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Heat treated alloys


#1

Recently I was given some on heat treated metals and what
was available for what I use to call ‘spring gold’.

I was told by different refiners that the metal alloy was to be put
in place, once heated it turns into spring gold or has a springy
effect. But this only happens one time. If it is heated again it
loses this action.

Now, from what I learned, was that every time you heat up a spring
type gold it loses its springy nature. makes sense because you are
annealing it. so let’s jump in on this and see what everyone has to
say.

For example, the spring tension in a lever back earring. if you heat
that up without taking it out for repair it loses its spring. So the
question is it must have been heat treated to the “springy” state
before assembly, hence once heated up again, bye bye goes the
spring…

Let’s hear from you…

Russ
thejewelrycadinstitute.com


#2

Russ,

One thing about lever backs is MOST brands have a tiny spring of base
metal in them that melts down readily when soldered. there is one
brand called “Secura” that has no spring so it’s safe to solder a
ring or bail, whatever, on to the earring. So an earring,
particularly a leverback isn’t a great example due to the spring
inside the assembly.

…However sheet or wire is the better example to discuss…Spring
gold anneals like normal gold: To anneal, heat the metal to 1200 F
for 10 to 15 minutes in an oven or kiln, or bring to a cherry red
color for 30 seconds with a torch. Follow this with a quench. This
insures that the alloy will respond to age hardening and develop its
characteristic durability. 14 kt yellow or 18 kt yellow spring gold
is specially formulated so that when it is heat treated, it will
harden the alloy in with the fine gold. All soldering should be done
before heat treating with the 18kt (or the 14 kt for that matter
though there is a bit more latitude with the 14 kt). With yellow
spring golds, you can use a lighter gauge and still maintain the
strength and durability of your piece. The gold will retain its
temper which works well for ring bridges, earrings, earring posts,
clasps, and bar type items like a money clip, tie bar, etc. or
basically for any lightweight jewellery. Then To age- harden, heat
the metal for one hour in a furnace at 700 F (370 C). Air cool the
metal before pickling . This process* is reversible and any heat
treated item can be re-softened or re-heat treated after
annealing*…so you can turn your alloy into non-spring gold- or
re-age harden after annealing but doing so more than once, maybe
twice with a 14 kt alloy (yellow) you will probably not be able to
regain the spring temper, and/or the spring temper will be lost as
the zinc content in many alloys (i say this as some karat gold
alloys are zinc free) becomes affected during pickling and the alloy
may not roll out well, particularly if you aren’t adding at least 50%
new fine gold or clean alloy to the melt or you may get a phenomenon
like stress corrosion happening (sometimes called “fire cracking”).It
is a common phenomenon with white golds, (nickel based alloys) and
low karat golds ( if one considers 6 kt actually gold, then 6-10 kt
gold alloys- those low karat alloys are more common in Europe than
the US). I hope this explains it to you: you can buy or make spring
gold and the process is reversible back to ordinary tempers, but not
spring gold once you have re-annealed it and age-hardened the stock.
White golds are a different story with many variables such as the
alloy- is it nickel based, or palladium included, and the karat makes
a difference as well. spring gold in high karats are virtually
impossible to achieve, that’s why any karat other than 14, and from
some 18 karat ordinarily available from manufacturers are a ‘special
order’ item, if they can be fabricated at all. and in thinking about
the different manufacturers i have dealt with spring gold is only
available in 14 kt as sheet and wire and only in yellow, maybe red or
’peach’ from one maker, and in 18 kt then, only as wire from a single
maker… the more fine gold an alloy contains the less 'alloy" is in
it to age-harden. rer


#3
..However sheet or wire is the better example to
discuss.....Spring gold anneals like normal gold: To anneal, heat
the metal to 1200 F for 10 to 15 minutes in an oven or kiln, or
bring to a cherry red color for 30 seconds with a torch. Follow
this with a quench. This insures that the alloy will respond to age
hardening and develop its characteristic durability. 14 kt yellow
or 18 kt yellow spring gold is specially formulated so that when it
is heat treated, it will harden the alloy in with the fine gold.
All soldering should be done before heat treating with the 18kt (or
the 14 kt for that matter though there is a bit more latitude with
the 14 kt). With yellow spring golds, you can use a lighter gauge
and still maintain the strength and durability of your piece. The
gold will retain its temper which works well for ring bridges,
earrings, earring posts, clasps, and bar type items like a money
clip, tie bar, etc. or basically for any lightweight jewellery.
Then To age- harden, heat the metal for one hour in a furnace at
700 F (370 C). Air cool the metal before pickling. This process* is
reversible and any heat treated item can be re-softened or re-heat
treated after annealing* 

You know if you are going to quote stuff verbatim you should at
least say where you got it and give credit. Otherwise it is called
plagiarism. Most of this section of your post was taken verbatim
from the technical article archive at Hoover and Strong in this
article.

http://www.ganoksin.com/gnkurl/ep808h

Changing the sentence order does not make it yours. Seriously if you
are going to continue to portray yourself as an expert you should at
least re-wite the stuff you “borrow” to post.

James Binnion
James Binnion Metal Arts


#4

I was hoping you would chime in on this James. The normal thought
for me through the years was that heating any spring gold it would
take out the spring.

So, from what I understand the heat treated alloy is now springy and
if you heat it up it loses its spring?


#5
I was hoping you would chime in on this James. The normal thought
for me through the years was that heating any spring gold it would
take out the spring. 
So, from what I understand the heat treated alloy is now springy
and if you heat it up it loses its spring? 

There are a couple of ways to harden gold to make it springy so it
will depend on what method was used to make it hard. Typically
though it will be hardened by adding a metal to the alloy that has
limited solubility in the alloy and whose solubility changes
significantly across a temperature range where the alloy is solid.
The heat treating is then done by heating the alloy to get all or as
much as possible of the low solubility metal (solute) into solution,
this is called solution annealing. The alloy is quenched from this
temperature which locks the solute in solid solution of the alloy.
To harden it is heated up to a point where the solute begins to
precipitate out of solution, typically at a much lower temperature
than the solution annealing temperature. Small precipitated crystals
of the solute form in the grain boundaries and in effect pin the
larger crystals in the alloy in place so that it is much harder for
them to move and change shape, this is what hardens the alloy. This
is also referred to as age hardening or artificial aging because in
some alloys, especially aluminum alloys this process occurs at room
temperature and was noticed as a difference between freshly produced
and “aged” aluminum. If the alloy is heated much beyond the aging
temperature the effect of pinning is lost as the solute crystals
grow in size and consolidate this is called over aging.

So to go back to your question, yes if you heat most spring golds to
soldering temperatures they will soften and you will loose the
spring quality. However if the alloy is hardened by precipitation
and you quench the piece immediately after soldering and then reheat
it in a kiln to the aging temperature you can regain some if not the
majority of the spring hardening.

Jim

James Binnion
James Binnion Metal Arts


#6
So to go back to your question, yes if you heat most spring golds
to soldering temperatures they will soften and you will loose the
spring quality. However if the alloy is hardened by precipitation
and you quench the piece immediately after soldering and then
reheat it in a kiln to the aging temperature you can regain some if
not the majority of the spring hardening. 

Thanks Jim appreciate the thoughts…

Russ