Corrosion behaviour of cold-rolled aluminium AA8015-alloy in natural seawater at 0.18 μm surface roughness

Aluminium is one of the most produced and used metals globally, second to ferrous metals. Its good corrosion resistance is one of the reasons for its heavy usage in typical applications, such as in marine applications. Electrochemical corrosion study of cold-rolled aluminium AA8015-alloy at 0.18 μm surface roughness in natural seawater was explored. The aluminium AA8015-alloy utilized in this study was cold rolled in a reversible Achenbach cold rolling mill in four pass schedules to a thickness gauge of 1.2 mm. A surface roughness of 0.18 μm with three cold mounted samples was achieved on an automated grinding/polishing machine using 320 grit, 800 grit, and 1200 grit SiC paper. Electrochemical corrosion experiments were conducted on the samples in natural seawater using a computer-controlled potentiostat in an open polarization cell set-up at room temperature. The corrosion behaviour on surface morphologies of the samples was observed by high mega pixel camera and scanning electron microscope. Findings reveal asymmetric polarization curves for all the samples and energy dispersive X-ray spectrometry elemental analysis shows the existence of insoluble substrate complexes formed on the surfaces. Consequently, the scanning electron microscope analysis confirms localised corrosion in the mode of pitting.