9
COPPER & COPPER ALLOYS
The majority of copper wires also contain
alloying elements. Although these elements generally decrease
the conductivity of pure copper, they
are necessary to increase strength, deoxidize the weld metal and
match the base material chemistry.
Tables
5-6 and 5-7, located in back of book present the various copper-
base wire electrodes and the required
transverse tensile strengths of the weld metal. Primarily, selection of the proper
wire depends on the
base plate chemistry; however, this is not always possible. Again, the choice
is not dependent on shielding
gas, as only argon and helium are recommended. The intended uses of the various
wire electrodes
are as follows: ERCu
(All-State Deox-Copper) – Because
of the low alloy content, ERCu wires are restricted to the
welding of pure copper. Deoxidized
and oxygen-free copper can be soundly welded with good strength.
However, electrolytic tough pitch copper
should not be welded with an ERCu electrode if quality
is required. ERCuSi-A
(All-State Silicon Bronze) – This
wire is primarily used to join copper-silicon alloys, as the
chemistry match is adequate. In addition,
it can be used to weld copper-zinc alloys. Because of the high
silicon level and the resulting deoxidation
of the puddle, electrolytic tough pitch copper can be adequately
welded. In this case, soundness and
mechanical properties will be superior to welds made with ERCu
electrodes. ERCuSi wires also perform
similarly to mild steel wires with respect to arc stability and weld
puddle fluidity. Because of this, the
welding of carbon steel plate and galvanized steel plate can be
successfully accomplished.
ERCuSn-A (All-State Phosphorus Bronze)
– Wire electrodes of this classification are primarily
used for welding
phosphor bronzes, but can be used to weld cast iron and mild steel. Again, because
of the deoxidizing
ability of the phosphorus, they can be used on electrolytic tough pitch. However,
ERCuSnA wires
do not yield a fluid weld puddle so preheating may be necessary. Copper-zinc alloys
can also be welded.
*Tables
5-4 and 5-5 appear in the back of this book.
