Influence of Auxiliary Process on Microstructure and Mechanical Properties of Wire Arc Additive Manufacturing of Thick Wall Depositions

Serious heat accumulation causes poor properties and anisotropy of products in wire and arc additive manufacturing, which restricts the further efficiency in application, especially in double-wire and double-arc depositions. Consequently, this study applied an auxiliary gas process in double-arc additive manufacturing and then compared two 50-layer depositions in morphology, microstructure, and properties to research the influence of the auxiliary process on the forming and performance. The results showed that the auxiliary gas process could improve the deposition morphology, and the efficiency was increased by 24%; moreover, the surface roughness was reduced. As the cooling and stirring effect of the auxiliary gas process, the deposition with the auxiliary gas process mainly presented short axis columnar crystal and less defects on cross-section, which was finally increasing the hardness, tensile strength, and impact toughness and bending force and decreasing the tensile strength anisotropy obviously.