Annealing Question (new member)

[rwj]

You guys “think” you’re all that and a bag a chips . There is in fact stages of annealing and VERY good reasons for it . It’s not an all or nothing proposition as some might believe . It appears some here can’t see the forest through the trees . Any of you expersts anneal your AR10 cases to 1200 degrees ? No - Didn’t think so cus you’d have to little bullet hold and jam the bullet into the case as it’s chamberd . Grain structure starts to change somewhere around 500* and 750* to 800* is perfect to relieve stress of very thin sheets of brass like cartridge case walls while still leaving some work hardening in the necks for more bullet hold . This reduces the possibility of bullet set back on aggressive auto loaders while also allowing for more reloads per case before necks start splitting/cracking . In these types of rifles you are not looking for “perfectly” prepped cases because they are so hard on cases in the first place . Generally when annealing auto loading cases you are looking to stress relieve to get a few more reloads out of the cases rather then bench rest quality case prep .

Just because you know one thing and know it well doesn’t mean you know everything!

What is the modulus of elasticity of cartridge brass?

Is the elastic modulus constant or does it vary with material hardness?

Is material hardness related to the yield strength of cartridge brass?

How does ductility effect bullet holding force?

 

[RegionRat]

The yield strength varies with the work hardening (hardness).

Off the top of my head I think it ran from from 75 MPa when fully annealed up to 450 MPa when fully hardened.

The actual tensile strength runs from about 300 MPa to about 900 MPa as I recall, and the modulus is roughly 110 GPa.

The tensile modulus stayed fairly constant underneath it all in terms of that linear slope region, let's just call it to the first order. The ductility was a range from roughly 70% elongation down to a few percent when fully hardened.

How that affects bullet grip is too long a story since friction plays a role. The important take away, is that the yield and the hardness vary with the work hardening and the yield is easily hit with the forced strains we apply with dies and bullets.

ETA: A sample plot that has been all cleaned up.

 

[Metal God]

What is the modulus of elasticity of cartridge brass?

Is the elastic modulus constant or does it vary with material hardness?

Is material hardness related to the yield strength of cartridge brass?

How does ductility effect bullet holding force?

I appreciate the questions but they are irrelevant to my point . Again you "experts" think fully annealed is the only thing a case can be or better said work hardened or fully annealed are the only two options . On a purely technical since that is accurate . However when annealing cartridge brass it is often more nuanced then that as I described earlier . I would never fully anneal a case that will be used in a auto loader . In all fairness I myself was not fully clear on this aspect . I should have added I use bushing dies on all of my bottle neck rifle cases . When I "fully" anneal a case neck and then size it to have .003 bullet hold which is the most I generally ever have regardless of cartridge . Reason being is once you start trying to have 5 , 6 , 7 thousandths bullet hold . All you really are doing is expanding the case neck not unlike a the expander button on your sizing die as you seat the bullet . I don't know the exact number but at some point you stop increasing bullet hold and are simply sizing the neck back out .

That said if my case neck is fully annealed I can force a .003 bullet hold seated bullet in that case deeper into the case simple by pushing the nose of the bullet into my bench top , not good if you plan to use that in a auto loader . However everything else being the same but only annealing to 750* I no longer can force the bullet deeper using the same method .

Then how do I know the case is even stress relieved ? Two reasons really , before I started annealing to 750* I would get split necks and after I almost never get split necks with the same number of firings . the other is I don't anneal every firing so I can actually feel the case necks getting harder after each firing when I seat the bullets the next time . My seating force becomes harder and very inconsistent after the 3rd and 4th firing . Once annealed to 750* every bullet is much easier and consistent to seat and that inconsistency repeats it's self once I get to the 3rd and 4th firing again .

So as you can see my experience comes from a very specific way I go about reloading & firing my cases . I also understand those that do benchrest type case prep and anneal every time . There experience is coming from a very specific method of case prep as well . I often agree when prepping cases for that purpose fully annealing cases is almost certainly the better and more consistent way to go . The difference IMHO is that I never say "750*" is the only way and you all don't have a clue . What I say is "some" of you don't have a clue because you think your way is the only way . There "IS" a difference .

 

[rwj]

I appreciate the questions but they are irrelevant to my point . Again you "experts" think fully annealed is the only thing a case can be or better said work hardened or fully annealed are the only two options . On a purely technical since that is accurate . However when annealing cartridge brass it is often more nuanced then that as I described earlier . I would never fully anneal a case that will be used in a auto loader . In all fairness I myself was not fully clear on this aspect . I should have added I use bushing dies on all of my bottle neck rifle cases . When I "fully" anneal a case neck and then size it to have .003 bullet hold which is the most I generally ever have regardless of cartridge . Reason being is once you start trying to have 5 , 6 , 7 thousandths bullet hold . All you really are doing is expanding the case neck not unlike a the expander button on your sizing die as you seat the bullet . I don't know the exact number but at some point you stop increasing bullet hold and are simply sizing the neck back out .

That said if my case neck is fully annealed I can force a .003 bullet hold seated bullet in that case deeper into the case simple by pushing the nose of the bullet into my bench top , not good if you plan to use that in a auto loader . However everything else being the same but only annealing to 750* I no longer can force the bullet deeper using the same method .

Then how do I know the case is even stress relieved ? Two reasons really , before I started annealing to 750* I would get split necks and after I almost never get split necks with the same number of firings . the other is I don't anneal every firing so I can actually feel the case necks getting harder after each firing when I seat the bullets the next time . My seating force becomes harder and very inconsistent after the 3rd and 4th firing . Once annealed to 750* every bullet is much easier and consistent to seat and that inconsistency repeats it's self once I get to the 3rd and 4th firing again .

So as you can see my experience comes from a very specific way I go about reloading & firing my cases . I also understand those that do benchrest type case prep and anneal every time . There experience is coming from a very specific method of case prep as well . I often agree when prepping cases for that purpose fully annealing cases is almost certainly the better and more consistent way to go . The difference IMHO is that I never say "750*" is the only way and you all don't have a clue . What I say is "some" of you don't have a clue because you think your way is the only way . There "IS" a difference .

They questions are directly related to the topic. Interesting that you completely avoided answering them. I’m not an expert on annealing, but I am willing to share my experiences and data sources to help those that are willing to learn and improve. It’s not worth my time engaging in labeling others. Good day sir…

 

[RegionRat]

BTW, nothing I did with milling rollers or dies when trying to simulate the firing cycle with cold working seemed to work.
I was trying to make it an easy study, but nothing I did with dies or rollers was the same as a few trips to 65,000 PSI duding a firing cycle.
Working the necks with dies certainly added cold work, but not the same way as firing. If I started with the neck at a 100HV, after a few firing cycles I was at 150HV if I didn't anneal.

 

[whatsupdoc]

Grain structure starts to change somewhere around 500* and 750* to 800* is perfect to relieve stress of very thin sheets of brass like cartridge case walls while still leaving some work hardening in the necks for more bullet hold .

Ok then give me the heating time you are using at 750* to 800* to relieve stress.

 

[Metal God]

Ok then give me the heating time you are using at 750* to 800* to relieve stress.

I don’t have a specific time . Each and every annealing session I apply a temperature indicator to five or 10 cases and place them in a heat source and time the duration it takes to melt the temp indicator . I then anneal all cases in that batch in the time those test cases gave me .

Based on general memory I think it’s somewhere between 4 and 6 seconds depending on my flame temperature, angle of flame to case and distance from case . I have a clamp system that allows me to get a repeatable position for each case but I must set it up for each batch .

Sorry I can’t give you anything more specific

MG

 

[JMayo]

Longer they are in the fire the more the whole case heats up... Not a good thing.

 

[Metal God]

Longer they are in the fire the more the whole case heats up... Not a good thing.

I’m on my phone right now so I can’t get in great detail. However I ran test on that very aspect and found that the torch and socket method is very hard to overheat the case body . Don’t get me wrong you absolutely can but you have to leave the case in the flame for 12, 14+ seconds which resulted in the case neck and shoulders glowing super Duper red lol .

I have photos and test data on all that but I can’t easily upload photos on the site here and I’m on my phone so I can’t anyways but the general point is the same . If annealing correctly with the flame in the correct place on the case it’s pretty hard to overheat the head of your case with the single flame and socket method .

Figured it out . These are some 308 and 223 cases . I put 750* tempilaq below the shoulders and 450 at the case head/web area . The flame was pointed right at the center of the shoulder at a 90* angle until the 750* indicator melted . As you can see many of the cases did not even reach the 450* mark at the case head . Keeping in mind the necks were glowing red hot as the 750* tempilaq started to melt . You would need to really leave the case in the flame for quite a while for the heat to transfer to the head to a temp high enough for grain structure to start changing there . Again I'm not saying it can't happen , only that you really have to screw stuff up to damage the case head with the single torch and socket method .

Add a second torch like many machines use and everything changes and that heat transfer is much quicker .

 

[Webster]

Thanks for the detailed feedback,
the cases were run through a wet tumbler that I also built, the darkness seems to be the result of how long I kept them in the flame. I have done other cases, 22-250, for no more than 5 or 6 seconds that have not discolored this way, so I suspect that the heat is causing the issue when the cases is rotating in the flame for an extended period of time. wet tumbler is nothing more than hot water, Dawn dw liquid, LemiShine, and s.s. pin media.

I was planning on touching the crayons to the case after they drop out of the drum.

also, not sure about the forum etiquette as I am not a typically an online poster, but I am going to respond to each of the responses I received as I appreciate the time it took to let me know your thoughts. thanks to all.

I don't think touching the necks with temp crayons after they drop out is valid. The necks are sheet metal around 0.013" thick. We don't know the cooling rate. The necks probably cool a much a a 100 degrees per second when the heat is removed. In 5 seconds with a single torch the temperature has to be over 400-500F. I anneal my cases 5-6 seconds with a torch and I am happy with the results for a very accurate varmint rifle. I used to anneal about 9 seconds but I decided to cut back because the neck end was getting red. Someone pointed out to me that an infrared red thermometer has to be calibrated for the type of surface you are getting the reading from (proper emissivity). They may be close enough for rough work.

 

[Webster]

Reese has some very good information regarding annealing. Unless you have access to a Vickers hardness tester or the ability to analyze brass via a microscope, some of what has been posted on this thread seems to be fairly arbitrary. I changed to an Annie induction annealer and tossed the Tempilaque that came with it after seeing Reese's video's. There's a member on this site who has access to Vickers testing in a lab. He was telling me he has to induction anneal his 6ppc brass to almost 1200 degrees for a proper anneal. You can also read on AMP's website regarding their research and testing. Not too different from Reese's info...

Depends on time to reach 1200F. I would like to see a picture of his vickers hardness tester. I did Vickers microhardness for 45 years. Amps shows a microhardness tester with an anvil inserted into the case mouth. for support. A special setup.

 

[Metal God]

I don't think touching the necks with temp crayons after they drop out is valid. The necks are sheet metal around 0.013" thick. We don't know the cooling rate. The necks probably cool a much a a 100 degrees per second

Agreed , I tried the stick temp indicator and just could not find a way to be consistent with them . Had to go to the stuff you paint on and you don't need to do them all . Just the first few to get your timing down and with practice you should be gtg .

 

[Ccrider]

And now you see. There is no definitive answer Grasshopper.

I say test for yourself and see what works. In my experience salt bath was the most consistent. Just was not worth the risk.

If you choose to anneal, and many top shooters don’t, save your money and buy an Amp. The time you save with it will quickly pay the cost.

Best.