Even after one billion cycles, components made of metallic materials may show traces of plastic deformation without being failed. However, the same components can fracture at the same load but a lower number of cycles. The hypothesis of the present research that the resistance of microstructural barriers to dislocation motion decides about the occurrence of fatigue damage will be quantified by duplex steel of different strength of the ferrite and austenite phase. Furthermore, important aspects, such as the simultaneous plasticity and residual stress distribution between the two phases, as well as the stochastic arrangement of fatigue-critical microstructural clusters will be analyzed. The important question about the influence of environmental effects on the VHCFdamage is going to be addressed by experiments in different atmospheres. Three interacting modern experimental and theoretical approaches are used: (i) ultrasonic fatigue testing in combination with in-situ analysis techniques (ii) three-dimensional microstructural reconstruction and spatially-resolved diffraction measurements using high energy synchrotron radiation and (iii) finite element modeling of the elastic and plastic anisotropic fatigue deformation within the twophase microstructure as a base of a damage-tolerant life prediction concept for the VHCF regime as well as an possibility for structural optimization of fatigue-resistant materials.
DFG Programme
Priority Programmes
International Connection
France
