Mechanisms of deformation, damage and life behavior of inconel 617 alloy during creep-fatigue interaction at 700 °C

The continuous fatigue tests and creep-fatigue tests with the imposition of strain hold at the peak strain were conducted at 700 degrees C on Inconel 617 alloy. The strain amplitude of 0.25%, 0.30%, 0.35%, 0.40%, and hold time of 60 s, 600 s and 1800 s were used. The cyclic deformation behavior and dynamic strain aging (DSA) were discussed. The strain localization, dislocation substructure and precipitation behavior were carefully characterized, which provided physical information to understand the cyclic deformation behavior. The dominant damage mechanism and damage interaction, responsible for the cracking behavior were identified based on the fracture surface observation and secondary cracks morphology. The cyclic life saturation effect was comprehensively elucidated from the perspective of macroscopic mechanical response and microscopic deformation mechanism.