The design, casting and mechanical test of single-throw ductile cast iron crankshaft is presented. Sand casting technique, with side gating system (riser contact in cope) was adopted. The ductile cast iron material was produced by inoculating molten iron (which contains sufficient amount of silicon) in the ladle. This was accomplished by adding small amount of magnesium in the form of magnesium ferrosilicon alloy (5% Mg, 45% Si, rest iron) into the ladle melt which resulted to nodularization of the free graphite carbon. The inoculants were introduced into the melt by sandwich method. Crankshaft was then cast at different pouring temperature and time. Mechanical properties test was conducted on the as- cast and annealed samples. Results show that best quality crankshaft can be produced at pouring temperature and time ranges of 1400- l415°C and 7-12 seconds respectively. Values of tensile strength, hardness and percent elongation for the as-cast samples were on the average found to be 620 N/mm2, 300BH and 4.5% respectively while for the heat treated samples the corresponding values were 500 N/mm2, 205BH, 12%. Also impact strength was found to be 13.0 J. On comparison, the mechanical properties were found to be in good agreement with that of forged/machined steel crankshaft material (773 N/mm2, 18% and 225-235BH) with even better hardness property in the as-cast condition.
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