Use of Pulse Current MIG Welding Improves the Weld Characteristics of Al-Zn-Mg Alloy

Abstract

Extruded sections of commercial Al-Zn-Mg alloy have been welded by continuous and pulsed current MIG welding processes, using 1.6mm diameter Al-Mg filler wire. During welding the current and other pulse parameters such as its frequency and duration are varied and their influence on the weld bead geometry, chemical composition, hardness and porosity content are studied. The influence of various parameters on the recrystallization at HAZ adjacent to the fusion line has been examined. Finally the performance of the weldments under static and dynamic tensile loading are also investigated. The properties of the weldments prepared under pulsed MIG process are correlated to those of the weldments prepared by the conventional continuous current welding. It has been observed that a critical and selective use of pulse parameters improve the weldment properties as compared with those of the conventional weldments.