Variable polarity plasma arc welding of 6·35 mm aluminium alloys: parameter development and preliminary analysis

AbstractThe application of the variable polarity plasma arc welding (VPPAW) process to two medium to high strength 6·35 mm thickness aluminium alloys is described. Automated computer controlled equipment was used to produce single pass, full penetration keyhole welds of even bead width. The paper covers the development and optimisation of the welding parameters and different material preparation procedures, providing macrographs, electrical transient traces, hardness profiles, and tensile results from some of the welds made. Repeatable procedures were obtained more easily by welding in the vertical up position, using the plasma gas flowrate in conjunction with the welding current to generate the desired bead profile. Autogenous welded joints were found to provide adequate root reinforcement with a slight degree of undercutting at the top bead. Example skimmed and as welded tensile tests were carried out on 2024 alloy, resulting in a typical overall ultimate tensile welded performance of 66% of the parent ...