Wire arc metal additive manufacturing using pulsed arc plasma (PAP-WAAM) for effective heat management

Abstract

To address the materials processing challenges resulting from high levels of heat input in wire arc additive manufacturing (WAAM), a novel wire arc metal additive manufacturing method using pulsed arc plasma (PAP-WAAM) was developed in this study. In this method, the pulsed arc plasma generated by the pulsed voltage was used as the heat source. Owing to the applied pulsed voltage, the arc plasma was alternately ignited and extinguished during additive manufacturing. By adjusting the relative positions of the tungsten electrode, filler wire, and substrate, the arc plasma was ignited between the tungsten electrode and the filler wire. This increased the proportion of discharge energy allocated to the filler wire, thus reducing the overall heat input required for material deposition. Furthermore, no heat was transferred to the deposited material because the arc plasma was extinguished during the discharge interval. Consequently, the previously deposited material was rapidly cooled. Preliminary experimental results showed that the newly developed PAP-WAAM process used 37 % less heat input than the conventional gas tungsten arc welding-based WAAM (GT-WAAM) process at the same wire feed speed of 350 mm/min. The PAP-WAAM process yielded smaller melt pools, higher cooling rates, and less heat accumulation than the GT-WAAM process, which was mainly attributed to the combined effects of low heat input and efficient heat dissipation by the pulsed discharge during PAP-WAAM. As a result, PAP-WAAM produced finer geometric features and microstructures as well as greater tensile strength than GT-WAAM.