Annealing in molten lead

[Webster]

Hmmm??? That doesn't sound like me, unless it's from several years ago when I was following those many articles touting 650°F - 750°F. Back then, that's what was kinda frustrating to me in that those temperatures were highly spoken of but no that read data to have an idea what was really going on. That led me to seek out more in depth empirical studies.


Often time of exposure, a key factor, is left out when I see suggestions as to a temperature to use. Like, "you should use 650°F tembleque" as a guide.


When I first started annealing my brass, I was using the "flame color" method doing flame annealing. I had no idea what temperature I was actually using and like so many, I assumed it was working as it appeared ok. I just had not way of knowing except seeing what my results were over a long period of time.


I know, as I've seen a lot of than too. Reporting 750°F for 4-5 seconds is problematic in that what does that really mean??? Is it that it's at that temperature for 4-5 seconds or the over all time subjected to the heat? It's like with flame annealing, the case enders the flame, but takes ~5 seconds before the neck reaches that temperature and once it reaches that temperature . . . how long should it be at that temperature???

Back in the fall of 2024 I acquired a tool to be able to actually measure some hardness and ran some experiments to see what it takes to get the kind of anneal we get on virgin brass. If you haven't already read it, here's a link: https://forum.accurateshooter.com/threads/flame-annealing-almost-perfect.4138833/



I've collected several reports on studies about annealing cartridge brass, one gong back to the 1960's. I'm attaching a PDF file I think you might find of interest and here's what some that that looks like:
View attachment 1753430

PS: I'm adding another pdf file, which is a good one but the file is too large, so I've included some of the pages you might find of interest too.

I am retired, I used to do that type of work. Good articles if you know how to interpret the data. The only issue I have is that the data was aquired with 15% and higher cold work. Look at the data with the lowest starting cold work only. I need to review the article to see if any data was with zero cold work.

New cases are factory annealed and have no evidence of cold work as evideced by etched Metallographic images of new and sized case necks on the AMPS website. You should have very little starting cold work before annealing as evidenced by none of the grains being elongated before and after annealing. I think you can have stress without cold working evidenced by the necks will crack. I have to keep going back to the AMPS images that don't show cold work which should always elongate the grains.

I noticed on metallographic cross-sections of cartridge necks on AMPS you always see little black particles. These should be iron oxide inclusions. These usually come from the cast iron vessels used in processing molten brass. Inclusions can be called stress risers leading to cracks initiating at the oxide particle.

I may be misinterpreting the AMPS pix. Cold rolling definitley elongates the grains. The sizing we do doesn't move the brass the same as cold rolling???

I am sure you have seen the annealing charts I have put up on the website many times. Based on years of collecting real data and my own annealing study at work I flame anneal till red for 1-2 seconds. It's simple and I believe it does a good job.

 

[Webster]

Hmmm??? That doesn't sound like me, unless it's from several years ago when I was following those many articles touting 650°F - 750°F. Back then, that's what was kinda frustrating to me in that those temperatures were highly spoken of but no that read data to have an idea what was really going on. That led me to seek out more in depth empirical studies.


Often time of exposure, a key factor, is left out when I see suggestions as to a temperature to use. Like, "you should use 650°F tembleque" as a guide.


When I first started annealing my brass, I was using the "flame color" method doing flame annealing. I had no idea what temperature I was actually using and like so many, I assumed it was working as it appeared ok. I just had not way of knowing except seeing what my results were over a long period of time.


I know, as I've seen a lot of than too. Reporting 750°F for 4-5 seconds is problematic in that what does that really mean??? Is it that it's at that temperature for 4-5 seconds or the over all time subjected to the heat? It's like with flame annealing, the case enders the flame, but takes ~5 seconds before the neck reaches that temperature and once it reaches that temperature . . . how long should it be at that temperature???

Back in the fall of 2024 I acquired a tool to be able to actually measure some hardness and ran some experiments to see what it takes to get the kind of anneal we get on virgin brass. If you haven't already read it, here's a link: https://forum.accurateshooter.com/threads/flame-annealing-almost-perfect.4138833/



I've collected several reports on studies about annealing cartridge brass, one gong back to the 1960's. I'm attaching a PDF file I think you might find of interest and here's what some that that looks like:
View attachment 1753430

PS: I'm adding another pdf file, which is a good one but the file is too large, so I've included some of the pages you might find of interest too.

Not sure how to explain this without comparing to charts that show hardness change at a given temperature to an amount of thickness reduction due to cold rollling which is not what we do when die sizing a cartridge neck. Cold working puts stored energy into the brass that reduces the time to anneal at a given temp.

Almost all the study reports use cold rolled plates which I don't think are the same as neck sizing in a die.

The formula for calculating % reduction is: original thickness - finished thickness / original thickness.

A made up example:
.013" - .0129" / .013" = .00769% reduction. Look like the decimal is in the wrong place. Need to multiply the result by 100 to convert from a fraction to a %. It should be .769%. It's been 15 years since I pulled tensile specimen.

This amounts to a small cold working of the brass. The published charts indicate that at about 1050F no softening of the brass would occur in several minutes at temp with low cold working. From experience I think I found the opposite? About ten years go I annealed some brass red for about 10 seconds with a single torch. Don't know what the temp was but it was very soft. It's obvious that the necks have to crack from cold working? Whats going on?

I anneal with a single torch red for 1-2 seconds and I am happy with the results. The AMPS data is real data with cartridge cases and not plates cold rolled in a rolling mill.

 

[TC260]

It's obvious that the necks have to crack from cold working? Whats going on?

"Cold work" as you correctly pointed out earlier in your post, is the percentage change in the material thickness. "Strain hardening", is what's going on when sizing/firing cases. Strain hardening increases the dislocation density which is the mechanism that causes cracking. As the dislocation density increases, the dislocations stack up against the grain boundary until they can no longer move and a crack results.

 

[Oldbloke]

That will work, however if you use a socket and a drill motor you will get more even heating results

I don't believe a drill is necessary. I don't use one. If the "handle" is say diameter of a pencil like mine is, it's very easy to rotate fairly quickly. Also brass is an excellent conductor of heat so getting even annealing is no problem.
Drill gets heavy after a while too.

 

[TA17rem]

I just took delivery of a Burstfire annealer, this thing is the cats ass. well-built and easy to set up and run. Comes with speed dial so you can get the right amount of heat all the way around, more uniform as well.

 

[Ccrider]

If I could keep my cases on the same number of firings I would not anneal.

With thin neck ppc cases, you can over anneal. If you do, the brass will yield and not hold the bullet with tight neck tension. With 268 neck ppc I have not had this happen.

I have used propane torches, various setups, salt bath and AMP. Other than the AMP, I got the best results from the salt bath. Hot melted salt is just not safe. Too much bad can happen.

 

[Straightshooter1]

If I could keep my cases on the same number of firings I would not anneal.

With thin neck ppc cases, you can over anneal. If you do, the brass will yield and not hold the bullet with tight neck tension. With 268 neck ppc I have not had this happen.

I have used propane torches, various setups, salt bath and AMP. Other than the AMP, I got the best results from the salt bath. Hot melted salt is just not safe. Too much bad can happen.

Even with thin necks, like at .008", it's really not that hard with flame annealing. . . if you simply get the timing right. Certainly, .008" necks will require a different amount of time (shorter) than something like .014" necks. And it helps to have a tool to measure hardness to find the right timing.

 

[Webster]

Even with thin necks, like at .008", it's really not that hard with flame annealing. . . if you simply get the timing right. Certainly, .008" necks will require a different amount of time (shorter) than something like .014" necks. And it helps to have a tool to measure hardness to find the right timing.

Read an article that said Tony Boyer didn't anneal or clean primer pockets. I think he tossed cases after 5-6 firings. He got his cases and powder for free.

 

[Straightshooter1]

Read an article that said Tony Boyer didn't anneal or clean primer pockets. I think he tossed cases after 5-6 firings. He got his cases and powder for free.

Some people are just minimalists.