Abstract
A study on the fatigue behavior of bearing steel by using rotating bending fatigue test rigs is carried out for bearing steel (JIS SUJ2) heat-treated to HRC58-62. P-S-N (Probabilistic Stress Life) curves and fatigue life distributions, such as Weibull and log-normal, are used for discussion. As a result, the best fit for a life distribution of six lots with each sample size of around thirty specimens, at the stress levels from 0.94 to 1.27 GPa, is obtained by 3-parameter Weibull distribution, followed by the log-normal distribution as second, and 2-parameter Weibull distribution as the third. From the observation of broken section in test piece the initiation point of fatigue failures are almost started from subsurface non-metallic inclusions, TiN, CaO-Al2O3 and CaO-MgO-Al2O3. The fatigue limit for the bearing steel could not be observed from the experimental result. It is also made clear that the statistical distribution and P-S-N curve model must be described from the same formula, and a rating stress such as bearing rating load is successfully introduced to the 3-parameter Weibull and log-normal distribution.
