The objectives of this study are to clarify the dissolution behavior of the ferritic phase (
α phase) and the austenitic phase (
γ phase) of a duplex stainless steel (DSS), and to propose a corrosion mechanism of the DSS through dissolution behavior of either the
α phase or the
γ phase at corrosion potential, respectively. Just a single phase specimen (
α or
γ phase specimen) was prepared by using selective dissolution of the DSS. The
α phase showed less-noble corrosion potential compared to the
γ phase, and passivated at less-noble potential. When the polarization curves of each phase are summed up, the obtained curve showed good agreement with the DSS polarization curve. The
α phase of the DSS dissolved preferentially at corrosion potential. Based on these results, a preferential dissolution mechanism model of a DSS is proposed using internal polarization curves of each phase.
View full abstract