(1. 上海宝信软件股份有限公司，上海 201203；
2. 上海大学 材料科学与工程学院 省部共建高品质特殊钢冶金与制备国家重点实验室，上海 200444)
摘 要: 在镁合金连铸过程中，结晶器内镁液的流场和温度场分布对镁合金凝固组织有着重大的影响。深入了解连铸结晶器内镁液流场及温度场的分布可以在很大程度上改善铸坯的质量。采用有限元方法对AZ61镁合金圆坯结晶器电磁搅拌(Electromagnetic stirring, EMS)过程中流场及温度场进行数值模拟，同时对电磁搅拌条件下镁合金组织进行数值模拟。结果表明：在旋转电磁搅拌条件下镁合金受到旋转的电磁力，镁液在水平方向上围绕结晶器中心做旋转运动。随着磁感应强度从0增大到100 Gs，水平方向平均流速从0增大到6 mm/s，熔体凝固速度加快，结晶器内液相穴深度从20.2 cm减小到10.6 cm，结晶器中心到边部温度梯度减小。在电磁搅拌条件下，镁合金凝固组织中等轴晶比率增大；当磁感应强度增大到40 Gs时，晶粒由枝晶状态完全转化为类球状，晶粒平均尺寸由未搅拌时的366 μm变为110 μm。
关键字: 镁合金；电磁搅拌；流场；温度场；凝固组织
（1. Shanghai Baosight Software Co., Ltd., Shanghai 201203, China;
2. State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China）
Abstract:The flow field and temperature field of molten magnesium alloy in the mold have significant influence on dendritic growth process during continuous casting. It is important to understand the distribution of flow field and temperature field. The flow field, temperature field during the electromagnetic stirring (EMS) of continuous casting of AZ61 magnesium alloy were simulated with finite element method, and the microstructure of round cast billet was simulated. The simulation results indicate that the liquid magnesium alloy flows around the mold in horizontal plane with rotational electromagnetic force. With the magnetic induction intensity increasing from 0 to 100 Gs, the flow velocity increases from 0 to 6 mm/s, and the depth of liquid phase decreases from 20.2 cm to 10.6 cm. The electromagnetic stirring accelerates the solidification rate, and the temperature difference between the melt edge and the melt centre becomes small. The equiaxed crystal ratio of solidification structure is improved significantly under the effect of the electromagnetic stirring. Meanwhile, the grain becomes more fine uniform spheroidal particals with size about 110 μm.
Key words: magnesium alloy; electromagnetic stirring; flow-field; temperature-field; solidification structure
