11 Copper
and Its Alloys 1.
GENERAL (a) The
weldability of each copper-alloy group
depends largely upon the alloying elements. For this reason,
we do not attempt to give one set of
welding conditions applicable to all groups. Each will be discussed
separately. (b)
DCSP is generally used for welding
most copper alloys. However, ACHF or DCRP is recommended for
beryllium copper or for copper alloys
less than 0.040-in. thick. (c)
Where flux is recommended, never use
a flux containing fluorides. The intense heat of the arc will
vaporize the fluorides which, if inhaled
in appreciable quantities, will irritate the lungs. (d)
Always provide good ventilation when
welding copper or any copper alloy. This is particularly
important when welding beryllium copper
or when using beryllium copper welding rod. The
dusts, fumes, and
mist of beryllium compounds in virtually every form are highly toxic. The
American Conference of Governmental
Industrial Hygienists has adopted a threshold limit value - TWA = 0.002 mg/m3
. The ACGIH has
also listed beryllium as an industrial substance suspect of carcinogenic potential
for man (refer to 1983- 84
edition ACGIH). Because of this, extreme precautions should be taken to reduce
the dusts, fumes, and mists
to zero. An effective high-velocity ventilating system should be used regardless
of the degree of contamination.
The welding operator should also be protected with clothing, gloves, and a mask
of an approved
type. 2. ELECTROLYTIC
COPPER Due to
the cuprous oxides contained in electrolytic copper, there is at present no known
welding method that can
produce sound, high-strength welds in this material. Electrolytic copper is sometimes
welded when tensile
strength requirements are only 19,000 psi or less, although porosity still occurs.
Approximately the same
welding conditions are used as those recommended for deoxidized copper below.
