Very high cycle fatigue of bearing steels with artificial defects in vacuum

At high-strength steels very high cycle fatigue (VHCF) failure always occurs at subsurface inclusions. As a result, the failure shows large scatter and is not observable or predictable prior to failure. In order to understand the mechanisms leading to crack initiation in VHCF, it is necessary to make the failure observable. Within our work, a new testing procedure is introduced that enables the simulation of subsurface conditions at the surface and thereby the localisation of the failure. Therefore, specimens with artificial surface defects were tested in vacuum atmosphere. In our work, we will show the testing procedure and the validation of the results. Further, the transferability of our results on the failure at subsurface inclusions is discussed.