Constitutive modelling for isothermal low-cycle fatigue and fatigue-creep of a martensitic steel

An improved unified viscoplastic model is developed within the framework of the Chaboche model in order to simulate the mechanical behaviour of a martensitic steel under Low-Cycle Fatigue (LCF) and Low-Cycle Fatigue-Creep (LCFC) loadings at 550 degrees C. The effects of strain rate sensitivity, static recovery, strain range-dependent cyclic softening, along with the effect of additional hardening under non-proportional loading are incorporated into the constitutive equations. The non-linear kinematic hardening rule is modified in such a way that it enables the simulation of the evolutionary behaviour of mean stress and the effect of decelerating stress relaxation. Finally, the prediction capability of the proposed model is illustrated for the experimental data obtained from the various strain-controlled axial-torsional tests.

Automated summary

An improved unified viscoplastic model is developed within the Chaboche framework to simulate the mechanical behavior of a martensitic steel under various loading conditions, with validation through experimental data.