Experimental characterization of short fatigue crack kinetics in an austeno-ferritic duplex steel

AbstractThe present work reports the damage evolution during low (LCF) and high (HCF) cycle fatigue behavior in an embrittled duplex stainless steel type DIN 1.4462. For LCF, the results have shown microcracks nucleating mainly along the most favorable oriented slip planes regarding the Schmid factor in the ferrite and propagating along similar planes. Occasionally, they nucleate at α-α grain boundaries. For these cracks, phase boundaries seem to be an effective barrier against the propagation in contrast to grain boundaries. During HCF, cracks initiate at α-α grain or at α-γ phase boundaries and propagate in an intercrystalline mode and propagate in the neighbor grain. LCF and HCF characteristics have been related to the associated dislocation structure and with the local crystallography obtained by EBSD analysis in order to understand the propagation behavior