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Thread: Did I damage my brass???

  1. #1
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    Default Did I damage my brass???

    Had a bunch of rifle brass that got in the mud at the range. Took it home and washed it, dried it with an old towel and then placed it on a cookie sheet in the oven at 150. Wife came and put the oven to 425 to bake a pizza. The brass "cooked" at 425 for about 10 to 12 minutes before I caught it. (about time the pizza was done) It discolored the brass from bright yellow to a golden hue. Is it OK to load. Looks good just a darker color. Pizza was fine.

    Thanks.

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    Member MaximumPenetration's Avatar
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    Not sure, but if you try it out and they hold up, let us know. Just in case any of our wives decide to bake our brass with the pizza.
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    I'd say NO, because when you anneal brass, to make it softer, you heat it much hotter than that.

    I had a similar experience, lower heat, but longer than 10 to 12 minutes. The brass was discolored, so I polished it using a case spinner and steel wool.

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    If you use it, watch the primer pockets; that is where the softening will act first. J.

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    I think your fine, The following is from a source that I trust:

    Optimal Case Temperatures for Successful Annealing
    Brass is an excellent conductor of heat. A flame applied at any point on a case for a short time will cause the rest of the case to heat very quickly. There are several temperatures at which brass is affected. Also, the time the brass remains at a given temperature will have an effect. Brass which has been "work hardened" (sometimes referred to as "cold worked") is unaffected by temperatures (Fahrenheit) up to 482 degrees (F) regardless of the time it is left at this temperature. At about 495 degrees (F) some changes in grain structure begins to occur, although the brass remains about as hard as before--it would take a laboratory analysis to see the changes that take place at this temperature.
    The trick is to heat the neck just to the point where the grain structure becomes sufficiently large enough to give the case a springy property, leaving the body changed but little, and the head of the case virtually unchanged.
    If cases are heated to about 600 degrees (F) for one hour, they will be thoroughly annealed--head and body included. That is, they will be ruined. (For a temperature comparison, pure lead melts at 621.3 degrees F).
    The critical time and temperature at which the grain structure reforms into something suitable for case necks is 662 degrees (F) for some 15 minutes. A higher temperature, say from 750 to 800 degrees, will do the same job in a few seconds. If brass is allowed to reach temperatures higher than this (regardless of the time), it will be made irretrievably and irrevocably too soft.
    Brass will begin to glow a faint orange at about 950 degrees (F). Even if the heating is stopped at a couple of hundred degrees below this temperature, the damage has been done--it will be too soft. From this discussion we can see that there are four considerations concerning time and temperature:
    1. Due to conduction, the amount of heat necessary to sufficiently anneal the case neck is great enough to ruin the rest of the case.
    2. If the case necks are exposed to heat for a sufficient period of time, a lower temperature can be used.
    3. The longer the case necks are exposed to heat, the greater the possibility that too much heat will be conducted into the body and head, thereby ruining the cases.
    4. The higher the temperature, the less time the case necks will be exposed to heat, and there will be insufficient time for heat to be conducted into the body and head.
    You can see that there are a couple of Catch-22s involved in this annealing business. On the one hand, the brass conducts heat quite rapidly, and a fairly high temperature with sufficient time must be attained to do the job. On the other hand, too much time cancels the effect, and we will be left with a case that is too soft and not suitable for anything but scrap.

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    Sponsor ADfields's Avatar
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    Your fine, first it didn't get hot enough and second you didn't quench it while it was hot enough. Brass anneals from rapid cooling from a high temperature which is the opposite of steel. If you heat it and let it cool in the air it’s “normalized” and cooling it slowly will “temper” it. You may have removed some of the temper but not enough to matter, first time you shoot it should work harden the temper right back in. You may well have refreshed its life cycle if it was on the older side and starting to get brittle from work hardening temper.

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    AD, just a quick comment. Annealing is heating followed by slow cooling. Quenching is when it's cooled quickly. Quenching will make it more brittle, annealing will make it more maleable and ease cracking problems of the brass. Reloaders anneal brass to make it last longer because firing it work hardens it, particularly the neck, and makes it crack.

    As I've read, not many people temper brass. I did watch this guy's video and he anneals a little differently than other folks I've seen. http://www.youtube.com/watch?v=190rC0iTN5M

  8. #8
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    Quote Originally Posted by Sir View Post
    AD, just a quick comment. Annealing is heating followed by slow cooling. Quenching is when it's cooled quickly.

    You are backward on that for non ferrous which is the opposite of ferrous metals like steel, rapid cooling will harden steel and soften brass. Take a piece of brass and heat it cherry red then water quench it, it will become extremely soft . . . you will Easley be able to crush it with your hand until it begins to work harden. Do the same with steel and it will be extremely hard and brittle. With brass quenching (rapid cooling from high tempature) softens . . . with steel quenching hardens.

    Ammunition brass is tempered in the manufacturing process at the factory and the head/rim temper is very important to preserve. The annealing method in that video is the most common method used in reloading and works very well. The case head standing in the water prevents it from losing any temper as the neck is heated. Then the case is tipped into the water quenching the hot neck and annealing the neck and shoulder area only.

    You are correct on the work hardening, both non ferrous and ferrous respond similarly to work and the neck shoulder of rifle brass is worked the most. Annealing as shown in the video will make brass last until ether the neck wall gets too thin and cracks, or the base near the head (where its not getting annealed) becomes too work hardened and cracks.

    In the case of this oven heated brass what happened was sort of a “normalizing” process (cooled in normal air) that may have relived some of the work hardening near the head but was never hot enough to kill the factory temper of the head and rim.

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    I searched and searched for terms like "annealing brass", "tempering brass" and such. I was surprised to see that not so much popped up. Instrument makers/repairers are pretty up on brass working. From all that I read, it seemed to me that brass only hardens when it gets worked, so I can see reason with your statement. It's kind of confusing how hard it is to find out metallurgical properties of brass being processed and what certain processes do to it.

    There's articles enough to bury the Library of Congress on steel, but no so much on brass. Thanks for the input.

  10. #10
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    I’m a machinist by trade and next to all things guns blacksmithing is my top hobby. So I’ve had lots of dealings with metallurgy over the last 35 years outside of reloading to figure some of this (by no means all) of this stuff out. Some will say brass can’t be “tempered” and they are right, to a point, it’s semantics though. Brass can be “hardened” but the word “temper” means to soften by heat to remove excess hardness which doesn’t actually need doing with brass because it will never get hard enough to be brittle from heat treating. But the words are hardened and tempered are often used interchangeably like the dissection we have had about 45 Colt and 45LC. When someone says 45LC you know they are talking about a 45 Colt and when someone talks about tempered brass they mean hardened brass.

    Tempering/hardening brass is a very complex chemical/heat process almost exclusive to cretin industries so very unlike steels so you aren’t likely to find DIY directions on the web. Steel tempering is easy and quite DIY friendly so info is all over . . . that’s simply heat, quench to harden, re-heat to soften to dissevered Rockwell hardness. But basically they react to heat and cooling in an opposite manner to each other.
    To soften brass cool it fast and to harden brass cool it slow in an environment that allows you to do that.
    To harden steel cool it fast and to soften cool it slowly over 8 hours or more.

  11. #11
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    adfields nailed the metallurgy process.

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