Abstract

Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average method to study the effect of in-mold electromagnetic stirring (M-EMS) on the negative segregation under the bloom surface. In the model, the influence of dendrite structure on the flow and solute transport was described by the change of permeability. The model was validated by the magnetic induction intensity of M-EMS and carbon segregation experiment. The results show that the solute C in the solidified shell in the turbulent zone of the bloom undergoes two negative segregations, whereby the first is caused by nozzle jet, and the second by the M-EMS. The severities of the negative segregation caused by M-EMS at different currents and frequencies are also different, and the larger the current is, or the smaller the frequency is, the more serious will be the negative segregation. With the M-EMS, the solute C distribution in the liquid phase of the bloom is more uniform, but the mass fraction of C in the liquid phase is higher than that without M-EMS.

中文翻译：

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模内电磁搅拌对大坯表面负偏析影响的模型预测

摘要

针对大方面下负偏析的问题，基于体积平均法建立了考虑电磁场，流动，热量和溶质运移的耦合宏观偏析模型，研究了模内电磁搅拌（M-EMS）的效果。在开花表面下的负偏析上。在模型中，通过渗透率的变化描述了枝晶结构对流动和溶质运移的影响。通过M-EMS的磁感应强度和碳偏析实验验证了该模型。结果表明，大方坯湍流区凝固壳中的固溶C经历了两个负偏析，其中第一个是由喷嘴射流引起的，第二个是由M-EMS引起的。在不同的电流和频率下，由M-EMS引起的负偏析的严重程度也不同，并且电流越大或频率越小，负偏析将变得越严重。使用M-EMS时，水华液相中的溶质C分布更均匀，但液相中C的质量分数高于没有M-EMS时的。