another Annealing ?

[686]

I keep my brass seprated inlots of times fired. I see people annealing from ever time to 4-5 times fired. If you had Batch #1 of 100 cases that you had been annealing every time and found there were 10 of them that had not been annealed for the last 5 shots, would they be ok to put back in the next annealing batch, and would they now all be the same?
If that works what about 3 different fired batches mixed together and all annealed at the same time. Does annealing uniform fore different numbers of times fired ?
Same question. If i had a batch of 3 rd fired brass and a batch of 5th and a batch of 7th fired, will they be the same if annealed all together and now have one big batch? Oh these are 6br brass . thanks for any help Charles

 

[Preacher]

Once annealed they should all be the same again no matter how many times they have been fired...

 

[686]

Preacher i would think that if in the same age batch but what cases from different batches mixed together then annealed? Are they now the same?






P

 

[686]

any more advice?

 

[markm87]

The 10 pieces were probably just not as uniform before in the neck tension area.... they should jump right back in tandem with the batch.

 

[686]

I am ok with keeping everything in times fires and anneal as batches. I know if i have 3 batches #rd, 4th, and 5th fired i just let 3&4 catch up to 5th fired then i have a bug batch. That is what i am thinking on dooing. I was just wondering if annealing put it back to factory spects and now any age brass is the same.

 

[amlevin]

Annealing is merely a process to remove any "work hardening" from the brass. If one case has been fired several times and another only once, if they're both annealed and all other things are equal, they now both have the same metal characteristics.

Whenever I get a batch that gets mismatched as to the number of times fires between annealing I just anneal the whole batch. Doesn't take that much time and it beats guessing on how they'll perform.

 

[necchi]

IMHO,
They are only the same as far as the softness of the metal after annealing.

There are other issues that "age" cases,
* Primer pockets
* Flash holes
* Head and web thickness (separation)

As mentioned, annealing only changes the brass characteristics of "work hardening"

 

[BoydAllen]

First of all with regard to what is generally done to case necks, annealing is probably a misnomer. I think that most of us do not want dead soft fully annealed case necks. Perhaps we need to start calling what we do to case necks something like reduction of work hardening. (Yea, I'll hold my breathe for that one;-)) In any case. I think that I remember that if you are modifying the hardness of work hardened brass, time and temperature are the major variables, BUT my friend the materials engineer tells me that the literature says that what you end up with depends on what you started off with, hardness wise, which translates to grain size. IMO the only way to know for sure if mixed use brass is made uniform by annealing is to have some definitive test that can be used to evaluate the brass for uniformity. For most of us, we are stuck with how uniform the force feels when seating bullets, ES of velocity, and of course, targets. Has anyone done any actual testing, or this one of those things that we make an educated guess on, and then wait for someone to prove us wrong?

 

[6BRinNZ]

First of all with regard to what is generally done to case necks, annealing is probably a misnomer. I think that most of us do not want dead soft fully annealed case necks. Perhaps we need to start calling what we do to case necks something like reduction of work hardening. (Yea, I'll hold my breathe for that one;-)) In any case. I think that I remember that if you are modifying the hardness of work hardened brass, time and temperature are the major variables, BUT my friend the materials engineer tells me that the literature says that what you end up with depends on what you started off with, hardness wise, which translates to grain size. IMO the only way to know for sure if mixed use brass is made uniform by annealing is to have some definitive test that can be used to evaluate the brass for uniformity. For most of us, we are stuck with how uniform the force feels when seating bullets, ES of velocity, and of course, targets. Has anyone done any actual testing, or this one of those things that we make an educated guess on, and then wait for someone to prove us wrong?

OP - I'm with necchi - there is more to be concerned with than with just the annealed state.

Boyd - for naming check out the comments and thread listed below. TC260 seems to have the most practical knowledge so far.

Annealing with automated annealers

« Reply #20 on: 11:07 PM, 06/02/12 »

A metallurgist ( as I understood his quals) in another thread somewhere suggested in the purest sense that using current process we weren't actually annealing but stress relieving.



We're still annealing, we just want a "partial" anneal as opposed to a "full" anneal. Yes those are actually correct terms . The brass gets strain hardened by working it. What's happening internally is the formation of dislocations and point defects within the lattice structure of the brass. As the concentration of dislocations increases so does the internal stress and we see that as a decrease in the ducility of the brass.

The reason why we don't heat the brass too hot is because we want to keep the brass in the "recovery" range. There's three phases of annealing, recovery, recrystalization, and grain growth. In the recovery phase, enough heat energy is applied to allow the dislocations to rearrange themselves back into a lower energy state. That's the "stress relieving" that the metalurgist you were refering to was talking about.

If the brass gets too hot, it goes beyond the recovery phase into recrystalization and grain growth. That's when we get a completely new grain structure and becomes "dead soft". Another possibility is called "liquation" which is when you just reach the melting temperature and the grain boundaries become liquid. Also not good.


« Last Edit: 11:14 PM, 06/02/12 by TC260 »

http://forum.accurateshooter.com/index.php?topic=3788491.msg36079398#msg36079398

 

[killahog]

First of all with regard to what is generally done to case necks, annealing is probably a misnomer. I think that most of us do not want dead soft fully annealed case necks. Perhaps we need to start calling what we do to case necks something like reduction of work hardening. (Yea, I'll hold my breathe for that one;-)) In any case. I think that I remember that if you are modifying the hardness of work hardened brass, time and temperature are the major variables, BUT my friend the materials engineer tells me that the literature says that what you end up with depends on what you started off with, hardness wise, which translates to grain size. IMO the only way to know for sure if mixed use brass is made uniform by annealing is to have some definitive test that can be used to evaluate the brass for uniformity. For most of us, we are stuck with how uniform the force feels when seating bullets, ES of velocity, and of course, targets. Has anyone done any actual testing, or this one of those things that we make an educated guess on, and then wait for someone to prove us wrong?

I anneal with a automated machine and can feel the difference in the amount of force it takes to seat the bullets afterwards. I feel it was necessary to do so because I am reforming 243 winchester cases into 22-250AI . The one thing that has always sort of bugged me is the lack of scientific evidence,of the grain restructuring or rearrangement. I would like to have a way of verifying this but I don't have a microscope and wouldn't really know what I'm looking at anyway.

 

[SDDasher]

Huh?

 

[TheSnake]

I am also with necchi on this. Another factor to consider is seperating the cases into lots by weight. If you have different weight lots, you would not want to mix them back up leaving you with a mixed bag.

 

[LIUNA]

I learned something this week, I was running the neck expander through 15 cases and had 2 that had strong resistance, I set them aside until I was finished with the 15.
I then ran the 2 cases through the expander again to see if they had accepted the resizing, and discovered they had the same resistance as before. So I decided to fire up the propane torch with my battery operated drill, I annealed the 2 cases, went back to the expander and ran them through, one case accepted the resizing and one did not. So inspected the cases and found one case with a full light blue ring below the shoulder, and one case with the faint appearance of change. I went back and annealed the case again, and after cooling ran the case through the expander, and it accepted the expansion. I went back and checked case a 2nd time and it was fine. This is the first time I was able to confirm how much annealing was required.

 

[TC260]

BUT my friend the materials engineer tells me that the literature says that what you end up with depends on what you started off with, hardness wise, which translates to grain size.

I believe your friend is right about that. Ductility is acutally what we're improving when we partial anneal brass, not hardness which is a different characteristic. Since we're not (not supposed to anyway) heating the brass hot enough for recrystalization, the grain characteristics are essentially the same before and after we anneal. The strain hardening effect we see in the brass is a result of what's happening on an atomic scale. Much smaller than what's being refered to with "grains".

A simple way to think of strain hardening is rows of atoms getting broken and dislocated preventing normal movement back and forth within the atomic lattice. When enough heat is applied, those dislocated rows of atoms can realign themselves back to their normal structure again.