Mechanismenbasierte Modellierung und Simulation des VHCF-Wechselverformungsverhaltens austenitischer Edelstähle

In this work, a model describing the VHCF deformation behaviour of a metastable and a stable austenitic stainless steel is presented and solved by means of a boundary element method. Based on the experimental examination of the fatigue behaviour of both alloys until very high number of loading cycles (very high cycle fatigue, VHCF) characteristic mechanisms of plastic deformation in shear bands and of deformation-induced phase transformation from the austenite to the α`-martensite are described. A 2-D boundary element method is extended regarding the description of elastic anisotropic properties and the calculation of spatial deformation. Solving the model by using the boundary element method allows simulating the cyclic plastic deformation within two-dimensional microstructures. In extended studies, the effect of a predeformed condition and of a moderate increase of temperature is also considered. Simulation results are directly compared to the observed deformation evolution on real fatigue specimen surfaces and, in addition, a comparison is carried out on the basis of the resonant behaviour of fatigue specimens and of modelled microstructures. Good accordance of results confirms the model assumptions and thereby provides a more profound understanding of the VHCF deformation behaviour of both austenitic stainless steels.