Influence of temperature on the pitting corrosion behavior of AISI 316L in chloride-CO2 (sat.) solutions

The paper discusses the pitting corrosion behavior of AISI (American iron and steel institute) 316L stainless steel in aerated chloride solutions (0.1-2 M NaCl) at 25, 50 and 80 °C using potentiodynamic polarization technique. A comparison is made with CO2-saturated chloride solutions. The results have revealed that pitting potential decreased in a logarithmic relationship with the chloride concentration, and decreased linearly with temperature. The influence of CO2 on the chloride pitting of AISI 316L stainless steel is quite complex and found to be dependent on chloride concentration and test temperature. At 25 °C the presence of CO2 appears to have insignificant effect on Ep irrespective of chloride concentration. As the temperature is raised to 50 or 80 °C the additions of CO2 has caused marked negative shifts in pitting potential. The detrimental effect of CO2 increases with NaCl concentration and temperature. The results indicate that pitting potential (Ep) is influenced by a synergy between chloride, CO2 and temperature, and that this synergy depends on the chloride concentration and test temperature.