连铸方坯拉坯方向凝固行为与偏析控制研究进展  

Research progress on solidification behavior and segregation control of continuous casting billet along casting direction

作　　者：侯自兵[1] 郭东伟 彭治强 文光华[1] HOU Zibing;GUO Dongwei;PENG Zhiqiang;WEN Guanghua(College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学材料科学与工程学院,重庆400044

出　　处：《钢铁》2024年第4期9-24,共16页Iron and Steel

基　　金：国家自然科学基金资助项目(51504047,U1860101,52274318)。

摘　　要：连铸方坯是棒线类钢铁产品的主要母材,其宏观/半宏观偏析等缺陷,一定程度反映了铸坯成分分布和组织性能的不均匀,是影响高端钢材质量提升的重要因素。从二维横断面入手对铸坯内部低倍组织进行表征、分析与优化是目前铸坯内部偏析缺陷调控的主要手段;然而,铸坯内部凝固枝晶和中心偏析均具有三维空间形貌和分布特征,导致仅通过二维横断面进行研究可能会存在一定误差;同时,连铸拉坯方向(垂直于横断面)上凝固枝晶与偏析的波动特征能够更直观地反映连铸坯内部组织性能和质量沿长度方向的波动,这也是影响高品质钢连铸坯及后续产品质量稳定性的关键之一。从凝固行为特点、组织波动变化规律、中心偏析控制等3个方面总结讨论近年来连铸方坯拉坯方向的凝固行为与偏析控制研究进展。CET转变是铸坯凝固组织调控的重点,其判定依据及其与偏析相关性的研究表明,拉坯方向上CET位置存在波动性且与中心偏析形貌特征相关。液相穴内非对称流场及温度变化会造成拉坯方向凝固枝晶的波动特征以及凝固终点的周期性波动;同时,实际铸坯以及相关定性定量模型也表明了拉坯方向偏析元素的分布具有波动特征,并可以利用时间序列技术等方法展开解析。中心偏析控制技术的发展明显提升了连铸坯内部质量的均匀性;同时,也可以基于偏析表征方法及遗传行为模型从拉坯方向减少偏析的发生。将来在连铸拉坯方向,可能会对三维凝固机理、各类连铸坯波动特征、表面质量、组织表征、高拉速、智能分析预测与精细化控制等方面开展越来越多的分析。Continuous casting billet is the main base material of rod and wire steel products.The defects such as macro/semi-macro segregation reflect the uneven microstructure and composition distribution of the billet to a certain extent,which is an important factor affecting the quality improvement of high-end steel.At present,it is the main means to control the segregation defects in the billet by characterizing,analyzing and optimizing the macrostructure in the billet from the two-dimensional cross section.However,both the solidified dendrites and the center segregation inside the billet have three-dimensional spatial morphology and distribution characteristics,so there may be some errors in the study only by two-dimensional cross section.At the same time,the fluctuation characteristics of solidified dendrites and segregation in the direction of continuous casting billet(perpendicular to cross section)can more directly reflect the fluctuation of internal microstructure and quality along the length direction of continuous casting billet,which is also one of the keys to affect the quality stability of continuous casting billet of high-quality steel and subsequent products.The research progress on the casting direction of continuous casting billets in recent years is summarized from three aspects:solidification behavior,structure fluctuation and center segregation control.CET transition is the key point of solidification structure control of casting billet,and its determination basis and its correlation with segregation show that the CET position along casting direction fluctuates and is related to the morphology of center segregation.The fluctuating characteristics of solidification dendrites and the periodic fluctuation of solidification end point are caused by the asymmetric flow field and temperature change in the liquid phase.Meanwhile,the actual casting billet and related qualitative and quantitative models also show that the distribution of segregation elements along casting direction is characteristic of fluctuati

关 键 词：连铸方坯 凝固组织 偏析 拉坯方向 遗传行为 

分 类 号：TF777[冶金工程—钢铁冶金]