a nitride treated barrel? Or, why no CHF barrels that have been given a salt bath and chrome lined? The manufacturer's scared they will not wear out?
CarbonCycles
04-18-12, 18:52
Chrome lining is an additive process in which a layer is added to the interior surface of the barrel. This process does not yield as uniform a surface compared to a strict surface treatment process.
In my experience, chrome lining is more suited for hard-use scenarios where precision is not paramount. I also owned a LWRC NI-COR (or whatever surface conversion process they call it), and I found the barrel to be more than sufficient in accuracy and durability. However, I'm comparing apples to oranges as well because of barrel profile...YMMV
Chrome = plating. Adding an additional layer of a harder material to the substrate with the intention of preserving the substrate while wear takes place on the chrome lining.
Nitriding = chemical process that infuses different elements into the outer layer of the material, thusly changing its properties and making it more durable in its own right.
Cold Hammer Forging = process by which steel is formed around a mandrel using a heavy press machine that "hammers" the steel into the form of the mandrel. Creates a harder metal(anytime you stress metal it becomes harder, not always a good thing, but in this case it is. Usually refered to as "Work hardening") that will be free of the associated stresses and imperfections of a broach or button that would be normally used to create rifling.
Chrome, as some of the common internet beliefs go, was originally intended to allow barrels made from less durable and easier to manufacture steels, to last longer and be easier for the basic infantry grunt to maintain properly. It has been said that because of this, nearly all modern military rifles (with a few exceptions) are required to have chrome lining. Chrome lining typically runs from .002" to .004".
Nitriding was initially developed (insofar as I know) in Europe and has slowly started getting a foothold here in the States. The process has vastly improved over the years and now there are several different versions of nitriding, each offering different qualities and intended use. Nitriding (depending on the process) can have a nigher natural lubricity then Chrome, be harder then chrome(depending on the alloy being nitrided), and in virtually all processes, is more corrosion resistant then chrome. Penetration into the material can vary depending on the alloy used (the higher the alloy content, the less penetration, but the harder steel will become), and will generally penetrate to approximatly the same depth as chrome adds in thickness, or in some cases it penetrates twice the depth that chrome would add in thickness, ususally between .004" to 0.008". Nitriding also increases the fatigue strength of the material, with the QPQ process more then doubling the fatigue strength of the material.
http://www.finishing.com/kolene/qpq/
In the end, for me personally, I was lucky enough to choose a CHF barrel AND nitriding (QPQ) to cap off a project that was 10 years in conception and building. The barrel steel is some proprietary unicorn tears infused German CHF barrel steel (that HK won't release the specs to) that I was able to have Quench/Polish/Quench (QPQ) nitrided.
I'm expecting this barrel to last at least 60,000 rounds based on previous testing of the barrel steel and current data avalible on the nitriding process. My only gripe is that i'll have to shoot about 20k rounds through it before it reaches its full accuracy potential.......No, i'm not joking.
See post #5 by a gentleman who used to work for HK= http://www.hkpro.com/forum/hk416-hk417-hq/123273-hk416-mr223-accuracy-problem.html
Senior Bigg
04-18-12, 19:56
Chrome, as some of the common internet beliefs go, was originally intended to allow barrels made from less durable and easier to manufacture steels, to last longer and be easier for the basic infantry grunt to maintain properly. It has been said that because of this, nearly all modern military rifles (with a few exceptions) are required to have chrome lining.
Nitriding was initially developed (insofar as I know) in Europe and has slowly started getting a foothold here in the States. The process has vastly improved over the years and now there are several different versions of nitriding, each offering different qualities and intended use. Nitriding (depending on the process) can have a nigher natural lubricity then Chrome, be harder then chrome(depending on the alloy being nitrided), and in virtually all processes, is more corrosion resistant then chrome.
I'm expecting this barrel to last at least 60,000 rounds based on previous testing of the barrel steel and current data avalible on the nitriding process. My only gripe is that i'll have to shoot about 20k rounds through it before it reaches its full accuracy potential.......No, i'm not joking.
How is it possible that a barrel will reach full accuracy potential with MORE use? Is this a common trait with Nitride?
If Nitride proves to be worth it's salt (no pun intended) will chrome lining still have it's place in the shooting world? I know I may be jumping the gun with that question.
How is it possible that a barrel will reach full accuracy potential with MORE use? Is this a common trait with Nitride?
If Nitride proves to be worth it's salt (no pun intended) will chrome lining still have it's place in the shooting world? I know I may be jumping the gun with that question.
It's not the nitriding process that does this, it's the barrel itself. The nitriding will just make it more difficult and make the process take longer. See the link I edited in above.
Also see post #4 in the following thread: http://www.hkpro.com/forum/hk416-hk417-hq/152388-review-mr308.html
SomeOtherGuy
04-18-12, 23:23
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?
Senior Bigg
04-19-12, 10:21
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;
So what you're saying, is that the nitide treatment can be so effective that CHF barrel may not be necessary? Just any high quality barrel?
Does nitriding lose its benefits at higher temperatures?
I would be interested to find that out as well, good question.
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.
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.
You just drove home the point that the quality of the materials is just as important as the finishing processes.
Coatings like chrome or processes such as nitriding can only make up for so much if the material they are applied to is of low quality.
Start with materials like a high quality alloy CHF barrel and perform high quality processes such as QPQ nitriding to get the best all around package that will last and perform.
Senior Bigg
04-19-12, 19:40
This is great information guys, thanks for the feedback!
Absolutely love this website, for this thread alone is worth the price of admission.
Absolutely love this website, for this thread alone is worth the price of admission.
And that aint cheap;)
From what I understand, nitriding reduced effects of friction, but not heat. I dont know what the final verdict was, but some people were discussing this in a previous thread and people were suggesting that the throat erodes quicker on a nitrided barrel(compared to a chome lined barrel) if you use it for high volume firing due to head effects.
however, nitriding protects the barrel from friction and its a surface treatement(more uniform) so its better for precision guns.
Chrome lining is a layer, it cannot be perfectly uniform so there are slight accuracy detriments, but it is better for high volume fire.
Adding one to the other is pointless. I dont think you can nitride chrome. Chroming over nitrided steel offers no benefits over plain chrome lining as you are still putting a layer on it, and once it wears out, you have a hole bigger than it should be for the application. Heat effects may also be the same, but I dont know how nitriding helps the steel handle heat.
And that aint cheap;)
From what I understand, nitriding reduced effects of friction, but not heat. I dont know what the final verdict was, but some people were discussing this in a previous thread and people were suggesting that the throat erodes quicker on a nitrided barrel(compared to a chome lined barrel) if you use it for high volume firing due to head effects.
They suggested this or did they provide data? If so, I would like to see the data on this. Link?
I'm not sure how chrome reduces the effects of heat and since much of the heat is created by friction, wouldn't reducing the effects of friction as nitriding does, help mitigate this issue from the get-go?
And what are "head effects"? Can't say i'm familiar with the term.
I personally think that the two main issues to look at are the hardness and the lubricity of the process/lining.
A harder material means that it wears slower, natural lubricity reduces friction, hence reducing friction generated heat, and in the end reduces wear even more.
Nitriding on cheap steel will result in a rockwell below that of chrome, thusly making it inferior to chrome lining in several aspects.
But nitriding on a quality alloy will produce a higher rockwell equal to or higher then chrome depending on the alloy, thusly increasing its hardness and natural lubricity all the way around and producing a superior product.
Also, nitriding, by its very nature, increases the natrual lubricity of the base metal as part of the chemical process, not just because it hardens it. All comparitive tests i've seen have shown that salt bath nitriding produces a much slicker surface then chrome, both with and without some form of lube.
Add to that the superior corrosion resistance and you've got yourself a winner as far as i'm concerned.
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.)
LWRCi has been doing CHF, nitrided barrels for some time now. I also believe the MR556A1 has some form of nitriding performed on it's cold hammer forged barrel.
FWIW: The barrels on Stoner 63 were nitrided. This came out in Stoner's testimony before the Ichord Subcommittee.
I have a copy of a 1968 .mil report where nitriding and chrome-lining was compared for barrels in high cyclic rate weapons. Chroming was considered superior, but noted that chrome over a nitrided barrel was better yet.
Materials for Small-Arms Gun Barrels (http://handle.dtic.mil/100.2/AD500112)
They suggested this or did they provide data? If so, I would like to see the data on this. Link?
I honestly cant remember, but I know at least one guy said chrome was better but nitriding was cheaper when you factor in cost to stay epa compliant. I'll try to find the thread...
I'm not sure how chrome reduces the effects of heat and since much of the heat is created by friction, wouldn't reducing the effects of friction as nitriding does, help mitigate this issue from the get-go?
And what are "head effects"? Can't say i'm familiar with the term.
Head effects = heat effects. It was a mistake, which happens since I dont always proof read forum posts.
to clerify how I understood, nitriding was better for the main part of the barrel, but chrome was better for protecting against throat erosion - which is more important for high volume barrels.
Let me try to find the thread-which I should have done in the first place- instead of posting what is starting to look like hearsay, I'm sure. I dont know the specs for all the materials so I cant reallygive solid info at this time.
Edit : Haha, its a thread you were active in. : https://www.m4carbine.net/showthread.php?t=83495&page=20
I only read it in the early stages and missed the last 12 pages or so. Just got caught up. I screwed up twice in one day... time to start reading more...
OP the very long thread above is well worth the read.
LWRCi has been doing CHF, nitrided barrels for some time now. I also believe the MR556A1 has some form of nitriding performed on it's cold hammer forged barrel.
Nope.
That's the biggest complaint about the MR556 actually aside from the stupid weight.
I did some major barrel work on my MR556 and it machined very nicely. It is a harder metal then typical OS, but it is through hardened, not surface hardened like nitride does.
I had the barrel QPQ nitrided as the final step in the build though so now it does have that protection and superior properties.
I honestly cant remember, but I know at least one guy said chrome was better but nitriding was cheaper when you factor in cost to stay epa compliant. I'll try to find the thread...
Head effects = heat effects. It was a mistake, which happens since I dont always proof read forum posts.
Ah, no worries, it happens to the best of us.
to clerify how I understood, nitriding was better for the main part of the barrel, but chrome was better for protecting against throat erosion - which is more important for high volume barrels.
Let me try to find the thread-which I should have done in the first place- instead of posting what is starting to look like hearsay, I'm sure. I dont know the specs for all the materials so I cant reallygive solid info at this time.
Edit : Haha, its a thread you were active in. : https://www.m4carbine.net/showthread.php?t=83495&page=20
I only read it in the early stages and missed the last 12 pages or so. Just got caught up. I screwed up twice in one day... time to start reading more...
OP the very long thread above is well worth the read.
I remember the thread. Unfortunatly I can't remember there being a whole lot of empirical data being thrown around in it one way or the other.
In my learning from sources other then those related to firearms (firearms related nitriding sources are pretty biased because they are trying to sell something) what ultimatly makes the difference in the effectivness of nitriding is the alloy used.
If it is a high quality alloy, then the material will be harder (and deeper in depth then chrome is thick) then chrome and will prevent throat erosion just as much or even better. If the base metal is a cheaper ordinary steel, then nitriding may not be able to perform as good as chrome. Although nitriding, regardless of base metal, still has a natural, inherent lubricity as a factor of the process that chrome simply cannot match.
Nope.
That's the biggest complaint about the MR556 actually aside from the stupid weight.
I did some major barrel work on my MR556 and it machined very nicely. It is a harder metal then typical OS, but it is through hardened, not surface hardened like nitride does.
I had the barrel QPQ nitrided as the final step in the build though so now it does have that protection and superior properties.
I'll be damned. You'd think they'd have QPQed it. I'm not interested in the MR556A1 because of the weight and how HK modified it so it can't work with full auto parts. It's too bad the real 416 14.5" uppers are so rare and expensive.
I'll be damned. You'd think they'd have QPQed it. I'm not interested in the MR556A1 because of the weight and how HK modified it so it can't work with full auto parts. It's too bad the real 416 14.5" uppers are so rare and expensive.
Like many, I was under the impression that the MR series was nitrided as well, so when I found out about the thickness and weight of the barrel, I was very discouraged. This was a project nearly 10 years in concept for me.
So in my case, lack of nitriding was a good thing because that meant I could customize the barrel.
I chucked it up in a lathe and took the pre-gas block barrel down to .7 inches. I wanted it lighter, but not true lightweight profile because I run a suppressor a fair amount and wanted less barrel flex. The .7 inch midweight profile is working very well for me.
And one of the first things I did once the barrel was removed from the upper was to remove the barrel extension tab that prevents the use of an FA BCG.
They have a Boron Carbide treatment available now. It uses a diffusion process similar to nitride so there are no tolerance differences. Boron carbide is the same stuff used to make hard armor plates.
Armor plates can crack due to their brittleness.
I'd hate to have that happen to a high impact gun part such as the bolt carrier or barrel extension.
As in I wouldn't want the coating to crack under repeated impacts and lose any anti-corrosive properties, nor would I trust such a lining on the inside of a barrel.
It would be great on the outside of a barrel to protect it though.
It isn't a plating. It becomes part of the steel. There is no cracking to worry about.
It only infuses the chamber and bore. Nothing else.
Armor plates can crack due to their brittleness.
I'd hate to have that happen to a high impact gun part such as the bolt carrier or barrel extension.
As in I wouldn't want the coating to crack under repeated impacts and lose any anti-corrosive properties, nor would I trust such a lining on the inside of a barrel.
It would be great on the outside of a barrel to protect it though.
I haven't looked into this in depth, but I'd guess he's talking about nickel boron coatings. You generally see them on bolts and bolt carriers. I've never seen one applied to the bore, I believe that Fail Zero tried it out and it didn't work out so well. I think it would work fine on the outside of the barrel, but I don't know if it would be enough of an improvement over something like QPQ to justify itself. As far as bolts and bolt carriers go, it's a fairly proven technology. I've been thinking about sending a couple carriers and bolts off to have it done.
It isn't a plating. It becomes part of the steel. There is no cracking to worry about.
Link?
Everything I can find says that at the most it's a coating. Can't find anything that says that it's a carbiding process.
Boron carbide is used for lots of things besides SAPI plates, up to and including sand blast nozzles.
But all of those things are made from boron carbide, not steel that is processed with "boron carbiding".
On that note, a search for the term "boron carbiding" didn't turn up anything either.
There's a few hits for tungsten carbiding, which is also a coating.
ETA: I finally found "Boronizing" as a process that produces an extremely hard outer layer of steel. It is mainly touted as an anti-corrosive/errosion treatment though and it's been around long enough for manufacturers to understand its limitations.
I bet there's a reason it's not in use in high impact processes.
I haven't looked into this in depth, but I'd guess he's talking about nickel boron coatings. You generally see them on bolts and bolt carriers. I've never seen one applied to the bore, I believe that Fail Zero tried it out and it didn't work out so well. I think it would work fine on the outside of the barrel, but I don't know if it would be enough of an improvement over something like QPQ to justify itself. As far as bolts and bolt carriers go, it's a fairly proven technology. I've been thinking about sending a couple carriers and bolts off to have it done.
I'm aware of this. I've had a fail zero BCG in one of my guns for about a year now.
Something tells me this isn't what he's talking about though.
Google B4C Technologies. That'll tell you everything you want to know. You can get it done through WMD guns.
Found it.
Next time, please refer to it by its proper name. Boron Carbide is not it.
It is a new form of "boronizing" that supposedly doesn't suffer the issues of the older boronizing processes.
The statistics they give for hardness are almost unbelieveable, yet at the same time they tout it as being nearly impervious to sulpheric acid, while showing no corrosion testing against common elements such as water.
What I find interesting is that the process doesn't affect the fatigue strength of the base material at all. One would think that by making the outer layer as hard as they claim, that the overall product would be stronger.
Don't get me wrong, the process looks very interesting. I like most of what I see, but there are some omissions that kind of bother me in the data. With how hard nitriding came under scrutiny, I think it would be in the best interest of those developing new processes to perform a thorough bank of tests and then make all of the results known.
The fact that boronizing has been around for awhile and not ever used in this manner (guns) and is mostly touted as an anti-corrosive/errosive makes me kind of leary.
And I can't find anything on WMDs site about it.
Boron carbide diffusion is its official name. Toget it you'd have to call wmd guns and ask for it.
Looks like that's a process off of my "interesting", list.
If the process has been around this long and hasn't been used in this manner and they can't detail testing and comparisons to existing processes, AND it's not listed but rather is a "call only" service with no user feedback to be found......well, I'm gonna consider it a "it sounded good at the time" idea and feel bad for the chumps who are first in line to get the process done. Sucks to be the test cases.
Good luck with it!
I've never used it myself. I happened to exchange some emails with wmd guns about nickel boron coatings and got to talking about nitriding. That was when I was told about it. It's still a very new type of treatment with the stuff involved and is little known.
An Undocumented Worker
04-25-12, 21:45
I have a couple of Benchmades with a Boron Carbide coating on the blades. On those knives the Boron Carbide coating is applied using a PVD process and only coats the surface of the steel. Is the treatment you are talking about similar or a different process?
No. It's different. From what I remember being told, the barrel received a slurry type treatment in a furnace. the temperature infused the boron carbide into the steel.
I have a couple of Benchmades with a Boron Carbide coating on the blades. On those knives the Boron Carbide coating is applied using a PVD process and only coats the surface of the steel. Is the treatment you are talking about similar or a different process?
It is not the same one.
There is a treatment (not coating) called "boronizing" that infuses boron into the top layer of the metal. Boron is an extremely hard metal and brings the surface hardness up to what is probably an excessive level.
There is a reason why barrel steel has the properties that it does. It must be hard enough to withstand the forces applied to it during firing, yet enouth elasticity so that it doesn't crack and create weak spots. Chroming helps extend the life of the barrel by adding a harder layer, but not too hard of a layer that will crack and flake out. Nitriding performs the same feature with the exception that it treats the surface of the steel.
Now if you treat the surface of hte steel to a point where it's too hard, the forced involved in the firing of a round will probably lead quickly to cracking and burn through at the cracks.
I would hope this isn't the case, but there is a point of diminishing returns when it comes to hardening metals.
At a claimed 116 Rc, I think that "boronizing" exceeds that point by several steps.
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