Abstract
Undercut and humping bead are the common defects that limit the maximum welding speed of tandem pulsed GMA welding. In order to raise the maximum welding speed, effects of the angle and distance between leading wire and trailing wire on the bead formation of high speed welding are investigated. The undercut and humping bead is attributed to the irregular flow of molten metal towards the rear part of the weld pool. This irregular flow can be prevented by the trailing wire with a push angle from 5 to 13 degrees that provides a proper component of arc force towards the welding direction. Moreover, the irregular flow is also related to the distance between leading wire and trailing wire and the flow becomes regular when the distance is in the range from 9 to 12mm. As a result, the maximum speed of tandem pulsed GMA welding is improved markedly.
