Study seismic performance of duplex stainless steel under large strain amplitude by cyclic loading test.

The existing experimental data on stainless steel are limited to a small strain range (<1.50%), which is not enough to analyze the response of stainless steel structures in large plastic strain under a strong earthquake. This paper presents cyclic loading tests containing constant and variable strain amplitude up to 5.0% to study the low-cycle fatigue properties of duplex stainless steel S2205. The cyclic skeleton curve and the fatigue life equation are established and the hysteretic behavior and cyclic hardening-softening characteristics are discussed. The analyzed results show that steel S2205 exhibits a nonlinear stress-strain relationship with high yield strength and good ductility. The hysteresis loops of the material are plump and the equivalent viscous damping ratio is about 0.5 at strain of 5.0%, indicating a good energy dissipation capacity. Under constant amplitude cyclic loading, steel S2205 exhibits cyclic hardening in the first few fatigue cycles and then undergoes prolonged cyclic softening until fracture. The plastic strain energy-life model is found to be appropriate for fitting the low-cycle fatigue life equation. Furthermore, the parameters of the cyclic constitutive model are derived, providing basic data for seismic analysis of duplex stainless steel structures under large plastic strain values. • Constant and variable strain-controlled cyclic tests were designed. • Parameters representing cyclic response characteristics were derived. • The degree of cyclic hardening and softening was quantified. • The low-cycle fatigue life equations under large strain are fitted. • Cyclic plastic constitutive parameters were fitted to describe mixed hardening behavior. [ABSTRACT FROM AUTHOR]