The effect of grain refiner and combined electro-magnetic field on grain evolution of horizontal direct chill casting 7075 aluminum alloy

Abstract

Abstract The effect of increasing the amount of added grain refiner (Al-5Ti-B) and combined electromagnetic field on grain size and morphology has been investigated in horizontal direct chill casting of 7075 aluminum alloy. The results show the grain size and the grain morphology are both changed with increasing the amount of Al-5Ti-B added. The grain size continuously decreased with increasing the addition of grain refiner. The slope of the grain size versus grain refiner content curve changes at the point of 0.1 wt.% Al-5Ti-B, and the slope coefficient before the point is larger than that of after the point. The results related to the conglobulation of the nuclei. Without grain refiner additions, an obvious transition in grain size and morphology is observed with the application of combined electromagnetic field. The grain refining efficiency of combined electromagnetic field decreases with increasing the amount of grain refiner. However, even when the addition of grain refiner is 2 wt.% Al-5Ti-B, 24 % grain size reduction is still observed due to the effect of the combined electromagnetic field. This result shows that the combined electromagnetic field can enhance the grain refining efficiency of grain refiner.