轻压下对连铸坯中心缺陷作用的量化模型研究

连铸坯内部的中心缩松和中心偏析是影响铸坯内部质量的主要缺陷,在凝固末端位置实施轻压下技术,是降低这类缺陷产生的重要手段.建立轻压下对中心缺陷作用的数学模型,可以定量地评价轻压下的作用,合理地确定轻压下的位置,科学地指导和制定轻压下工艺.在金属凝固过程热力模型和缩孔缩松传统预测判据的基础上,提出了轻压下对连铸坯中心缺陷作用的量化模型,通过与传统的Niyama缩松判据进行对比研究发现,提出的轻压下对连铸坯中心缺陷作用的量化模型可以定量评价糊状区压力状态和流动状态对中心缺陷的直接影响,克服了Niyama判据无法考虑流动和压力作用的不足.

Study on Quantitative Model of Effect of Soft Reduction on Centerline Defect and Its Application

It is well known, that centerline shrinkage and segregation of continuously cast strand are the main defects. The soft reduction applied at the final stage of solidification has obvious effect on interal quality. A new quantitative model based on thermal-stress model and shrinkage criterion function is proposed, which is able to estimate the effects and position of soft reduction more appropriately, implement the technique more scientifically. Compared with the traditional criterion functions, such as Niyama criterion function, the model takes into account pressure and flow pattern in mushy zone, for control of solidification and centerline defects. In order to improve internal quality, the soft reduction should be installed at the end of mushy zone.