Annealing ?????
- Thread starter LarryDScott
- Start date
Some how that is what annealing is.
Larry
itchyTF
Gold $$ Contributor
I realize "annealing" reduces hardness but if heating to around 750 for a relatively short time does not constitute annealing but rather stress relieving, is that enough to reduce hardness?
According to that paper (above) it sounds like it might. The graph he shows was annealing for an hour. I have yet to see a similar graph when the time is only seconds.
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Annealing can be far more than just stress relieving. You can actually get recrystallization where all of the accumulated cold work is eliminated. This is a good thing if you want your brass to last a very long time. If you get the brass too hot grain growth happens and that is a not so good thing.
There is a time at temperature requirement for these processes. Higher temperatures require less time.
There is a minimum of cold work accumulation for these processes. About 40% usually. And each firing cycle accumulates about 15%.
The reason there isn't any data for short time annealing like reloaders do is that industrial users generally want to anneal the whole part. We don't.
You should throw away the brass by your fifth trimming and annealing doesn't help in reducing trimming.
Annealing every firing probably won't be effective in recrystallization. It will only remove the accumulated residual stress. The cases will likely fail within one or two firings as if you didn't anneal. If your primer pockets get loose by then you've lost nothing. However, if you want the longest brass life because they're scarce or you've invested some time in their preparation then you might want to anneal less often. For relatively common brass like 223 it isn't worth the bother. But for neck turned 6.5 Gee-Whiz-Bang it might.
There is a time at temperature requirement for these processes. Higher temperatures require less time.
There is a minimum of cold work accumulation for these processes. About 40% usually. And each firing cycle accumulates about 15%.
The reason there isn't any data for short time annealing like reloaders do is that industrial users generally want to anneal the whole part. We don't.
You should throw away the brass by your fifth trimming and annealing doesn't help in reducing trimming.
Annealing every firing probably won't be effective in recrystallization. It will only remove the accumulated residual stress. The cases will likely fail within one or two firings as if you didn't anneal. If your primer pockets get loose by then you've lost nothing. However, if you want the longest brass life because they're scarce or you've invested some time in their preparation then you might want to anneal less often. For relatively common brass like 223 it isn't worth the bother. But for neck turned 6.5 Gee-Whiz-Bang it might.
itchyTF
Gold $$ Contributor
The don't jack up the temperature because of grain growth issues. The higher the temperature the faster and larger the grains get.
There isn't much data that I've been able to find on grain recrystallization and temperature. Much of it is empirical and may be dependent on other things like nature of cold work (rolling vs bending, etc.). I dunno as I've never been a copper/brass metallurgist.
I do know that if all the parameters aren't exactly the same different results can happen.
Such is the black art of heat treating non-ferrous metals particularly selective heat treatment like we're doing.
There isn't much data that I've been able to find on grain recrystallization and temperature. Much of it is empirical and may be dependent on other things like nature of cold work (rolling vs bending, etc.). I dunno as I've never been a copper/brass metallurgist.
I do know that if all the parameters aren't exactly the same different results can happen.
Such is the black art of heat treating non-ferrous metals particularly selective heat treatment like we're doing.
The data I have available indicates the nominal annealing range for cartridge brass (UNS C26000) is from 800-1400F. A google-fu'ed scholarly article indicates recrystallization and a restoration of ductility in work hardened samples of the material began at ~ 570F. At 750F, grain growth along with a significant reduction of hardness and strength was noticed. The artlcle went on to say one should avoid the 750-1200 annealing range unless subsequent cold work is applied to restore mechanical properties. The "sweet spot" for us then would be this 550-750F range to reduce the hardness and restore ductility without significantly reducing material strength in the case neck area.
Theoretical phases of annealing in any metal are recovery, recrystallization and grain growth. My take-away and learning here is what we are calling "annealing" with our brass is a "light anneal" at best carried out in the stress-relief or recovery range of the material. A look at an ASM handbook Vol 2 might confirm this ...
Best Regards,
Scott
Theoretical phases of annealing in any metal are recovery, recrystallization and grain growth. My take-away and learning here is what we are calling "annealing" with our brass is a "light anneal" at best carried out in the stress-relief or recovery range of the material. A look at an ASM handbook Vol 2 might confirm this ...
Best Regards,
Scott
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Great article... THE END
Money couldn't buy it Joe - I knocked it up in my home workshop.XTR
F-TR obssessed shooting junkie
Most of you that took any chemistry or physics probably learned the Bohr model of the atom. It's the one that everyone recognizes as the nucleus with the electrons orbiting it. Modern physics will tell you that is that model is pretty far from reality; however, it is a model that works way better to than teaching Cloud Theory at the same time you are trying to teach first yr chemistry students about electron bonds. So even if it is not actually an accurate model, it is useful to understand how something works.
The metallurgical discussions are fun, and in many cases some of the articles linked to get over my level of understanding. I think what most of us can take from annealing discussions is that no matter what you call it, or how you accomplish it, if you heat the neck until just before it glows you get more consistent sizing, and more consistent precision from your rifle. Personally I cant speak to brass life, I always lose the primer pockets before the necks split.
The metallurgical discussions are fun, and in many cases some of the articles linked to get over my level of understanding. I think what most of us can take from annealing discussions is that no matter what you call it, or how you accomplish it, if you heat the neck until just before it glows you get more consistent sizing, and more consistent precision from your rifle. Personally I cant speak to brass life, I always lose the primer pockets before the necks split.
Dennis does it the way I do, you'll notice right away that you have to angle the pan you drop into..
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