Galvanic Corrosion of Mill-Scaled Carbon Steel Coupled to AISI 304 Stainless Steel in the Chloride-Contaminated Mortars

In order to assess the durability of concrete structures reinforced by different types of steel in aggressive environments, the galvanic corrosion of mill-scaled carbon steel was investigated when it was connected to AISI 304 stainless steel characterized by various cathode/anode surface area ratios (A(s):A(c)) in chloride-contaminated mortars. The galvanic potential and the galvanic current density of the coupling carbon steel were measured, and the corrosion state of the mill-scaled carbon steel was inspected after 1,450 days. The results indicated that the potential of the carbon steel was slightly positively shifted by the stainless steel. High A(s):A(c) ratios promoted the passivation of the coupling carbon steel and lowered the corrosion current density in the chloride-contaminated mortars. The galvanic current densities of the carbon steel-stainless steel couples increased with A(s):A(c) ratio. Because the corrosion current density of the mill-scaled carbon steel was nearly one order of magnitude higher than the galvanic current density, the total corrosion current density of the coupling mill-scaled carbon steel generally decreased, and its overall corrosion diminished with increasing A(s):A(c) ratio. Finally, based on the results of this study, the A(s):A(c) ratio is recommended to be higher than 2:1 to ensure the sufficient durability of submerged concrete structures in an aggressive concrete environment. (c) 2023 American Society of Civil Engineers.