The formation of puckered beads at high welding currents is a
well-known
phenomenon that occurs in gas metal arc (GMA) welding of
aluminum alloys. It
is possible to increase the threshold welding current at which
puckering occurs to
higher alues and to arrest puckering by using an improed GMA
welding
techni!ue. The techni!ue uses a double wire feed in which a cold
filter metal wire(called filler metal wire hereafter) is fed into
the molten pool behind the electrode
wire. "#perimental inestigations were carried out to
clarify this phenomenon
and the main conclusions obtained are as follows$ (%)
entrainment of air is the
direct cause of puckering& (') the effectieness of double
wire gas metal arc (
GMA) against puckering can be e#plained by the fact that
introduction of the
filler metal wire enables sufficient !uantities of molten metal
to be maintained
directly under the arc* which remains stable een at high
currents.
