Analysis of rolling contact spall life in 440C bearing steel

Abstract 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 440C steel. Preliminary results of two-body, finite element calculations of repeated rolling contact with a dent in the running surface are described. Measurements of the nucleation and growth components of the life are derived from observations of cracks nucleated at small dents. The three-dimensional character of the spalls is examined. Calculations of the fracture mechanics driving force for surface breaking cracks are reviewed and compared with the measurements. The agreements provide support for the view that surface irregularities and the hydrostatic pressure of fluid in the crack cavity play a role in the nucleation and growth of the spall and that there is a threshold contact pressure for spall growth.