On Fri, 19 Mar 2010 18:34:19 -0700, John Larkin
wrote:

On Fri, 19 Mar 2010 18:02:05 -0700, Archimedes' Lever
wrote:

On Fri, 19 Mar 2010 15:01:19 -0700, John Larkin
wrote:

The work hardening probably has less effect on the resistance
than the elongation;


Elongation IS where the work hardening occurs. D'oh!

The change of resistance from elongation is purely geometrical; the
wire gets longer and its cross-sectional area/diameter correspondingly
drops, and the area reduction increases its per-unit-length
resistance. There will be additional resistance increase from messing
with the crystal structure. Two things are going on here. You could
anneal out the crystal thing but not the elongation.


Sure... smaller diameter equates directly to reduced current carrying
capacity. Not so much due to resistance, but more so because high
currents generate heat. Each wire size has an upper limit before the
metal melts. Then all hell breaks loose. I am sure that your wires
would have a reduced capacity due to the stretch effects as well as the
reduced diameter. In other words, if you draw it down to a 20Ga size, it
will likely NOT carry the same current that a 20Ga wire would. Well, it
would be "hotter" at any given current than the equivalent sized
un-stretched wire.



Copper... if you move it, it will harden.

Unless you move it *very* slowly.

How slowly would I have to stretch it to avoid work hardening?

John

I reference to bends and the like where there is no (very little)
deformation pressure. In stretching, I think that it is unavoidable. The
stretch would have to be over a period of hours to keep the lattice from
hardening, and not even likely then.