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Copper Cracking


AKHunter

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I'm having problems with my copper cracking quite badly when I work it with any heat. I made a copper rose out of 3/4" type M copper pipe. I wanted to make another, but all I had left was 3/4" type L soft copper. It is supposed to be the same stuff as type M (C12200) but thicker. It wasn't soft at all, so I tried annealing it, but no luck. I tried heating and cooling slowly- still no luck. Then I tried heating it to dull red and it works very well. But 1/4th of my pieces are cracking badly. I tried at a lower temp and at higher temps but it still does the same. I'm not trying anything extreme, just flattening it into a sheet of copper. What am I doing wrong?

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Not completely sure. You are aware that copper work hardens right?  You probably just need to anneal it more often during the process.  When you feel it starting to stiffen up under the hammer,  anneal again. Typically you only have to take it to cherry red, then can quench. Copper shouldn't harden from the quench. If you are pickling be careful of splashing though. Good luck,  perhaps someone more expert in coppersmithing can better advise you. 

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Heat and quench to anneal plain copper.  ALSO if you keep it hot for an extended period of time copper oxide builds up along the grain boundaries and cracks.  So short heats and as few as possible if you are having problems  (rather like what happens to steel when there is too much sulfur in it)

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Thanks guys! To anneal I was heating to cherry and quenching. Not sure what to make of the annealing not working. @ThomasPowers, I think you hit the nail on the head about too long of a heat causing it! I had my forge turned way down low, and stuck 2 or 3 in to heat. come to think of it, it always was the last piece out of the forge that cracked, and the cracks had large visible grains in them.

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Ayup, that sounds like the problem. Only heat it when it needs annealing and don't do a lot of hammering between annealing. Just bring it to red in a dim place, that's all it needs, more is NOT better. Copper alloys work harden abruptly, blow one it moves like butter, the next not so well and two more blows and it's breaking up. They will go as far as you can make them on the first blow but you only get 3 before you're risking failure, even pitty pats count.

When I anneal copper alloys I don't bother to quench I pull it out and go to work on it, copper, brass work nicely at near red heat. Bronze isn't so cooperative some alloys forges nicely some not at all. Worse still it's hard to find an actual difference between a lot of modern brass and bronze alloys. The stuff is fun to work though but be very careful NOT to mess with Beryllium Bronze alloys, beryllium is darned toxic, BAD stuff. You find it in a lot of electrical buss bars and it's more gold colored.

Are you going to bring your copper flowers to the Nov 12th. meeting? You can do a flower demo and I'll be happy to talk about annealing the stuff.

Frosty The Lucky.

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Beryllium copper can look like copper if it has been heat treated. When I would pull parts out of the heat treat oven they would have a dull copper tone to them. That oxide layer once rubbed off would expose the more normal gold tint. It is hot short , so it cannot be forged hot, only after annealing. I have forged some spikes out of it, and it work hardens quickly, so lots of annealing. Like Frosty said, try and move copper alloys as much as you can as quickly as you can.   

And when using BeCu alloys proper procedures are required when doing anything that will create fumes or fine dust particles as it is an inhalation hazard and can cause lung damage. Turning it or milling it was not an issue as the chips were large. 

Other things to watch with copper alloys are the lead, and nickle contents and zinc with brass. All metals pose some hazard if dust or fumes are inhaled, so always protect your lungs when sanding or polishing. 

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Frosty  Making it to the meeting would be a long shot, but not impossible. It's a $250 ticket to fly in, so it'll only happen if it coincides with a pre-planned trip. I'll keep you posted if it looks like I'll make it.

I'm making a candle holder with a copper flower 'cup' to hold a standard tall taper candle and a copper rose coiling around the base. It has a forged steel stem/base and leaves. I'm trying to raise ( I think that's the right term) the cup that the candle sits in, but my copper is too thin (or I'm doing something wrong) for how deep I'm trying to go. Any recommendations for how thick of metal to start with? My copper is .025 when I start, and I'm trying to raise to 3/4". Am I raising too much for a candle holder?

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