Friction Stir Welding: Mitigating the Susceptibility to Intergranular Corrosion of Alloy 625

In this work, friction stir welding (FSW) was employed to alloy 625 grade I (soft annealed) sheets. Therefore, solid-state based welding was undertaken with a tool rotational speed of 200 rpm and welding speed of 1 mm/s. Microstructural features were analyzed by light optical and scanning electron microscopy (SEM). Moreover, microhardness measurements were performed. The susceptibility to intergranular corrosion was verified by the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test. Complementary, intergranular corrosion was evaluated by ASTM G28 Method A. FSW promoted grain refinement, increased microhardness, and reduction in the degree of sensitization. Finally, the mean corrosion rate observed in the ASTM G28A test was 0.4406 mm/year, which suggests a good weld quality.