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为了获得7A04铝合金在矩形波磁场下晶粒尺寸及凝固冷却曲线的变化规律,结合有限元数值模拟方法分析熔体内部磁感应强度、电磁力及磁能分布情况,研究了矩形波磁场特性对晶粒细化效果的影响。结果表明,在矩形波磁场作用下,7A04铝合金凝固组织得到不同程度的均匀细化。最佳矩形波磁场参数:频率为20Hz,峰值电流为100A,电流占空比为20%处理后,铸锭中心处、1/2半径处、边缘处晶粒平均尺寸分别为122.9、120.4、114.7μm,较未处理铸锭平均晶粒尺寸分别降低了24.3%、15.3%、22.6%。此时熔体内单周期产生电磁力密度最大值为7.01×104 N/m3,磁能密度为3 862.62J/m3,形成了良好的凝固条件。
In order to obtain the regularity of the grain size and solidification cooling curve of 7A04 aluminum alloy under the rectangular wave magnetic field, the magnetic induction intensity, electromagnetic force and magnetic energy distribution in the melt were analyzed by the finite element numerical simulation method. The effect of refinement. The results show that under the action of rectangular magnetic field, the solidified microstructure of 7A04 aluminum alloy is uniformly refined to different degrees. The best rectangular wave magnetic field parameters: the frequency is 20Hz, the peak current is 100A, the current duty cycle is 20%, the center of the ingot, 1/2 radius, the average grain size at the edge are 122.9,120.4,114.7 μm, which is 24.3%, 15.3% and 22.6% lower than the average grain size of untreated ingot respectively. At this time, the maximum single-period electromagnetic force density generated in the melt was 7.01 × 104 N / m3 and the magnetic energy density was 3 862.62 J / m3, forming a good solidification condition.