Direct chill casting with reversing rotational electromagnetic field

Abstract

In order to achieve higher qualities of aluminum metal products, fine grain structures of materials are required. It is well known that agitation of a liquid metal during solidification process is effective to promote grain size refinement. In this research, the reversing RMF, i.e., the RMF that reverses rotation direction of an electromagnetic field at regular intervals, was applied to a molten metal pool in a cylindrical container of a round billet of DC casting. Electromagnetic fields generated by the reversing RMF stirrer were measured and compared with simulation results of electromagnetic analysis. The molten metal in the pool caused a clockwise and a counter-clockwise flow by applying the reversing RMF, and the flow field was simulated by a CFD calculation. It was found that the liquid metal was effectively stirred with the reversing RMF, resulting a higher turbulent intensity of the liquid metal. Grain sizes of a billet were measured and a relation between the flows and the sizes were investigated.