Abstract: The present study aimed to investigate the effect of different rare earth contents on inclusions in high-grade non-oriented silicon steel through industrial experiment. The results revealed that at a compound rare earth content of 0.002 1 %（mass fraction）, the rare earth elements predominantly formed (La, Ce)AlO3 rare earth inclusions.These inclusions serve as deoxidizers and modifiers, transforming steel Al2O3 inclusions. With an increase in the rare earth content in steel, the formation of rare earth inclusions shifts towards (La, Ce)AlO3(La, Ce)2O2S and (La, Ce)2O2S inclusions. These inclusions mainly reduce the formation of sulfides in the steel. However, their influence on the numerous Al2O3 inclusions formed during temperature drops and secondary oxidation in steel is limited. Consequently, this leads to a significant increase in the number density of Al2O3 inclusions in steel with a high rare earth content. Furthermore, rare earth treatment induced notable spheroidization of inclusions in casting billets. However, during the subsequent hot-rolling process, minimal differences were observed in the average aspect ratio of inclusions between conventionally treated plates and those treated with rare earth. Therefore,the primary factor influencing the aspect ratio of inclusions is the relevant process parameters of the rolling process.

Key words: rare earth treatment, inclusions, high-grade non-oriented silicon steel