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Melt convection and macrosegregation in the vacuum arc remelted Ti2AlNb ingot: Numerical methods and experimental verification
Journal of Materials Processing Technology ( IF 6.3 ) Pub Date : 2022-07-19 , DOI: 10.1016/j.jmatprotec.2022.117729
Jingjing Han , Neng Ren , Yi Zhou , Ruiyao Zhang , Jun Li , Xu Huang , Jinfu Li

Vacuum arc remelting (VAR) is an ultra-high temperature and opaque process. It is difficult to conduct experimental research on the melt flow behavior and the formation of macrosegregation in this process. This work develops a two-dimensional Eulerian three-phase model to predict the solidification structure and macrosegregation of industrial Ti2AlNb ingots under complex multi-physics mechanism. The model is also used to study the influence of stirring magnetic field on the melt flow behaviors and macrosegregation of VAR ingots. The results show that Al content of the columnar zone increases gradually from the outside to the inside due to the flow behavior of the melt and the sedimentation of equiaxed grains. External magnetic field applied to stabilize the arc also makes significant effects on the melt convection and macrosegregation. Stirring Lorentz force induced by the external magnetic field drives the melt flow to rotate as a centrifugal force in the top, while drives the melt to flow downward along the metal pool and reduces the influence of the self-induced Lorentz force in the bottom. Superimposing the proper stirring magnetic field on the self-induced magnetic field can strengthen the solute mixing in the molten pool and improve the overall macrosegregation degree of the ingot. Increasing the stirring magnetic field can improve negative segregation in the center of the ingot but intensify the positive segregation in the periphery of the ingot.



中文翻译:

真空电弧重熔 Ti2AlNb 锭中的熔体对流和宏观偏析:数值方法和实验验证

真空电弧重熔 (VAR) 是一种超高温且不透明的工艺。很难对这一过程中的熔体流动行为和宏观偏析的形成进行实验研究。本工作开发了一个二维欧拉三相模型来预测工业 Ti 2的凝固组织和宏观偏析复杂多物理机制下的AlNb锭。该模型还用于研究搅拌磁场对 VAR 铸锭熔体流动行为和宏观偏析的影响。结果表明,由于熔体的流动行为和等轴晶粒的沉降,柱状区的Al含量由外向内逐渐增加。用于稳定电弧的外部磁场也对熔体对流和宏观偏析产生显着影响。外磁场产生的搅拌洛伦兹力在顶部以离心力的形式带动熔体流动旋转,同时带动熔体沿金属熔池向下流动,减少了底部自感洛伦兹力的影响。在自感磁场上叠加适当的搅拌磁场,可以加强熔池中的溶质混合,提高铸锭的整体宏观偏析程度。增加搅拌磁场可以改善铸锭中心的负偏析,但加强铸锭外围的正偏析。

更新日期:2022-07-19
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