Process and apparatus for reducing macrosegregation adjacent to a

Abstract

A process and an apparatus are disclosed for reducing macrosegregation adjacent to a longitudinal centerline of a solidified cast body. Such cast bodies are preferably large size aluminum alloy ingots made in a continuous casting mold. The ingot is formed from a pool of molten metal having flow currents present therein. The flow currents tend to detach the tips of dendrites growing around the edge of the liquid pool and transport them to the center of the ingot. These detached dendrites, which are lean in eutectic elements, cause negative macrosegregation of the cast ingot. The process includes the step of weakening the magnitude of the flow currents within the liquid pool by placing a mechanical damper therein. The mechanical damper reduces shear acting on the dendrites and minimizes detachment and transport of dendrite particles to the center of the solidified body. The magnitude of the flow currents can also be reduced by increasing the metal head of the liquid pool or by reducing the kinetic energy of newly added molten metal. The apparatus claims a mechanical damper consisting of two or more parallel plates or concentric rings which extensively increases the surface area within the liquid pool. The plates or rings are spaced apart so as to provide flow passages for the molten metal which encourages laminar flow and tends to reduce turbulence within the pool.