Emergence of micro-galvanic corrosion in plastically deformed austenitic stainless steels. (May 2021)

• Record Type: Journal Article
• Authors: Chen, Xin; Gussev, Maxim; Balonis, Magdalena; Bauchy, Mathieu; Sant, Gaurav
• Is Part Of: Materials & design. Volume 203(2021)
• Publication Date: 2021-05
• Subjects: Passive film -- Corrosion -- SECM -- EIS -- Interface charge transfer; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2021.109614
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Localized plastic deformation has been observed to render nuclear reactor components more susceptible to stress corrosion cracking (SCC). However, it is not fully clear how localized strain impacts corrosion (oxidation) behavior. Herein, the surface reactivity and corrosion behavior of 304 L stainless steel specimens, deformed to different strain levels, was analyzed using advanced multimodal and multiscale methods. For the first time, we observed that localized deformation regions, e.g., deformation bands and α'-martensite featured smaller Volta potentials than the parent austenite matrix. This resulted in the establishment of localized corrosion potential gradients and the emergence of accelerated microscale galvanic corrosion. Particularly, regions that featured higher dislocation concentrations were more reactive on account of the reduction in the activation energy of corrosion due to the stored energy. The superposition of surface reactivity and strain distributions reveals that, SCC cracking is expected to initiate in regions of strain localization wherein micro-galvanic corrosion is favored. Graphical abstract: Unlabelled Image Highlights: The corrosion reactivity of deformed 304 L stainless steels was analyzed using advanced multimodal and multiscale methods. We observed that localized deformation regions featured smaller Volta potentials than the parent austenite matrix. The localized corrosion potential gradients resulted in the emergence of microscale galvanic corrosion. SCC cracking is expected to initiate in regions wherein micro-galvanic corrosion is favored.