Neal, Might want to look at: http://www.key-to-metals.com/Article25.htmISTR that copper may be annealed by heating and then quenching in a liquid -- sounds like what would actually temper steel, but copper works differently.
Many years ago, I played with a catalysis of methanol to formaldehyde by holding a flat pancake coil of red hot 12 Ga copper wire in methanol vapor above a pool of MeOH in a small beaker. Trick was to not have the MeOH ignite. The catalysis process released a lot of heat, and was self-sustaining as long as the MeOH lasted. The neat thing was that the process left the copper surface absolutely clean and pink, a color obtainable only when totally free of oxide. You could see waves of pink pure copper and brown copper oxide moving rapidly across the wire surface, depending on which areas were in the highest vapor concentrations.
If I quenched the copper in the MeOH, of course the MeOH started to boil, and caught fire, but the copper stayed perfectly pink and ended up absolutely dead soft, so that is behavior you might be able to use. You might try both fast and slow cooling to see what produces the softer result.
HTH, Dave Henry Hallam wrote:
I've tried it not in the oven, but on a gas burner ring and separately with a blowtorch. Both worked pretty well, though it's still a pain. Henry On Fri, Jul 11, 2008 at 2:37 PM, Neal Namowicz <neal@xxxxxxxxxxxxxxxx> wrote:I have a couple of lengths of "salvaged" tubing myself with a few too many bends in it. I wouldn't have bothered in the past, but with the cost of copper... Anyway, I was wondering if anyone has managed to UN-work harden tubing? I was thinking of sticking it in the oven on high heat for a while and letting it slowly cool. Anyone ever try it? It's a pain in the neck, sure, but compared to unpotting an nst for example, it doesn't sound too bad. Neal.
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