Effects of low-frequency electromagnetic field on microstructures and macro segregation of continuous casting 7075 aluminum alloy

The influences of low-frequency electromagnetic field on microstructures and macrosegregation in continuous casting process were investigated experimentally. Ingot of 7075 aluminum alloy with a diameter of 200 mm was produced and as-cast structures were examined. In the presence of an electromagnetic field, a substantial reduction of grain size and the macrosegregation of alloying elements was achieved. Further, a pronounced evolution of microstructures and segregation with the frequency of electromagnetic field is presented. The results show that frequency plays a significant role in grain refinement and macrosegregation inhibition. A fine equiaxed as-cast structure is obtained when frequency reaches 15 Hz, while a proper frequency (30 Hz in this study) can inhibit the macrosegregation to the best effect. (C) 2003 Elsevier Science B.V. All rights reserved.