双辊连铸纯铝元胞自动机-有限单元法微观组织模拟

Simulation of Microstructure Evolution in Twin-Roller Continuous Casting Pure Aluminum by Cellular Automaton-Finite Element Method

采用元胞自动机-有限单元法模型对双辊连续铸轧纯铝凝固组织进行了模拟。形核模型采用基于高斯分布的连续性形核模型,辊面和熔体内部形核采用两种形核分布函数;枝晶尖端生长速度和局部过冷度的关系采用修正的KGT模型。并研究了工艺参数和凝固参数对凝固晶粒组织的影响。结果表明,所建立的数学模型能够合理描述晶粒沿任意角度生长的过程,对温度场、溶质场和微观组织形貌的模拟计算结果合理。随着辊面传热系数的增大,薄带柱状晶宽度增加;随着体积形核密度的增大,薄带柱状晶宽度减小且晶粒组织变得细小均匀。

The solidification structure of twin-roller continuous casting pure aluminum was predicted by a 3D cellular automaton （CA）-finite element （FE） model. In the present CA-FE model, Gaussian distribution of nucleation sites was adopted both at the roll surface and in the melt. Then the modified Kurz- Giovanola-Triedi（KGT） model was used to describe the growth kinetics of dendrite tip. Simulated resuits show that the grain growth in random preferential growth directions can be described by the model reasonably, and the simulated results are coincident with actual phenomena in temperature field, solute field and microstructure evolution. By use of the model, the effects of process and solidification parameters on the solidification structure of grain zone were understood. The results show that the width of co- lumnar grain zone is increased with increasing in roll surface heat transfer coefficient, while it is decreased with the increase of inner max nucleation density, and fine and uniformly distributed grain in the solidification structure can be observed.