Solidification structure and compactness degree of central equiaxed grain zone in continuous casting billet using cellular automaton-finite element method

Abstract

A Cellular Automaton-Finite Element (CAFE) coupling model was developed to analyze the evolution of solidification structure of high-carbon steel continuous casting billet and the compactness degree of central equiaxed grain zone. Comparison between the simulated and actual solidification structure was first made under three different conditions, i.e., without MEMS (mould electromagnetic stirring), with MEMS and with MEMS plus intensive cooling. It is indicated that the model can provide a good simulation of the actual solidification structure. Thereafter, the model was used to simulate the solidification structure under different superheats and casting speeds. It is shown that the width of equiaxed grain zone increases with the decrease of the superheat, and decreases with the decrease of the casting speed. The compactness degree of central equiaxed grain zone is also evaluated by the grain number in the same area under different conditions in this study. It is demonstrated that the compactness degree of central equiaxed grain zone in the billet is increased obviously when the MEMS is applied, and is further increased with MEMS plus intensive cooling. In addition, it is also increased when decreasing the casting speed. However, the compactness degree of central equiaxed grain zone is decreased when decreasing the superheat. Moreover, it is found that the compactness degree of central equiaxed grain zone in the billet is closely related to the centre solidification time, i.e., it decreases with the increase of the centre solidification time. © 2012 ISIJ.