Numerical Simulation of Solidification Structure of Continuously Cast Billet with Grain Motion
Numerical Simulation of Solidification Structure of Continuously Cast Billet with Grain Motion
复制标题
晶粒运动连铸坯凝固组织的数值模拟
DOI：
10.1007/s11663-020-01953-2
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发表时间：
2020
影响因子：
3
通讯作者：
Zhu Miaoyong
中科院分区：
文献类型：
--
作者：
Wang Zhaohui;Luo Sen;Wang Weiling;Zhu Miaoyong
自由晶粒的运动对大型铸件的凝固组织、溶质分布和缺陷有重要影响。然而，很少有研究模拟大型铸件的凝固组织考虑晶粒运动。本文提出了一种考虑自由晶粒运动的多尺度元胞自动机模型，用于预测连铸坯的凝固组织。该模型与实验测量进行了验证。采用该模型研究了方坯断面尺寸为160 mm × 160 mm的弓形连铸机生产的82 b线材的凝固组织演变。结果表明，自由等轴晶的沉积促进了铸坯内弧柱状晶的长大。而铸坯外弧区的柱状晶一旦在其前形核，就会被阻挡。定量确定了拉速为1.8m/min时82 b铸坯凝固组织的不对称形态，铸坯内弧和外弧柱状晶长度分别为57.0mm和31.0mm。此外，与二冷区内外弧冷却强度的差异相比，82 b铸坯中的非对称形貌主要是由自由晶粒的运动决定的。
The motion of free grains has a significant influence on the solidification structure, solute distribution, and defects of large casts. However, few studies have modeled the solidification structure of large casts considering grain motion. In this paper, taking into account the motion of free grains, a multiscale cellular automaton model is proposed to predict the solidification structure of continuously cast billets. The model is validated with experimental measurements. Then, the proposed model is adopted to investigate the solidification structure evolution of a wire steel 82b cast by a bow-type continuous caster with a billet section size of 160 mm × 160 mm. The results show that the growth of columnar grains in inner arc of billet strand is promoted by the sedimentation of free equiaxed grains. But the columnar grains in outer arc of strand are blocked once free grains nucleate before them. Thus, asymmetric morphology of solidification structure in the 82b billet with casting speed of 1.8 m/min is quantitatively determined and the length of the columnar grains in the inner arc and the outer arc of strand is 57.0 mm and 31.0 mm, respectively. Moreover, compared with the difference of cooling intensity between inner arc and outer arc in secondary cooling zone, the motion of free grains dominates the asymmetric morphology in the 82b billet.