Atomic-scale evidence for the intergranular corrosion mechanism induced by co-segregation of low-chromium ferritic stainless steel. (15th August 2021)

• Record Type: Journal Article
• Authors: Hu, Shuai; Han, En-Hou; Liu, Xianbin
• Is Part Of: Corrosion science. Volume 189(2021)
• Publication Date: 2021-08-15
• Subjects: Ferritic stainless steel -- Intergranular corrosion -- Co-segregation -- Cr-depletion -- Prevention; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2021.109588
• Languages: English
• ISSNs: 0010-938X

Abstract

Graphical abstract: The mechanism of intergranular corrosion of the low-chromium ferritic stainless steels was investigated by the method of 3DAP at the atomic level, and the concept of reducing the segregation of Cr to prevent intergranular corrosion was proposed. (Figure (a) and (b) are cited from our previous report). Highlights: Distinct co-segregation of Cr and other solute atoms around GBs was observed by 3DAP without Cr-carbides precipitation. The co-segregation induced the formation of a Cr-depleted zone leading to intergranular corrosion. The novel concept of suppressing the GB segregation at the level of dynamics/thermodynamics to prevent IGC was proposed. Abstract: The composition distribution around grain boundaries of low-chromium ferritic stainless steels was investigated by the techniques of three-dimensional atom probe and focused ion beam. It was found that Cr atoms segregated largely (up to as much as 22.4 at.%) at grain boundaries with co-segregation of other solute atoms in the absence of Cr-carbides precipitation. The co-segregation induced the formation of a Cr-depleted zone (down to only 9.3 at.%) leading to intergranular corrosion. Based on the new mechanism, a novel concept of reducing or even preventing the grain boundary segregation to prevent intergranular corrosion at the level of dynamics/thermodynamics was proposed.