Annealing with automated annealers

[TC260]

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.

 

[6BRinNZ]

tc260 - thanks. My comment was a poke at internet terminology as much as anything. Terminology is half the reason why we end up at a tangent somewhere.

Good to know that "partial annealing" is a legitimate reference.

 

[TC260]

I hear ya about the terminology thing. I believe "process" annealing is also another term for partial annealing. When it comes down to it though most everyone has the important part right, don't let the brass get too hot and everything's fine .

I don't know if this will be of any interest to anyone but this is a brass phase diagram. It may need to zoomed in a little bit and there's a lot of weird looking lines on but the one we're interested in is the lime green line. Temperature is on the left scale and if you follow the green line up, at approx 925 degrees it crosses a diagonal line. That's when it starts becoming liquid and the brass is ruined. We've all seen it, the difference between 750-800 and 925 when there's a 3600 degree flame beating on the case is not very much time at all.

http://lpc1.clpccd.cc.ca.us/lpc/eng/course_websites/Engineering46/glos324/brass.htm

 

[roundknob]

Does everyone here anneal after every firing or are some using different cycles? I do it every time. I have also been told not to let all the cases bunch up in the bin as this will gather to much heat and effect the whole case. What I am getting to is I had a major gun malfunction a few weeks ago where a case head seperated and some of my fellow shooters think the brass was to soft at the head. They dont anneal by the way.
Steve

 

[Rustystud]

I bought a Bench Source case annealing machine. Very well made machine and well thought out (way to go Dave). I will say that the experimentation I have done showes it greatly improves my groups (fliers). It is interesting that over the last 5 years my loading has gone through more changes than the prior 40 years combined. The addition of floating dies, electronic scales, case prep station, and annealing, use of Lapua brass, Varget, and H-4831SC.
Nat Lambeth

 

[BoydAllen]

If your primer pocket was not enlarged, I doubt that you had a head hardness issue. How many times had the case been reloaded, and do you use one of those caliper attachments to measure shoulder bump when you set your FL die? You should check your shoulder bump every time you size cases. If you were using an old die setting for brass that had not been annealed to repeatedly size annealed cases, you were bumping the shoulders of the softer cases back quite a bit farther than they should have been, and with repetition, this could lead to a head separation.

 

[Hondo]

Many years ago I owned a Winchester Mod. 70 Varmitter .243. When I got tired of case head separation after 3 firings I decided to improve the chamber with .010" body taper and a30 deg. shoulder. I know this long winded I do have a point. Before fire forming I would anneal the cases using the fallowing method.
Holding the case head between thumb and finger apply propane flame to shoulder area of case when I felt the case head getting hot in my fingers drop case into a bucket of water.
Never had another case failure after that.

 

[stebbins243]

I bought a Bench Source case annealing machine. Very well made machine and well thought out (way to go Dave). I will say that the experimentation I have done showes it greatly improves my groups (fliers). It is interesting that over the last 5 years my loading has gone through more changes than the prior 40 years combined. The addition of floating dies, electronic scales, case prep station, and annealing, use of Lapua brass, Varget, and H-4831SC.
Nat Lambeth

I am right there with you. i don't have 40 years experience by any means, but the past 2-3 months of developing and testing my 243 and searching for best results possible i have changed technique and employed different methods more so in the 3 or so years of reloading. i used to just reload what i could and when a case started to split or show to much wear and tear id simply throw it out and start with new brass. the annealing thing has been my biggest change and its only been the past few days. i started annealing the brass the way i knew how to anneal non ferrous metals, tho i am annealing, i am going to soft. i was careful not to overheat the case and cause problems, but it seems my annealing procedure is incorrect of reloading standards. simply put i thought annealing was a full annealing, instead the goal outcome is to stress relieve the neck and upper body, not anneal to a dead soft neck.