Fusion zone of AA6061 alloy GTA welds : electrochemical polarisation and impedance study

The corrosion behaviour of the fusion zone of gas tungsten arc (GTA) welds of AA6061 alloy was studied. Welds were made of AA4043 and AA5356 fillers using the continuous current (CC) and pulsed current (PC) techniques of GTA welding. Dynamic polarisation and impedance testing were used to determine the pitting and general corrosion resistance of the fusion zone respectively. Optical and scanning electron microscopy (SEM) studies were carried out to find the mechanism of corrosion. The fusion zone of welds made with the AA4043 filler was found to show better corrosion resistance than those made with AA5356 filler. The PC technique improved the pitting and general corrosion resistance of the fusion zone of AA6061 GTA welds.