Effect of Casting Velocity on Microstructures of Almg0.9Si0.7 Alloy by Low-Superheat DC Casting

Abstract

The billets of AlMg0.9Si0.7 alloy, which were cast through the direct chill (DC) casting process of low superheat, were analyzed to study the effect of casting velocity on the surface quality and the morphology of primary α grains. The results show that the nucleating quantity of primary α grains in the melt is increased obviously due to the low pouring temperature during DC casting of low superheat. The suitable temperature gradient in front of the solid-liquid interface is obtained by changing the casting velocity, and the dendritic growth of the primary α grains is inhibited effectively. The billet of AlMg0.9Si0.7 alloy with smooth surface and homogeneous, fine rosette-shaped grains is obtained at the velocity of 130mm/min.