Study on the Microstructure and Corrosion Behavior of Dissimilar Aluminum Alloy Welded Joints Formed Using Laser Welding.

Abstract

This study investigates the evolution mechanisms and electrochemical corrosion behavior of laser-welded joints (WJs) between 6063 and 6082 dissimilar aluminum alloys under varying welding powers. The analysis focused on the microstructure of the weld metal zone (WMZ), its grain boundary (GB) features, and its electrochemical corrosion properties. Data from the experiments indicate that a higher laser power (LP) leads to an increase in grain size within the WMZ. At an LP of 1750 W, the weld surface exhibits the poorest corrosion resistance, while other parameters show a relatively better resistance. Additionally, electron backscatter diffraction tests indicate that the high-angle GB fraction on the 6063-T6 side of the heat-affected zone exhibits a substantially reduced measurement compared to the 6082-T6 side. The corrosion form in the WMZ is intergranular, with energy-dispersive spectroscopy (EDS) scans revealing that the poor corrosion resistance is primarily due to the presence of a large amount of Mg₂Si phase.