Cyclic deformation behavior and damage mechanism of 316H stainless steel under low-cycle fatigue loading at 650 °C

Abstract

Low-cycle fatigue tests were conducted at 650 °C to investigate the cyclic deformation behavior and damage mechanism of 316H stainless steel at various strain amplitudes ranging from 0.2 % to 1.0 %. The relationship between macroscopic deformation properties and microscopic physical mechanisms was revealed based on the comprehensive analysis of local deformation misorientation and dislocation microstructure. Results showed that the 316H stainless steel presented non-Masing behavior at strain amplitudes lower than 0.6 %, and Masing behavior at strain amplitudes larger than 0.6 %, which was primarily attributed to the evolution of dislocation configurations. The crack initiation and propagation behavior at 0.2 % strain amplitude, characterized by the transgranular mode, was dominated by fatigue. However, the intergranular damage became dominant at the strain amplitude larger than 0.2 %, due to the intensified strain localization at grain boundaries. Moreover, the plastic strain energy was used for life assessment with the consideration of non-Masing behavior.