Surface quality of columnar aluminum ingots cast in metal mold

Abstract

Al, Al-1% and -4.5%Cu and Al-11.6%Si alloys were bottom poured in a cylindrical steel mold (70mm dia. and 200mm height). The cast surfaces have such patterns as spiral grooved patterns on pure Al and Al-Si ingots, spiral white bands, dappled patterns on Al-Cu ingots, small semispherical protuberances in dia.200 to 400μm especially on Al-1%Cu ingots, and indistinct white stripes on pure Al. Cu segregates on the surfaces of Al-Cu ingots. These surface appearances are susceptible to the rate of melt-surface rise, pouring temperature and grain refining. The experimental facts are explained on the bases of solidified structures, remelting, coarsening and resistance of meniscus to deformation.