Study of Microbiologically Influenced Corrosion of the Welded Stainless Steel 316L

Microorganisms are acknowledged to be responsible for corrosion failures worldwide; however, some recent studies have indicated that in some environments, bacteria activities can decelerate the corrosion rate of metals. This research investigated the microbial corrosion behavior of welded stainless steel 316L by sulfate-reducing, sulfur-oxidizing, and iron-oxidizing bacteria. The corrosion evaluations were performed using potentiodynamic and cyclic polarization tests. Furthermore, the scanning electron microscope and energy-dispersive spectroscopy analysis were executed after 90 days of bacteria exposure to determine the biofilm morphology changes over time. The results suggested that while the base metal (unwelded area) was unaffected by SRB, a vast increase in corrosion rate was observed in HAZ and welded area. On the other hand, analyzing the SEM morphology, EDS results, electrochemical tests and the corrosion rate obtained from Tafel extrapolation showed that SOB and IOB reduced the corrosion rate of the alloy and acted as inhibitors