Electrolyte and temperature effects on pitting corrosion of type 316LN stainless steels

Abstract

AbstractThe influence of electrolyte composition and temperature on the pitting corrosion resistance of nitrogen bearing (0·015, 0·198, and 0·56%N) type 316L stainless steels has been investi gated. Anodic polarisation curves were determined in neutral chloride solution at room temperature and at elevated temperatures of 308, 318, and 333 K. Similar polarisation studies were also conducted at room temperature in 1N H2 SO4 and in an acidic chloride solution containing 1N H2 SO4 and 0·5M NaCl. The results show that the critical pitting potential Epp in neutral chloride and acidic chloride media increases as the nitrogen content of the alloy increases, indicating that resistance to pitting increases with the addition of nitrogen. However, in 1N H2 SO4 solution, the transpassive potential was almost independent of the nitrogen content. As the temperature of the neutral chloride medium was increased, the Epp values decreased, irrespective of nitrogen content. The decrease in Epp is attributed not only to the t...