Fatigue and Cyclic Plasticity Properties of a Super-Austenitic Stainless Steel
Tension-compression, torsion and axial-torsion experiments were conducted on AL-6XN® alloy. The main goal was to investigate experimentally, in detail, the cyclic plasticity behavior as well as fatigue life of AL-6XN® steel. Details of cyclic stress-strain response were collected during the experiments, which can serve as a baseline for development of cyclic plasticity model for this material. Microscopic observations of cracking behavior conducted in the present study allow connecting the fracture mechanism with fatigue life prediction. It was observed, that fatigue life of this material is a function of the fracture mode (mixed or tensile). The mixed cracking was observed in the specimens tested under higher applied strain levels, while the tensile cracking was revealed in the tests under lower strain amplitudes. Strain-life curves of the specimens failed in mixed mode and of those failed in tensile mode run parallel to each other, but the specimens that exhibit mixed failure mode show lower fatigue life as compared to the tensile mode specimens. Transition between mixed and tensile cracking orientations was studied in detail. The results of the experimental work presented in this study can serve for design of fatigue models for this material in the future.