How hot to anneal brass?

[longcruise]

I'm wondering what temperature is needed to anneal brass.  I can get it very hot but is it necessary?  What would be the lowest temperature that would do the job?

[Mark Elliott]

It just needs to start glowing red in low light.    The same goes for copper and silver.   If you do that and it is still not soft,  heat it just a little brighter red.    If you get to a salmon color, you are too hot.    You can quench once you remove the heat and it goes to black in the same light. 

[David Rase]

I don't know what the temperature is, I just heat it to an orange color and quench in H2O.
David

[Daryl]

I heat brass to dull red in a no-light situation, then quench or let air dry - same result, dead soft. The brass I use has zinc in it.

[redheart]

Is there a way to harden it again?

[Dennis Glazener]

Only way I know to harden it back is to work/hammer it will harden it.
Dennis

[PPatch]

Is there a way to harden it again?

Given enough time, something like a week or so, it will harden on its own. I have never had occasion to re harden it, and like Dennis says I know of no reverse process that will do that quickly except hammering it. Not all "brass" will anneal btw, an example is the brass wire coming from china that just about every US store sells these days.

dave

[jerrywh]

1350°F

[longcruise]

Thanks to all.  I have been under the impression that it would soften at much lower temperatures.  I'm probably going to have to come up with a better heat source for larger parts than a propane torch.

[bama]

I use map gas now but I have used propane in the past for anything that I have come across in long rifle building. Like the others have said, heat to an orange red and then quench in water. If you watch you can see the metal relax in many cases as the metal comes to temperature.

[M. E. Pering]

I have never found any need for anything more than a large propane torch.  You should never have to anneal anything but sheet brass, since castings should come already annealed due to the casting process.  As far as quenching goes, this is not even necessary, but more of a convenience so you can immediately return to work on the part.  If you heat it to temp and let cool naturally, it will still be annealed.  In my experience, the only parts really need annealing are the ramrod entry pipe, and the domed patch box lid.  Hinges and ramrod pipes I also anneal, but I doubt it to be that necessary.

M. E. Pering

[Dan Fruth]

Annealing silver is a little different....Draw on the silver with a magic marker, and heat with a propane torch till the writing dissapears, then quench...I learned this from a jeweler...

[BOB HILL]

Thanks, Dan. Great tip on the magic marker as e heat gauge on silver.
Bob

[Davemuzz]

For annealing centerfire brass there is a product called Tempilaq Temperature Indicator. This stuff you apparently brush on the brass, and when the temp of 750 degrees is reached, it melts (I think.....I've never used it) off the brass. Apparently 750 degrees is the proper point to anneal brass.

Just thought I'd provide an option. I don't know if it would be a good option.

FWIW

[LRB]

750°F would be a good temp for a fast anneal. Annealing starts at around 500°, but would have to soak for maybe an hour. Anywhere around 700° to 800° will give you a fast anneal in just seconds.

[Acer Saccharum]

Some alloys won't anneal.

There are castings out there that look like brass, but are actually silicon bronze. I've never had luck annealing them.

Sheet brass, like 360 alloy, cartridge brass, or engraver's brass, all anneal beautifully. You can hammer the brass out to thin the sheet, anneal as it hardens from hammering. Or hammer the brass to make it spring hard. If you are going to form or bend the sheet, anneal it every so often as you work it to prevent cracks.

[Willbarq]

Only way I know to harden it back is to work/hammer it will harden it.
Dennis

This is what I found.

[longcruise]

Maybe the simple approach with my limited equipment would be to put it in oven at max for an hour or so?

[LRB]

If you have any kind of a torch, just bring it up to a dull red then quench or air cool.

[JCKelly]

Quench it.
Do quench it in water
Quench it, quench it, quench it.

Reason?

Much brass, as in most bar and castings, some sheet, contains just a little lead, to make a sounder casting and to improve machinabililty and engraving, as in sheet. The lead does not dissolve in the brass, it exists as tiny specs of metallic lead.

If you anneal at or above the melting point of lead, the molten lead can seep into the grain boundaries. Then when you hammer or bend the thing it will have only the strength of lead, and it will break.

Yep, it will.

Courtesy Your Local P.I.T.A. Metallurgist

[Acer Saccharum]

J. C., I had no idea! That's great to know! Keep the hot time short, and rapid cool to prevent lead migration.

[G_T]

How do you think the lead got in the brass in the first place? Melted... just like the copper and zinc. These aren't sintered or modern specialty powder tech alloys. I'd have to check to see if there is an interalloy crystal formed from either Cu+Pb (probably not) or Zn+Pb (probably so; it is called solder). If so, you probably don't have any lead as separate crystals in the mix as the lead concentration is low in brass alloys which have lead.

For annealing discussion:

Go get a strip of the K&S brass. Heat it dull red and quench. Bend it in your hand some to get a feel for how soft it might be. Then heat it to a medium red, quench, and bend test. Then heat it to orange and repeat. Or do it with three separate strips to separate out the reheating aspect. You'll find different degrees of annealing. I'm guessing you'll probably want the minimum annealing which lets you get the job done, whatever that job might be, so that you have the maximum hardness when done. When doing a little chasing and repousse, I head more for the orange. But I'm expecting to be distorting the metal a lot! If only bending it a little and I thought the metal was sound (as in not a brittle casting) then I'd go for a lower temperature anneal to leave it a little harder. YMMV.

Spend the minimum time required to get the metal up to a uniform temperature. Copper and Zinc oxidize as you are heating unless you are using a good fire coat of some sort, which most here would probably not be doing, along with a reducing flame.

If you want to fire coat, get some borax or some boric acid. Mix some up in a strong alcohol and paint the slurry all over the brass part. Light it to burn off the alcohol and adhere the borax or boric acid to the surface. This will cut down on oxidation when annealing.

Then pickle to remove the firecoat and any surface oxidation. You can use salt and vinegar as readily available chemicals to make a pickling solution for this purpose. I tend to use a reasonably concentrated solution of citric acid for gold/silver/copper related alloys. The fumes don't tend to rust steel in the immediate area! The pickle solution ideally should be hot. If the metal wasn't too oxidized, it should come out bright.

Gerald