The Corrosion Behaviors of X70 Steel Under the Effect of Alternating Current and Sulfate-Reducing Bacteria in Seawater

Abstract

The influence of alternating current (AC) and sulfate-reducing bacteria (SRB) on the corrosion behaviors of X70 steel in seawater was investigated by different electrochemical tests and surface examination methods. It was found that the activity of SRB was affected by AC. When the AC current density sustains at the low level of 0  A/m2 and 50 A/m2, the activity of SRB is not high enough to produce a significant impact on the AC-induced corrosion process. As the current density increases to 80 A/m2 and 100 A/m2, SRB could alter the corrosion kinetics by forming a more intact film on the corrosion surface. However, the activity of SRB is inhibited by AC with the current density up to 200 A/m2. The intact corrosion product formed by SRB in high activity could influence the AC corrosion kinetics, but the product film can not prevent AC-induced corrosion. The localized corrosion was more significant under the effect of AC and SRB probably because the biofilm formed by SRB produced uneven electrochemical properties on the corrosion surface.