Influence of crevice width on sulfate-reducing bacteria (SRB)-induced corrosion of stainless steel 316L
Cong Wu, Zhaopeng Wang, Zhan Zhang, Bowei Zhang, Guojia Ma, Qiong Yao, Zhaohong Gan, Junsheng Wu, Xiaogang Li
Abstract
In the present work, the distribution of sulfate-reducing-bacteria (SRB) inside the crevice and the effect of crevice width on SRB-induced corrosion of stainless steel 316L (SS 316L) were systematically investigated. A cambered crevice configuration consisting of a convex lens and a wire beam electrode (WBE) was employed to measure the current and potential distributions under different crevice widths. Subsequently, scanning electronic microscopy (SEM), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were adopted to study SRB-induced corrosion behavior of SS 316L in different crevice locations. Results show that crevice width plays an essential role in corrosion on SS 316L in crevice environment with SRB. The most severe corrosion with dense pits occurred at the crevices with 150 μm in width due to the combined effects of microbiological corrosion and crevice corrosion. In narrow crevices, corrosion is much slighter since SRB can hardly enter into the crevices to induce corrosion. In contrast, the crevices with 700 μm in width suffer the mildest corrosion because the influence of crevice corrosion is negligible with a weakened crevice corrosion tendency. Additionally, it was found that SRB could affect the composition of the passive film and destroy its compactness, thus accelerate the crevice corrosion of SS 316L in artificial seawater. The findings of this work are beneficial to understanding the mechanisms of MIC-induced corrosion in various environments.