【作者】 李兵；

【导师】 任廷志；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2013， 硕士

【摘要】 溶质元素的宏观偏析是铸坯的主要内部缺陷之一，在低碳钢中尤为明显。偏析影响到坯壳凝固以及缩松和热裂等凝固缺陷的产生，并降低钢材的使用性能。而目前针对结晶器钢液凝固过程的数值模拟中，大都忽略钢液中的溶质输运现象，并将钢液的固、液相线温度设为常值，这将无法获得溶质的分布规律，并且影响结晶器内温度分布和坯壳生长结果的准确性。在薄板坯连铸过程中，结晶器内空间小，拉速高，钢液流动强度大，导致易于发生卷渣现象。而目前关于薄板坯结晶器钢液流动的数值模拟中，大多数将钢液自由表面作壁面或对称面条件处理，忽略保护渣的存在，从而无法获得液面形状，并且影响自由液面附近钢液流动的准确性。本文针对含碳量为0.1%的Fe—C二元合金，以CSP薄板坯结晶器内流体(钢液与保护渣)为研究对象，根据钢厂实际生产数据和连铸工艺要求，利用商业软件Fluent，数值模拟了结晶器内钢液流动、传热凝固和溶质输运过程，并利用VOF模型来获取钢液自由表面形状。研究得出了不同参数(拉速、水口浸入深度、过热度、结晶器宽度)下，CSP结晶器内钢液流动规律、温度分布规律、坯壳凝固规律、溶质碳分布规律以及液面波动规律。在实际连铸生产中，为提高铸坯质量提供可靠参考和指导。更多还原

【Abstract】 The macrosegregation of solute element is one of the strand’s main inner defects,especially in low-carbon steel. The segregation influence the solidification of shell andthe formation of solifification defects such as shrinkage porosity and hot tearing. It alsolower the steel’s usability. But most of numerical simulations about the process of liquidsteel’s solidification in the mold ignore the phenomena of solute transport in liquid steel,and treat steel’s solidus temperature and liquidus temperature as constant. Then there isno way to get the distribution regularities of solute. it also lower the accuracy of resultabout the temperature distribution in the mold and the growth of sheel.During the process of thin slab continuous casting, the small inner space of mold,high casting speed and large flow intensity of liquid steel cause that casting powder iseasy to be entrapped. But most of numerical simulations about the fluid flow in the moldtreat the free surface of liquid steel as wall or symmmery plane and ignore the exist ofcasting powder, then there is no way to get the shape of free surface, and it will lower theaccuracy of the fluid flow around the free surface.Taking the fluid flow inside the CSP thin slab continuous casting mold as researchobject, according to steel mill’s actual production data and continuous casting’stechnological requirements, using business sofeware Fluent, it researchs the process offluid flow, heat transfer and solute transport inside the mold, and gets the shape of freesurface using the VOF model. Through the research, it gets the law of liquid steel’sturbulent flow, temperature distribution, shell’s solidification, solute transport and freesurface’s fluctuation during different parameters(casting speed, depth of nozzle, degree ofsuperheat, width of mold). During actual continuous casting production, it can providereliable reference and guidance for improving the strand’s quality.更多还原