钢中非金属夹杂物分布均匀化的基础研究

Homogenization is an important developing direction of steel and iron products of which uniform distribution of inclusions is the important content. Currently, there is a lack of comprehensive experimental analysis and quantitative study of influencing factors in the research on inclusion distribution in the steel. Besides, it is not clear about different behavior mechanism and stress state of inclusions in front edge of solidified shell during cooling process..The project plans to carry out research on the distribution of inclusions during refining process and the behavior of inclusions during cooling process. The experimental methods of cold modeling, thermal state experiment, numerical simulation and calculation can be adopted to study the influence of physical properties of inclusions on the their distribution, understand the relationships among wettability of inclusions and molten steel, polymerization of inclusions and inclusion distribution, and to obtain the controlling condition of molten steel for homogenous distributed inclusions. Then the stress state of inclusions under different behavior in front edge of solidified shell can be obtained and the influence of cooling condition on the inclusion distribution can be studied by numerical simulation. Finally the mechanism of homogenous distribution of inclusion in the steel can be revealed and controlling condition for obtaining homogenous distributed inclusion can be mastered which provides theoretical and technical support for solving the problem of inclusion aggregation in the steel.

“均质化”是钢铁产品的重要发展方向，夹杂物的均匀分布是均质化的重要内容。目前，关于钢水中夹杂物的分布研究缺乏系统的实验分析和影响因素的定量化研究，冷却过程中凝固前沿夹杂物的不同行为机理和受力状态尚不明确。.本课题分别针对钢水冶炼过程中夹杂物的分布和冷却过程中夹杂物的行为进行研究。采用冷态水模拟、热态实验、数值模拟和计算等方法，研究夹杂物的物理特性对钢水中夹杂物均匀分布的影响，明确夹杂物与钢水润湿性、夹杂物间聚合力与夹杂物分布的关系，获得利于夹杂物均匀分布的钢水控制条件；分析凝固前沿夹杂物不同行为转变的受力状态，并通过数值模拟研究冷却条件对夹杂物分布的影响，最终揭示夹杂物在钢材中均匀分布的机理，掌握夹杂物均匀分布的控制条件，为解决夹杂物在钢材中聚集问题提供理论和技术支持。

控制夹杂物细微弥散分布是氧化物冶金技术的关键研究内容。本项目针对“钢中非金属夹杂物分布均匀化”展开研究，通过物理模拟试验获得夹杂物性质与其均混和上浮行为的定性关系，通过热态实验、高温共聚焦原位观察、热力学计算和夹杂物间作用力计算等方法研究了夹杂物弥散分布的控制方法，掌握了夹杂物“形核-生长和碰撞-吸引与排斥-聚集与弥撒”等行为的影响机制。降低钢液中限制性扩散元素含量、改善夹杂物润湿性，从而控制夹杂物的形核和特征、降低夹杂物的碰撞、减小夹杂物间的毛细作用力和液桥力是提高夹杂物弥散化分布程度的关键方法。.取得的主要进展有：.（1）建立了夹杂物在钢中分布的物理模型，测量粒子与溶液间的接触角，基于相似原理进行夹杂物在钢中分布的物理模拟实验，测定了不同特性粒子在溶液中均匀混合性和上浮率。.（2）根据FactSage热力学软件计算各类夹杂物稳定区域图，根据计算结果制定了合理的高温试验方案，完成高温实验，利用image-ProPlus统计钢中夹杂物坐标和尺寸面积等参数，通过测量夹杂物间界面间距将夹杂物分布均匀性定量化，探索有利于钢中夹杂物弥散化的条件。.（3）通过经典形核理论、Ostward熟化理论和碰撞理论，结合FactSage热力学软件计算了夹杂物的形核规律、夹杂物的粗化率和碰撞率，获得了脱氧制度与夹杂物尺寸分布之间的定量关系。高温共聚焦显微镜原位观察和分析钢液表面各类氧化物夹杂的行为和受力，利用Paunov理论、分子间作用力理论和液桥力理论，计算了夹杂物间毛细作用力、范德华力和液桥力，探索了冶炼条件、夹杂物特征等对夹杂物受力的影响规律。.（4）基于夹杂物细微弥散化机理的理论分析和高温实验的相互验证得到夹杂物细微弥散化的控制方法。