Effect of low-frequency magnetic field on microstructures and macrosegregation of horizontal direct chill casting 7075 aluminum alloy

The horizontal direct chill (HDC) casting process is a well-established production route for an aluminum alloy ingot; however, the ingot may suffer from inhomogeneous microstructures and serious macrosegregation due to the unbalanced cooling condition and gravitational effect. In order to control the defect, a low frequency electromagnetic field has been applied in the HDC casting process and its influences on cast surface, microstructures and macrosegregation have been studied. The results show that the low frequency electromagnetic field can effectively improve surface quality, reduce inhomogeneous microstructures and macrosegregation in HDC product; and two main parameters of the electromagnetic field—density and frequency, significantly influence the microstructures and solution distribution along the diameter of the ingot. In the range of ampere-turns and frequency employed in the experiments, the optimum ampere-turns and frequency are found to be 10,000 At, 30 Hz.