Time-Dependent Changes in Electrochemical Surface Resistance and Localised Corrosion Behaviour of UNS A93003 in a Saline Solution

This study investigated the localised corrosion behaviour of UNS A93003 alloy in a chloride environment, employing potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), and surface analysis techniques. Potentiodynamic polarisation results indicated that, as the chloride concentration increased, the alloy surface exhibited higher anodic current densities at the same overpotential, suggesting an accelerated rate of localised corrosion. During the initial immersion period, electrochemical reactions on the alloy surface were dominated by protective mechanisms such as passivation and re-passivation, resulting in an increase in surface resistance. However, as immersion time progressed, localised corrosion became the dominant process, leading to a significant reduction in surface resistance. With prolonged exposure, extensive localised corrosion was observed with corrosion products such as aluminium oxide and hydroxide accumulating around the affected areas. These corrosion products acted as intermediaries that promoted further electrochemical reactions, potentially accelerating the propagation of localised corrosion. These findings confirm that the corrosion behaviour of the UNS A93003 alloy surface evolved dynamically over time, highlighting its susceptibility to localised corrosion in chloride environments. The results provide essential insights that could support efforts to enhance alloy durability and effective corrosion prevention strategies for industrial applications.