Effects of cerium on the compositional variations in and around inclusions and the initiation and propagation of pitting corrosion in hyperduplex stainless steels

摘要

Ce addition to a hyperduplex stainless steel increased its resistance to pitting corrosion because of the formation of stable Ce oxides and a decrease in the area of microcrevices between the matrix and inclusions that act as pit initiation sites. In addition, Cr-enriched zones were formed around Ce oxides with low Cr content in the Ce added alloy. Pitting corrosion in the base alloy initiated at the microcrevice and propagated to Cr oxides, which deteriorated the pitting corrosion resistance. However, pitting corrosion in the Ce added alloy propagated not to the stable Ce oxides but to the matrix.