Effect of inorganic anions on the corrosion behavior of UNS S32750 duplex stainless steel in chloride solution

The present study explored the electrochemical behavior of UNS S32750, a super duplex stainless steel which was not commonly researched in previous studies. The effect of bicarbonate (HCO3-) and sulfate (SO42-) on the electrochemical behavior of UNS S32750 duplex stainless steel in the chloride (Cl-) solution was investigated using potentiodynamic polarization, scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. The electrochemistry behavior shows that with the addition of HCO3- and SO42-, pitting potential increased and passive current density decreased, indicating that bicarbonate or sulfate can reduce sensitivity to pitting corrosion of UNS S32750 duplex stainless steel in Cl- solution, and film resistance (R-1) and lower charge transfer resistances (R-2) increased, and the carriers density (N-A and N-D) values are about 10(20) cm(3), and the carriers density decreases. The results may provide theoretical guidance for material-choosing in the wastewater treatment industries containing high chloride concentration such as nonferrous metallurgical wastewater.