The Influence of pH on type 316L stainless steel in simulated circulating cooling water

A study was conducted to investigate the effects of pH on Type 31 6L stainless steel (SS) to determine if pH affected the corrosion resistance of the steel in circulating cooling water. The hydroxides and oxides that were produced during the tests thickened the passive film of the SS as the pH increased from 6.5 to 9.0. The investigations were conducted in simulated circulating cooling water under different pH conditions using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The potentiodynamic anodic polarization curve tests were initiated after nearly steady-state open circuit potential had developed and a potential sweep was made in the cathode direction at -1.2 V for removing the oxide film. Additional tests showed that the pitting potential in the NaCl + Na₂SO ₄ environment increased as pH increased from 6.5 to 9.0.