Pouring and then forging

[Ethan the blacksmith]

Hello everyone, long time no see.

i have tried to melt down old copper pipes, make ingots, and then forge them, with no success. Is copper always forgable (meaning the problem could come from impurities such as the solder on the pipes) or do you have to treat or stir it the way you would with iron? Maybe anneal it lots? Help appreciated!

Ethan

[Frosty]

Welcome to forging copper alloys! No idea what the solder did to the alloy you made from scrap pipe. Did you dexodize the melt before you poured the ingots?

Copper is VERY soft and you can forge it a huge distance with the first blow if it's hard enough. However copper alloys work harden abruptly you get 3 maybe 4 blows when forging before you need to anneal. Listen to the metal so you know when it's going on you. If you continue to forge when it hardens it tends to: split, break up, crumble, say harsh unkind things to you, etc. It goes over FAST, sometimes between blows. Brass is the worst and pure copper the nicest to work. Bronze can be one or the other depending on alloy.

Anneal by bringing it to low red heat and you can quench in water, let it air cool or just go back to work on it, either is fine. I've never noticed a difference.

It's a lot of fun to forge once you get a feel for it.

Frosty The Lucky.

[Ethan the blacksmith]

21 hours ago, Frosty said:

Welcome to forging copper alloys!

Thank you, I should clarify when I’m talking about forging, I mean hot forging! Like at a red heat. 

[Frosty]

2 minutes ago, Ethan the blacksmith said:

Thank you, I should clarify when I’m talking about forging, I mean hot forging! Like at a red heat. 

No need and you can get in trouble faster just a few degrees too hot. Hot forging copper can be dramatic with it's ease. 

Cold forging copper alloys just cries out for the bigger hammer method. You can take it as far as you can make it go in the first blow. Seriously smash it to foil with one blow but somewhere around blow 3 it's done cooperating.

Fun stuff, lots.

Frosty The Lucky.

[ThomasPowers]

Biggest problem is that at red heat the copper is absorbing O2 and building up oxides along the grain boundaries making it crack/fracture/crumble if you let it happen too long---especially small stuff as the exterior vs interior ratio gets smaller.

Tin based solder should be fine making a very low tin bronze.  I have not worked copper alloyed with lead though.  Biggest issue I have had is deoxidizing the copper before casting.  Melting under a flux or layer of powdered charcoal can help that.  Not letting it sit around at heat is another big help and I always used to stir with a DRY DRY DRY charcoal stick right before pouring. (Nassau Refining used to drop a full sized tree, green, into their molten copper to "clean it up. Remotely of course!)

[Mark Ling]

Very intersting. Never had heard that learn something new everyday I guess. 

[ThomasPowers]

My Father was an AT&T bigwig and He got to watch them do it as Nassau Refining was the Bell System's recycler. He said they owned a mountain side to provide the trees.  Just like the old iron smelters use to own their own "coaling woods".  That later were bought by the paper mills or became state parks in South Eastern Ohio, (I attended the IronMasters Conference that was held in Athens OH back when...)

[Ramsey26]

Hello I have actually just recently done exactly what your trying to do so maybe I could help. I’m not sure what your were having problems with but I can start with saying what I did. I started with pipes same as you. I first cut them into smaller chucks and clean them. I cut off any piece that had solder or anything simply because I didn’t like the idea of lead or anything to contaminateing the copper. Then when I melt it down I have to borrow a friends propane forge because the coal forge has a hard time heating up a large amount to melting temperature. After pouring into a long bar shaped mold I made I forged it like a would forge a piece of iron. I dont see any reason not to forge it hot as long as your mindful of its melting temperature. The picture shows some of the stages I did it in raw pipes, chopped up smaller, washed and sorted free of solder/brazing, poured bars, and a forged leaf.

as for “deoxidizing” the copper I never did anything like that and I was also surprised that there was absolutely zero slag on the surface before pouring. I’m not sure what I did right to have it work out so clean maybe because I cleaned it a lot in advance I don’t know.

[ThomasPowers]

If the propane forge is running a true neutral to reducing then you will not have much O2 to worry about. (and please say "my" coal forge instead of "the" coal forge as the issue is specifically with the one you have to use.)

[Ethan the blacksmith]

On 12/26/2018 at 11:10 PM, Ramsey26 said:

 

thank you for this I really appreciate it.