Chloride attack on the passive film of duplex alloy

• Published in: Corrosion science 2019-07, Vol.154, p.123-128
• Main Authors: Zhang, B., Wei, X.X., Wu, B., Wang, J., Shao, X.H., Yang, L.X., Zheng, S.J., Zhou, Y.T., Jin, Q.Q., Oguzie, E.E., Ma, X.L.
• Format: Article
• Language: English
• Subjects: Chloride; Chloride attack; Chloride ions; Cs-corrected TEM; Duplex alloy; Duplex stainless steels; Passive film; Transmission electron microscopy
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2019.04.012

•Evolution of the passive film on DSS induced by chloride is directly visualized.•The passive film has a step-like unevenness at the austenite/ ferrite boundary.•Passive film on austenite has a more pronounced growth rate yielding lower interface.•Chloride ions attack mechanisms differ from austenite to ferrite phase.•Chloride induces a thicker Mo-rich passive film from the original Cr-rich film. Passive films on duplex stainless steels are heterogeneous, with properties depending on the two-phase microstructure. Accordingly, the interaction of chloride ions with the passive films on either of the two phases ought to vary. These issues have been investigated by some indirect methods, not sufficiently nor directly corroborated by experimental evidence. Using aberration-corrected transmission electron microscopy, we simultaneously investigate the films on the ferrite and austenite phase near the phase boundary, as well as the film evolution in chloride-containing media. This study provides some virtual experimental insights into the features of chloride attack on the passive film of duplex alloys.