Multiaxial low cycle fatigue behavior and life prediction method of 316LN stainless steel at 550 °C

This work studied the uniaxial, torsional and multiaxial low cycle fatigue behavior of 316LN stainless steel at 550 °C. Results show that the normalized kernel average misorientation value can be used to describe the loading path non-proportionality quantitatively. The formation of equiaxed and small-sized dislocation cells leads to the occurrence of continuously cyclic hardening under circular loading path. The crack initiation and early crack growth is dominated by intergranular mode in uniaxial test, whereas the transgranular cracking is observed in multiaxial test. Moreover, a weighting factor, evaluating the contribution of shear fatigue damage to the total multiaxial damage is proposed to modify the damage parameter of Chen-Xu-Huang (CXH) life prediction model, which enables all life data falling into the scatter band of 1.5.