Numerical simulations of solidification structures and macrosegregation by a cellular automaton model coupled with flow calculations

Joint 5th International Conference on Advances in Solidification Processes;5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining

土木建筑工程;计算机科学

Natsume, Y.^1

Department of Materials Science, Akita University, 1-1 Tegata-Gakuenmachi, Akita

010-8502, Japan^1

关键词: Cellular automaton models;    Direct simulation;    Flow calculations;    Macrosegregations;    Solidification grain structure;    Solidification structure;    Three-dimensional cellular automatons;    Unidirectional solidification;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/529/1/012038/pdf
DOI  :  10.1088/1757-899X/529/1/012038

来源: IOP

【 摘 要 】

In this study, a numerical model was developed, and direct simulations were performed to predict solidification grain structures and macrosegregation based on a three-dimensional cellular automaton finite difference (CAFD) method coupled with flow calculation of natural convection and shrinkage flow. First, to evaluate the model coupled with natural convention, simulations of unidirectional solidification for Al-10wt% Mg alloy were performed. Mg-rich plumes rising in the melt were seen due to subsequent upward flow, and Mg-rich channels forming in the mushy zone were observed. Columnar grains were then formed, and they became coarse afterwards. Next, to evaluate the model coupled with shrinkage flow, simulations of casting Al-10wt% Cu alloy in a unique mold, which can form macrosegregation in the central region of the small ingot, were performed. The bridging of columnar grains formed during solidification, and the positive segregation was generated in the region below the bridging. Thus, the main factor for this macrosegregation is the shrinkage flow with bridging. From the comparison of simulation results with and without the chill for the unique mold, it was established that the shrinkage flow and the bridging of solidification structures play an important role in macrosegregation.