Creep and fatigue behavior of 316L stainless steel at room temperature: Experiments and a revisit of a unified viscoplasticity model

A series of experiments was conducted to determine the fatigue and time-dependent behaviors of 316L stainless steel, including monotonic tensile and stress relaxation with different strain rates, fully reversed cyclic plasticity, creep and relaxation interaction, and cyclic stress relaxation tests. Although the material exhibited slight strain rate sensitivity from monotonic testing, considerable decay stress was observed in the relaxation during the following strain holding period. From the interaction tests between creep and stress relaxation with alternate strain and stress holding, we examined the evolution of the inelastic strain rate and found that the overall decelerating inelastic strain rate was detected regardless of the sequence of the stress and strain holding. Moreover, a typical unified viscoplasticity model was selected to simulate the creep and fatigue behaviors for time-dependent materials. We found that despite satisfactory description for most experimental results, inclusion of the static recovery term in the back stress evolution led to inappropriate prediction of the inelastic strain rate evolution.