Effect of nanosecond laser line patterning on roughness, wettability, and potentiodynamic polarization of aluminum alloy

This research investigates the influence of underwater nanosecond laser texturing on the potentiodynamic properties of AA5754 aluminum alloy. 5xxx series aluminum alloys are mainly used in marine related applications due to its high magnesium content making it lightweight and its low weight to strength ratio. Although this alloy has high corrosion resistance in normal atmosphere, its anti-corrosion properties get highly affected in chloride-rich atmosphere. Laser texturing is an effective technique to enhance various surface properties including corrosion resistance by altering its surface morphology. In this study, a simple line based nanosecond laser texturing was deployed on AA5754 surfaces. Experiments were carried out in open-air and water submerged medium. Submerged water condition was found to significantly impact the laser beam-material interaction process by improving the surface hydrophobicity and reduced oxidation. A 70 W MOPA nanosecond laser was utilized to create line textures on the surfaces. Scanning electron microscope (SEM), an optical microscope, and a confocal laser microscope was utilized to study surface morphology, and change in roughness values. Element dispersive spectroscopy (EDS) was used to study change in surface chemistry, goniometer for water contact angle, and a potentiostat for corrosion properties. Underwater texturing resulted in more uniform surface morphology, increased contact angles (contact angle up to 136.40°), and significantly reduced corrosion current density by up to 65.42%. These enhanced properties may be attributed to decreased thermal defects when processed in underwater conditions. The findings suggest that submerged laser texturing is a promising surface modification strategy for marine-grade aluminum alloys.