电磁搅拌参数对椭圆坩埚中半固态铝合金熔体流动与凝固组织的影响

Effect of electromagnetic stirring parameters on melt flow and microstructure of semi-solid aluminum alloy melts in oval crucible

运用ANSYS有限元分析软件对半固态A356铝合金凝固过程中的流场进行模拟,研究电磁搅拌参数(电磁频率和电流强度)对合金熔体流动与凝固组织的影响。结果表明:随着电磁频率和电流强度的增大,半固态铝合金在椭圆坩埚长轴X和短轴Y上的最大电磁力和最大流速均呈现出先增大后减小的趋势,并且长轴X上的最大电磁力和最大流速均大于短轴Y上的;施加电磁搅拌后,电磁力从坩埚的中心处沿半径方向逐步增大,到0.8~0.9倍的坩埚半径处电磁力达到最大,超过该距离后,电磁力又开始急剧降低。椭圆坩埚中电磁力受电流强度的影响更大,而流速受电流强度和电磁频率的敏感度不如电磁力,但电流强度对流速的影响依旧略强于电磁频率;当电磁频率和电流强度分别为30 Hz和5 A时,半固态A356合金初生相的平均等积圆直径为106.1μm,平均形状因子为0.72,此时制备出的半固态合金组织最好。

ANSYS finite element analysis software was used to simulate the flow field in the solidification process of semi-solid aluminum alloy A356,and the effects of electromagnetic stirring parameters,such as electromagnetic frequency and current intensity,on the flow field were studied.The results show that,with the increase of electromagnetic frequency and current intensity,the maximum electromagnetic force and maximum flow velocity of semi-solid aluminum alloy on the long axis X and the short axis Y of oval crucible show a tendency to increase first and then decrease,and the maximum on the long axis X.After the electromagnetic stirring is applied,the electromagnetic force gradually increases from the center of the crucible in the radial direction,it reaches the maximum at the radius of 0.8-0.9 time and starts to decrease sharply beyond the distance.The electromagnetic force is more affected by the current intensity and the flow rate is less sensitive to the current intensity and electromagnetic frequency than the electromagnetic force,but the influence of the current intensity on the flow rate is still slightly stronger than the electromagnetic frequency in oval crucible.When the electromagnetic frequency and current intensity are 30 Hz and 5 A,the average equal-area circular diameter of the primary phase in semi-solid A356 alloy reaches 106.1 μm,and the average shape factor increases to 0.72,the best microstructure of the semi-solid alloy can be obtained in this condition.