A comparison of the swing and non-swing arc behavior in arc ultrasonic assisted narrow gap GMAW

Abstract

The arc ultrasonic technology was applied to the swing arc narrow gap GMA welding process of aluminum alloy. The ultrasonic energy acts on the welding process by superimposing an ultrasonic current on the basis of pulsed welding current. The arc behavior will be significantly different from that in the conditions of non-narrow gap and non-swing due to influences from the narrow gap groove constraint and the arc swing. In this paper, the behavior of swing arc and non-swing arc at different positions in narrow gap groove are compared, and the influence mechanism of arc ultrasonic on arc behavior is analyzed. Results indicate that the arc expands after superposition of ultrasonic current, and that the arc behavior is different at different positions of the narrow gap groove. In the sidewall, the expansion degree of the non-swing arc is obviously greater than that of the swing arc. The swing arc area increases by 50.33% at most, and the non-swing arc area increases by 117.94% at most. In the groove bottom, the expansion degree of the swing arc is greater than that of the non-swing arc. The average area and width of the swing arc in the groove are nonlinear relationships with the ultrasonic current amplitude and a linear positive correlation with the ultrasonic frequency, respectively. Arc swing and ultrasonic action make the arc length longer. The difference in speed between arc expansion and contraction and the oscillation of arc plasma under the arc ultrasonic action together promote arc expansion.