Fatigue life assessment regarding different influences on the HCF/VHCF behavior of a martensitic steel

¹ Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Strasse 18, Leoben 8700, Austria
² LEC GmbH, Inffeldgasse 19/II, Graz 8010, Austria

^* Corresponding author: igor.milosevic@unileoben.ac.at

Abstract

Modern applications require a special treatment when the conventional specimen size is much larger than the component size. Additional to that, high sophisticated materials are used for highly loaded components. Often the conventional fatigue limit is exceeded and loads are applied in the VHCF regime. Focus was put on the lifetime calculation and the implementation of investigated fatigue data of a X5CrNiCuNb-16-4 type steel. Two specimen geometries with diameters D_7.5=7.5 mm and D_2.5=2.5 mm were tested at R=-1, at room temperature and up to 10⁹ cycles to failure. The application of different software tools (FEMFAT, fe-safe) showed several issues based on the current results. Results showed a change of crack initiation mechanism to subsurface crack initiation at approx. 2x10⁶ cycles to failure. The gradient based correction of the reference fatigue data showed a good applicability up to 2x10⁶ cylces. The application of fe-safe allows the flexible modification of S/N parameters over the whole cycle range. The usage of the actual material configuration introduced several important questions regarding the fatigue data and the implementation into lifetime calculation tools.