Analysis of Metal Transfer Characteristics in Low-Heat Input Gas Metal Arc Welding of Aluminum Using Aluminum–Silicon Alloy Fillers

Welding of thin aluminum sheets with high heat input conventional welding processes often results in heat-affected zone softening, distortion, and burn-through problems. In this study, metal transfer characteristics are optimized in a gas metal arc-welding process to achieve low heat input and high productivity to weld aluminum sheets. The main objective of this study is to achieve maximum droplet transfer rate at low heat input in AA 1050 alloy using short circuiting (CMT) and short circuiting with pulse (CMT-P) gas metal arc-welding processes. Metal transfer characteristics are studied while depositing the AlSi5 and AlSi12 fillers on to an AA 1050 aluminum plate. Experiments are conducted to investigate the influence of mean current (90 to 110 A) and pulse frequency (5, 6, and 7) on heat input, droplet transfer rate, and its diameter. Kinetics of the metal transfer during welding is correlated with the corresponding current and voltage waveform and bead geometry. Results showed that for a given heat input, the droplet transfer rate is high in CMT-P at all mean current amplitudes compared to short-circuiting process for both the fillers. Analysis of the bead geometry indicated that for a given mean current, bead width of the AlSi12 filler is always higher than the AlSi5 filler in both the modes of metal transfer due to the near complete eutectic solidification in the former case. It is also found that the filler wire composition does not affect the droplet transfer rate for a given mean current in CMT and CMT-P processes used in this study.