Original Article

Research on the improvement and mechanism of La-Ce on inclusions in GCr15 bearing steel

Center for Advanced Solidification Technology (CAST), School of Materials Science and Engineering, Shanghai University, Shanghai 201900, China

^* e-mail: fujianxun@shu.edu.cn

Received: 14 May 2024
Accepted: 12 August 2024

Abstract

Rare earth can effectively improve the morphology of inclusions in steel. This paper investigates the modification effects and mechanisms of La-Ce composite rare earth on the inclusions in GCr15 bearing steel by adding different contents of La-Ce. The research shows that the typical inclusions in GCr15 bearing steel were Al₂O₃ and MnS. The addition of La-Ce enhanced the cleanliness of the molten steel and caused a morphological transformation of the inclusions. With La-Ce content less than 96 ppm, as the La-Ce content increased, the inclusion types in GCr15 bearing steel transition from Al₂O₃ + MnS → REAlO₃ + RE_xS_y → RE₂O₂S + RE_xS_y. (RE were La and Ce). Due to the higher interfacial energy between the rare earth inclusions and the matrix, their morphology tended to be more spherical. When the La-Ce content exceeded 96 ppm, it led to the formation of RE₂O₃ inclusions in the steel. Although the morphology of individual RE₂O₃ inclusions also tended towards spherical, the overall morphology became irregular due to the aggregation and growth of the inclusions.