can't see the blue

Andy showed me this post

Hi Guys,
My name is Phil. Andy showed me this post and asked me to comment. I am a metallurgist working in the air frame industry. On the subject of annealing brass cartridge cases. Releaving the surface stress using the techniques listed here doesn't really do a lot. It will only lower the surface stress a small amount a few molecules deep. The stress will return after a couple of firings. The surface tension has to be releaved throughout the entire structure which can only be effectively done by completly melting it and reforming it. Otherwise known as recycling. Much of the color change that occurs is contributed to the various surface contaminants and other impurities in the alloy not so much the temperature reached. Hope this information is of some help.
Phil.
 
Hello Phil,
Thank you for your comments on a subject that can only be FULLY understood by a person with your qualifications. Having said that, how would you go about annealing cartridge brass? I am assuming that you know that ONLY the neck and shoulder are to be annealed, and that the base and head area MUST remain un- annealed.

What temperature would YOU recommend we heat the neck / shoulder area to? I do understand that it is your belief, that the techniques we are using doesn't do a lot, but it is all we have. So , any advice that you can give us to get the most out of our annealing procedure would be greatly appreciated .

Thank you,
Dick
 
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ok. i listened to the advice offered. i made a shell holder for my hand drill. I purchased some 700 degree Tempilaq. i installed a metronome app on my iPhone and timed a case with the Tempilaq. It worked out to 7 seconds.

i annealed around 40 cases.

next question: Is there any way to empirically know what value there is on what i have done?
 
Phils post

ConRich said:
Hello Phil,
Thank you for your comments on a subject that can only be FULLY understood by a person with your qualifications. Having said that, how would you go about annealing cartridge brass? I am assuming that you know that ONLY the neck and shoulder are to be annealed, and that the base and head area MUST remain un- annealed.

What temperature would YOU recommend we heat the neck / shoulder area to? I do understand that it is your belief, that the techniques we are using doesn't do a lot, but it is all we have. So , any advice that you can give us to get the most out of our annealing procedure would be greatly appreciated .

Thank you,
Dick
Click to expand...

I am back in Sydney now and Andy is in Brisbane. He e-mailed a copy of the above request for me to reply to. Annealing alloys is a bit like dancing in a mine field. Just when you think you have the formula right the manufacturers change the ratio of components in the brass and you start over.

However the first rule is don't allow an oxidizing flame come into contact with the metal. By oxidizing I mean propane, acetlyene, butane etc. It's ok to use those energy sources to heat up the air but don't let the flames to come into contact directly. If you do there will be scalloping occuring and various color changes caused by the oxidized compounds. This color changing is surface stress which is one of the issues you are trying to resolve.

Apply a heat sync to the lower portion of the cases. Ceramics work well to rob heat from the lower region of the brass. Allow non recirculated air to pass around the lower portions of the brass. This should allow you to get the top part of the brass up to a temperature of 400 degrees F whilst keeping the rest around 150 or so. Don't allow the brass to glow red. This isn't a high temperature but when the cases are allowed to soak at this temperature for 24 to 36 hours then allowed to cool down until ambient air temperature is reached they will be greatly stress relieved. I know Lapua used this technique for many years and possibly still do. Their brass wasn't tumble polished after annealing and stll had the top portion of the cases burnished as a result.

If you can set your equipment up to anneal this way it should work fairly well.

Regards,
Phil Wyat via Andy.
 
Andy Cross said:
I am back in Sydney now and Andy is in Brisbane. He e-mailed a copy of the above request for me to reply to. Annealing alloys is a bit like dancing in a mine field. Just when you think you have the formula right the manufacturers change the ratio of components in the brass and you start over.

However the first rule is don't allow an oxidizing flame come into contact with the metal. By oxidizing I mean propane, acetlyene, butane etc. It's ok to use those energy sources to heat up the air but don't let the flames to come into contact directly. If you do there will be scalloping occuring and various color changes caused by the oxidized compounds. This color changing is surface stress which is one of the issues you are trying to resolve.

Apply a heat sync to the lower portion of the cases. Ceramics work well to rob heat from the lower region of the brass. Allow non recirculated air to pass around the lower portions of the brass. This should allow you to get the top part of the brass up to a temperature of 400 degrees F whilst keeping the rest around 150 or so. Don't allow the brass to glow red. This isn't a high temperature but when the cases are allowed to soak at this temperature for 24 to 36 hours then allowed to cool down until ambient air temperature is reached they will be greatly stress relieved. I know Lapua used this technique for many years and possibly still do. Their brass wasn't tumble polished after annealing and stll had the top portion of the cases burnished as a result.

If you can set your equipment up to anneal this way it should work fairly well.

Regards,
Phil Wyat via Andy.
Click to expand...

Phil,
I am not a metallurgist, but I have to question two points that you have made:

1. You claim that heating necks as reloaders do only relieves surfaces stress, but realize that the neck is only about 0.010" thick, so it is being heated all the way through. There is certainly a difference between surface stress relief and true annealing. I tend to think that what happens to brass case necks is true annealing - a change in grain structure throughout the neck.

2. The process you say Lapua used (uses) of keeping the necks at 400F and the base at 150F for 24-36 hours would require a constant heat source at the neck and a constant heat sink at the base. The amount of energy needed to keep such a process going for that long on thousands of cases at a time would be enormous, not to mention the expense of the extra production time. If they if fact do this, I am curious what machinery is used to keep their cases from being more expensive than they already are.

Thanks,
Keith
 
Actually the cheapest metronome is a freebie you can get for an iPhone.
 
AMMASHOOTA said:
I'm trying to learn to anneal my cases but for the life of me I can't see the darn things turn blue (i sure can see them turn red -- I am not color blind). I have tried in close to dark conditions, but that does not seem to help. I have tried simply timing some cases and then examining them after water cooling, but they don't have the blue tint i see on properly annealed cases.

any ideas?
Click to expand...

You want them to turn red, very dim red, not cherry red!
 
mks said:
Phil,
I am not a metallurgist, but I have to question two points that you have made:

1. You claim that heating necks as reloaders do only relieves surfaces stress, but realize that the neck is only about 0.010" thick, so it is being heated all the way through. There is certainly a difference between surface stress relief and true annealing. I tend to think that what happens to brass case necks is true annealing - a change in grain structure throughout the neck.

2. The process you say Lapua used (uses) of keeping the necks at 400F and the base at 150F for 24-36 hours would require a constant heat source at the neck and a constant heat sink at the base. The amount of energy needed to keep such a process going for that long on thousands of cases at a time would be enormous, not to mention the expense of the extra production time. If they if fact do this, I am curious what machinery is used to keep their cases from being more expensive than they already are.

Thanks,
Keith
Click to expand...

I had a quick phone call with Phil. He knows how think the cases are. Changing the molecular structure will happen but it has to happen evenly. It's the evenness that is more important than anything else. Building oxides up on the surface with an oxidizing flame will induce stresses due to the contamination it causes. It happens a lot more when the cases change color to red. That is a no no for soft alloys like brass. Soaking the alloy and allowing it to cool down slowly promotes very even distribution of stress.

The lapua system was about 15 years ago. Technology changes so no doubt a more efficient process is now used. You are right the cost of annealing that way actually cost more than the value of the brass. Go figure.
Andy.
 
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