SCM435钢大方坯凝固过程组织的模拟

Simulation on solidified microstructure of cast bloom of SCM435 steel

为了模拟不同冷却状态下的连铸坯的凝固组织,利用反算确定了SCM435钢325 mm×280 mm连铸坯的换热系数,采用有限元法模拟了连铸传热过程,获得了连铸坯的温度场及冷却速率,在此基础上与元胞自动机耦合模拟了连铸坯的凝固组织.研究发现,表面细晶区很大,且在连铸结晶器中完成形核并长大形成,而柱状晶开始形核于结晶器末端.降低形核数,晶粒密度、最大晶粒面积、平均半径存在不同程度的改变,其中晶粒的最大截面积增加了2.7倍,而微调成分对晶粒密度与平均半径影响较小,但同样凝固条件下晶粒不均匀程度有所加剧.

To simulate the solidification structure of bloom continuous casting under different cooling condition,the coefficient of heat transfer was obtained by using inverse calculation for SCM435 casting bloom of 325 mm×280 mm,the solidification process were simulated by using finite element method,and then the temperature field and cooling rate of cross-section during solidification process were obtained.The solidification microstructures were simulated by coupling cellular automaton（CA） with temperature field.The results show that the fine-grain area on surface is large,and the fine-grain nucleates and grows up in casting mold,however the columnar crystal nucleation starts at the end of casting mold.By reducing the number of nucleation,grain density and max section area,and by altering mean radius at different level,the max section area of grains has increased 2.7 times,the optimization ingredients have little influence on the grain density and mean radius,but the non-uniformity of grain sizes increase at the same solidification condition.