Investigation of Inhibitory Effects of Chitosan on Pitting and Electrochemical Corrosion Behavior Caused by Sigma Phase in Duplex Stainless Steels (DSS)

Abstract

In this study, as a result of the heat treatment parameters applied to 2205 duplex stainless steel (DSS), the sigma phase formed in the microstructure and changes in the corrosion behavior of DSS due to this sigma phase were investigated in solutions with and without inhibitor. 1 g L–1 chitosan (CS) solution was used as an inhibitor. To investigate the effect of the inhibitor on the corrosion behavior, a pitting corrosion test was performed in the inhibitor and noninhibitor FeCl3 solution in accordance with the ASTM G48 standard. In addition, electrochemical corrosion experiments were carried out in a 3.5% NaCl corrosion solution with and without inhibitor, to investigate the effect of the inhibitor on electrochemical corrosion conditions. The effects of the inhibitor on DSS were examined by the stereo microscope, optic microscope (OM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) analysis. Weight loss and surface coverage measurements were performed to determine inhibitor efficiency. Phase analyzes of DSS samples were determined by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) analysis. As a result of the study, it has been determined that CS plays an effective inhibitor for DSS material, even in the presence of the sigma phase.