Cyclic deformation response of austenitic Ni-based alloy: Mechanical behavior, internal stress evolution and microstructural feature.

Cyclic deformation response of an austenitic Ni-based alloy was investigated by symmetrical/asymmetrical strain cycling tests at room temperature (RT) and 350°C. The effects of strain amplitude/ratio and ambient temperature on the cyclic deformation behavior were discussed in terms of microstructural features and internal stresses. Results indicate that the cyclic hardening/softening at RT is mainly attributed to the increase/decrease in back stress. Whilst at 350°C, the contribution of effective stress to cyclic deformation response becomes important due to the planar slip promoted by the occurrence of dynamic strain aging (DSA) throughout the fatigue process. Accordingly, the continuous cyclic hardening at 350°C comes from the combined action of back stress and effective stress. • DSA is present throughout the fatigue life at 350°C. • Physical origin of discrepancy in cyclic deformation response between RT and 350°C is clarified. • Continuous cyclic hardening at 350°C results from the increase of both back and effective stress caused by DSA effect. [ABSTRACT FROM AUTHOR]