含P高强IF钢液与耐材及夹杂物间界面性质的基础研究

Light of automobile prompts the development of high strength steel sheet. The high-strength IF steel with high phosphorus content is booming nowadays due to its both high strength and ultra-deep drawing property. But one of problems restricts the blossom of high-strength IF steel that nozzle clogging during continuous casting causes a serious problem, such like poor cleanliness of molten steel and defects of cold sheet. However, at present, it is unclear that the influence of the composition of molten steel on the interfacial property between steel and refractory, inclusions, also the relationship between the interfacial property and the behavior of inclusions. The experimental study and theoretical calculation are adopt in the project, which illustrates that the influence of composition of steel and the surface property of refractory on the interfacial property and put forward the effective criterion on bonding and separation of inclusions onto the refractory. The relationship between composition of the steel and the size, aggregation and dispersion of inclusions are studied, which can explore the mechanism of influence of interfacial properties on the inclusion behavior. In the end, the independent factors influencing the nozzle clogging are quantized and the dynamic growth and formation mechanism of clogging are obtained under the effect of interfacial property, surface property of refractory and the inclusion behavior. The study provides the basic theory to solve absolutely the nozzle clogging of casting high-strength IF steel with high phosphorus content.

汽车轻量化促使汽车板向高强度方向发展，含P高强IF钢因兼有高强度和超深冲性得到迅速发展，连铸过程水口结瘤带来的钢液洁净度低、冷轧板缺陷等问题是冶炼中制约高强IF钢发展的关键难题之一。钢液与耐材及夹杂物间的界面性质对水口结瘤现象影响较大，然而目高强IF钢液成分对钢液与耐材及夹杂物间的界面性质的影响及界面性质与夹杂物行为之间的关系尚不明晰。本项目采用实验研究结合理论计算的方法，阐明钢液成分对钢液与耐材（不同表面性质）、夹杂物间界面性质的影响规律，提出夹杂物与水口内壁粘合与分离的有效判据；研究钢液成分与夹杂物尺寸、聚合及弥散等行为的关系，并探究界面现象对夹杂物行为的作用机制；量化影响水口结瘤现象的独立影响因素，解析界面性质、耐材表面性质及夹杂物行为等因素作用下水口结瘤的动态演化进程及形成机理，为减轻含P高强IF钢水口结瘤现象提供理论依据。

含P高强IF钢因具有高强度及良好的深冲性能，在汽车行业广泛引用，但是含P高强IF钢在生产过程中水口易出现水口结瘤，导致冷轧板缺陷等。钢液与耐材及夹杂物间的界面性质对水口结瘤现象影响较大，然而目高强IF钢液成分对钢液与耐材及夹杂物间的界面性质的影响及界面性质与夹杂物行为之间的关系尚不明晰。本研究通过实验研究，阐明了不同条件下P、Ti元素对钢液与夹杂物间的润湿角影响规律，并解析了P、Ti元素交互作用下对钢液、耐材间界面性质的影响规律，结果表明，P、Ti元素对钢液与耐材间的润湿角影响较为明显；研究采用原位观察了钢液中P、Ti元素对夹杂物运动行为的影响，分析了夹杂物在团聚过程中的受力情况，并提出夹杂物在水口壁面的粘合分离判据；通过数值模拟的方法建立了夹杂物在水口壁面分离及粘合的数学模型，以实验得到的润湿角及力学分析为基础，分析研究了不同界面性质下夹杂物在水口内壁的沉积粘合规律。最后，通过工业对比实验验证了含P高强IF钢生产中P元素对水口结瘤的影响。本研究为含P高强IF钢生产中如何减轻水口结瘤现象提供了理论依据，同时，研究方法可适用于其他易产生水口结瘤的钢种。