Impact of Desulfovibrio ferrophilus IS5 biocorrosion time on X80 carbon steel mechanical property degradation
Zhong Li, Jike Yang, Shihang Lu, Wenwen Dou, Tingyue Gu
Abstract
Three different incubation times (7, 14 and 21 d) were used to immerse ×80 carbon steel dogbone coupons in deoxygenated enriched artificial seawater at 28 °C inoculated with Desulfovibrio ferrophilus (strain IS5), a very corrosive sulfate reducing bacterium to cause microbiologically influenced corrosion (MIC). It was found that 21 d immersion had the largest weight loss (24.8 mg cm−2 equivalent to 0.55 mm/year corrosion rate), smallest sessile cell count (6.8 × 108 cell/cm2), deepest pit depth (30.6 μm), and most severe mechanical degradation (9 % loss in ultimate strength and 18 % loss in ultimate strain). Due to nutrient depletion in the static incubation system, corrosion rate and sessile cell count were the highest at 0.82 mm/year and 1.1 × 109 cell cm−2, respectively at 7 d. The results from scanning electron microscopy, X-ray photoelectron spectroscopy and confocal laser scanning microscopy analyses and electrochemical corrosion measurements supported the sessile cell counts and biocorrosion weight loss data.