Abstract
Bearing steel (JIS: SUJ2) heat treated to hardness value above 58 HRC has been overwhelmingly used for rolling bearings, ball bushes, and ball splines with rounded shape rolling machine elements. It is thought that for this material when the fatigue test is carried out in the domain of high cycle fatigue of the S-N curve- the so-called Wöhler curve, a fatigue limit appears. This type of fatigue limit has been used in the ISO standard since the year 2000 within life modification factor aXYZ or aSL or aISO for rolling bearings. However, at present even in the life test of bearing or S-N fatigue test of material, the experimental data does not show any apparent sign of the fatigue limit. In this research work, alternating torsion fatigue test for probabilistic stress life (P-S-N) evaluation is carried out under standard stress values, from τ=1 GPa to τ=0.5 GPa for 6 lots made up of a total of 150 samples, and P-S-N curves were determined based on the three-parameter Weibull distribution and lognormal distribution. Based on the result, it is reported that the bearing steel does not show any fatigue limit.
