Composition changes around sulphide inclusions in stainless steels, and implications for the initiation of pitting corrosion

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• 作者：David E. Williams ; Matt R. Kilburn ; John Cliff ; Geoffrey I.N. Waterhouse
• 关键词：A. Stainless steel ; B. SIMS ; B. XPS ; C. Pitting corrosion ; C. Segregation ; C. Inclusion
• 刊名：Corrosion Science
• 出版年：2010
• 出版时间：November 2010
• 年：2010
• 卷：52
• 期：11
• 页码：3702-3716
• 全文大小：1373 K

文摘

We report high-resolution SIMS microscopy measurements, which show that many ‘MnS’ inclusions have surrounding them a narrow ‘halo’ of half-width typically 100 nm that is strongly enriched in Fe, forcing consideration of the electrochemistry of FeS as a determinant of the behaviour of the inclusion boundary. We suggest that on exposure to water a very thin and porous metal-deficient polysulphide skin forms between the bulk of the inclusion and the steel, within which a pit can be triggered. The results resolve a controversy concerning the composition of the boundary region around inclusions in stainless steel and re-emphasise its potential significance.