View Full Version : Annealing brass?

01-10-2007, 08:48 PM
I have some brass sheet that was actually kick plates for the bottom of doors. It's about .045" thick and quite stiff. We want to use it to make the water hopper on a Hit & Miss model that we're working on, and it doesn't bend all that well.

The end shape is like a 'U', with the top legs bent inwards. I machined up punches & dies to bend the bottom 'U' and the top legs where they bend in, using wood. Figured on bending in an arbor press. As it's not a good idea to learn on your good project parts, I first tried a piece of aluminum sheet that was a bit thinner. Worked great, and I was highly encouraged.

Well, that all came to an end when I tried the brass. It's very springy, and I couldn't get the bottom 'U' to bend properly, it wants to spring back. Bending by hand, out of the die doesn't get it, as it wants to kink instead of bend smoothly.

So, I got this great idea to anneal it. It's my understanding that annealing brass is done by heating, then quenching; I've seen a procedure for annealing the necks of rifle brass by such a procedure. Now, I have this really neat little heat-treat oven with digital temperature control, so it should be easy to get the right temperature.

Questions: Am I on the right track? And, what temperature should I set the oven at?

TIA: <<Jim>>

01-10-2007, 09:35 PM
I thought you annealed it by heating it and letting it cool really slowly, but I have never done it. Threw a little web searching I found that most of the brass varieties said to anneal at a temp of 797 - 1380 F or 425 - 750 C give or take a few depending on the type of brass.

If millman was here he would probably tell you it is all in the machinist bible and that you will never be a man.:D


J. Randall
01-10-2007, 09:57 PM
I don't think it really matters, you can heat to a dull red and quench, or let it cool on its on. Either way will anneal it. James

01-10-2007, 10:04 PM
To anneal brass, heat it to a dull red and allow it to cool. It doesn't matter if it is quenched or air cooled, the results are the same.

Brass will work harden, and depending on the bend or draw involved, several annealings may be required.

01-10-2007, 10:15 PM
Made brass medals by the jillion at Green Co. in Kansas City, MO when I was a kid. High School athletic medals, year pins etc. Used a forced air and natural gas torch (about 1" dia x 2" blue flame) to heat a batch of them (about 10" square on wire mesh) medium red and quench them. The water had some kind of acid in it to loosen the scale. I think we cleaned the scale off with a rotary brass wire brush.

01-10-2007, 11:00 PM
Might be a good idea to make sure you are really dealing with solid Brass. Could be "brass plated" steel. A magnet will tell quick enough.

01-10-2007, 11:31 PM
i had to do something similar to what you're doing with about 1/8" brass sheet. oh, i could get it to bend into a sharp radius alright, with big stress cracks along the bend. :)
so, i have some experience with anealing case necks on brass cartridge shells (don't ask, a big project of mine), so figured to give the brass sheet a try. you want to heat it and immediately quench it in water. after i did this i could not only make the tight bends, but i could almost fold the sheet in half and there were no cracks or spring-back.

andy b.

Al Messer
01-10-2007, 11:39 PM
To anneal Brass, heat to dull red heat and quench immediately in water---room temperature is O.K.

01-10-2007, 11:58 PM
To remove the firescale from copper,brass and silver ect not iron or steel yopu can use the PH reducer for swimming pools. same stuff as the fancy sparex works as good and is cheaper for a whole lot more. You will need to anneal often as the brass hardens with only a small amount of working compared to copper.

black powder
01-11-2007, 12:03 AM
I have made several trigger guards from the same material, Heat to to a bright red ,guickly quench in water . Don,t be suprised if it quickly work hardens, I had to anneal several times just to make 1 trigger guard.

01-11-2007, 09:25 AM
Heating to a dull red will burn the zinc on the surface of the alloy...When you remove the scale afterwards (add some sulphuric -battery?- acid to water) you'll see pink patches where all the zink has gone. Only sanding and polishing will remove these...
If you blacken the brass with soot first (propane torch, no oxigen) and then heat the brass until all the soot has gone, it'lhave been annealed enough...

01-11-2007, 09:33 AM
Annealing copper and brass, cherry red then quench.
"Ph reducer" is common HCl, hydrochloric acid and yes, a splash of that in the quench water will remove scale and clean up for soft soldering. You're probably using ZnCl flux? (zinc chloride) Usta call it "killed spirits". Cut up old zinc battery cases and dissolve em in HCl.

Must include the usual caution, ALWAYS add acid to water, never the reverse.
Rgds, Lin