[en] Microstructural observations of friction stir welds of A517(B) steel showed that within the range of welding variables, martensite phase was hindered. Stir zone microstructure displayed coarse-grained upper bainite associated with granular bainite. HAZ consisted of decomposed bainite morphology of lath-like and equiaxed. Electron backscatter diffraction analysis showed a random oriented recrystallized grain. The corrosion behavior in 3.5 wt% NaCl solution revealed negatively shift of corrosion potential with increasing of traverse speed. However, the effect of welding parameters on cathodic behavior was more predominant than that on anodic behavior; associated with the microstructural alterations. Pitting of corrosion rust layer was identified as the main mechanism of corrosion attack in base material and welds. Although, corrosion current density of weld in all of the applied welding condition was slightly lower than that in the base material, however, this study provides recommendation for application of A517 steel jointed by friction stir welding in marine environment. (paper)