Effect of Friction Stir Welding (FSW) on Corrosion Resistance of Lean Duplex Stainless Steel

In the present study, the effect of friction stir welding (FSW) on the corrosion behavior of lean duplex stainless steel was investigated. The alloy was welded using a rotation speed of 800 rpm and welding speed of 150 mm/min. The microstructures of the base and weld metals were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Corrosion behavior of the specimens was investigated using open circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and zero-resistance ammeter (ZRA) tests in 0.1 M sulfuric acid. Results revealed that FSW decreased the grain size of the α and γ phases and improved the corrosion resistance of the stir zone (SZ). This was attributed to the grain refinement and recrystallization during the FSW that resulted in improving the stability of the passive film.