ANALYSIS OF ROLLING-CONTACT SPALL LIFE IN 440C BEARING STEEL

This paper describes calculations and measurements aimed at resolving and analysing the nucleation and growth components of the near-surface mode of rolling contact failure of 44 degrees C steel. Preliminary re sults of two-body, finite element calculations of repeated rolling con tact with a dent in the running surface are described. Measurements of the nucleation and growth components of the life are derived from obs ervations of cracks nucleated at small dents. The three-dimensional ch aracter of the spalls is examined. Calculations of the fracture mechan ics driving force for surface breaking cracks are reviewed and compare d with the measurements. The agreements provide support for the View t hat surface irregularities and the hydrostatic pressure of fluid in th e crack cavity play a role in the nucleation and growth of the spall a nd that there is a threshold contact pressure for spall growth.