The Effect of Temperature on Electrochemical Corrosion Behavior of HDR Duplex Stainless Steel

Abstract

To study the effect of temperature on the electrochemical corrosion behavior of HDR duplex stainless steel, the corrosion resistance of HDR at different temperatures was investigated using the electrochemical test method and combined with metallographic microstructure observation and the EDS analysis based on the characteristic that the metal structure determines. The results show that the HDR contains inclusions such as silicide and nitride, mainly distributed in the ferrite phase and its boundary. The pitting of HDR occurs when the polarization potential of -0.5–1.5 V is applied at different temperatures ranging from 10 °C to 80 °C. The pitting occurs mainly in the ferrite and its boundary below 50 °C and in the austenite and ferrite tissues above 60 °C. Cl−, inclusions, and Cr oxides are the important factors affecting corrosion. The corrosion rate of HDR increases with the increase in temperature; the higher the temperature is, the more serious the corrosion is. The critical pitting temperature of HDR is between 50 °C and 60 °C. The pitting potential below 50 °C is above 0.65 V, while that above 60 °C is below 0.60 V.