(1. 上海寶信軟件股份有限公司，上海 201203；
2. 上海大學 材料科學與工程學院 省部共建高品質(zhì)特殊鋼冶金與制備國家重點實驗室，上海 200444)
摘 要: 在鎂合金連鑄過程中，結(jié)晶器內(nèi)鎂液的流場和溫度場分布對鎂合金凝固組織有著重大的影響。深入了解連鑄結(jié)晶器內(nèi)鎂液流場及溫度場的分布可以在很大程度上改善鑄坯的質(zhì)量。采用有限元方法對AZ61鎂合金圓坯結(jié)晶器電磁攪拌(Electromagnetic stirring, EMS)過程中流場及溫度場進行數(shù)值模擬，同時對電磁攪拌條件下鎂合金組織進行數(shù)值模擬。結(jié)果表明：在旋轉(zhuǎn)電磁攪拌條件下鎂合金受到旋轉(zhuǎn)的電磁力，鎂液在水平方向上圍繞結(jié)晶器中心做旋轉(zhuǎn)運動。隨著磁感應(yīng)強度從0增大到100 Gs，水平方向平均流速從0增大到6 mm/s，熔體凝固速度加快，結(jié)晶器內(nèi)液相穴深度從20.2 cm減小到10.6 cm，結(jié)晶器中心到邊部溫度梯度減小。在電磁攪拌條件下，鎂合金凝固組織中等軸晶比率增大；當磁感應(yīng)強度增大到40 Gs時，晶粒由枝晶狀態(tài)完全轉(zhuǎn)化為類球狀，晶粒平均尺寸由未攪拌時的366 μm變?yōu)?10 μm。
關(guān)鍵字: 鎂合金；電磁攪拌；流場；溫度場；凝固組織
（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
