Abstract: In order to reduce the harm of inclusions on the fatigue properties of bearing steel, the modification behavior of inclusions in GCr15 bearing steel by rare earth Ce and heat treatment was studied. It is found that rare earth treatment can spheroidize inclusions in the tested steel and reduce their average size, which is helpful to reduce the hazard of inclusions in aluminum deoxidation bearing steel. Heat treatment (1 250 ℃) can also spheroidize and refine inclusions in the tested steel. With the increase of heat treatment time (0-330 min), the average size, length-width ratio and area fraction of inclusions show a downward trend. Extending the heat treatment time (330-510 min), the proportion of large-size inclusions in aluminum deoxidation bearing steel increases, and the spherical homogeneous Ce-Al-O-S inclusions in rare earth bearing steel transform into Al-rich and Ce-rich heterogeneous inclusions, which is harmful to the fatigue performance of bearing steel. Therefore, when the heat treatment is 330 min, the inclusion characteristics of aluminum deoxidization and rare earth bearing steel are optimal under the conditions of this study.

Key words: bearing steel, rare earth treatment, heat treatment, inclusion modification