Cast ingot of aluminum alloy available for rolling operation and method for manufacturing the same

摘要

An improved cast ingot of aluminum alloy satisfactorily available for rolling operation containing Fe is disclosed which has no fir-tree structure or has only a very small region of fir-tree structure. This cast ingot of aluminum alloy contains calcium in the range of 0.0005 to 0. 05% and has a grain size smaller than 150 microns in the region extended inward of a coarse cell phase on the surface area of the cast ingot, particularly in the vicinity of said coarse cell phase. The cast ingot is manufactured by way of the steps of addition of the above amount of calcium to molten aluminum alloy, supplementary addition of 0.005 to 0. 1% Ti and 0.0001 to 0.02% B to the molten aluminum alloy and then continuous D.C. casting.