Macrofouling-induced localized corrosion behaviors of 304 stainless steels exposed in the tidal zone of South China Sea

In this paper, the corrosion behavior of 304 stainless steel was investigated in the tidal zone of South China Sea through the field exposure tests. Results reveal that specimens exposed for 0.5 years exhibit minimal corrosion, with surfaces predominantly covered by algae, calcium-magnesium deposits, and barnacle. With prolonged exposure, the number of barnacles attached increases and occluded corrosion micro-cells are formed on the attachment zone, aggravating the localized corrosion condition. Electrochemical results show that specimen exposed for 0.5 years has a self-corrosion potential of -0.07 V (vs. SCE), while that for two years shifts negatively to -0.15 V accompanying a self-corrosion current density increase from 1.91 × 10–8 A cm−2 to 3.89 × 10–8 A cm−2. With prolonged exposure, barnacle attachment increases progressively, reaching 30% after 2 years. The charge transfer resistance decreases from 6.37 × 105 to 4.05 × 105 Ω·cm2, and the maximum pitting depth surges to 380.03 μm. Power function models for corrosion loss and pitting depths were constructed with a goodness of fit exceeding 0.95, effectively describing the corrosion evolution process and providing critical data for material selection and service life evaluation in this marine environment.