Manufacturing induced residual stress influence on the rolling contact fatigue life performance of lubricated silicon nitride bearing materials

Experimental results of the residual stress measurements on failed ceramic elements are presented in this paper. Residual stress measurements were performed through a small volume of irradiation. Residual stress relation to number of stress cycles, distance from induced ring crack, residual stress relation to contact path and measuring direction was studied. Residual stress measurements were performed on fatigue spall. A residual stress survey on the secondary cracks is also provided presented in this paper. Analysing the relationship of residual stress with rolling contact fatigue is an important study which will provide guidelines on the design process and manufacturing of these elements. Two compressive residual stress values of 213 and 228 MPa were recorded on either edge of the contact path, these values are higher compared to 84 MPa at the centre of the contact path. This phenomenon indicates that compressive residual stresses are relieved much faster during rolling contact fatigue at higher contact stress level. The spall depths in ceramic rolling contact bearing elements were found to be ranging from 100 to 148 μm. The variation of the compressive residual stress values is prominent at this depth. The decrease in the compressive residual stress values is registered in the spall region and demonstrates sub-surface damage in the region.