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Hardening copper wire that has been annealed


#1

Hi all,

I have been looking for a way in which I can re-harden 14G copper
wire that has been annealed during the soldering process. This is for
a bangle project and hence I need the bangle to retain its shape and
hardness. However, they become really soft after the annealing and
tumbling in stainless steel shot for 5-6 hours doesn’t seem to have
done the trick of hardening them back to the required stiffness.

Some of the techniques I read on the internet are. …

  1. Heating the metal to just below the annealing temperature and
    quenching in ICE COLD water repeatedly (Though some people say that
    quenching in water or letting it air cool does not affect the
    hardness at all)

  2. Sand blasting (but that would change the texture of the metal)

  3. Hammering with raw hide mallet (But that would take too long
    doing one bangle at a time. I was hoping for a more effective
    process that did not require me to hammer away for long hours :))

  4. Age hardening I read an article on Ganoksin by Gary Dawson about
    heat treating metals where he talks about a process called Age
    hardening to bring back hardness onto annealed metal. Also, it talks
    about karat metal and sterling silver.

However, I am novice enough not to understand the actual process. I
would really appreciate it if someone could simplify it for me and
say what exactly to do in terms of copper metal.

Looking forward to hearing back from you. …

Thanks,
Kappu

P. S: It would be great if someone could provide a source for 14G
round HALF HARD copper wire. The highest gauge I have been able to
find in HALF HARD copper round wire is 16G.


#2

Age hardening is easily done. You hold the metal at about 600 deg in
your oven for, say, 2 hours, then turn the oven off, let it cool
overnight to room temperature, then you are done.

hardening of metals (well, copper, gold, silver) happens when there
is internal crystal structure growth. heating these metals to near
the melting temperature, then cooling quickly, prevents the crystal
growth formation, which makes the metal soft. heating it to about
550-600 deg and holding it there, then cooling slowly, lets the
crystal grow, and this makes i harder. for copper and silver, t his
will not be as hard as a hammered finish, but maybe about 70%? as
hard.

other metals (steel, aluminum, etc) work differently, for example
steel, cooling quickly makes it hard.

Mark Zirinsky
denver


#3
Age hardening is easily done. You hold the metal at about 600 deg
in your oven for, say, 2 hours, then turn the oven off, let it cool
overnight to room temperature, then you are done. hardening of
metals (well, copper, gold, silver) happens when there is internal
crystal structure growth. heating these metals to near the melting
temperature, then cooling quickly, prevents the crystal growth
formation, which makes the metal soft. heating it to about 550-600
deg and holding it there, then cooling slowly, lets the crystal
grow, and this makes i harder. for copper and silver, t his will
not be as hard as a hammered finish, but maybe about 70%? as hard.

Basically everything in the above paragraphs is incorrect. First you
cannot age harden copper and the rest is not quite right either.

Age hardening comes up every so often on this list and is typically
not well understood. I just made a post for my Orchid blog

http://ganoksin.com/blog/binnion/2013/01/02/age-hardening-sterling/

that covers it in some detail but hopefully in an understandable
fashion.

James Binnion
James Binnion Metal Arts


#4

Jim,

Thanks for the link to your blog and BRAVO for possibly the best
introduction to binary phase systems and diagrams that I have ever
read, I wish I had been lucky enough to read an explanation like
that back when I had my first courses in petrology and inorganic
chemistry some 40 years ago.

Regards,
Dallas Meloon