电磁搅拌对大圆坯结晶器冶金行为影响的探讨

 为了探究结晶器电磁搅拌(M EMS)对大圆坯结晶器内综合冶金行为的影响。以大断面圆坯连铸结晶器冶金行为为研究对象，基于电磁热流体与凝固传输理论建立三维耦合数值模型。揭示大圆坯连铸常用五孔水口浇注条件下结晶器内电磁场、流场、传热与凝固等综合冶金行为，提出电磁搅拌对结晶器冶金性能影响的多参量评价方法。以中碳铬钼齿轮钢650 mm大圆坯连铸为例，指出结晶器电磁搅拌存在最佳搅拌电流，可获得相对较好的综合冶金效果。具体表现为弯月面保持一定的切向速度和过热度，有利于保护渣的熔化和夹杂物的上浮去除；液面波动幅度在控制范围内，可避免卷渣、改善表面质量；结晶器内钢液过热得到有效耗散，有利于等轴晶形核改善铸坯内部质量；侧孔出流钢液速度得到有效控制，可抑制注流对初凝坯壳的冲刷，提高了初生坯壳生长的均匀性。此外，电磁搅拌产生的水平旋流强度也可得到有效控制，有利于避免常见的皮下白亮带现象。

Investigation of mold metallurgical behavior under #br# electromagnetic stirring for round bloom

 In order to explore the effect of mold electromagnetic stirring(M EMS) on the overall metallurgical behavior in the round bloom. Based on a round bloom special steel casting process，a coupled three dimensional numerical model was developed to describe the influence of electromagnetic stirring on the overall mold metallurgical behavior. The reliability of the model was verified by experimental results，the electromagnetic field，fluid flow，heat transfer and solidification in mold under the five hole nozzle casting conditions for round bloom casting were revealed. The comprehensive influence of electromagnetic stirring on the metallurgical behavior in mold was proposed based on a multi parameter evaluation. According to the study results，when the current intensity is 280 A for a middle carbon alloy steel casting，the meniscus can maintain a certain tangential velocity and superheat，which is beneficial to melting of mold powder and the floating removal of inclusions. Additionally，the mold fluctuation has been kept under control to avoid slag entrapment，and the superheat of melt steel is well dissipated through a moderate horizontal swirling flow induced by M EMS to enhance the formation of equiaxed crystals. A much weak impingement of the outlet flow on the shell has been observed as well，which can be expected to eliminate the popular subsurface white band phenomenon with an even shell thickness in the mold region.