关键词: 双相不锈钢, 选择性腐蚀, 微区电位分布

Abstract: In duplex stainless steel, the two constituent phases, namely ferritic (α)and austenitic(γ) phases, have different crystal structure and chemical composition. They may thus exhibit different corrosion resistances in aqueous environment. In this investigation, an electrochemical technique with spatial resolution was employed to measure the potential difference between these two constituent phases in 2205 duplex stainless steel. Image analyzing techniques were also used to examine the preferential corrosion between α and γ phases. The experimental results showed that ferrite had a higher potential than austenite in0.01 mol/L NaCl solution. In 2 mol/L H2SO4+x mol/L HCl solution, two distinct peaks appeared in the anodic polarization curve in the passive_to_active transition region. Preferential corrosion occurred in the ferrite phase at a lower anodic peak potential, while in austenite at a higher anodic peak potential.