Original Article

Improving cleanliness of SWRS82B steel by rare earth-containing refining slag

¹ School of Materials and Metallurgy, Guizhou University, Guiyang, Guizhou 550025, PR China
² School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, PR China
³ Shougang Group Shuicheng Steel Company, Liupanshui, Guizhou 553028, PR China
⁴ School of Materials and Energy Engineering, Guizhou Institute of Technology, Guiyang, Guizhou 550025, PR China

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 13 January 2026
Accepted: 1 June 2026

Abstract

SWRS82B steel has high requirements for inclusions and optimization of refining slag is crucial for the control of inclusion characteristics. The effect of CeO₂ in refining slag on SWRS82B steel cleanliness was investigated at 1873 K by thermodynamic calculations and microstructural characterization. The results indicated that the 5 wt% CeO₂-added refining slag exhibited the optimal effect on improving the cleanliness of SWRS82B. The oxygen content decreased to 0.0016% and the sulfur content decreased to 0.0032% in the steel refined by slag with 5 wt% CeO₂. The average size of inclusions in steel decreased from 2.71 μm to 1.71 μm. The number density of inclusions decreased from 172 to 121 per mm² and the high-temperature deformability of inclusions was improved. Thermodynamic calculations indicated that SiO₂ activity decreased with increasing content of CeO₂ in refining slag, thereby lowering the equilibrium oxygen content in the steel. The addition of CeO₂ depolymerized the [Si–O] structure in slag, reducing its polymerization and improving reaction kinetics. Meanwhile, increasing CeO₂ addition raised the Ce³⁺ content in the slag, leading to an increase in dissolved oxygen in the molten steel. The mechanism of oxygen transmission and reaction in gas-slag-molten steel was discussed in this study.