Abstract An industrial continuous casting process of steel billet is analysed using a novel, integrated numerical model for the heat transfer and solidification of the molten metal as it passes through the mould. One of the major difficulties related to determination of thermal resistance at the mould-strand interface is addressed in the present study. Contrary to empirical or semi-empirical methods commonly used in the industry for determination of the heat transfer at the interface, the present work deals with the determination of the interfacial thermal resistance by adopting a novel mathematical approach. A two-dimensional, transient, finite difference method based code is developed for a plane slice of molten steel moving with a given casting speed down the mould. The resultant solidification and thermal shrinkage are calculated from the temperature distribution and knowledge of the temperature dependent density of steel. The heat transfer from the cast strand to the cooling water is modelled by a network of thermal resistance. The model is validated against experimental data obtained from literature. The numerical results reveal a dominant role of advection of the gaseous mixture of air and other components from pyrolysis of casting oil, in the interfacial gap formed due to the shrinkage of steel, which has not been considered previously in the formulation of thermal resistance. The numerical model is also used to analyse the heat transfer in the mould and the growth of the solidified shell as the strand moves down the mould. In particular, the corner regions of the strand are found to be hotter than the off-corner regions, due to non-uniform heat transfer across the periphery. Also, the effect of casting speed in the mould is found to be dominant in comparison to other casting parameters, such as mould thickness and cooling water velocity.

中文翻译：

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钢坯连铸收缩引起的结晶器-铸坯界面热阻的测定——新型集成数值模型的开发与应用

摘要 使用一种新颖的集成数值模型来分析钢坯的工业连铸过程，该模型用于熔融金属在通过模具时的传热和凝固。本研究解决了与确定模具-股线界面热阻有关的主要困难之一。与工业中常用的确定界面传热的经验或半经验方法相反，本工作通过采用新的数学方法来确定界面热阻。开发了一种基于二维瞬态有限差分方法的代码，用于以给定的铸造速度沿模具向下移动的钢水平面切片。由此产生的凝固和热收缩是根据温度分布和钢的温度相关密度的知识计算出来的。从铸坯到冷却水的热传递由热阻网络建模。该模型根据从文献中获得的实验数据进行了验证。数值结果揭示了空气和其他成分的气体混合物的平流在由于钢的收缩而形成的界面间隙中的主导作用，这在之前的热阻公式中没有考虑过。数值模型还用于分析模具中的热传递和铸坯在模具中向下移动时凝固壳的生长。特别是，发现股线的拐角区域比离拐角区域更热，这是由于整个周边的热传递不均匀。此外，与其他铸造参数（例如模具厚度和冷却水速度）相比，模具中的铸造速度的影响占主导地位。