NOUFERROUS METALLURGICAL EQUIPMENT

Inclusions are inevitable during the steel smelting process, mainly consisting of oxides, sulfides, nitrides and composite. These inclusions have significant physical property differences from the steel matrix, leading to discontinuities in the microstructure and physical properties of the steel, thereby affecting the performance and service life of the steel. Rare earth elements, as modifiers, have shown excellent performance in improving the properties of inclusions, mainly through microalloying, inclusion modification, and improvement of the steel solidification structure to optimize performances of steel. The paper focuses on the modification effects of rare earth elements (RE) on inclusions during steel smelting and their impact on steel performance, systematically summarizes the phenomena, patterns, mechanisms of rare earth-modified inclusions, and their effects on steel properties, analyzes the effects of different rare earth elements (such as Ce, La, Y) on inclusions and structures in steel, discusses the effects of rare earth complex addition and modification of inclusions in conjunction with heat treatment processes, and covers thermodynamic calculations and kinetic analyses of inclusion modification mechanisms. Thermodynamic calculations can predict the formation order and existence form of rare earth inclusions, optimize reaction conditions, and determine the optimal addition amount of rare earth elements. Kinetic analysis shows that rare earth inclusions are prone to collision, agglomeration, and growth during the molten steel temperature and cooling process, floating and removing, which helps to reduce the content of inclusions in the molten steel. The modification of inclusions by rare earth elements can significantly improve the performance of steel, increase the production efficiency of steel, and is of great significance for promoting the sustainable development of the steel industry.