Work Hardening brass

[std7mag]

While researching some things a question popped into my mind about work hardening brass.
Would it be possible to work harden brass by shot peening?

If so is there a way to locallize the hardening, say to just the head/rim area? Or is it a matter of annealing the area you want soft again?

I've heard from several sources that Lazzeroni cases have a "very hard head".

I welcome any input into this matter.
Std7mag

 

[Unclenick]

If you read Hatcher's Notebook, he describes having the headstamp on some Frankford Arsenal cases struck extra deep to increase the hardness of the heads. He'd been having trouble with them blowing out before he could get to a pressure high enough to damage the Garand action. That worked and he finally was able to produce some cracks without the brass letting go first.

You do not need to reanneal. That would take you in the wrong direction and destroy hardness you might never get back again. Shot peening would probably affect the surface hardness of the brass, but I wouldn't expect anything to change appreciably deep inside from it unless you peened it so hard it was seriously distorted. You might be able to do something like roll the extractor groove a little deeper until the rifle barely closes on it, then firing to flatten the head back out. That should work it some.

If you need extra hard heads for some reason, you might buy some foreign steel case ammunition and pull the bullets and work up a load with your powder and bullets for them, but you won't normally be able to reload them, as they then develop microcracks that leak gas and cut pits into a chamber.

 

[T. O'Heir]

Work hardening is done by repeatedly moving the brass. Hammering it doesn't do that. Brass is hardened when it is heated and allowed to cool slowly. However, there's really no purpose to hardening case heads.
http://chestofbooks.com/crafts/machinery/Shop-Practice-V1/Hardening-And-Annealing-Brass.html
"...get to a pressure high enough to damage the Garand action..." JC did it (proving how strong the Rifle is) by loading increasingly higher pressure 'blue pill' loads. No special cases. He got to 120,000 PSI when one locking lug cracked. No damage to the receiver. No further damage to the Rifle. Took an 8mm Mauser round to do that.

 

[RC20]

To make it clear, do not anneal the head of the case.

That has to remain hard or it will let go and then its an explosive gas release you do not want to be part of.

Annealing for a re-loader is purely the neck and shoulder.

You do not want that going down the case. Really bad things happen.

Before we shoot it, the case is put through a series of process and that include the correct hardness for the base as well as the annelaed end.

Some mfgs leave that on (Lapua) so you can see it. Its the last stage of case conditioning and only for the neck and shoulder (polishing to bright is an appearance thing not condition) .

Most polish the anneal appearance off, they are annealed the same as Lapua, it just no longer shows, bright pretty at one time perceived good vs the less pretty anneal that is now something of a signature for Lapua though others leave as is as well.

That ability to polish off is a signature that it is not over annealed.

 

[std7mag]

I know better than to anneal the head of the case.
The casing i'm looking to work with has a rather severe rebate to the rim. Others had reported case expansion at the base. Catching on the extractor.
I'm looking to eliminate that.

 

[F. Guffey]

Brass is hardened when it is heated and allowed to cool slowly.

I am not one of those reloaders that checks the direction of the wind before posting. Again, I dug for rules that would cover annealing. I decided a few rules covered a lot of ground, I can not find anywhere there is a rule that suggest heating brass and allowing the brass to cool slowly hardens the brass.

F. Guffey

 

[F. Guffey]

However, there's really no purpose to hardening case heads.

My opinion: the difference between case head separation and catastrophic failure depends on the case head staying together as in being allowed to stretch, crush and or expand. I am the fan of case head expansion; and then? the reloader must be able to measure the expansion. Before all reloaders became experts .00025 case head expansion was a good number. Reloaders that wanted to repeat the text could not continue using the same case because the case head would hardened from being hammered against the bolt face.

F. Guffey

 

[Grey_Lion]

Yeah - Guffey - I'm with you there -

I anneal 9mm shells to swage into .40 JHP jackets and I purposefully allow them to air-cool after making the whole case cherry red to soften up the brass and remove any work-hardening in the brass.

Quenching usually hardens. Not air-cooling. Hardening comes about when carbon becomes trapped in the matrix / crystaline structure of the metal by fast cooling - not slow cooling.

 

[RC20]

I know better than to anneal the head of the case.

It sure had a different tone to me.

Any annealing work with that area has to be totally restrictive.

I can see why you suggested shot peening. sort of.

If so is there a way to localize the hardening, say to just the head/rim area? Or is it a matter of annealing the area you want soft again?

Annealing and hardening are two different things. So call me totally confused. It would help if you would describe the case and its issues or have a link.

 

[std7mag]

I'm essentially stuck with having to machine a piece of brass to make my casing. Extremely hard to find, and extremely expensive.

With the rebated rim,(the original casing was only using 40k psi) I'm looking to hopefully keep it from expanding into the extractor groove.

I was thinking of shot peening my material first, machining, then annealing the neck/shoulder area to form them.

My apologies for the confusion.

 

[RC20]

Thank you, it begins to track.

Proverbial Rock and a hard case.

 

[std7mag]

Lol

 

[MagnumManiac]

Quenching BRASS has no effect on hardness, it merely cools it, or in other words, STOPS the annealing process, which many do wrongly anyway.
BRASS can only be hardened by working it, which means moving it’s grain structure by stretching it, compressing it and pounding it.

If you anneal to ANY red colour, cherry or dull red is often coined, you have essentially ‘burned’ the metal. Burnt in this instance means that you have broken the grain structure by CHANGING the chemistry of the brass by forcing molecules to ‘gas off’. The grain structure when properly aligned through annealing run parallel and have ‘gas’ adhesion, when hardened, the grain jumbles around and loses this gas adhesion. Burning the brass destroys the gas adhesion.
If you anneal correctly, time and heat is spot on, just as the annealing temp OF THE BRASS is reached, an orange/pink flame occurs, or hue, is seen, this is the gas in the grain structure releasing, go beyond this point and you ruin the grain structure. Just as that point is reached and the case is removed from the heat, the gas resettles and annealing has taken place. If you quech at this time, as many do, it does not change the annealing that just occurred.
In my job, I am required to anneal to certain conditions of the metal in question. I make copper, aluminium and brass element windings for helical type induction, if the anneal is wrong the metal will crack as it is wound, that is unacceptable in my industry.

We manually anneal copper bar because you can SEE when it gasses off and sags, other metals are induction furnace heated, but checked by hand first for the correct temp.

It is rare to get ANY type of hardness back from ‘burnt’ brass.

Hope this helps.

Cheers.

 

[dahermit]

Work hardening is done by repeatedly moving the brass. Hammering it doesn't do that.

Soft brass has a large grain structure. When brass is hammered, the grains are broken up. Hard brass has small grain structure. Repeated firings and resizing (hammering, bending) results in the hardening of the brass.

Brass is hardened when it is heated and allowed to cool

Brass is annealed (softened) when it is heated (to a high enough temperature) to allow the small grains to grow into larger grains. Sudden cooling stops the process. https://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing

 

[Unclenick]

Brass is hardened when it is heated and allowed to cool slowly. However, there's really no purpose to hardening case heads.
http://chestofbooks.com/crafts/machi...ing-Brass.html

As far as I know, this information on that link is nonsense. If board member Mete (a metallurgist) sees this, perhaps he'll comment. Brass is hardened by cold working which displaces crystal grain plates, causing their bonds to be stressed. It can then be tempered by slow heat to reduce that hardness to a specific degree, but I know of no reason to think the crystal structure would stress itself because of slow cooling. I think that's just bad web information.

No special cases. He got to 120,000 PSI when one locking lug cracked.

That's all the information that is in Hatcher's Book of the Garand. The deeper headstamp is mentioned in his Notebook, but it's been some time since I read it, so I may be misremembering that it was for Garand. I'll have to check. But either way, deeper stamping does displace more grain boundaries and increase hardness.


Std7mag,

You can buy brass with different tempers. Here's a list of temper designations. You can look up the hardness at Matweb.com. Search under Cartridge Brass or 260 Brass. You want the H08 temper to match what most .308 case heads have, but H06 may be OK for lower pressure. Turning will affect at least the surface hardness, and I don't know what turned case makers typically do about taking that into account, if anything. After you have it turned, you would anneal the mouth same as for any case.

 

[JeepHammer]

From the industral end of things, true shot peening *Can* case harden, but it's normally used to evenly stress the surface of steel.

Shot peening of cast iron can go one of two ways,
It can clean & even out the surface, very slightly case hardening,
Or, it can stress nodular iron unevenly, setting you up for cracks.
Depends entirely on the carbon introduced into the iron and/or the nickel content.

It will compact & case harden aluminum.
Shot peening aluminum will allow you to polish it to near chrome finish.

Shot peening is used on bronze to surface harden it for bearing applications.

I can't see how you could harden a cartridge case with standard shot peening equipment, and I don't think you would like the surface it leaves behind.

 

[F. Guffey]

While researching some things a question popped into my mind about work hardening brass.

I would not take the time to work harden brass any other way to load it up and pull the trigger. And then there is the discipline: Measure the diameter of the case head diameter before firing and again after firing.

Remember, if you are using Federal cases look for big time case head expansions. I say that because there are so many reloaders that claim Federal case heads are soft. If the case head is soft someone should suspect a problem with the manufacturing process.

Again, I found a bucket of 30/06 cases at a Iron and Metal salvage yard. The cases were not to be resold but no one informed the I&M operation. I fired the cases before I was advised not to use them. I thought the cases were magnificent cases.

F. Guffey

 

[F. Guffey]

If so is there a way to locallize the hardening, say to just the head/rim area? Or is it a matter of annealing the area you want soft again?

There is only one area I anneal; when I form cases I anticipate the distance from the end of the neck to below the new shoulder when formed forming. If for some reason I thought the case head required working without firing I would expand the neck of the case to a diameter that would accommodate a drift that would fit inside the case and match the cup above the web. After all of that I would hammer the from the inside/down. Again, I would measure the outside diameter of the case head before and after.

And if I was serious I would made a short die that that would support the case head. I understand the case would have to be pushed out of the die of the case head expanded.

F. Guffey

 

[indie_rocker]

I would not take the time to work harden brass any other way to load it up and pull the trigger. And then there is the discipline: Measure the diameter of the case head diameter before firing and again after firing.

Remember, if you are using Federal cases look for big time case head expansions. I say that because there are so many reloaders that claim Federal case heads are soft. If the case head is soft someone should suspect a problem with the manufacturing process.

Again, I found a bucket of 30/06 cases at a Iron and Metal salvage yard. The cases were not to be resold but no one informed the I&M operation. I fired the cases before I was advised not to use them. I thought the cases were magnificent cases.

F. Guffey

That's why I crush the case mouth on all of my recycle brass. Channel locks make quick work of it, especially if you do it right as you find a case out of spec. Deform it and toss it in the bucket. No chance of the yard manager looking at the bucket of cases and deciding they look fine!

 

[std7mag]

Alas i'm not working with casings that are already drawn at a factory, rather i would be machining a case from a piece of solid bar. Usually sold in 10ft lengths.
I would cut into workable lengths, and machine on a lathe.
Would the cutting/shearing action of the lathe harden the brass?
Annealing would take place at the mouth for forming the neck and shoulder with forming dies.