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Annealing thick metal


#1

I read that thick metals require multiple annealings for the effect
of the annealing to completely penetrate the entire thickness. Is
this correct?

If so, what metals, what thicknesses, etc. and why is this so?
Thanks so much.

Jamie


#2
I read that thick metals require multiple annealings for the
effect of the annealing to completely penetrate the entire
thickness. Is this correct? 

No

If you get the metal to annealing temperature it will anneal without
multiple annealing operations. However to get fully annealed some
time is necessary. In studio practice when annealing with a torch
metals are typically heated above the annealing temperature to get
the annealing time down to a reasonable time. In industrial practice
the temperature is lower but the annealing time maybe 30 min. or
more. This results in smaller crystal size in the annealed metal
which is a desired attribute. Torch annealing can result in large
grain size which makes for weaker metal that is prone to orange peel
surface defects when bent or stressed.

James Binnion
James Binnion Metal Arts


#3
I read that thick metals require multiple annealings for the
effect of the annealing to completely penetrate the entire
thickness. Is this correct? 

No.

Complete annealing can require a little longer at the appropriate
temperature for thick metal, but not multiple annealings. Most gold
or silver alloys anneal quickly at normal “torch” annealing temps, so
you don’t normally need to worry about whether it’s been long enough,
only whether it’s reached the needed temperature. Platinum, on the
other hand, anneals more slowly, so thicker metal may need to be held
at that nice orange glow for more than a few seconds, to fully
anneal, though often, even partially annealed platinum is quite soft
enough. If you anneal in a furnace, which can then, with tight
temperature control, do your annealing at a lower temperature but for
longer time, then adjusting the time for the thickness may be needed.
The lower temps that you can practically anneal at with a furnace
allow you to minimize grain growth and surface oxidation or loss of
finish.

Peter Rowe


#4

Best way of annealing thick metals is in a temperature controlled
furnace. the time will be dependant upon the size and thickness of
the metal. Quenching is best done in ice cold water.

Nick