Experimental Analysis and Constitutive Modeling of Cyclic Behavior of 304L Stainless Steel: Introduction of Isotropic Hardening Fading Effect

In this study, the mechanical behavior of Austenitic stainless steel 304L under low cycle fatigue was investigated under different uniaxial strain-controlled loadings of 0.5%, 0.8%, 1.0%, 1,2% and 1.5%. The analysis of the experimentally determined strain vs stress hysteresis curves were carried out to achieve stress quantities such as amplitude stress, peak effective stress, and peak back stress. It was observed that in the early stage of cyclic loading, material underwent initial hardening, followed by softening phenomena which were more considerable in the lower strain range. Before the failure, the secondary hardening was observed at the final stage. In addition to accumulated plastic strain, it was shown that the peak back stress and peak effective stress which is associated with isotropic hardening and kinematic hardening behavior, respectively, are influenced by the strain range effect. Therefore, the coefficient of recall term that appeared in the Armstrong_Frederick nonlinear kinematic hardening model was considered to be dependent on the radius of the memory surface. Furthermore, to increase the ability of the plasticity constitutive model to show a smooth transition between various hardening stages, the radius of the yield surface which is associated with the isotropic hardening rule was equipped with the fading effect. Finally, by the comparison of numerical and experimental results, the capability of the rate-dependent constitutive model over classical rate-independent plasticity in the prediction of mechanical behavior of steel 304L under strain-controlled cyclic loading was revealed.