A NEW METHODOLOGY TO EVALUATE THE ROLLING CONTACT FATIGUE PERFORMANCES OF BEARING STEELS WITH SURFACE DENTS -APPLICATION TO 32CRMOV13 (NITRIDED) AND M50 STEELS

摘要

A new methodology is proposed to evaluate the rolling contact fatigue (RCF) performances of bearing steels in presence of surface dents. The experimental procedure consists in denting the raceway of the test specimen with a hardness machine using spherical diamond tips of different radius, i.e. 200, 400 and 600 μm, and normal loads ranging from 5 to 50 daN. Analysis of various dent geometries yields to an analytical law with five parameters useful to fit experimental profiles for contact simulation. Besides local residual stresses and plastic strains around the dent have been obtained by finite element simulations of the indentation process. RCF tests performed on a two-disk machine have shown better performances of nitrided 32CrMoV13 steel compared to M50 reference steel. The dominating role of sliding has been highlighted and two areas where damage initiates were identified, while the effects of the normal load and hoop stresses are less marked.