Using a three-phase deterministic model for the columnar-to-equiaxed transition
Using a three-phase deterministic model for the columnar-to-equiaxed transition
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DOI：
10.1007/s11661-007-9175-9
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发表时间：
2007-07-01
影响因子：
2.8
通讯作者：
Ludwig, A.
中科院分区：
文献类型：
--
作者：
Wu, M.;Ludwig, A.
为了克服以往柱状晶等轴晶（CET）模型忽略熔体对流和自由等轴晶运动的局限性，本文提出了一种三相确定性CET模型。通过适当的多相体积平均方法，可以解释在柱状前沿生长之前等轴晶粒的成核和生长、熔体对流和晶粒沉积的影响以及工程规模铸件中CET的发生。特殊的建模假设确保CET机制，即“硬”和“软”阻塞，都得到了解决。强烈建议应考虑这两种机制，特别是在存在晶粒沉降和熔体对流的情况下。虽然目前的模型包含了几乎所有与CET事件相关的物理变量，但在一维情况下，该模型仍然再现了Hunt经典CET方法的结果。
In order to overcome the limitations of previous column ar-to-equiaxed (CET) models, which neglect melt convection and the movement of free equiaxed grains, this article presents a three-phase deterministic CET model. With appropriated multiphase volume-averaging approaches, it is possible to account for nucleation and growth of equiaxed grains ahead of a growing columnar front, the influence of melt convection, and grain sedimentation, and the occurrence of a CET in a casting of engineering scale. Special modeling assumptions ensure that both CET mechanisms, namely, "hard" and "soft" blocking, are tackled. It is highly recommended that both mechanisms should be considered, especially in the situation where grain sedimentation and melt convection are present. Although the current model incorporates almost all the physical variables relevant to a CET event, under special condition of a one-dimensional case, the model still reproduces the results of Hunt's classical CET approach.