Crevice corrosion behaviour of a duplex stainless steel

S. Aoki, Y. Nada, H. Yakuwa, M. Miyasaka, J. Sakai

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Preferential dissolution behaviour in corroded areas and solution pH inside the crevice in growing crevice corrosion of duplex stainless steels were investigated. Using potentiostatic method, potential was held at various values during the crevice corrosion test (up to 10 4 min). 0.6 M NaCl aqueous solution was used in the test at 50 ± 2 °C. The current first decreased according to passivation of the specimen. After a certain incubation time, the current increased for initiation of crevice corrosion. Then crevice corrosion grew continuously with fluctuation behaviour of current until the test was finished. Preferential dissolution was observed at corroded areas in all the potentials tested. It was found that three regions could be distinguished from the fringe to the center of the crevice; they were the passive region, the preferential region of dissolution of austenitic phase, and that of the ferritic phase. After the test was finished, the specimen was immersed into liquid nitrogen immediately so that the solution inside the crevice was frozen. Then the solution pH inside the crevice was measured by pH test papers. The minimum pH value was lower than the depassivation pH of the specimen in the test environment. According to these results, including our previous study, it is concluded that potential gradient formed from the fringe to the center of the crevice. This result is described by the IR drop theory and a galvanic cell between inside and outside the crevice.

    Original languageEnglish
    Title of host publication18th International Corrosion Congress 2011
    Pages1018-1023
    Number of pages6
    Volume2
    Publication statusPublished - 2011
    Event18th International Corrosion Congress 2011 - Perth, WA
    Duration: 2011 Nov 202011 Nov 24

    Other

    Other18th International Corrosion Congress 2011
    CityPerth, WA
    Period11/11/2011/11/24

      Fingerprint

    Keywords

    • Crevice corrosion
    • Depassivation pH
    • Duplex stainless steel
    • IR drop
    • Preferential dissolution

    ASJC Scopus subject areas

    • Surfaces, Coatings and Films
    • Surfaces and Interfaces

    Cite this

    Aoki, S., Nada, Y., Yakuwa, H., Miyasaka, M., & Sakai, J. (2011). Crevice corrosion behaviour of a duplex stainless steel. In 18th International Corrosion Congress 2011 (Vol. 2, pp. 1018-1023)