Passivation Behavior of Ce-Containing Hyper Duplex Stainless Steels in Sulfuric Acid Solution

Abstract

The passivation behavior of Ce containing hyper duplex stainless steels in sulfuric acid solution was investigated by electrochemical testing and X-ray photoelectron spectroscopy surface analysis. The addition of Ce to the alloy increased the corrosion resistance at a passive region of 0.4 V SCE . The Ce addition also improved the stability of the passive film because of the formation of inclusions containing Ce with low Cr content and an enrichment of the Cr oxide and hydroxide in the passive film. Further, Ce addition to the alloy decreased the interface between the inclusion and the metallic matrix functioning as defects in the passive film. The Cr-enriched zones formed around the Ce containing inclusion improved the corrosion resistance of the metallic matrix around the inclusions, which act as corrosion propagation sites.