Improvement of Casting Speed and Billet Quality of Direct Chill Cast Aluminum Wrought Alloy with Combination of Slit Mold and Electromagnetic Coil

Abstract

A mold with slits and external cooling water channels was designed for the direct chill casting processing. By imposing a high frequency magnetic field, the surface quality and microstructure of the direct chill cast billets are improved. The casting speed could be improved by the simultaneous use of mold and electromagnetic coil. In the case of one kind of Al-Cu-Mg alloy with a wide freezing range, the critical casting speed to break-out can be improved 60%. The microstructure of the billet cast with electromagnetic field is more fine and uniform than that of the conventionally cast billet, and the subsurface segregation usually observed in the conventional billets is eliminated.