Studium plnění a tuhnutí ocelového ingotu pomocí numerické simulace v prostředí software QuikCAST

Abstract

This dissertation thesis is focused on the casting and solidification of a steel ingot. The work has two main parts: The first part is based on the general literary knowledge of casting and solidification of steel including the formation of defects that can occur in steel castings. The basic methods of study of metallurgical processes are described with focus on the numerical modelling of these processes, the structures and description of some available numerical programs. Numerical modeling of flow during casting and solidification of steel including prediction of defects are discussed from a theoretical perspective. The thesis includes theoretical and practical knowledge in the field of thermodynamic parameters determination (temperature liquidus and solidus of steel, heat capacity of steel and mold, density of steel, etc.) by using the methods of thermal analysis. The determination of thermodynamic parameters is a necessary step to obtain the corresponding data for correct simulation setup. The second part of dissertation deals with the experimental study of numerical simulation of casting and solidification of 90-ton steel ingot in the numerical program QuikCAST. The principle of simulation in this program including setting individual calculation parameters as creation of geometry, generation of computational mesh, defining of material properties, definition of initial and boundary conditions is described. The effect of changes in parameters of the whole model of casting assembly on the simulation (size and refinement volume mesh settings, heat transfer coefficients, casting speed or calculation of microporosity) is confronted on the results of the simulated cases that are compared in terms of total simulation time, the resulting temperature fields inside the ingot during solidification, the ratio of the solid fraction during solidification, the internal porosity and shrinkage in the volume of steel ingot and finally with the results of experimental studies carried out on the real steel ingot.