AUTHOR=Wu Jinyi , Zhang Weixiong , Chai Ke , Yu Aimin 

TITLE=Corrosion Behavior of AISI 1045 Steel in Seawater in the Presence of Flavobacterium sp.

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00303

DOI=10.3389/fmicb.2020.00303

ISSN=1664-302X

ABSTRACT=<p>A systematic comparison study was carried out to investigate the effect of <italic>Flavobacterium</italic> sp. on AISI 1045 steel corrosion by weight loss, fluorescence microscopy (FM), surface analysis, cell count, pH measure, electrochemical impedance spectroscopy (EIS), and polarization curves. The impedances were considerably increased by <italic>Flavobacterium</italic> sp. between 1 and 7 day exposure and after 30 day exposure but considerably decreased by <italic>Flavobacterium</italic> sp. after 15 and 21 day exposure, which were supported by the I<sub>corr</sub> results and the weight loss data. Furthermore, the biofilm was formed on the coupons. The pH values were considerably decreased by <italic>Flavobacterium</italic> sp. after 15 and 21 day exposure. The results proved that <italic>Flavobacterium</italic> sp. decreased the corrosion rates between 1 and 7 day exposure and after 30 day exposure and increased the corrosion rates between 15 and 21 day exposure, which could be ascribed to the protective biofilm and the secreted corrosive acid, respectively. In addition, <italic>Flavobacterium</italic> sp. considerably increased the pit numbers, the maximum pit depths, and the corresponding widths and considerably decreased the E<sub>pit</sub> values. Importantly, the coverage and the heterogeneity of the biofilm were positively correlated with the increases in the maximum pit depths and the corresponding widths and the decreases in the E<sub>pit</sub> values by <italic>Flavobacterium</italic> sp. The results demonstrated that <italic>Flavobacterium</italic> sp. increased the pitting corrosion, which could involve the heterogeneous biofilm cover.</p>