Effect of pre-filming potential on the electrochemical characteristics of 2205 duplex stainless steel in NaCl solution

Abstract The effects of pre-filming potential on the electrochemical characteristics and structure of the passivation film of 2205 duplex stainless steel (DSS) in 3.5% NaCl solution were investigated by electrochemical technology and XPS methods. The results showed that when the pre-filming potentials were 0.1 and 0.6 V, the formation process of passivation film was first porous and then dense. However, when the potential rose to 0.9 V, the passivation film eventually underwent an additional porous process. The passivation films pre-formed at different potentials were all bilayer structures. The passivation film of 2205DSS was composed of an inner rich-Cr oxide and an outer rich-Fe oxide. When the pre-filming potential was 0.9 V, FeOOH appeared in the iron-rich oxide layer. The semiconductor properties of the passivation film were independent of the pre-filming potential. With the increase in pre-filming potential, the diffusion coefficient and diffusion flux of the cation vacancies increased, and the migration of cationic vacancies in passivation films became easier.