Have I annealed my cases?

[wjg686]

I've been cleaning my handgun brass in a Lyman 1200 tumbler for several years. Last week, I bought a Hornady ultrasonic cleaner. I love it! Cases are shiny in 8 minutes, rather than two hours. But they're wet. So I put them on a cookie sheet in the oven at 350 degrees. They discolored. At 300 degrees, the next batch discolored. At 250 degrees, the next batch did not discolor.

I can't imagine that 350 degrees is hot enough to soften brass. I see on another thread that it takes 650 degrees to do so. Can anybody reassure me? Thanks, and Merry Christmas!

Bill

[Kevin Rohrer]

Depends on how long you kept them in the oven. The rule for annealing is 650-degrees for about 6-seconds. At 350-degrees it would take a along time. That discoloring was the chemicals in the water discoloring the metal, which is harmless.

When I dry brass in the oven, I keep it at 150-225 degrees for a half hour or less.

[savagelover]

Yes I was going to day the same thing,that it is a moisture issue...Let them air dry if you can.

[hounddawg]

at 350 degrees your brass is unaffected, brass grain structure starts being affected at 495 degrees and at 600 it is thoroughly annealed.

If you had managed to anneal your cases in the oven the first time you had fired one the case head would have separated and the case would have spit possibly causing you and your gun major damage. You only anneal the neck of the case.

might want to read this

http://www.6mmbr.com/annealing.html

[Elkins45]

^^^^^ I find information from a website advertising mechanical annealing machines that is critical of the other methods to be just a bit suspect. Isn't that a bit like trying to learn about hand saws from the SKIL website?

If I need a $300 machine to properly anneal my cases then I guess I will just continue to use improperly annealed cases.

[hounddawg]

I find information from a website advertising mechanical annealing machines that is critical of the other methods to be just a bit suspect. Isn't that a bit like trying to learn about hand saws from the SKIL website?

If I need a $300 machine to properly anneal my cases then I guess I will just continue to use improperly annealed cases.

scroll to the bottom of that page I linked, they also show several "free" methods of proper annealing methods using everything from electric screwdrivers to a chopstick.

[Unclenick]

Wjg686,

Below is a 1 hour exposure plot for brass. You can see stress relief begins at about 250°C, which is 482°F. At 350°F you are at just 177°C. I suppose longer exposure might lower the numbers a little, but an hour is a pretty good soak.

You may want to check the accuracy of your oven. I did that with mine using a thermocouple thermometer. It's a gas oven, and I found that at 400°F, the thermostat hysteresis is about 50°F (difference from peak to valley) and that it was averaging off on the high side by 24°F at about 1/3 on time duty cycle. So actual temperatures would peak about 57°F above the knob setting. So if mine were set on 350°, the peaks would be at 407°F. Still safe, but other ovens may be further off.

If you set the brass mouth-up on top of a pizza stone that will average the temperature and keep the heads from getting much above average during the peaks.

[wjg686]

Thank you all! The cases spent no more than 20 minutes in the oven, so they have to be all right. I haven't loaded or fired any of them yet. Some are air-drying right now. The 250 degree oven dried them well over about 20-30 minutes and they didn't discolor. I'll probably do that from now on.

[m&p45acp10+1]

Did you sbmerge the brass in clean, water to rinse before putting it on the oven. I personaly just put mine on a towell and let it air dry for a day.

When I first started I just ran some warm water over the basket. I noticed the brass looking duller when it dried. I started dipping it in a bowl of clean water and then rinsing off with running water. Brass did not look so dull after it dried. Cleaning solution that dries on will not hurt performance. Though if you are picky about super duper shiny cases you may have to run another short cycle, then submerge them in clear water, then air dry.

[hounddawg]

apologies for my first post, for some reason I thought you were attempting to anneal your cases in the oven not just dry them, and thanks for the info on the Hornady , I have been debating getting one.

[wjg686]

I rinse them in the pan I used to use to collect tumbler media from the Lyman. I'm not patient enough to leave them to air dry. The Hornady U/S cleaner is sweet -- holds a little over 100 .44 spl cases, more .45 ACP's, and is easy enough that I'll just clean them when I get back from the range, rather than saving up several hundred for a batch. Many fewer to deal with in a batch.

[Unclenick]

If you final rinse with a small amount of distilled or deionized water, you won't have water marks.

Heat causes any portion of the surface activated by the cleaner to oxidize faster than it otherwise would. Some of that will more gradually happen in air over time anyway.

Polishing after chemical cleaning is the only way I know to get rid of all traces of surface activation and prevent all post-cleaning dulling and darkening. It may actually not be a good thing to do if you don't shoot your ammo promptly. The reason oxides from manufacturing and annealing are left on military (and Lapua) brass is not, as some assume, to see whether or not the brass was annealed, but rather because it resists corrossion better than a polished case does. An experiment done at Frankford Arsenal between the WW's showed that polished brass left exposed on the roof of the building for a year would be heavily corroded while unpolished brass would be fine.

[wjg686]

Thanks again. My only concern with the discoloration was whether it indicated softening of the brass. Clean is good -- I don't care what color it is.

[HiBC]

I cannot say for sure,but I will throw out another thought.Your oven's thermostatic control monitors the air temp inside the oven.

It may not give you accurate information about how hot an object can get from radiant heat.

The radiant heat from the heating elements may have heated your brass hotter than 300 deg before the air temp in the oven was 300 deg.

Think about broiling a steak in an electric oven.

I cannot say what happened,but it is something to consider.

[Unclenick]

That's probably less of a concern than you might expect. It would happen to anything you put in the oven, so for the temperature control to be meaningful the net effect of all heat sources have to be taken into account. Any radiant heat source you have will also irradiate the sides of the oven, heating them, and they, in turn will affect the temperature of the air. Since, unlike a broiler, the heater cycles on and off, the air will take up heat from radiantly heated objects by convection during the off portion of the oven cycle. The average temperatures of the objects will go up some, but they won't run away.