Effects of alloying elements, Cr, Mo and N on repassivation characteristics of stainless steels using the abrading electrode technique

Cr, Mo and N are important alloying elements for passive film formation and repassivation but their roles in passive film still need explainable. In order to investigate effects of alloying elements on the stability of passive film and its repassivation, ferritic stainless steels such as Fe–Cr and Fe–Cr–Mo alloys and austenitic stainless steels such as type 316L, and type 316LN were examined. The electrochemical characteristics of the passive film were investigated by in situ dc and ac electrochemical methods. The resistance to localized corrosion is believed to have much to do with the repassivation of the passive film and its stability. The effects of alloying elements on the current transients were systematically examined by using the abrading electrode technique and electrochemical impedance spectroscopy (EIS). The experimental results were analyzed in order to elucidate the relationship between passive film stability, repassivation, and alloying elements.