基于氧化物冶金的微合金化研究

介绍了国内外氧化物冶金技术的进展情况；分析了微合金体系中各元素的协同及交互作用以及夹杂物、第二相粒子析出、演变对钢的相变、组织结构和性能的影响规律；阐述了冶炼、凝固过程中“有益”夹杂物析出的热力学、动力学研究现状，分析了夹杂物性质、尺寸、分布等对诱发晶内铁素体形核的影响；综述了热加工和焊接过程对组织演化、晶粒细化、晶内铁素体优先析出及提高母材钢和焊接热影响区强韧性机制。总结了氧化物冶金研究工作进展及存在的问题，结合课题组研究的成果，提出了基于氧化物冶金的微合金化思想并比较了其与传统微合金化的异同；展望了基于氧化物冶金的微合金化理论方面需要进一步开展的研究工作。 

Fundamental research of the microalloying theory based on oxide metallurgy technology

In China’s marine strategy, using oxide metallurgy technology to develop high heat input welding steel is an important guarantee for developing marine engineering equipment and high-tech ships. The theory of microalloying based on oxide metallurgy studies the mechanism of multiple factors that induce preferential competitive precipitation of ferrite in grain. This theory integrates the oxide metallurgy technology into the entire process of design, production, and welding of high heat input welding steels and considers the requirements of strength, toughness, and weldability of thick plate steel. Herein, the development of oxide metallurgy technology at home and abroad was introduced, and then the progress of microalloying theory based on oxide metallurgy was expounded. Meanwhile, the coordination and interaction of various microalloying elements, as well as the influence of the precipitation and evolution of inclusions and second-phase particles on the microstructure transformation and steel properties, were investigated. The thermodynamics and kinetics of the precipitation of beneficial inclusions during smelting and solidification were analyzed. The effects of the inclusions’ properties, size, and distribution on the nucleation of Ferrin were analyzed. The mechanisms of microstructure evolution, grain refinement, preferential precipitation of ferrite, and improvement of strength and toughness of base steel and weld heat-affected zone during hot working and welding were reviewed. The research progress and existing problems of oxide metallurgy were completely summarized. Combined with the results of the research group, the theory of microalloying based on oxide metallurgy was put forward, and microalloying based on oxide metallurgy has been proposed. Including the design theory of the microalloy system, the synergistic and interactive mechanism of microalloying elements under the condition of multi-element coexistence, and the effects of microalloying elements oxidation, carbonitriding, and sulfurization on the formation, evolution, and distribution of inclusions and second-phase particles in the whole process. The mechanism of inclusions and the properties and distribution of the second-phase particles improving the strength and toughness of coarse-grain heat-affected zone (CGHAZ) and inducing the preferential precipitation of ferrite in grain were also discussed. Microalloying based on oxide metallurgy is a further development of the oxide metallurgy technology. This research will greatly promote the development of oxide metallurgy technology. This will provide a theoretical and technical basis for developing steel materials with high strength, high toughness, and excellent weldability. It will provide an effective method for producing high-strength and high-toughness thick plate steel, section steel, and nonquenched and tempered steel by oxide metallurgy technology.