Fe-3%Si合金薄带连铸板热处理过程层状异构组织演变的相场模拟研究

Study on the Evolution of Layered Heterogeneous Microstructure of Fe-3%Si Alloys Strip Continuous Casting Plate During Heat Treatment by Phase Field Simulation

本研究基于Fe-3%Si合金铸轧板材组织特征,构建了不同类型柱状晶/等轴晶层状异构组织相场模型,实现了界面曲率为驱动力的情况下层状异构组织的高温粗化过程模拟,量化分析了层状异构特征对铸轧组织演化过程的影响规律。研究表明,由于晶粒长径比对晶粒尖端曲率的影响,当初始状态下柱状晶长径比较高时,在界面曲率的驱动下最终会形成等轴化的多晶组织;反之则等轴化程度减小。明确了不同类型异构组织演化特征,相同退火时间下组织的等轴化程度受其层状异构特征的影响,这一现象的本质是等轴晶通过自身演化引起柱状晶两端曲率变化,诱发柱状晶间的相互“吞噬”并发生等轴化,柱状晶则在部分结构的组织中生长至带钢表面后停止生长,最终保持柱状特征。本研究进一步加深了对铸态薄带中初始凝固组织在后续热处理时演化过程的认识,对硅钢制备工艺优化具有重要的理论指导意义和实际应用价值。

Based on the microstructural characteristics of Fe-3%Si alloy strip continuous casting plates, a phase field model was employed to investigate the coarsening process driven by grain boundary curvature in alloy systems with varying combinations of columnar/equiaxed grains at 1 253 K. Aquantitative analysis was conducted to evaluate the impact of layered microstructure on the evolution process of strip continuous casting plates. The results indicate that when the ratio of the length to diameter of the columnar grain is high, equiaxed grains eventually form under the influence of grain boundary curvature, while the degree of equiaxation decreases with a low initial ratio. The study elucidates the evolution characteristics of different microstructures and reveals that the equiaxed level varies with the initial microstructure features. The phenomenon is attributed to the curvature change induced by equiaxed grains at both ends of the columnar ones, which leads to the mutual ‘engulfment’ of columnar grains and equiaxation. In some cases, columnar grains maintain their columnar characteristics by growing to the surface of the strip steel. This study dee- pens our understanding of the evolution process in strip continuous casting plates during heat treatment and provides important theoretical and practical guidance for the optimization of silicon steel preparation processes.