Flow patterns and re-melting during filling of a large composite casting

Abstract

The filling and remelting of an industrial scale composite casting has been simulated to investigate the effect of fluid flow patterns in the liquid metal on the remelting of the shell material of the composite casting. In the composite casting under investigation, an outer shell material is first cast inside a large cylindrical mould, which is then assembled to additional mould parts, and the core material is poured into the shell/mould assembly. During casting of the core, a thin layer of the shell material re-melts and mixes with the core material producing a bonding layer of intermediate composition. Obtaining the optimum re-melting and thus intermediate bonding zone between the shell and core is critical to producing high quality rolls. The present numerical model employs the volume of fluid method and an enthalpy-porosity technique to couple the filling of the core material and re-melting of the shell material. The interface between the solid and liquid phases is tracked and can be used as a guide to examine the extent of remelting and, to some degree, mixing of the shell and core material. Simulations have shown that the circulation loops that form in the liquid metal pool significantly affect the amount of shell material that remelts.

Keywords:

• COMPOSITE CASTING
• REMELTING
• CASTING FLOW PATTERNS