Abstract: The heat transfer and solidification of secondary cooling zone in bloom continuous casting were simulated based on a fluctuated cooling approach-improved (FCA-I), and the three simulation methods, monotonic cooling approach (MCA), fluctuated cooling approach (FCA) and FCA-I, were compared. The results show that the bloom surface temperature before straightening and liquid core length calculated by the three methods have not much difference with the measurements, but FCA-I is more accurate, which can real-time predict the distribution of bloom surface temperature and the liquid core length change with casting speed. FCA-I not only retains the advantages of FCA which can accurately reflect the actual temperature change of foot-roller, but also overcome the shortcomings of FCA which is difficult to adapt to the changing of casting speed. The relationship between the solidification time (t) and shell thickness (dshell) in mold and secondary cooling zone calculated by FCA-I are regressed as dshell=19.62t1/2-2.52 and dshell=29t1/2, respectively, the simulation results basically agree with literatures.

Key words: continuous casting, bloom, heat transfer, solidification, fluctuated cooling approach-improved

摘要： 采用改进的波动冷却法(FCA-I)对大方坯连铸二冷区传热与凝固过程进行数值模拟，并与单调冷却法、波动冷却法(FCA)的计算结果进行比较. 结果表明，3种方法计算所得铸坯矫直前温度及液芯长度均与实测值相近，但FCA-I法计算结果更准确，可实时预测拉速变化时铸坯表面温度分布与液芯长度变化. FCA-I法既保留FCA法能准确反映铸坯足辊间温度、凝固壳厚度变化的优点，同时也克服了其难以适应变拉速的缺点. FCA-I法模拟所得结晶器内和二冷区凝固壳厚度dshell与凝固时间t的关系分别满足dshell=19.62t1/2-2.52和dshell=29t1/2，模拟值与文献结果基本一致.

关键词: 连铸, 大方钢坯, 传热, 凝固, 改进的波动冷却法