超纯铁素体不锈钢中Ti-Al系氧化物夹杂控制机理的研究

Complex oxide inclusions containing Ti-Al in ultra clean ferritic stainless steel can easily cause some problems, such as nozzle clogging and surface sliver defect, which have a detrimental effect on the surface quality and corrosive resistance of the finished steel. However, the control mechanism of the complex particles has not so clearly been understood yet. This project systematically studies the fundamental principles of the thermodynamics and behavior mechanism of complex oxide inclusions containing Ti-Al in the ultra clean ferritic stainless steel，then forecast models of the composition and the behaviors of inclusions are designed，which provide theoretical and technical supports for the control of the particles. On these bases, combining with the different features and the production process of titanium-containing steel , an accurate control technologyof calcium treatment process is established through a systematic study about the proper calcium treatment technology; for the modification of MgO•Al2O3 in stainless steel, Ti treatment technology is put forward and series of laboratory studies are conducted to make it clear for the mechanism, conditions and methods of the Ti treatment; comparing with the traditional calcium treatment technology ,determine the best ways of spinel modification in steel. Through above mentioned studies, the applicant can realize the precise contral of complex oxide inclusions containing Ti-Al in the ultra clean ferritic stainless steel，thus improve the cleanliness of the liquid steel.

超纯铁素体不锈钢中的Ti-Al系氧化物夹杂容易导致浇注过程水口堵塞、冷轧板表面鳞折等问题，对钢材表面质量及耐蚀性能产生不利影响，但目前针对Ti-Al系氧化物夹杂控制机理缺乏系统研究。本课题对超纯铁素体不锈钢中Ti-Al系氧化物夹杂的热力学及其行为机制展开系统研究，进而开发超纯铁素体不锈钢中Ti-Al系氧化物夹杂的成分和行为预测模型，为Ti-Al系氧化物夹杂的控制提供技术支撑。据此结合不同超纯铁素体不锈钢的特点及生产工艺，研究合适的钙处理工艺，实现超纯铁素体不锈钢钙处理工艺的精确控制；通过实验室研究明确超纯铁素体不锈钢中钛处理改性MgO•Al2O3尖晶石的机理、条件、途径，并将钛处理与钙处理工艺进行优化并提出不锈钢中MgO•Al2O3尖晶石改性的最佳方案。综合上述研究，实现超纯铁素体不锈钢中Ti-Al系氧化物夹杂的精确控制，进一步提高钢水洁净度。

超纯铁素体不锈钢中钛的加入可提高钢种的耐腐蚀性能，但又易导致钢液中生成复杂的Ti-Al系氧化物夹杂。这类复杂夹杂物的存在不仅增加了钢水洁净度的控制难度，还会显著影响连铸工艺的顺行。本课题采用实验室冶炼的方式，借助ASPEX夹杂物自动分析技术、无水有机溶液电解技术等多种分析手段，结合理论计算分析，对超纯铁素体不锈钢中Ti-Al系氧化物的精准控制展开了系统研究。课题阐明了铝钛复合脱氧夹杂物瞬态产物的演变机理、含钛钢种Al2O3和 MgO•Al2O3夹杂物的钙处理改性机理和含钛钢种水口结瘤的生成机理，建立了钢中夹杂物与水口结瘤问题的联系，提出了提高含钛钢种MgO•Al2O3改性效果的技术方案。本课题为超纯铁素体不锈钢钢水洁净度的提高以及水口结瘤问题的改善提供了技术支撑。