Pitting Susceptibility of 316L Stainless Steel in NaCl Solution with Different Dissolved Gases

The anodic polarization curves and current-time curves of 316L stainless steel in NaCl solution with different dissolved gases,such as CO2,N2,O2,H2S+CO2 and H2S,were obtained by potentiodynamic polarization and potentiostatic polarization test methods respectively,the pitting susceptibility of 316L stainless steel was studied,as well as the morphology of the corrosion pits and element distribution in the corrosion pits.The results show that the increasing order of pitting susceptibility of 316L stainless steel influenced by dissolved gases was CO2,N2,O2,H2S+CO2 and H2S.The pitting of 316L stainless steel was mostly controlled by H2S when the volume ratio of H2S to CO2 was 11.The pitting was prior to nucleation at the location of Al-oxide in 316L stainless steel,and the corrosion pit further developed because of the decrease of Cr,Mo and Ni contents around inclusions location.