Observation of Corrosion-Pits Formation and Growth Behavior in SUS304 Stainless Steel by Atomic Force Microscope

摘要

In order to investigate the formation and growth mechanism of corrosion pits on solution-treated and sensitization-treated specimens of SUS304 stainless steel, in-situ observation was carried out in 3.5mass% NaCl solution using an atomic force microscope (AIM) equipped with an electrochemical cell. During the observation by the scanning of the probe, the formation of pits on pre-selected areas of solution-treated specimens was difficult and the growth of pits was slow, while the formation and growth of pits on pre-selected areas of sensitization-treated specimens was relatively easy. Corrosion product over pits was observed and they accelerate the growth of pits. The current density on pits, especially of sensitization-treated specimens, was much higher than the average current densities on the entire surface.