Tailoring the effect of pulsed GTAW factors on the fusion zone microstructure, hardness and corrosion properties of dissimilar 2060-T8/2099-T83 Al-Li alloys through response surface method

This study investigates the joining of dissimilar 2060-T8 and 2099-T83 Al–Li alloys through the pulsed gas tungsten arc welding (PGTAW) process in butt configurations. The effects of key PGTAW parameters, namely, pulse frequency, pulse time ratio, and shielding gas flow rate on the fusion zone microstructure and properties were analyzed using the response surface method (RSM). Microstructural characterization was performed using optical microscopy, electron backscatter diffraction, X-ray diffraction, and transmission electron microscopy, along with hardness and electrochemical corrosion evaluation. Results revealed that the pulse frequency was the most influential factor affecting joint properties, followed by pulse time ratio and gas flow rate. A significant grain refinement (MGS: 13.90 ± 0.41 μm) and pronounced grain boundary transformations (HAGBs: 70.32%) were achieved under optimized PGTAW conditions. Texture analysis revealed the development of Cu {112}〈111〉 and S {123}〈634〉 components with a maximum intensity of ∼7.03. Phase analysis confirmed the presence of α-Al along with Al2Cu, Al3Li, Al2CuLi, and Al6CuLi3 precipitates, which were uniformly distributed under optimized conditions. The joint exhibited improved performance with a maximum microhardness of 94.15 HV, a nanohardness of 1.5 GPa, and a minimum corrosion rate of ∼0.193 mm/year, demonstrating the effectiveness of parameter optimization in enhancing joint performance.