Semi-empirical model for predicting LAB and HAB formation in bearing steels

Abstract

The formation of white etching bands (WEBs), including both low- (LAB) and high- (HAB) angle bands, in the subsurface of steel bearings due to rolling contact fatigue (RCF) has been investigated over decades to understand their characteristics and predict their formation during operation. A few studies recently have modelled the development of LABs theoretically based on thickening of lenticular carbides adjacent to the band controlled by dislocation-assisted carbon migration. To date, no study has been reported to predict the formation of HABs. Based on the percentage of white etched region formed in the subsurface of the bearings, this study presents a semi-empirical model that predicts the formation of both LABs and HABs in steel bearings for different contact pressures. The LAB semi-empirical model is compared with a theoretical model from literature and experimental data. According to this, the new model more realistically predicts the initiation of LABs than the carbide thickening model. This is achieved by involving the formation of ferrite (cellular and elongated) shown as white areas under optical images. Literature data have been used to evaluate the LAB and HAB models. The growth pattern obtained in this study provides strong evidence of a diffusion-based mechanism leading to WEB formation.