In this study, arc and droplet transfer behavior were investigated during wire arc additive manufacturing (WAAM) of Ti-6Al-4V alloy. Pulsed gas metal arc welding (GMAW-P) with an electrode-positive (EP) polarity and cold metal transfer (CMT) process with an electrode-negative (EN) polarity were employed in the WAAM process. High-speed imaging was performed to investigate the mechanisms to stabilize cathode plasma jets, arc plasma, and molten metal transfer. In the EP GMAW-P, the composition of shielding gas was examined, and Ar50%/He50% mixed shielding gas showed the best performance in terms of arc stability, wire melting, droplet transfer, and spatter suppression. In the EN CMT process, sound cathode jets were shrouded by arc plasma in the EN mode, and the metal transfer was also stabilized by balanced plasma formation.
Acknowledgments: This research was supported by the MOTIE (Ministry of Trade, Industry, and Energy) in Korea, under the Human Resource Development Program for Industrial Innovation(Global) (P0017303, Smart Manufacturing Global Talent Training Program) supervised by the Korea Institute for Advancement of Technology (KIAT).