大方坯连铸过程凝固规律

通过建立425mm×320mm连铸大方坯二维凝固传热数学模型，模拟了凝固坯壳的长大过程，并通过窄面射钉实验对数学模型进行了验证，精确得到了任意位置处大方坯凝固坯壳的厚度分布情况及最终凝固终点的位置，发现经典的凝固平方根定律对于连铸大方坯的凝壳长大进程不再适用．回归宽面中心坯壳厚度与凝固时间平方根的关系式发现，结晶器弯月面至二冷区出口，近似为线性关系，符合平方根定律，二冷区出口至凝固终点，二者为非线性关系，不再符合平方根定律．

Solidification regularity of a bloom during continuous casting

A two-dimensional mathematical model of solidification and heat transfer for a bloom with the cross section of 425 mm×320 mm was established,which simulated the growth process of the solidified shell.The model was verified by nail-shooting experiments in the narrow side of the bloom.The solidified shell thickness distribution at any fixed location in the casting direction and the position of the solidification end point were got by the model.It is found that the traditional solidification square root law is not fit for describing the solidification process.A mathematical relationship was regressed between the solidified shell thickness and the square root of solidification time in the center of the wide side.The regression results show that it is approximately linear from the mold meniscus to the secondary cooling zone export,which satisfies the square root law.However,from the secondary cooling zone export to the solidification end point,it is a non-linear relationship,which no longer follows the square root law.