Investigation of Wall Geometry, Cooling Curves, and Microhardness of Multi-layer Material Deposition by Wire Arc Additive Manufacturing

Additive manufacturing is a technology for developing structures by adding and fabricating material layer upon layer. Wire Arc Additive Manufacturing (WAAM) is a new metal additive manufacturing process that uses an electric arc to deposit material layer-by-layer, enabling the fabrication of metal elements with high mechanical characteristics. It enables the fabrication of complex geometries like freeform structures, easily and efficiently. However, a major limitation of the WAAM process lies in controlling the thermal cycle during the deposition of material layer upon layer. Also, obtaining a suitable bead geometry is challenging work. Therefore, the objective of the present work is to fabricate a multi-layer wall structure using stainless steel metallic wire as a filler material, and Gas Tungsten Arc Welding- (GTAW) based robotic wire arc-based AM process, which enables precise control over heat input, resulting in little distortion and heat affected zone. The bead depositions study layer upon layer is carried out and focuses on the bead geometry along with the cooling curve of the bead following material deposition. The welding current, wire feed rate, and shielding gas flow rate were chosen as input process parameters, while the bead height-to-width ratio, as well as mechanical properties such as hardness, and cooling rate, were chosen as output parameters. The study found direct dependence of heat input, microhardness, and the existing thermal cycle measured through an IR pyrometer during material deposition onto the geometry of the WAAM-built structure.