Improving arc stability during wire arc additive manufacturing of thin-walled titanium components

Fabrication of thin-walled titanium structures by a gas metal arc based wire arc additive manufacturing process is considered challenging due to arc instability. This instability is primarily caused by the cathode spot oscillations. In this work, attempts were made to improve the cathode spot stability by using a surface oxidised titanium feedstock. The deposition behaviour was analysed by a high-speed camera analysis under straight and reverse polarities. Current-voltage waveforms were suitably modified to achieve a stable short-circuiting transfer in bare and surface oxidised conditions. The surface oxidised wire was found to provide a stable arcing and reduction in arc wandering. Based on the correlation between current-voltage waveforms and metal transfer characteristics, optimum deposition procedures were identified to manufacture thin-walled titanium components.