Effect of heat treatments on the electrochemical behavior of 304L stainless steel in nitric acid

Abstract

In this study, the intergranular corrosion behavior of 304L stainless steel (SS) after heating at different temperatures and times was investigated by using the double loop electrochemical potentiokinetic reactivation (DL-EPR), the potentiodynamic polarization electrochemical and the electrochemical impedance spectroscopy (EIS) methods. It was found that there was no significant difference in the potentiodynamic polarization curves of the specimens after different heat treatments. However, the corrosion resistance of specimens could be clearly distinguished by EIS. Between 650 to 750°C, the degree of sensitisation (DOS) had a maximum value and the decrease in Rct was more prominent for the specimens aged at 650 and 750°C. Heat treatments conducted in the range of 650-750°C, even a brief heating time, caused a serious decline in the corrosion resistance of 304L SS. The Rct-values of the specimens aged at 650 and 750°C decreased with the increase of the heating time. However, the Rct-values of the specimens aged at 850°C increased with the increase of the heating time.