Abstract This study evaluates the influence of rotational speed on the mechanical and microstructural properties of T-joints fabricated via friction stir welding (FSW) using dissimilar aluminum alloys, AA5083 and AA6082, for naval applications. Three types of joints were produced by maintaining a constant traverse speed of 100 mm/min and varying the tool rotational speed at 500, 700, and 900 rpm. Mechanical performance was assessed through pull-out tests and microhardness measurements. The joints fabricated at 500 rpm demonstrated superior mechanical properties, including a more uniform hardness distribution and higher pull-out strength, attributed to optimized material mixing and heat input at this speed. In contrast, higher rotational speeds led to defect formation, such as wormholes, and compromised mechanical performance. These findings underscore the importance of optimizing rotational speed to enhance joint quality, making FSW a viable solution for manufacturing durable, lightweight structures in demanding marine environments. Keywords: friction stir welding; joining; aluminum; shipbuilding; manufacturing