Effect of applied current density on corrosion behavior and protection efficiency of hanger steel wire for suspension bridge in marine rainfall environment

The hanger steel wires of suspension bridge are suffering serious electrochemical corrosion in harsh marine rainfall environment. This article investigates the application of the electrochemical anti-corrosion method to unsheathed hanger steel wires utilizing rainwater conductivity. The influence of aggressive chloride ions and applied current density on corrosion behavior and protection efficiency was experimentally studied. Results indicate that in simulated marine rainfall environment, the corrosion rate of hanger steel wires increases with chloride ion concentration. Furthermore, chloride ions enhance the electrochemical anti-corrosion efficiency by raising rainwater electrolyte conductivity. Protection efficiency increases with applied current density, and the increase rate gradually decreases in the range of 0–100 mA/m2. Protection efficiency can exceed 37% compared to unprotected steel wire with acceptable applied current density. The corrosion resistance of hanger steel wire significantly enhanced due to the denser, flatter, and more intact corrosion products layer formed on the steel wire surface, and the area near the cathodic access point is best protected. The suitable applied current density decreases with increasing chloride concentration; in marine rainfall environment with 1% NaCl solution, the suitable applied current density is approximately 100 mA/m2, while in environment with 3.5% NaCl solution, this range is around 50–100 mA/m2. •Investigated the electrochemical anti-corrosion of the unsheathed steel wire in a simulated marine rainfall environment.•Optimized the applied current density range of hanger steel wire in marine rainfall environment.•Protection efficiency can exceed 37% compared to unprotected steel wire with acceptable applied current density.