There seems to have been some sort of mix up with my post and this
one “Heat/Age Hardening 18k yellow gold” so I’ll try again.
From what I understand is that fine silver does not age or
precipitate harden because the lack of copper. Is this process the
two metals working together. In other words does near pure copper
age harden? I’m using scrap copper pipe. That what I understand is
that it’s supposed to be 99.xx pure copper.
I’ve noticed pieces that I have left for some time and they seem to
have gotten harder. My imagination?
Also could someone explain the problems associated with over
annealing silver or copper.
I'm using scrap copper pipe. That what I understand is that it's
supposed to be 99.xx pure copper.
It is also my observation that old copper tubing (plumbing) does
harden with age, even when it has just been stored in the original
roll for several years.
I believe most copper pipe and plumbing fittings are made from
copper with residual phosphorous, a deoxydizer. This is the reason
the stuff makes for clean ingots when used for alloying. I’m sure
the type of copper varies among manufacturers but it seems to be
pretty consistant.
I believe most copper pipe and plumbing fittings are made from
copper with residual phosphorous, a deoxydizer. This is the reason
the stuff makes for clean ingots when used for alloying. I'm sure
the type of copper varies among manufacturers but it seems to be
pretty consistant.
It should be Oxygen free copper grade C12200 that would have been
deoxidized with some residual phosphorous.
Peter Rowe gave a good description of annealing . It is easy to
overheat and heat for too long when annealing which causes grain
growth. This permanently damages the metal structure until it is
remelted.
I believe most copper pipe and plumbing fittings are made from
copper with residual phosphorous, a deoxydizer. This is the reason
the stuff makes for clean ingots when used for alloying. I'm sure
the type of copper varies among manufacturers but it seems to be
pretty consistant.
Phill is correct the standard plumbing tube alloy is C1220
(Phosphorus-Deoxidized, High Residual P) which is 99.9 copper with .
015-.040 phosphorus. Good stuff for alloying.
James Binnion @James_Binnion
James Binnion Metal Arts
It is easy to overheat and heat for too long when annealing which
causes grain growth.
True. more for some alloys than others, as well as the degree to
which it then causes problems.
This permanently damages the metal structure until it is remelted.
True also, unless you are able to continue cold working the metal.
While initially the larger grain size means you cannot work the metal
quite as far without risking cracking of the metal (rather like a
newly poured ingot sometimes), if you overanneal the metal at a stage
where you can still work the metal some more, deforming the crystals
again, then a subsequent careful anneal will result in smaller
crystals again.
So while over annealing does damage the metal structure, if you do
it early enough in your working process to allow sufficient
subsequent working, you may be able to pretty much repair the damage.
Your final crystal size may not be as small as it could have been
otherwise, but it may be just fine. But to do this, you really do have
to be deforming the crystal shapes. Rolling, forging, drawing down in
size, twisting wire, or the like. Anything that will cause it to work
harden to a goodly degree, so that with subsequent annealing the
crystals again are forced to break down and recrystalize into smaller
crystals. This will require more work hardening than you might get
with a bit of gentle flexing or banging on the metal with a soft
mallet or something. You really do need to change the shape somehow.