Firecracking vs Barrel Steel

[riflewoman]

I think Webster’s original question was about the atmosphere in secondary heating processes such as stress relieving and heat treating (if any). And to answer his question, with atmosphere control you get two main benefits. Scale formation control and hydrogen embrittlement control. In short cleanliness of the part.

 

[Texas10]

What difference does the protective gas make if metal is turned off of the O.D. I did metallurgical failure analysis for 45 years.

To answer your question, here's a real world example. Some years ago a major aircraft reciprocating engine manufacture was experiencing inflight crankshaft failures which resulted in several serious accidents and as I recall, at least one fatality.

Analysis determined that the old way of making the steel used, melting in an open atmosphere was leading to cracks forming INSIDE the steel. These crack developed during use and were not detectable during manufacture.

They recalled all the crankshafts, and replaced with controlled gas melt process steel at a cost of millions of dollars in losses, lawsuits, etc.

Here's link to a discussion on the subject for further reading.

https://www.supercub.org/forum/archive/index.php/t-36459.html

 

[riflewoman]

It sounds like the problems with Continental. Their approach was to impose that the cranks have to be made from a Vacuum Arc Remelt billet.

 

[Dud]

Barrelmakers spec their steel way more in depth than knife makers down to the gases used in heat treat. They each have their own formula they refine and perfect over years not just send us some 416

I have to say this is probably not true.

Custom knife makers value their labor. The smart ones buy top quality super alloy steel and tune their heat treat to get more hardness without sacrificing very much ductility compared to a "book" heat treat.

They buy the best because crap steel makes the result of their labor a mediocre knife. If the foundry doesn't deliver a consistent product that is going to make it impossible to tune their heat treat to the level that a high end custom demands.

A production knife is made by a factory, not by a knife maker and they do often suffer from variability in lesser alloys that don't have the benefit of well controlled powder metallurgy.

On the other hand, comparing knife steel to barrel steel is tough, barrel steel has to resist high heat and pressure, knife steel has to have edge retention but generally it operates much nearer to room temperature.

I think the heat created by shooting a rifle is pretty close to an annealing process so I'm not sure how much long term effect barrel heat treatment will have. A heat treated knife will retain it's hardness unless it is abused some way, like heating the blade untill it is orange to sear/brand something.

 

[FrankG]

If I recall correctly and it varies with cartridge and type of powder used....but the temperature in the throat area of the barrel when a round is fired in a rifle...is from 2200 to about 4000 degrees F. 2200 degrees is the temperature of lava for a mental note. Food for thought.

 

[moondog]

It would be interesting to get a list of suppliers/ manufacturers of barrel steel.
I asked my Barrel guy where he gets his.

 

[butchlambert]

It would be interesting to get a list of suppliers/ manufacturers of barrel steel.
I asked my Barrel guy where he gets his.

Why? What will it tell you?

 

[moondog]

Just curious is all.

 

[butchlambert]

Just curious is all.

Me too, but I wouldn't know what to do with it.

 

[davidjoe]

Why? What will it tell you?

It would be interesting to see what’s in use, but probably just a snap shot. I’ve got to think that if a supplier felt irreplaceable, the price would creep up or the quality down. And even if it did not, closing the door to better options presented down the road isn’t good, either. As to the discussing details of the exact steel specified, ... if there aren’t going to be any options to choose from anyway, then there’s probably a downside to a maker, or all of them going down that road, without any upside. I would not personally want to have a year’s supply of something that got prejudged as second best before I even touched it.

 

[moondog]

Western Branch is the supplier for my Barrel maker. I asked him the other day out of curiosity. He specs a lot# because of experience with others. Basically reinforced what Frank posted on manufacturers. Like most here, when I do a new chambering, I get multiple barrels done at the same time. Sometimes different makers. I HAVE seen a difference in throat wear/ fire cracking within the same caliber. Different barrel manufacturers is the only difference. Just curious is all.

 

[FrankG]

Here are some pics of the barrel that has 14,560 rounds on it. Sorry they are not the greatest.....but it should give you an idea of what it looks like.

The first one is at the case mouth.

The next one is the lead in. Well kinda! I know what reamer was used in the barrel and a close number is the beginning part of the throat/lands are worn completely away for about .375".

Next picture if I recall correctly was a little in from the throat area. The copper color is fouling from the bullets. The barrel was not cleaned. It's as we received it. Other than wire EDM cutting the barrel in half.

Last picture is in further yet.

 

[butchlambert]

It would be interesting to see what’s in use, but probably just a snap shot. I’ve got to think that if a supplier felt irreplaceable, the price would creep up or the quality down. And even it did not, closing the door to better options presented down the road isn’t good, either.

So you would be able to know without a doubt which is the better steel from this?

 

[moondog]

So you would be able to know without a doubt which is the better steel from this?

No, but pretty sure Frank would

 

[davidjoe]

So you would be able to know without a doubt which is the better steel from this?

... If more steel details were provided, just speaking for me here, sure, I would make the effort to read up on it. Readers here are at the very technical end of the spectrum; I don’t know if you mean by “you” me, all of us forum types, or just barrel customers in general. But even Frank’s post above mentioning a special order being placed requiring a different spec of steel was intriguing. Would written details alone prove out the best steel, nope. But if the details for example said we are trying a three point harder alloy with a higher carbon and chrome content to see what long string shooters think, because they don’t let these barrels rust, but they do heat them up, that would be interesting.

 

[CharlieNC]

This is such a fundamental principle, I would be shocked if it has not been studied extensively. If not directly on barrels, at least relating to applications with similar conditions. Unless you know the correct key words, Google will not necessarily uncover the info. For example I am heading out on a hunt soon and researching terminal ballistics again and this time uncovered comprehensive studies about wounding, incapacitation, hydrostatic shock, etc conducted by the military and FBI. People, not deer or elk, but directly applicable. I bet a similar analog is the situation here.

 

[FrankG]

... If more steel details were provided, just speaking for me here, sure, I would make the effort to read up on it. Readers here are at the very technical end of the spectrum; I don’t know if you mean by “you” me, all of us forum types, or just barrel customers in general. But even Frank’s post above mentioning a special order being placed requiring a different spec of steel was intriguing. Would written details alone prove out the best steel, nope. But if the details for example said we are trying a three point harder alloy with a higher carbon and chrome content to see what long string shooters think, because they don’t let these barrels rust, but they do heat them up, that would be interesting.

Sorry to disappoint ya but....To me the grade was a little different than what we normally use but nothing that would last longer per say. It's a standard grade spec. that is out there but just not normally used on a daily basis. We've made barrels out of that grade before. The grade was spec'd because of size (diameter of material) and that it had be chrome moly steel just a different grade of CM. For the one order I tried in the hardest way to get them to go to S.S. material. I could get it in the diameter and quantity I needed in our normal time frame of about 22 weeks. No deal it had to be c.m. material. I told them up and down that the stuff they we're wanting to use wasn't going to work any better or last any longer and for us to order it was going to take X amount of time and they wanted the barrels quicker than what we we're being told. No dice. They had to have that spec. and where going to wait for it.

The kicker is they would accept using s.s. for the 50cal. test barrels (accuracy barrels) but they wouldn't accept it for the 5.56 and 7.62 test barrels.

Speaking of special steels we've worked with at least 4 different grades of material this year for special jobs. Everyone is looking for that magic recipe for longer life. Some of the stuff we worked with was awful to machine. One grade wasn't even machinable! Not the first time that's happened. All of these where for test barrels for specific purposes and nothing that the match shooter would see at this point in time.

That's the kicker guys.....there are grades out there that can possibly help barrel life but it has to be readily machinable at a reasonable cost. If there is a grade that can be machined but the grade of material costs us two or three times more and our tools don't last as long and I say the barrel costs will double...is the average guy willing to pay for it to get a 50% or double the barrel life? Also keep in mind that the average gunsmith.....will he want to work with it if his chamber reamer is only good for making one or two barrels?

We tried to rifle some material about 10 years ago and the only way to even get close to rifling it was they had to wire edm burn a hole in the blank of the barrel. Yes burned a hole thru the length of the barrel. I didn't even ask what that cost them to do in a 21" long blank! Guess what....the stuff couldn't be rifled. They told us they had the grade of material to use for the cutters...and supplied it. Guess what? Barely put a scratch in the bore. They spent two days in the shop with us hanging over our shoulder watching everything we did.

 

[butchlambert]

No, but pretty sure Frank would

I'm sure Frank has dealt with this, But I was asking why you and 99% of the rest of the folks would do with it.
TRUST YOUR BARRELMAKER.

 

[Tim s]

To Frank or anybody for that matter, are most of the SS barrels made today largely derived from 416 or 416R with the big variable with the R being the sulphur content ?

 

[Tim s]

Barrelmakers spec their steel way more in depth than knife makers down to the gases used in heat treat. They each have their own formula they refine and perfect over years not just send us some 416

Maybe the mass/semi mass production guys but the custom guild guys have some unbelievable spec steels that many use to turn out some of the high end customs, and that is just for the SS formulations, especially some of the stuff sourced from Japan.
If you move into custom Damascus, some of it will blow your mind as to some of the custom billets being made, including custom powdered metal patterns forged throughout the billets. Some guys even managing to forge/weld dissimilar Damascus in single blades.