Probing the influence of cold wire gas tungsten arc welding current waveforms on the aluminum-steel joining

Abstract Cold wire gas tungsten arc welding (GTAW) process is used to join AA6061-T6 and galvannealed (GA) steel. The welding current distributed in sine, rectangle, square, and triangle AC waveform is used to understand their influence on the arc behavior, temperature distribution, joint profile, and the intermetallic compound (IMC) layer thickness. The instantaneous welding current and voltage waveforms are recorded in synchronization with the high-speed arc images to understand the arc behavior and heat input. The rate of change of instantaneous welding current between the polarities and the arc duration at the peak current is more in square and rectangle waveforms. The peak current in both the positive and negative pulses and the arc heat input of the triangle waveform is the highest among all the waveforms considered in the present work. The wetting length increases along with the reduction in the bead height sequentially with sine, rectangle, square, and triangle waveforms for a constant machine setting welding current. IMC layer thickness is minimum for the sine waveform and maximum for the triangle waveform. Overall, the welding current distributed in sine waveform is found to be suitable among all the waveforms studied in the present work for dissimilar metal joining of aluminum to steel.