Fabrication of improved corrosion resistant Al-Mg alloy surfaces using underwater Laser surface texturing

This study investigates underwater nanosecond laser texturing as a novel method to enhance the corrosion resistance of Al-Mg alloy (AA5754). Compared to open-air processing, underwater texturing significantly reduces thermal defects (burrs, recast layers) and promotes stable surface properties. Grid patterns were fabricated at varying pitch distances (200 µm and 400 µm) and scanning speeds (2 mm/s and 200 mm/s). Underwater-textured surfaces exhibited superior hydrophobicity, achieving a contact angle of 141°, compared to 96.77° for open-air textures. Electrochemical tests in 0.5 M NaCl revealed a 83.17% improvement in corrosion resistance for underwater processing, with a corrosion current density of 0.18 × 10⁻⁷ A/cm² and a corrosion rate of 0.19 µm/year – significantly lower than untextured samples. The enhanced performance is attributed to the formation of a passive oxide layer and reduced thermal degradation. These findings demonstrate the potential of underwater laser texturing for durable anti-corrosion applications in marine and aerospace environments.