RUNNER ANGLE MODIFICATION FOR ENHANCED MACROSEGREGATION REDUCTION IN ALUMINIUM-ZINC ALLOY

Abstract

Macro-segregation is an irreversible defect in non-ferrous alloy casts. This can only be significantly minimized by controlling the melt and its flow trajectory during casting. The study identified runner angle inclination as a critical parameter that impacts the development, size and volume of macro-segregation occurrence in binary alloys. The methodology entails variation of runner angles to include 90°, 105°, 120°, 135°, and 150° at a constant casting speed of 100mm/s being the optimum casting speed established in previous study. The casts microstructure was examined using both optical and electron microscopes complemented with energy dispersive spectrometry. Results show that runner position at 120° is the most appropriate for the casting of aluminium-zinc alloy as this gave a highly homogeneous distribution of solute element in the microstructure with corresponding improved mechanical properties