The effect of mold materials on solidification, microstructure and fluidity of A356 alloy in lost foam casting.

摘要

The total solidification times for plate lost foam castings (LFC) were experimentally determined using three mold materials (silica, mullite and steel shot) and five pattern thicknesses. The applicability of Chvorniov's rule to LFC was confirmed and values deduced for appropriate constants. The influence of mold materials on the cooling rates was explained using a combination of endothermic effect of foam and the mold properties. Taking into account the energy balance and initial temperatures, an attempt was made to predict total solidification times. For each of the mold materials the dendrite arm spacings were related to local solidification times, and an overall correlation established. The measured lower velocity of liquid metal in vertical patterns was attributed to pattern thickness and the effect of gravity. The flow lengths (fluidity) in different mold materials were related to the effective superheats and total solidification times.