Early bearing fatigue initiation by the identification and selection of bearings with near race defects

Document Type

Conference Proceeding

Publication Date



Steel cleanliness is critical to the performance of tapered roller bearings in the rail industry, particularly under heavy axle load conditions. Non-metallic impurities present in bearing steels can manifest themselves as hard/brittle inclusions, which are detrimental to bearings in service due to the potential for the development of sub-surface rolling contact fatigue (RCF). Therefore, advanced methods for evaluating steel cleanliness are needed in today’s increasingly demanding railroad environment and high axle loads. Previously published work by the authors estimated bulk steel cleanliness from ultrasonic C-scan images of entire bearing cups and cones and identified “good” or “bad” bearings based on bulk assessments of the overall inclusion content. An extension of this technique developed for this study is the identification and quantification of near-race inclusions through an ultrasonic surface wave technique. For this study, bearing components were first subjected to ultrasonic testing to identify near surface defects, and then underwent simulated service life testing under heavy axle load conditions to assess the onset and propagation of RCF failure. Ultimately, the onset of RCF was then correlated to the inclusions identified with ultrasonic surface wave scanning techniques. The results clearly demonstrate the susceptibility of bearings to early RCF failure when near-race surface defects are present.

Publication Title

Proceedings of the 2015 International Heavy Haul Association Conference