The passive behaviors of coarse and nano/ultrafine grain austenitic stainless steels processed by cold rolling and reversion annealing were investigated. The average grain about 200 nm was obtained by cold rolling down to 94% reduction in thickness and reversion annealing at 800 °C for 250 s. Passive films formed in borate buffer solution (pH 9.2) have been characterized by electrochemical impedance spectroscopy and Mott-Schottky plots. The impedance results indicated a distinct inflection was observed with the increasing of potential, however, the Mott-Schottky analysis did not show such inflection point in the same potential range. There were not evident differences in passive properties between coarse and nano/ultrafine grain samples. This was attributed to synergistic effect of grain refinement and orientation. However, the corrosion resistance of the passive film in nano/ultrafine grain sample was higher than that in coarse grain sample after immersion test by the three-point-bend loading.
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