Weld formation, microstructure and mechanical property of oscillating laser welding of 6061 aluminum alloy with ceramic particle reinforcement

Laser welding of 6061-T6 aluminum alloy confronts several challenges, including porosity, loss of alloying elements and weld collapse, which significantly limits its application in aerospace and automobile industries. To address these issues, this study employed oscillating laser welding (OLW) combined with ceramic particle (CP) augmentation to butt-weld 6 mm thick plates. Weld formation, microstructure, and mechanical properties were systematically characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). The OLW-CP process improves melt pool fluidity and viscosity, effectively suppressing porosity and collapse. It promotes a columnar-to-equiaxed transition, refining the average grain size in the weld center from 54.8 μm to 13.6 μm and reducing texture intensity by 82.68%. Decomposition of Ti₃SiC₂ particles produces secondary phases such as Ti₈C₅, which enhances strength through the Orowan mechanism. The resulting joints achieve a tensile strength of 212 MPa and an elongation of 13.4%, corresponding to 68.8% and 65.7% of the base metal properties, and represent increases of 28.2% and 31.4% over conventional laser welding. This study clarifies the synergistic strengthening mechanisms of grain refinement and second-phase dispersion, offering a robust foundation for high-quality aluminum alloy welding.