Study on the Coordinated Deoxidation and Inclusion Modification Behavior of Carbon–Cerium Core–Shell Microspheres in High‐Temperature Bearing Steel

To tackle fine‐inclusion removal difficulties and low rare‐earth recovery during single rare‐earth modification of high‐temperature bearing steel, this work adopts carbon–cerium(C–Ce) core–shell microspheres as a new deoxidation modifier to explore their synergistic deoxidation and inclusion‐modifying effects. Combining thermal tests, thermodynamic calculations, and microcharacterization, the reaction mechanism of the microspheres in molten steel and their regulation of oxide/sulfide impurities are systematically analyzed. Carbon in the microspheres realizes preferential predeoxidation to optimize molten steel thermodynamics, while cerium captures residual O and S to lower dissolved oxygen. The lowest dissolved oxygen of 6.5 ppm, occurs when carbon accounts for 30%–40% of the Ce–Fe alloy mass. Though inclusion phases remain consistent with single cerium treatment, coarse rigid inclusions are converted into tiny, evenly distributed spherical CeS, Ce ₂ O ₂ S, and CeAlO ₃ composite inclusions. Compared with pure cerium modification, inclusion density drops by 19.54% to 243 inclusions/mm ² , and average inclusion size decreases by 20.34% to 0.94 μm. Carbon predeoxidation greatly improves cerium recovery, peaking at 36.02%. This paper reveals the coupled deoxidation‐inclusion modification mechanism of C–Ce microspheres, overcoming drawbacks of single rare‐earth treatment, including uneven reactions, agglomeration, and low utilization efficiency. It offers theoretical support for clean smelting and precise inclusion control of high‐performance high‐temperature bearing steel.