Effect of Ce on the transformation of inclusions in the production process of duplex stainless steel F53

Inclusions significantly impact the metallurgical quality of stainless steel. Duplex stainless steel F53, produced by a domestic special steel enterprise, was found to exhibit surface cracks, severely compromising its mechanical properties. Laboratory microscopic analysis revealed that these defects are primarily caused by inclusions. To investigate the transformation of inclusions during production and the effect of the rare earth element cerium, this study analyzes the inclusion transformation mechanisms throughout the entire production process of duplex stainless steel. Samples from various stages were examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and ASPEX. The results show that, at the end of the AOD process, the inclusions in the molten steel primarily consist of MnS-MgO-Al 2 O 3 composites. During the early LF stage, the inclusions are mainly MnS-MgO-CaO composites. After adding aluminum, the inclusions revert to MnS-MgO-Al 2 O 3 composites, which remain throughout the LF process. Upon adding cerium, thermodynamic analysis using the FactSage 7.3 software reveals a significant reduction in sulfur content and a noticeable decrease in inclusion size. The main inclusions transform from MnS-MgO-Al 2 O 3 to rare earth Ce 2 O 3 and Ce 2 O 2 S inclusions, demonstrating effective modification. The precipitation sequence of rare earth inclusions is Ce 2 O 3 first, followed by Ce 2 O 2 S, with Ce 2 O 3 -Ce 2 O 2 S composite inclusions forming simultaneously.