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

E-ISSN： 1521-4176|66|10|1077-1083

ISSN： 0947-5117

Source： MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Vol.66, Iss.10, 2015-10, pp. : 1077-1083

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Abstract

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 (R1) and lower charge transfer resistances (R2) increased, and the carriers density (NA and ND) values are about 1020 cm3, 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 non‐ferrous metallurgical wastewater.