CHARACTERIZATION OF LOW-CYCLE FATIGUE AND CREEP-FATIGUE INDUCED DAMAGE IN A 316L STAINLESS-STEEL

The damage induced by low-cycle fatigue and low-cycle fatigue/creep of a 316L stainless steel has been quantified both at the fracture surfa ces and in the bulk of the tested material. Examination of the fractur e surfaces revealed that continuous fatigue produces transgranular dam age, but, with the incorporation of dwell periods, into pure low-cycle fatigue cycles, an alternation of transgranular and intergranular dam age regions is observed. A rationalization of both the mechanical low- cycle fatigue response of the material and the characterizing paramete rs of the damage induced by the deformation, for the investigated mate rial and similar steels reported in the literature, has been performed . The predictions of the microstructural damage based relationships yi elded by this approach have been examined against experimental observa tions. Low-cycle fatigue crack nucleation and crack propagation lives agree with those experimentally observed. Finally, a re-formulation of these relationships in terms of fracture mechanics has been attempted . The applicability of the concepts underlying this approach is critic ally examined.