电磁搅拌下半固态A356铝合金凝固时电磁场−流场数值模拟与实验研究

Numerical simulation and experimental research on electromagnetic field-flow field during solidification of semi-solid A356 aluminum alloy under electromagnetic stirring

采用数值模拟,建立磁场二维有限元模型和流场三维有限元模型,研究电磁搅拌参数对磁感应强度、电磁力、半固态铝合金熔体最大流速的影响,以及对初生相的影响。结果表明:由于集肤效应,熔体中电磁力由内向外逐渐增强,磁感应强度随电磁频率的增大呈现出“中心小,边缘大”的特征,且在结晶器径向的0.80R^0.85R处达到最大值;在电磁搅拌频率为25 Hz、电流为4 A、搅拌时间为12 s时,熔体流速较其他参数最大;半固态A356铝合金在650℃浇铸后恒温电磁搅拌,在电磁搅拌参数为30 Hz、4 A时搅拌12 s后,590℃保温10 min得到的初生相形貌最佳,此时平均等积圆直径为80.6μm,形状因子为0.78。

A two-dimensional finite element model of magnetic field and a three-dimensional finite element model of flow field were established by using numerical simulation to study the effects of electromagnetic stirring parameters on magnetic induction strength,electromagnetic force,and the maximum flow rate of semi-solid aluminum alloy melt,as well as on the primary phase.The results show that the electromagnetic force in the melt gradually increased from inside to outside due to the skin accumulation effect,and the magnetic induction intensity show the characteristics of“small center and large edge”with the increase of electromagnetic frequency,and reach the maximum value at 0.80R−0.85R of the radial direction of the crystallizer.When the electromagnetic stirring frequency is 25 Hz,the current is 4 A,and the stirred time is 12 s,the melt flow rate is the largest compared with other parameters.The morphologies of primary phases of semi-solid A356 aluminum alloy cast at 650℃are the best after electromagnetic stirring at 590℃for 10 min at stirring parameters of 590℃,30 Hz,4 A and 12 s.Finally,the microstructure of semi-solid A356 alloy with the average grain equal-area circle diameter of 80.6μm and the shape factor of 0.78 is obtained.