A new proposed Weibull distribution of inclusion size and its correlation with rolling contact fatigue life of an extra clean bearing steel

Abstract The rolling contact fatigue life (RCF-life (N)) of an extra clean bearing steel of GCr15 is examined by Thrust rolling test. The variation of RCF-life with failure probability (P(N)) is analyzed by the Weibull function, which shows a very nice linear relationship between ln(N) and ln(−ln(1 − P(N))). The nonmetallic inclusions measured by rotated bending fatigue test and Aspex are evaluated by the statistics of the inverse value of the inclusions (1/DIn), which shows a perfect Weibull distribution between ln(1/DIn) and ln(−ln(1 − P(1/DIn))). Based on the similarity of the two Weibull distributions, the correlation between RCF-life and the largest oxide inclusion size is derived to be N = k(1/DIn)p both experimentally and theoretically. This finding not only gives us a clear understanding of the size and distribution effects on the variation of the subsurface controlled RCF-life, but enable the prediction of RCF-life based on the characterization of inclusions and the Paris law on crack propagation.