Effect of Anisotropy and Varying Parameters for Micro-Plasma Wire Arc Additive Manufacturing

Wire arc additive manufacturing (WAAM) is a metal 3D printing process that employs the use of arc welding processes to generate parts. The advantages of this method such as high deposition rates, low cost, and suitability for the creation of large complex components highlight its potential. However, due to the intense heat input associated with arc welding processes as well as the continuous heating and cooling cycles of WAAM during fabrication, the final part created will result in large temperature gradients between the top and bottom layers, resulting in geometrical deviations from the desired dimensions as well as anisotropy within the final component. Anisotropy is an important phenomenon which can arise in WAAM, thus greatly affecting the mechanical properties and microstructures. The process of interest in this research is micro-plasma arc welding due to its very low heat input. The present work firstly evaluates the effect of anisotropy on the properties of a thin-walled structure fabricated using micro-plasma WAAM, revealing mainly uniform properties along the build and travel directions, except for the modulus of elasticity. Also presented are the volumes of material added onto the melt pool based on variations within the wire feed speed. This provided improved part quality when manually fixing any height deviations within the bead and applying proper parameter selection on the second pass. Finally, different bead overlap parameters were tested for single and multiple beads, obtaining the optimum distance between two beads for good plate fusion and best quality for building complex parts.