A comprehensive study of layer casting process by a four-phase filling-solidification model

Abstract

Abstract In order to alleviate the macrosegregation during the solidification of ingots, an additive casting process called layer casting (LC) was previously proposed. The experimental results show that the macrosegregation had been greatly improved, however, the understandings of the solidification process and the improvement mechanisms of the macrosegregation under the LC method are still lacking. In this research, by means of the four-phase filling-solidification model, we have carried out the first numerical simulation of the LC method. The four-phase filling-solidification model takes into account the filling, growth of columnar and equiaxed crystals, nucleation and sedimentation of equiaxed crystals, shrinkage cavity, and thermal-solutal convection, etc., which, thus, makes the capability to model the entire LC fabricate processes including mold filling, solidification, remelting, and shrinkage. The results show that the numerical simulation results are consistent with experimental results in terms of as-cast structure and macrosegregation. Results also show that the macrosegregation is alleviated by artificially controlling the flow domain of melt during the LC process, in which the liquid melt is poured into mold step by step and solidifies layer by layer.