Solidification Analysis of Steel Ingots with Consideration on Fluid Flow

Abstract

A numerical technique of solidification analysis is presented, which is based on “Inner Nodal Point Method” and takes account of fluid flow induced by solidification shrinkage and variable fluid density. First, the effects of the coupling of heat and fluid f lows and the permeability in the mushy zone on the solidification have been analyzed for columnar steel ingots. The solidification was affected considerably by the permeability. A step-by-step method with a proper time step, where the equations for the heat and fluid flows are solved alternately, can be available instead of solving the equations simultaneously. Second, as numerical examples, the solidification process in tapered steel ingots has been analyzed. The experimental results about macrosegregations and porosity have been explained in terms of the ingot taper, the negative pressure, the velocity field, the fraction solid contour line and the movement of solid phase. Although the more precise analysis may request to consider the movement of solid phase and to use an accurate permeability, the proposed technique which can handle complicated boundary shape may be more useful for the determination of ingot shape and casting conditions than conventional ones.