Investigation of hybrid gas metal arc welding-wire arc additive manufacturing and milling process parameters on AA6061 substrate and ER5356 filler

Wire arc additive manufacturing based on gas metal arc welding (WAAM-GMAW) offers high deposition speeds, is more economical, and minimizes material waste compared to conventional production methods. The formation of a deposit layer limits surface quality and geometric precision. Hence, a hybrid method combining WAAM and milling is proposed in this study. The parameters affecting fusion stability in the WAAM-GMAW process are the filler wire travel speed and gas flow rate. Inadequate travel speed and shielding gas flow can increase porosity or degrade weld-bead quality in the WAAM-GMAW process. The effect of travel speed and gas flow rate on the weld bead of one-layer deposition of ER5356 filler on AA6061 by the WAAM-GMAW process was investigated with real-time temperature monitoring and current, measuring bead geometry with 3D Scan; travel speeds were 1.67, 2, and 2.33 mm/min, while gas flow rates were 10, 12.5, and 15 L/min. The milling process was applied after the WAAM-GMAW process, and various tests were conducted, including hardness, surface roughness, macrostructure, microstructure, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDS). While the average current and average power were closely correlated with the arc energy, the volume and material utilization affected the travel speed. The Ra values of the as-deposited beads decreased to 0.46–2.17 µm (by 74–85%) after milling from an initial range of 1.78–14.45 µm. Softened heat-affected zones had hardness values ranging from 51 to 60 HV. As the travel speed increased, SEM-EDS showed a decrease in magnesium concentration from 5.10% to 4.32% weight, and the bead profile symmetry due to arc instability.