Fatigue limit prediction of notched hard steel parts under uniaxial and torsional loading

摘要

The fatigue limit of notched and smooth specimens of a bainitic bearing steel is measured and calculated under tension-compression, repeated tension, rotating bending and alternating torsion. The notch effect in this steel can be fully explained as a statistical size and multiaxiality effect. The calculation is based on the weakest link model after Weibull and a new three parametric high cycle fatigue criterion, which includes the effect of multiaxiality and mean stresses. It is shown that the physical basis of the weakest-link model are inclusions which cause crack initiation at the fatigue limit, if the stressed volume exceeds a certain value.