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在利用双辊连铸机生产7075铝合金中,会发现许多微观缺陷,如粗大完整的枝晶和严重偏析等。利用金相和SEM测定了7075板坯组织形貌和相成分,并通过与传统生产方式的对比,研究在铸轧工艺中施加0.13 T大小的电磁场对溶质成分分布的差异。就板材显微组织大量细化和偏析带缩小而言,最有效的方式是386 A,50 Hz工频电流下交变振荡电磁场铸轧工艺。另外,晶界处存在大量t(AlZnMgCu)相,并按照直流磁场、半波振荡磁场和交变振荡磁场顺序逐渐均匀细化。并且在振荡电磁场下网状沉淀相完全消失。
In the use of two-roll continuous casting machine 7075 aluminum alloy, you will find many microscopic defects, such as coarse and complete dendrites and severe segregation. The microstructure and phase composition of 7075 slab were measured by metallography and SEM, and the differences of solute composition distribution by 0.13 T electromagnetic field in casting process were studied by comparison with traditional production methods. The most effective way to reduce the microstructure of the slab microstructure and narrow the segregation zone is the alternating-current oscillating electromagnetic field casting process at 386 A and 50 Hz power frequency current. In addition, a large number of t (AlZnMgCu) phases exist at the grain boundaries, and are gradually and uniformly refined according to the order of DC magnetic field, half-wave oscillating magnetic field and alternating oscillating magnetic field. And in the oscillating electromagnetic field completely disappeared reticular precipitation phase.