大方坯皮下负偏析带形成过程的数值模拟

针对某钢厂大方坯连铸过程中铸坯内部质量问题,通过耦合电磁-流动-热-溶质传输,建立多尺度、多物理场的三维数学模型,研究了高碳钢大方坯皮下负偏析带的形成过程。结果表明,铸坯皮下负偏析带是铸坯凝固前沿钢液流速和凝固速率共同作用的结果。对于四孔水口大方坯,铸坯皮下会经历两次负偏析,第一次负偏析是由水口射流造成的,第二次负偏析是由结晶器电磁搅拌造成的。磁搅参数的改变只会影响电磁搅拌影响区的负偏析程度,而不会影响负偏析带在铸坯中的位置及宽度,也不能改善铸坯中心的正偏析度。

Numerical simulation of formation process of subcutaneous negative segregation zone in billet

In response to the internal quality problems of the bloom in a steel plant, coupled with electromagnetic-flow-heat-solute transport, three-dimensional mathematical model was established to study the formation process of negative segregation band under the surface of bloom. The results show that formation of negative segregation band is the result of combined action of the solidification front flow rate and solidification rate. For the four-hole nozzle, there will be undergo twice negative segregation under bloom surface, and the first negative segregation was caused by nozzle jet, the second is caused by the M-EMS. The change of magnetic stirring parameters will just affect the degree of negative segregation but neither can affect the position and width of the negative segregation band, nor can it improve the positive segregation degree of the bloom center.