Abstract: Variation characteristics of inner and outer diameter and surface residual stress of straight wall cylindrical bearing outer ring made of 8Cr4Mo4V steel at different working temperatures were measured, the factors causing the dimension variation and surface residual stress variation of bearing outer ring were analyzed, and the microstructure of the bearing outer ring was observed. The results show that at different working temperatures, the outer diameter increment of bearing outer ring all reaches 1-2 μm after holding for 300 h, which is greater than that of inner diameter; And the retained austenite transforms into martensite at the working temperatures, and deep tempering of martensite leads the surface compressive residual stress value at inner diameter of bearing outer ring to increase. When the working temperature is 150 ℃, the surface compressive residual stress absolute value increment on both the inner and outer diameter reach the most, and with the increase of temperature, the increment in surface compressive residual stress absolute value decreases. The increase of the surface compressive residual stresses on the inner and outer diameters of bearing outer ring is caused by the transformation of retained austenite into martensite, that resulted volume expansion. Deep tempering of martensite leads to volume shrinkage, and different shrinkage of inner and outer diameter will lead to different changes of compressive residual stress value on inner and outer diameter surface. The size shrinkage will lead to the increase of compressive residual stress on inner diameter and decrease of that on outer diameter.

Key words: bearing ring, working temperature, size change, residual stress, 8Cr4Mo4V steel