<p>The findings of this study demonstrated that doubling the welding passes from single to dual passes substantially decreased grain size in both the stir zone (SZ) and weld cross-section relative to the base metal, resulting in improved nanoparticle homogeneity and distribution within the microstructure. It was observed that single-pass samples without nanoparticles displayed intergranular corrosion cracking at the boundaries of the thermomechanically affected zone (TMAZ) and the SZ. In contrast, the nanoparticle-reinforced and double-pass samples were free of such cracks. Salt spray and EIS tests notably improved the corrosion behavior of the weld cross-section in double-pass, Al₂O₃ nanoparticle-reinforced welds. Furthermore, the wear behavior of the samples was evaluated. The findings revealed that single-pass FSW negatively impacted wear behavior. Conversely, the double-pass, nanoparticle-reinforced welded samples showed a reduction in the coefficient of friction, a decrease in the volume of material wear, and an abrasive wear mechanism. Surface chemical analysis was conducted using EDS, and the results correlated well with the observed data. EDS indicated higher oxygen peaks in alumina nanoparticle samples, suggesting the formation of a denser, protective oxide layer. The morphology of the wear chips was also investigated, confirming the type of wear mechanism involved.</p>