An accurate control over the rate of heat input and material deposition is essential in gas metal arc welding for its greater use in joining of sheet metals. Although pulsed current gas metal arc welding facilitates excellent control over the rate of material deposition, greater rate of heat input due to high peak pulses remains critical. Gas metal arc welding with conventional short-circuiting mode of metal transfer provides a significant reduction in the rate of heat input while an uninterrupted and spatter-free material deposition is too difficult to achieve. A novel low energy input short-circuiting gas metal arc welding is proposed here that facilitates short-circuiting mode of metal transfer with a very low power detachment phase. Here we present an investigation on the current, voltage and consequent metal transfer sequences in pulsed current, and the conventional and the novel low energy input short-circuiting gas metal arc welding processes of high strength automotive steel sheets. It is realized that the low energy input short-circuiting process could provide uninterrupted and nearly spatter-free metal transfer at significantly reduced electrical power in comparison to both pulsed current and conventional short-circuiting gas metal arc welding. The low energy input short-circuiting process could also facilitate fairly small angular distortion of weld joints.

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High peak temperature and continuous deposition of electrode droplets in the weld puddle inhibit realtime monitoring of thermal cycles and bead dimensions in gas metal arc welding. A three-dimensional numerical heat transfer model is presented here to compute temperature field and bead dimensions considering a volumetric heat source to account for the transfer of arc energy into the weld pool. The heat source dimensions are analytically estimated as function of welding conditions and original joint geometry. The deposition of electrode material is modeled using deactivation and activation of discrete elements in a presumed V-groove joint geometry. The computed values of bead dimensions and thermal cycles are validated with the corresponding measured results. A comparison of the analytically estimated heat source dimensions and the corresponding numerically computed bead dimensions indicate that the former could rightly serve as the basis for conduction heat transfer based models of gas metal arc welding process.