连铸坯凝固晶粒生长的元胞自动机模型

Grain growth of continuous casting slab solidification based on cellular automata model

首次将元胞自动机(Cellular Automata,CA)方法和有限差分法结合起来,建立了连铸坯凝固时内部等轴晶和柱状晶的随机形核和晶粒生长模型。结合某钢厂实际生产情况,对实际工况下连铸坯凝固组织进行模拟,再现了连铸坯内部组织的演变规律,发现晶粒呈现等轴晶-柱状晶-等轴晶的转变,以及不同工艺制度下3个晶层的厚度情况,表面激冷层和中心等轴晶层厚度随拉速增加而减小,随下钢水过热度降低而增大,但柱状晶层厚度却随拉速和钢水过热度的增加而增加。仿真结果对晶粒的随机形核、晶粒的择优生长、竞争生长以及晶粒的随机取向都有比较好的体现。

The cellular automaton（CA） method is coupled with finite difference method to establish a stochastic nucleation and growth model.According to the actual production conditions,the solidification structure of continuous casting slab is simulated and the evolution law of the inner structure is reconstructed.It is showed that grain transformation is from equiaxed crystal to columnar crystal and then to equiaxed crystal.Thickness of three crystal layers are different in various production technological systems,thickness of surface equiaxed crystal and inner equiaxed crystal are reduced,and the results of the columnar crystal thickness are contrary,while casting speed and superheat are increasing.The results show well agreement with the stochastic nucleation,preferred growth,competitive growth and random orientation of grain.