EFFECTS OF NITROGEN ON THE METASTABLE PITTING AND REPASSIVATION BEHAVIOR OF AUSTENITIC STAINLESS STEELS IN CHLORIDE SOLUTIONS

摘要

Effects of nitrogen on the metastable pitting and repassivation behavior of 304L alloys in chloride solution were examined using the electrochemical noise analysis (ENA) and the scratching electrode technique. Results of ENA showed that the addition (0.1 wt. %) of nitrogen to 304L alloy increased significantly the resistance to metastable pitting, which was confirmed by the appreciable decrease in the number of metastable pitting event simultaneously with the reduction in the intensity of the power spectrum density (PSD). Further, repassivation occurred much faster in the nitrogen added alloy than did in the alloy without nitrogen. These beneficial influences of nitrogen on the metastable pitting and repassivation behavior of austenitic stainless steels were discussed and rationalized based on the selective dissolution theory.