Interior failure mechanism and life prediction of surface‐treated 17Cr‐Ni steel under high and very high cycle fatigue

The understanding of very high cycle fatigue (VHCF) mechanisms is critical to the development of life prediction approach. For this purpose, high cycle fatigue (HCF) and VHCF properties of a surface‐treated 17Cr‐Ni steel were investigated under axial loading with stress ratio of 0. This steel exhibits the constantly decreasing S‐N characteristics associated with the inclusion‐fisheye induced failure under the HCF and the inclusion‐FGA (fine granular area)‐fisheye induced failure under the VHCF. The cyclic pressing plays an important role in the FGA formation process, but the FGA still can be observed for the stress ratio of zero due to the slight crack closure effect. Two life modelling approaches associated with related failure mechanisms in the HCF and VHCF regimes are proposed based on the agreement between experimental and predicted results.