Corrosion Behaviour of Hot Rolled AA8015 in Natural Seawater at 1.37 µm Surface Roughness

Aluminium alloy 8015 (AA8015) is a general-purpose alloy having a wide range of applications that include household appliances and marine ship structures. Electrochemical testing of hot rolled AA8015 with a particular roughness immersed in natural seawater solution was investigated. The AA8015 under investigation in this research is manufactured by a continuous casting method and subjected to mechanical hot rolling process at a temperature above its recrystallization temperature into 7 mm thickness plate. A roughness average of 1.37 µm with three cold-mounted samples was accomplished on an automatic dual multi-purpose grinding-polishing machine with the aid of 320 grit silicon carbide waterproof paper sheet. Corrosion experiments via electrochemical reactions were conducted on the corrosion samples immersed in natural seawater with the aid of a computerized controlled Ivium potentiostat in an open electrochemical polarization cell arrangement at ambient temperature condition. Observation of the surface morphologies of the corroded samples was achieved by a high megapixel camera and scanning electron microscope (SEM). Findings show asymmetric polarization curves for all the investigated samples, showing an actively corroding region. Consequently, the SEM examination confirms corrosion occurring at localized areas in the form of pitting.