Effect of galvanostatic condition on growth behavior and repassivation potential of crevice corrosion of duplex stainless steels

The purpose of this study is to clarify effect of galvanostatic condition on growth behavior and repassivation potential (ER.CREV) of crevice corrosion of duplex stainless steels. ER.CREV measurements, microscopic observation of corroded area, and solution pH measurements inside crevice were carried out. Under the condition of large holding current in propagation step of ER.CREV measurements, the crevice corrosion grew from the bottom to the edge of crevice. Then, it grew towards depth direction, and the sharp corroded area formed near the edge of crevice. Solution pH inside crevice lowered easily under the condition of large holding current in repassivation step, and it induced the repassivation of corroding crevice at noble potential. It was suggested that the sharp corroded area formed near the edge of crevice under the large holding current condition contributed to lowering corrosivity of solution inside corroding crevice and the repassivation of corroding crevice at the noble potential.