Abstract: Suspected crack punctiform and linear defects in the surface of the finished ring were found in the production of bearing steel inner ring, which was analyzed by using nondestructive detection, optical microscope, scanning electron microscopy, energy spectrum analysis. The results show that a few big size of aluminum oxide and silicate compound inclusions exist. By improving the purity of molten steel by adopting measures such as “high carbon pulling”, “white slag operation”, “soft blowing” and “protective casting”, the recurrence of punctiform and linear defects disappear.

Key words: GCr15 steel, bearing steel, defects, white slag