As-Cast Structure and Temperature Field of Direct-Chill Cast 2024 Alloy Ingot at Different Casting Speeds

Abstract

The ingot was prepared at different casting speeds, and temperature measurements were taken during the direct-chill (DC) casting process. The results showed that the grain size of the equiaxed grains decreases, the volume fraction of the floating grains increases, and the negative centerline segregation becomes more serious as the casting speed increases. Moreover, the vertical widths and the cooling rates of different regions during the solidification process were analyzed through temperature measurements. At the casting speed of 50 mm/min, the vertical widths of the transition, slurry and mushy regions in the ingot center are relatively small (51, 15, and 36 mm, respectively). As the casting speed increases to 65 mm/min, the vertical widths of the transition, slurry, and mushy regions in the ingot center increase to 70, 29, and 41 mm, respectively. The increase in the vertical width of the slurry region is considered to be the main reason for the increase in the volume fraction of the floating grains. Besides, as the casting speed increases, the cooling rate in the mushy region and the region above the liquidus increases, so the grain size of equiaxed grain decreases.