The influence of temperature on the corrosion behaviour of high nitrogen austenitic stainless steel in chloride media

The electrochemical behaviour of high nitrogen SS in comparison of conventional grade 304 SS was examined in aqueous 3.5% chloride solution at 20-80 degrees C using open circuit potential vs. time, potentiodinamic and galvanostatic tests. The raising of the temperature was found to have no important influence on the corrosion potential, but destabilise the passive film formation on both steels. At the critical value of anodic polarisation the passive films were damaged and pitting corrosion occurs at lower potential with the increasing of temperature. The high nitrogen steel demonstrates faster formation of passive films, but pitting potential of this steel is more sensitive to temperature changes in comparison with those of chromium-nickel one. The temperature has slight influence on repassivation process, which is generally steel composition dependent. At all experimental conditions the nitrogen steel has greater difficulty to repassivate.