Nitrogen significantly enhances corrosion resistance of 316L stainless steel in thiosulfate-chloride solution

Thiosulfate is a threat to corrosion resistance of steels in chloride solution. This work revealed the inhibitory effect of nitrogen (N) on thiosulfate-accelerated corrosion of stainless steel by electrochemical measurements, microscopy observation and X-ray photoelectron spectroscopy analyses. Results manifested that N-alloying significantly enhanced pitting corrosion resistance and repassivation ability of 316 L steel in thiosulfate-chloride solution. On the one hand, N consumed H+, then restrained reduction of S2O32- and subsequent formation of S and MS2. On the other hand, N reduced defect density and strengthened passive film by increasing fraction of Cr2O3 and Fe2O3, thus improving protective ability of passive film.