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The effect of the use of mill scale admixtures in sand mould on the mechanical properties of cast aluminium was
investigated. The sand mould contains varying proportions of the mill scale such as 0 %, 10 %, 15 %, 20 %, 25 % and
30 % volume/weight. The cooling rate of the mould was considered while the mechanical properties and the
microstructure analysis of the cast metal were carried out. It was observed that percentage increase in mill scale
promotes rapid cooling which enhances grain refinement. The tensile strength was found to increase from 143.42
N/mm2 to 191.69 N/mm2 while the hardness properties were found to increase from 42.9 BHN to 61.5 BHN. The
microstructural examination of the specimens were observed and revealed more fine grains as the percentage of mill
scale increases from 0 % to 30 % in the sand mould. Mill scales from steel rolling mills could find application as
additives to moulding sands for the production of cast aluminium in foundry industries in Nigeria.