Effect of the Molten Surface Vibration on the Cast Structure of Ingots and Controlling the Structure

Abstract

The authors have already proposed that most of the crystallites which form an equiaxed zone originate at the initial stage in the upper part of the growing interface, then fall along the interface to the bottom. The present work using vibrations and agitation on the molten metal in the mold, clearly confirmed the above mechanism. The molten surface vibration at the initial stage of solidification is very important for controlling the ingot structure. Several pouring methods were applied to aluminum-0.2% copper alloy ingot casting: top pouring, bottom pouring, pouring with pencil ring gates, and pouring into a tilting mold. The resulting macrostructures showed that the pouring process which produces violent wave action at the point where molten surface touches the side of the solid shell is most effective for the formation of a fine equiaxed structure. In addition, the pouring temperature should be as low as possible.