薄板坯连铸连轧液芯压下工艺研究

Research on Liquid Core Reduction for Thin Slab Casting and Rolling

针对薄板坯连铸工艺中的关键技术液芯压下特点,选取沿柱状晶方向的铸态钢试样分别在不同温度和应变速率下进行热压缩模拟试验,为液芯压下结构提供材料高温流变应力模型。通过建立液芯压下过程数值模型,研究和分析液芯压下工艺中铸坯变形特征和凝固坯壳的应力应变分布规律,以及液芯形态变化情况。为了找到薄板坯连铸液芯压下工艺的最佳工艺参数组合,对坯壳厚度、压下量和辊间距三个参数进行优化设计。通过建立响应面来构造液芯压下近似模型,描述各工艺参数与液芯压下结果之间的关系。在近似的模型的基础上,利用遗传算法,通过全局最优优化算法寻找出构造近似模型的最优解,从而得到板坯液芯压下最佳工艺参数组合,并进行了压下试验。

In order to provide material＇ s high temperature flow stress model for the structure of liquid core reduction, the as-cast samples along the columnar crystal direction were selected to perform the high temperature compress test and analysis at different temperatures and strain rates separately on the basis of the characteristics of the liquid core reduction of thin slab casting and rolling. Through establishing a process numerical model for the liquid core reduction, the characteristics and rules of slab deformation were investigated. The rules of the solidified shell＇ s stress and strain distribution were also analyzed, together with the variation in the liquid core shape. In order to get the best operating mode of the liquid core reduction, the optimization of processing parameters, inclu- ding shell thickness, reduction quantity and roll pitch was performed. The approximate relation model of parameters was established through constructing of response surface. Meanwhile, the genetic algorithm was utilized to search the optimum solution of the approximate model through the globally optimal algorithm, and the best parameters combination was got for the thin slab reduction with a liquid core.