Influence of anion and sulfate-reducing bacteria on the stress corrosion behavior and mechanism of X70 steel in a marine mud environment. (January 2023)

• Record Type: Journal Article
• Authors: Xie, Fei; Wang, Yuxin; Wang, Dan; Sun, Dongxu; Zhou, Yi; Wang, Yichuang
• Is Part Of: Engineering failure analysis. Volume 143:Part A(2023)
• Publication Date: 2023-01
• Subjects: Anion -- Sulfate-reducing bacteria -- Stress corrosion cracking -- Marine mud environment; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2022.106834
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: Both C l - and SO2-4 affect the the survival of SRB. C l - determines the osmotic pressure of the solution and there is a critical value for the survival of SRB with respect to C l - concentration. During corrosion, there is competitive adsorption of SO2-4 and C l - on the electrode surface. A synergistic effect between anion and SRB promotes the SCC of X70 pipeline steel. Abstract: Subsea pipeline steel was severely corroded due to the presence of huge quantities of C l -, SO4 2-, and sulfate-reducing bacteria (SRB) in marine mud. In this paper, the synergistic effects of C l -, SO4 2- and SRB on the stress corrosion cracking (SCC) behavior of X70 steel in a simulated solution of marine mud in the South China Sea were examined using slow strain rate tensile (SSRT) tests, surface morphology analysis, and combined electrochemical experiments. The results indicated that the sensitivity of the specimens to stress corrosion increased as the concentration of C l - rose. C l - not only encouraged pitting and intensified the corrosion autocatalytic process but also influenced the number of surviving SRB. At a concentration of 20 g/L, the greatest number of SRB survived in the present investigation. However, when the C l - concentration was 30 g/L, the anodic dissolution rate was the quickest and the SCC sensitivity was the highest, due to the synergistic impact of the high C l - concentration and SRB. SO4 2- functions as an electron acceptor for SRB in the electrochemical reaction process and influences the adsorption of C l - . Its rising concentration sped up the anodic dissolving process and increased the sensitivity of SCC.