【摘要】 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。更多还原

【Abstract】 Under the low frequency electromagnetic field, a super-high strength 7A60 Al alloy was semi-continuously cast into billets with diameter of 0.2 m. The surface properties, inner cracks of billets and the effect of electromagnetic frequency and intensity on as-cast microstructures were investigated. The microstructures of 7A60 Al alloy cast under low frequency electromagnetic field are fine, uniform and equiaxed, the difference of the microstructures between the border and center of the billet is small, their average sizes are 30 and 45 μm, respectively. The decrease of electromagnetic frequency and increase of intensity are helpful for obtaining fine, uniform and equiaxed as-cast microstructures. The optimum electromagnetic parameters are that the frequency is 25 Hz and the number of ampere turns is 18 000 A·turn.更多还原