Analysis of melting-to-solidification flow patterns with changes in depositional position during the wire–arc direct energy deposition process

Molten pool behavior plays an important role during bead formation in wire–arc direct energy deposition (DED) processes. However, this pool is susceptible to external forces, particularly the changes in direction of gravity when the depositional position is changed. In this study, a 3D simulation of the wire–arc DED was performed using computational fluid dynamics (CFD) considering various depositional positions. The experiments in − 30°, 0°, and 30° positions were performed using a tilting table to visualize the influence of the components of gravity. The volume of fluid method was used to represent the deposition and solidification process of the molten pool. A high-speed camera and cross-sections of the bead were used to evaluate the CFD model by comparing the molten pool lengths and bead geometries; the simulation and experimental results were similar. Based on these verified results, flow patterns, temperature distributions, and solid fractions were used to elucidate the changes in each position (such as a 14.3% decrease in the molten pool length and a 13.3% increase in the bead width between downward and flat positions) and the unstable deposition in the upward position.