Influence of Chloride ion on Critical Pitting Temperature of 316L Stainless Steel

The influence of Cl^- on critical pitting temperature (CPT) of 316L stainless steel was studied by monitoring the evolution process of corrosion current density with temperature at a constant applied potential. The passive film could form on the surface of the sample when temperature was below the CPT. The pitting corrosion occurred on the surface of the sample when temperature was above the CPT. As the Cl^- concentration rose, the critical pitting temperature of the stainless steel declined, and the number of pits on it increased. The analysis of corrosion products from the field showed that the surface of corrosion products was sparse, and the main elements were oxygen, iron, carbon and chlorine. The concentration of Cl^- in water was as high as 21.431 g/L, and the corrosion of 316L stainless was extremely serious.