LOW-CYCLE FATIGUE PROPERTIES OF AUSTENITIC STAINLESS STEEL S30408 UNDER LARGE PLASTIC STRAIN AMPLITUDE

Abstract

The application of stainless steel materials in civil structures for seismic protection lies in its low-cycle fatigue characteristic. However, the data of existing research are mainly based on the low-cycle fatigue in small strain amplitudes. To this end, we perform low-cycle fatigue testing of Austenitic stainless steel S30408, which has low yield point and good elongation performance, under the cyclic load with a maximum strain amplitude reaching up to 5%, to fill the gap. The stress-strain response characteristics of the stainless steel material under the cyclic load are analyzed; then, the parameters of the strain-fatigue life relationship and the cyclic-plastic constitutive model used for FEA simulation are extracted. Results show that the stainless steel’s stress-strain curve is nonlinear without a yield plateau, thus presenting a high strength yield ratio and ductility. The hysteresis loops of the material are plump with a shuttle shape and are symmetric to the origin, indicating a fine energy dissipation capacity. The skeleton curve under cyclic loading with cyclic hardening can be significantly reflected by the Ramberg Osgood model, which is affected by the strain amplitude and loading history; it is also different from the monotonic tensile skeleton curve. The strain-fatigue life curve fitted by the Baqusin Manson Coffin model can predict the materials’ fatigue life under different strain amplitudes. The mixed hardening model, including isotropic and kinematic hardening, based on the Chaboche model, is able to simulate the cyclic stress-strain relationship. Further, its parameters can provide basic data information for the seismic design of civil structures when Austenitic stainless steel S30408 is used.