EFFECTS OF SELECTED CASTING METHODS ON MECHANICAL AND CORROSION BEHAVIOUR OF Al-Mg-Si ALLOY

Abstract

This study investigated the selected casting methods on mechanical and corrosion behaviour of Al-Mg-Si alloy. The casting methods used were spin, sand and die casting. These were done with a view to determine which of the casting methods will produce the best properties. The pure aluminium scrap, magnesium and silicon were subjected to chemical analysis using spectrometric analyser. Thereafter the charge calculation to determine the amount needed to be charged into the furnace was properly worked out and charged into the crucible furnace from which as-cast aluminium was obtained. The mechanical properties of the casting produced were assessed by hardness and impact toughness test. The corrosion behaviour of the casting produced in acid (0.1M, 0.3M, and 0.5M H2SO4) and saline (0.1M, 0.3M, and 0.5M NaCl) environment were investigated using corrosion rate, mass loss. The optical microscopy, experimental density and % porosity were also investigated. From the results it was observed that magnesium and silicon were well dispersed in aluminium matrix of the spin casting. It was observed from visual examination after machining that there were minimal defects. It was also observed that out of the three casting methods, spin casting possesses the best mechanical properties (hardness and impact toughness). However, during the corrosion test in H2SO4, die casting exhibited best corrosion resistance followed by spin and sand casting. The spin, sand and die casting all exhibited good corrosion resistance in NaCl.