Evaluating porosity formation in gas metal arc directed energy deposition of an aluminium alloy

Porosity formation in gas metal arc directed energy deposition of aluminium alloys is a critical challenge as it affects the structural integrity of build parts. An experimental investigation is reported here to examine the influence of energy input on pore size and area fraction in single- and multi-layer build samples of an aluminium alloy for short-circuiting and pulsed current gas metal arc. The energy input is estimated from real-time current and voltage transients. The porosity distribution in deposited samples is measured using an image segmentation approach. The pulsed current mode yielded 16–22% lower pore area fraction in comparison to short-circuiting mode. For the range of process conditions considered, an increase in energy input reduced pore area fraction significantly.