Preprint for: "Optimization of preheating and interpass temperature in WADED magnesium alloy AZ61: A comparative study on microstructure, residual stresses, and internal defects"

This study examines the effect of base material preheating in Wire Arc Direct Energy Deposition (WA-DED) of AZ61 magnesium alloy. First, the influence of preheating on the geometry of single-track weld beads was evaluated. These findings were then used to identify an appropriate preheating temperature for stabilising the layer width in thin-walled structures. Two preheating strategies were tested, showing that preheating the base material to 200 °C with the same interpass temperature provided the best stability and improved the uniformity of individual layers. In the second part, the impact of preheating on residual stress reduction was assessed by analysing the deformation of the base material. Results showed that preheating reduced residual stresses by up to 50% compared with fabrication without preheating. In addition, material characterisation was performed to evaluate the microstructure and clarify the mechanisms of porosity formation, which was revealed by μCT scanning in the samples. Preheating positively affected wall thickness stabilisation, residual stress reduction, and porosity. Overall, a temperature of 250 °C was assessed as the most suitable preheating and interpass temperature.