Alloy design employing high Cr concentrations for Mo-free stainless steels with enhanced corrosion resistance. (1st August 2018)

• Record Type: Journal Article
• Authors: Jung, KiMin; Ahn, SooHoon; Kim, YoungJun; Oh, SeKwon; Ryu, Won-Hee; Kwon, HyukSang
• Is Part Of: Corrosion science. Volume 140(2018)
• Page Start: 61
• Page End: 72
• Publication Date: 2018-08-01
• Subjects: Stainless steel (A) -- Localised corrosion -- Repassivation (C) -- Passive films (C) -- Molybdenum -- Pitting corrosion (C); Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2018.06.021
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Mo was strategically replaced with Cr in stainless steels. The feasibility of developing Mo-free, high-Cr stainless steels was investigated. Pitting corrosion resistance was superior for Fe-25Cr compared to Fe-20Cr-2Mo. The enhancement of corrosion resistance by Cr addition was investigated. Abstract: In this study, we demonstrate the strategic replacement of Mo with excess Cr in Fe-Cr alloys and report their corrosion resistances. To better understand pitting corrosion, the electrochemical properties of the passive films observed on different alloys (Fe-20Cr-2Mo and Fe-25Cr) were compared. Mo-free Fe-25Cr offered comparable or better pitting corrosion resistance than Fe-20Cr-2Mo during film breakdown, repassivation, and pit propagation stages. We investigated the reason for enhanced stability against pitting corrosion as a result of Mo exclusion in such alloys. Mo accelerated co-dissolution of Fe and Mo itself, consequently enriching Cr on the surface and ultimately promoting onset of passivity.