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.

中文翻译：

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基于四相充填凝固模型的层状连铸工艺综合研究

摘要 为了减轻铸锭凝固过程中的宏观偏析，先前提出了一种称为层状铸造（LC）的增材铸造工艺。实验结果表明宏观偏析得到了很大的改善，但对LC方法下宏观偏析的凝固过程和改善机制的认识仍然缺乏。本研究利用四相充填凝固模型，对LC法进行了首次数值模拟。四相充填-凝固模型考虑了柱状和等轴晶的充填、生长、等轴晶的成核和沉降、缩孔和热-溶质对流等，因此，能够模拟整个 LC 制造过程，包括模具填充、凝固、重熔和收缩。结果表明，在铸态组织和宏观偏析方面，数值模拟结果与实验结果一致。结果还表明，在LC过程中，通过人为控制熔体的流动域，将液态熔体逐步倒入模具中，逐层固化，宏观偏析得到缓解。