Mechanical Characterization and Prediction of Aluminum Alloy Laser Welding Joints Including Roles of Geometries and Porosity

This paper investigate the geometric morphologies, microstructure, and porosity of the aluminum alloys laser welding joints (ALWJ) under various welding processes through a series of tests, including the optical microscope (OM) and computed tomography (CT) tests. The mechanical properties are subsequently analyzed by the tensile tests and finite element simulation. A prediction model that considers the role of geometry and porosity is proposed to predict the ultimate strength of ALWJ. Results show that the geometries significantly depended on the welding process, particularly for the penetration depth, which increases with the elevation of heat input, increasing the mechanical strength of joints. The T-joint is not connected correctly when the heat input is less than 42.8 J mm−1, which increases with the elevation of heat input until the heat input researches to 60 J mm−1. But the higher heat input also induced more pores due to the burning damage of the magnesium (Mg) element, which deteriorates the mechanical strength. Finally, the developed strength prediction model is proved to be accurate and reliable enough to predict the strength of the ALWJ with pore defects. The error of the predicted values compared with the experimental is within 15%.