【摘要】 中心疏松是连铸圆坯生产过程中的主要缺陷之一。为有效改善这一缺陷，对连铸圆坯开发了凝固末端压下工艺。基于某钢厂的实际生产条件，研究团队首先建立了三维传热模型，系统模拟了连铸圆坯的凝固过程，并依据传热计算结果确定了不同压下位置。随后，采用热力耦合模型对直径350 mm连铸圆坯在不同位置处的压下过程进行了数值模拟分析。采用缩孔体积相对变化量作为评价指标，定量评估了压下位置对缩孔愈合效果的影响。为验证模拟结果开展了连铸圆坯压下工艺实验。研究结果表明：在连铸圆坯压下过程中，中心缩孔通过金属填充和塑性变形的协同作用实现有效愈合。压下位置与铸坯中心固相率呈严格对应关系，不同压下位置会导致金属流动行为的显著差异。在15 mm恒定压下量条件下，研究发现随着铸坯中心固相率(f_s)的增加，压下过程中中心金属的流动范围逐渐减小，而金属的相对流动距离则呈现先升高、后稳定、最终降低的变化规律。相应地，铸坯中心缩孔尺寸持续减小直至完全闭合。研究确定了最优压下工艺窗口为中心固相率f_s=0.6～1.0的区间。现场实验数据证实，采用该压下工艺后，连铸圆坯的内部疏松缺陷得到显著改善。更多还原

【Abstract】 Center porosity is one of the main defects of continuous casting round billet. In order to reduce the center defect of the continuous casting round billet, the mechanical reduction is performed at the solidification end of the continuous casting round billet. According to the actual production situation of a factory, a three-dimensional finite heat transfer model of the continuous casting round billet was first established to simulate solidification, and according to the results of the heat transfer model, different reduction positions were determined. Then, the mechanical reduction processes of the continuous casting round billet with a diameter of 350 mm were simulated using a thermodynamic coupling model. At the same time, the relative change of the shrinkage cavity volume was used as the standard to evaluate the influence of the reduction position on the shrinkage cavity healing. Finally, the experiment of continuous casting round billet pressing was carried out. The results show that during the reduction process of continuous casting of round billet, the central shrinkage cavity became closed under the combined effects of metal filling and compression deformation. The reduction position corresponds to the solid fraction in the center of the continuous casting billet, and the metal flow condition is different at various reduction positions. Under the same reduction amount, when the central solid fraction of the continuous casting round billet increases, the flow range of the central metal of the continuous casting round billet will gradually decrease, and the relative flow distance of the metal will first increase, then remain unchanged, and finally decrease, and the central shrinkage cavity of the casting round billet will gradually decrease and finally become close. When the reduction is 15 mm, the optimal reduction interval of the continuous casting round billet is f_s=0.6-1.0. The experimental results show that the inner porosity of continuous casting round billet decreases after reduction.更多还原