Preferential dissolution mechanism of α or γ phase in crevice corrosion of duplex stainless steels

摘要

Duplex stainless steels (DSS) possess a ferritic (α) phase matrix dispersed with austenitic (γ) phase precipitates. Due to the chemical compositional arrangement and the characteristic α/γ dual phase structure, DSS possess superior mechanical properties and corrosion resistance without sacrificing economic performance. In any case, even DSS suffer from crevice corrosion. Accordingly, the measure of crevice corrosion is of pragmatic importance. The modes of crevice corrosion on DSS were complex because of its preferential dissolution and distinguishable as some types from the outside to the center of the crevice: The passivity retention region, the region with preferential dissolutions of γ phase precipitates, and the region with preferential dissolution of the α phase matrix. It is described the study to elucidate the preferential dissolution mechanism of crevice corrosion on DSS, based on the in-situ observation of crevice corrosion dissolution behavior, and the analysis of dissolution behavior of DSS, α and γ phases in a simulated crevice solution.