连铸过程中钢水中夹杂物的形核、长大、运动与捕捉的模拟研究

The inclusions in steel have great influence on the perfarmance of steel profucts. Inclusions should be removed as much as posibily during steel production processes. Inclusions remained in the steel should be small in size and uniformly distributed in the product. Mathematical modeling is an economical and efficient method to investigate inclusions in steel.The current project will apply and integrate theories in fluid dynamics(molten steel- argon gas two-phase flow),heat transfer, solidification, thermodynamics, and models for the nucleation, growth, motion and entrapment of inclusions to bubbles and the solidification front, predict the final distribution of inclusions in the continuous casting slab, and thus optimize casting operation to remove more inclusions from the molten steel and achieve high clean steels. This work consists of four tasks: ⑴. Development of nano- and micro-scale models of inclusion phenomena (nucleation and growth model, bubble attachment model, thermodynamic model, inclusion entrapment models); ⑵. Combining the nano- and micro-scale inclusion models with the macro-scale fluid flow models, and predicting the final distribution of inclusions in the continuous casting slab; ⑶. Validating the models using laboratory experiments and industrial trials, and (4) Optimizing the casting process using the developed models. The purpose is to find the best operation casting parameters to achieve ultra clean continuous casting slabs with low amount of inclusions and uniform distribution of inclusions. The improved modeling methodologies and new fundamental insights into the phenomena governing inclusion behavior that will result from this research comprise important and novel intellectual contributions to science. The direct impact of the proposed work is quality improvement, cost reduction, and energy saving in the cast steel products.

钢中夹杂物直接影响钢铁产品的性能，生产过程中必须尽可能多地去除夹杂物，同时要求残留在钢中的夹杂物尺寸要小、分布要均匀。数学模拟的手段是一种经济、有效的研究钢种夹杂物的手段。本研究通过整合流体动力学（钢水－氩气两相流）、传热、凝固、热力学、夹杂物形核、长大、运动和被气泡和凝固前沿捕捉等理论和模型，预测连铸坯中夹杂物的最终空间分布，从而可以优化连铸工艺操作以从钢水去除更多的夹杂物，获得高洁净钢。主要工作包括：⑴.开发夹杂物行为相关的纳米和微米级现象的模型(形核、长大、气泡浮选、热力学模型、和凝固前沿对夹杂物捕捉模型)；⑵. 将所开发的纳米和微米级别的夹杂物模型与宏观流场相耦合来计算预测夹杂物在铸坯中的最终分布；⑶.通过实验室实验和工业试验对模型进行验证和校核；（4）应用模型来优化连铸操作，确定获得最佳洁净度的连铸操作参数。最终的目标是实现高洁净的连铸坯:夹杂物含量低，夹杂物在铸坯中的分布合理。

钢中夹杂物直接影响钢铁产品的性能，生产过程中必须尽可能多地去除夹杂物，同时要求残留在钢中的夹杂物尺寸要小、分布要均匀。数学模拟的手段是一种经济、有效的研究钢种夹杂物的手段。本研究通过整合流体动力学（钢水－氩气两相流）、传热、凝固、热力学和动力学、夹杂物形核、长大、运动和被气泡和凝固前沿捕捉等理论和模型，预测连铸坯中夹杂物的最终空间分布，从而可以优化连铸工艺操作以从钢水去除更多的夹杂物，获得高洁净钢。主要研究内容及成果包括：（1）开发了夹杂物生成热力学和动力学模型；（2）开发了夹杂物行为相关的纳米和微米级现象的模型（形核、长大、碰撞聚合、气泡浮选、渣钢界面去除和凝固前沿对夹杂物捕捉模型）；（3）将所开发的纳米和微米级别的夹杂物模型与宏观流场相耦合来计算预测夹杂物在铸坯中的最终分布；（4）通过实验室实验和工业试验对模型进行了验证和校核；（5）应用模型来优化连铸操作，确定了获得最佳洁净度的连铸操作参数。最终的目标是实现高洁净的连铸坯:夹杂物含量低，夹杂物在铸坯中的分布合理。并且通过研究发现，在渣钢界面，相较于液态夹杂物，固态夹杂物更容易穿过渣钢界面被渣吸附。通过本研究改进的建模方法以及新的控制夹杂物行为的相关基本原理将会对洁净钢生产相关的科学发展做出重要贡献。