8
ALUMINUM The
most common and preferred method for welding aluminum is with the spray arc process,
regardless of the
material thickness or position of welding. The high heat conductivity of aluminum
is such that even with the
high heat input produced with a spray arc, the solidification rate of the weld
puddle is rapid enough to allow
welding out of position. Pure argon shielding gas is most commonly used for semi-automatic
(manual) welding
as the weld puddle is very controllable and the resulting weld exhibits good bead
shape and soundness.
However, if a hotter puddle is desired, for thick plate or automatic welding for
example, argon- helium
mixtures may be used. Although the short arc process may be used for welding extremely
thin aluminum,
spray arc should be used when- ever possible. If care is not taken to provide
a clean welding surface,
the fast freezing puddle produced by the short arc process is very likely to yield
porosity. The welding
conditions appearing in Table 8-4*
were developed using argon shielding gas and the spray arc
process. Figures
8-5 and 8-6 show accurate burn-off characteristics for various
size 4043 and 5856 wires and Figure
8-7
shows deposition rates for these wire-feed speeds.
Figure 8-3 - Burn-Off Characteristics
- 300 Type Stainless
Steel Wire Continued
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