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基于CA-FE方法对工业H13钢进行凝固过程数值模拟,建立了宏观温度场、浓度场和微观生长过程耦合的凝固组织模拟模型。以元胞自动机模型为基础,耦合有限元模型,在晶粒尺度上模拟了其凝固过程。应用建立的微观组织模型,研究了过冷度、形核数对凝固组织的影响。结果表明,过冷度处于0.1~5℃,晶区主要是中间等轴晶区为主,柱状晶区占有比极小,且生长趋势受到等轴晶的抑制;当过冷度处于5~7℃,柱状晶生长速度增大,占有比增加,但是中间等轴晶内部组织粗化,形状因子增大,晶粒尺寸和晶粒度偏差表现为先增大,后减小;然而,过冷度达到7~15℃,柱状晶生长受到内部等轴晶的抑制,柱状晶占有优势,且随过冷度增加,晶粒尺寸得到细化;且形核数增加,柱状晶区减小,等轴晶区增大,同时晶粒先增大后减小。
Based on the CA-FE method, the solidification process of industrial H13 steel was numerically simulated, and the simulation model of the solidified structure coupled with macro-temperature field, concentration field and microscopic growth process was established. Based on the cellular automaton model, coupled with the finite element model, the solidification process is simulated on the grain scale. The microstructure model was established to study the influence of undercooling and nucleation on the solidified structure. The results show that the supercooling degree is in the range of 0.1 ~ 5 ℃, and the grain boundary is dominated by the equiaxed zone. The occupancy ratio of the columnar zone is extremely small and the growth trend is restrained by equiaxed grains. When the undercooling is in the range of 5 ~ 7 ℃, the growth rate of columnar grains increases and the occupation ratio increases. However, the coarsening of the internal equiaxed grains and the increase of the shape factor increase the grain size and grain size deviation first and then decrease; however, Degree of 7 ~ 15 ℃, columnar crystal growth is inhibited by the internal equiaxed grains, columnar crystals dominate, and with the degree of undercooling, the grain size is refined; and nucleation increases, columnar grain area decreases, etc. Axial grain area increases, while the grain increases first and then decreases.