Influence of the casting process on corrosion behaviour of 2024-T6 aluminium alloy in different conditions of pH and NaCl concentration

Abstract

Corrosion behaviour of 2024-T6 castings produced by sand mould and metallic mould has been studied in media with different sodium chloride concentrations and pH values, using electrochemical techniques and scanning electron microscope. Corrosion rates and anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of 2024-T6 at different conditions. The study shows a different corrosion mechanism depending on the pH. At pH 12, the more negative values of E _corr confirmed that the alkalinisation of aluminium incites the dissolution of the Al substrate. The effect of chloride concentration is reflected in shifts of E _corr towards more negative values. The research on the effect of the used mould demonstrates that the impact of the casting process in the cooling rate affects the pitting corrosion resistance.