Modeling the Influence of Microstructure in Rolling Contact Fatigue

Crack nucleation, first spall generation, and spall growth in rolling contact fatigue (RCF) are known to be highly sensitive to the heterogeneity of the microstructure. Yet the current state-of-the-art in the design of high performance bearing materials and microstructures is highly empirical requiring substantial lengthy experimental testing to validate the reliability and performance of these new materials and processes. We have laid the groundwork necessary to determine the influence of microstructure in RCF to aid in the development and processing of bearing steels. Microstructure attributes that may control the fatigue behavior are explicitly modeled in a 41xxx steel. The methodology is demonstrated by studying the role of an aluminum oxide inclusion embedded in a matrix of tempered martensite and retained austenite. The matrix is represented by crystal plasticity, which provides more realistic accumulations of localized plastic strains with cycling compare to homogenized J2 plasticity. As a demonstration of the approach, the relative influence of the volume fraction of retained austenite on RCF is evaluated.