采用CA-FE法模拟双辊连铸纯铝凝固微观组织

Microstructure Simulation of Twin-Roll Continuous Casting Pure Aluminum by Using Cellular Automaton-Finite Element Method

使用有限元软件Procast中的元胞自动机-有限元模型,建立了一个模拟双辊连续铸轧纯铝凝固微观组织形成的随机性模型。综合考虑了溶质再分配、界面曲率、晶粒择优生长的作用,基于有限元建立了宏观温度场计算和一个改进的元胞自动机模型。采用基于高斯分布的连续性形核模型,辊面和熔体内部的形核分别采用两种形核分布函数;枝晶尖端生长速度采用与局部过冷度有关的修正KGT模型。利用软件计算结果模拟了不同浇注温度和熔液内部平均形核过冷度对凝固微观组织形成的影响。

A stochastic model for simulating the microstructure formation of twin-roll continuous casting pure aluminum during solidification process has been established based on a 3-D cellular automaton（CA）-finite element（FE）model in Procast package.Based on the finite element method（FEM）,macroscopic model of heat transfer calculation and a modified Cellular Automaton were established,in which the effects of solute redistribution,interface curvature,and preferred orientation were considered.Different Gaussian distribution of nucleation sites was adopted on the roll surface and in the melt,meanwhile,the modified KGT model related to partial undercooling was used to describe the growth kinetics of dendrite tip.The influence of processing parameters such as pouring temperature and average nucleation undercooling rate in the melt on the solidification microstructure of strip is evaluated.The simulation results show that the nucleation,growth,columnar-to-equiaxed transition（CET）,and microstructure evolution of free dendritic crystal can be predicted reasonably.