合金钢连铸坯动态凝固过程数值模拟

针对合金钢连铸坯凝固过程中存在的疏松、偏析、裂纹等问题,以现场实际连铸机为研究对象,依据200mm×200mm合金钢的连铸工艺,建立了铸坯凝固传热数学模型,确定了边界条件,初始条件,不同冷却段的表面热流,以及所研究钢种的物性参数·特别是通过把坐标系建在连铸坯之上,解决了计算整个铸坯纵断面上在不同过热度、不同拉速、不同时间、不同位置上动态凝固过程的温度场问题·模拟计算结果与实际铸机上的测试结果吻合较好,从而为调整连铸工艺参数,确定连铸坯末端电磁搅拌器安装位置及电磁参数,提高连铸坯质量找到依据·

Dynamic Modelling for Solidification Process of CC Alloy Steel Billets

The porosity, segregation and cracks of continuous casting (CC) alloy steel billets in solidification process were investigated in situ, of which the 200 mm × 200 mm billets of GCrl5 (for use of bearings), 40Cr and 20CrMnTi were taken as specimens. A mathematical model of heat transfer in solidification process is therefore set up, with boundary condition, initial condition, surface heat flux at different cooling sections and physical parameters of different steel grades all determined. In particular the 2-dimensional coordinate system is set up on the billets, thus solving dynamically the problem of temperature field on the whole sectional area of billet in solidification process at different overheated temperatures, drawing speeds, times required and positions. The model shows a fairly good agreement with the measurements in situ as verified through numerical calculation. It will provide a reference for taking measures to improve the quality of billets, such as, adjusting technological parameters in continuous casting process, positioning the electromagnetic stirrer at the final solidification area for billets and determining electromagnetic parameters.