Comparative evaluation of mechanical, microstructural and corrosion characteristics of AA6061-T6 aluminium alloy joints under various GMAW variants

Aluminium alloys are metallic materials composed primarily of aluminium, combined with elements such as copper, magnesium, manganese, silicon, tin, nickel, and zinc to enhance specific properties like strength, corrosion resistance and machinability. Metal transfer plays a vital role in determining the stability of the arc, weld productivity, weld bead appearance and quality in Gas Metal Arc Welding (GMAW) process. This research offers an in-depth examination of AA6061 aluminium alloy weldments created using ER5356 filler wire through the constant current, pulsed current, cold metal transfer and pulsed cold metal transfer (PCMT-GMAW) techniques. This study presents the comparative evaluation of metal transfer modes on mechanical, microstructural and corrosion characteristics of GMA welded AA6061 aluminium alloy joints. Mechanical tests including tensile and hardness assessments revealed increased strength and hardness in the PCMT-GMAW weldments compared to the other modes. Potentiodynamic corrosion tests demonstrated that the PCMT-GMAW weldments had recorded higher corrosion potential (Ecorr) and lower current density (Icorr) values compared to the other modes. The results revealed that PCMT-GMAW mode imparted superior mechanical properties and corrosion resistance characteristics compared with the other modes owing to the low thermal gradient triggered by the joint influence of arcing and short-circuiting phase with pulsing.