耦合搅拌制备7075铝合金大铸锭均匀性

Uniformity of 7075 aluminum alloy ingot with big size produced by coupled stirring technology

结合电磁搅拌和机械搅拌,提出一种新型耦合搅拌技术,并利用该技术制备直径为300 mm的7075铝合金铸锭,研究该技术对半连续铸造参数、熔体温度波动、铸造液穴、铸锭组织和成分以及合金流变应力的影响。结果表明:相比普通半连续铸造,利用耦合搅拌技术后,半连续铸造工艺参数范围扩大,铸造效率得到提高,铸造过程中熔体温度波动由40~50℃减小到1℃,液穴深度由128 mm减小到88 mm,铸锭平均晶粒大小减小13%,且偏差由30%减小到9%,成分偏析也明显减小。此外,合金流变应力减小,且铸锭不同部位的流变应力大小差异也明显减小。耦合搅拌技术显著地改善熔体和铸锭的均匀性。

Combined with the electromagnetic stirring and mechanical stirring, a coupled stirring technology was proposed and used to produce 7075 aluminum alloy ingot with diameter of 300 mm. The effect of the technology on the semi-continuous casting parameters, melt temperature fluctuation, sump, microstructures, compositions of the ingot, flow stresses was studied. The results show that, by the coupled stirring technique, the range of casting parameters expands, the casting efficiency raises, the melt temperature fluctuation decreases from 40-50 ℃ to 1 ℃, the sump depth decreases from 128 mm to 88 mm, the average grain size of ingots decreases by 13%. The deviation of grain size along radius direction decreases from 30% to 9%, and the composition segregation also decreases obviously. The stresses decrease and the differential stress of different parts in ingots decreases remarkably. The coupled stirring technology obviously improves the uniformity of melts and ingots.