基于元胞自动机有限元法对方坯凝固组织的数值模拟

Numerical Simulation of Solidification Microstructure of Billet Based on Coupled Method of Cellular Automation and Finite Element

基于元胞自动机有限单元法(CAFE)对国内某钢厂220mm×220mm方坯的三维显微凝固组织进行模拟,分析了CAFE法模拟凝固过程显微组织的物理本质,对形核密度、枝晶尖端生长动力学、枝晶生长的择优取向以及FE与CA耦合的实现分别进行了探讨。用该方法对方坯的三维显微组织进行模拟,并对结晶器出口处方坯的角部温度、中心表面温度及坯壳厚度进行了计算。模拟结果表明:当拉速为0.85m/min,浇铸温度为1 535℃,浇钢过热度为30℃时,结晶器出口处方坯角部温度在850～950℃之间,中心表面温度在1 050～1 170℃之间,坯壳厚度在15mm左右,铸坯柱状晶发达,等轴晶比率较小。模拟的铸坯组织的等轴晶比例与低倍试验结果吻合较好,可以很好地预测方坯实际凝固组织。

Based on the coupled method of cellular automation（CA） method and finite element（FE） method,the solidification microstructure of 220 mm×220 mm cast billet was simulated.The nucleation density,kinetics of the dendrite tip growth,crystallographic orientation,coupling of FE and CA method were discussed respectively.The temperature field at the mould exit and the thickness of the billet was calculated.The results show that the corner temperature is between 850 ℃ and 950 ℃,surface temperature is between 1 050 ℃ to 1 170 ℃,the thickness of the solidified shell is 15mm,when the casting speed and casting temperature is 0.85 m/min,1 535 ℃,respectively.The columnar grain is well developed and the ratio of equiaxed grain is low.The 3D microstructure of billet steel can be simulated by the CAFE method due to its agreement with experimental results.