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采用低频电磁铸造技术 ,半连续铸造制备了直径为 0 .2m的 7A6 0超高强铝合金锭坯。研究了铸锭表面质量和内裂纹发生情况 ,考察了电磁场频率和强度对铸态组织的影响。结果表明 :低频电磁场可消除锭坯裂纹 ,改善其表面质量。在低频电磁场作用下 ,半连续铸造组织得到显著细化 ,铸锭边部和中间部位的晶粒大小差别减小 ,其平均晶粒尺寸分别为 30 μm和 4 5 μm。适当降低电磁场频率和增加强度有利于获得细小均匀的等轴晶组织 ,铸造组织最佳的电磁场频率为 2 5Hz,安匝数为 180 0 0A·turn。
7A6 0 ultra-high strength aluminum alloy billet with diameter of 0.2m was prepared by semi-continuous casting using low-frequency electromagnetic casting technology. The ingot surface quality and the occurrence of internal cracks were studied. The effects of the electromagnetic field frequency and strength on the as-cast microstructure were investigated. The results show that the low frequency electromagnetic field can eliminate the crack of the billet and improve its surface quality. Under the action of low frequency electromagnetic field, the microstructure of the semi-continuous casting was significantly refined, and the difference in grain size between the edge and the middle part of the ingot was reduced. The average grain size was 30 μm and 45 μm, respectively. Appropriate to reduce the frequency and increase the strength of the electromagnetic field is conducive to obtain a fine uniform equiaxed grain structure, the casting of the best electromagnetic field frequency of 25Hz, ampere turns 180 0 0A · turn.