The variation of grain size and solidification cooling curve of 7 A04 aluminum alloy in the rectangular magnetic field was analyzed.The distribution of magnetic induction intensity

electromagnetic force and magnetic energy in the melt were analyzed by finite element method.Effect of the rectangular wave magnetic field on the grain refinement was expounded.The results reveal that the solidification structure of 7 A04 aluminum alloy can be refined to some extent by the rectangular wave magnetic field.With the optimized processing parameters

such as frequency of 20 Hz

peak current of 100 Aand current duty cycle of 20%

the average grain size in the ingot at the center and 1/2 radius as well as surface reach 122.9μm

120.4μm

114.7μm

respectively

which are decreased by 24.3%

15.3%

22.6%

respectively

compared with those of un-treated ones.In addition

the maximum density of electromagnetic force is 7.01×104 N/m3

and the magnetic energy density reaches 3 862.62 J/m3

forming agood solidification structure refinement conditions.