A multiscale numerical model based on nonequilibrium thermal effect formelting of metal powder bed subjected to constant heat flux is developed. Thevolume shrinkage due to density change is taken into account. Thenonequilibrium model is discretized by an implicit finite difference method andsolved numerically using an iterative tri-diagonal matrix algorithm. Theevolutions of powder bed surface temperature and various interfacial locationsas well as the melting temperature range during the melting process areinvestigated. The results show that liquid region, upper and lower parts ofmushy zone are formed on the top of unsintered zone as the melting progresses.The duration of the preheating stage shortens and the melting rate acceleratesas the initial porosity or initial temperature increases while particle sizehas much less effect on the melting process. The parametric study shows themelting temperature range of the powder bed widens with increasing initialporosity, decreasing initial temperature or increasing particle size.
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