Experimental characterization and two-dimensional simulation of short-crack propagation in an austenitic–ferritic duplex steel

On the basis of a thorough experimental study of the interactions between microstructural features, like the crystallographic orientation distribution and the respective crack propagation rate a numerical micro-mechanical crack-propagation model has been developed, which accounts for the abnormal propagation behaviour of short cracks as compared to long cracks in a two-phase austenitic-ferritic duplex steel. In order to simulate real cracking events, the barrier strengths of phase and grain boundaries, beside the orientation of slip planes as the most important input parameters for the model, were determined by means of a Hall–Petch analysis using cyclic stress–strain data of single-phase austenitic and ferritic steels as well as of the duplex steel.