The influence of pH and chloride concentration on the corrosion behaviour of AISI 316L steel in aqueous solutions

The effect of chloride concentration, pH, dissolved oxygen and temperature on the pitting behaviour of 316L SS in aqueous solutions has been investigated under dynamic and static conditions. Weight loss, metallography and electrochemical polarization techniques have been employed during the investigation. It has been found that the corrosion rate generally increases linearly with increasing Cl concentration in the range 100–5000 ppm. With increasing pH, the corrosion rate decreases, being highest at pH 4 and lowest at pH 9. The number and depth of pits increase with increasing Cl − concentration. From the results of cyclic polarization studies it is inferred that the pitting potential, E pit is shifted to a more negative potential with increasing Cl − concentration and temperature and decreasing pH. It has been established that low pH, high Cl − content and stagnancy are the conditions most suitable for initiation and propagation of pitting in AISI 316L stainless steel.