EFFECTS OF COOLING RATE DURING CASTING ON THE CORROSION RESISTANCE OF 6XXX ALUMINIUM ALLOY

Abstract

6xxx aluminium alloy, despite its good mechanical properties do undergo corrosion attack thereby reducing the lifespan of the alloy and increasing liability in its application. This study investigates the effects of cooling rate during casting process on microstructure, mechanical properties and corrosion behaviour of 6xxx aluminium alloy. Aluminium ingot was melted in a muffle furnace and cast into rods. The cooling rate was controlled by holding the moulds at different temperatures. Microstructural characteristics were examined by optical microscopy. Mechanical properties such as impact strength, hardness, and tensile strength were analysed using standard methods. Corrosion behaviour was evaluated by potentio-dynamic polarization. It was found that increasing cooling rate resulted in a significant improvement in mechanical properties and corrosion resistance of the 6xxx alloy. The findings were explained in terms of microstructural refinement and chemical homogeneity of the alloy.