Evolution of inclusions in the whole process of GCr15 bearing steel

Inclusions have an important effect on the fatigue performance of bearing steels. Therefore, the study of the evolution of inclusions in the whole process and the reasonable control of inclusions (quantity, type, size, etc.) in steel can improve the production stability and fatigue performance of bearing steel. In this study, with the help of thermodynamic calculations and experimental studies, the evolution of the whole-process refining slag, oxygen and nitrogen content, and inclusions in bearing steel produced in a plant is systematically investigated. Overall, the refining slag composition of the refining process fluctuates less, and the oxygen content during LF refining and RH refining has been trending down, with an oxygen content of 5.7 × 10 ‒6 in the bearing steel billets. Although the cleanliness level is good for bearing steels, there is still room for improvement in refining slag composition, refining time, protected casting, and cut waste length.