Re: [TCML] Winding the primary

[Quarkster <quarkster@xxxxxxx>]

David -
   
  I don't believe copper (as used in refrigeration tubing, etc) requires any post-anneal quenching to achieve a "dead soft" condition.
   
  I read Article 25 several times, but could find nothing about quenching as a required step for annealing copper.
   
  There was brief mention of water quench as part of the process for annealing exotic zirconium-copper and chromium-copper alloys, but that's not applicable to common copper refrigeration tubing.
   
  An interesting technical paper with temperature vs hardness annealing curves for copper shows that no quenching is required to achieve maximum softness.
   
  See:
  http://www.wsp-ingenieure.de/deutsch/downloads/paper_TBerrenberg_08.pdf
   
  Regards,
  Herr Zapp

David Speck <Dave@xxxxxxxxxxxxxxxx> wrote:
  Neal,

Might want to look at:

http://www.key-to-metals.com/Article25.htm

ISTR 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 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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