Abstract
The role of thermal cycling on the deformation behaviour and microscopic damage mechanisms of 316L stainless steel are clarified through isothermal fatigue (IF) and thermomechanical fatigue (TMF) tests under various temperature ranges. Corresponding microscopic damage mechanism is revealed based on the analysis of dislocation structure, plastic deformation, and crack initiation mode. Results show that the introduction of thermal cycling, as well as an increase in average temperature and temperature difference, result in the saturation of cyclic peak stresses, a decrease in fatigue life, and an intensification of dynamic strain ageing (DSA). Notably, under TMF loading at the same average temperature, there is a significant recovery process compared to IF. High-density dislocations transform into low-energy dislocation structures through cross-slip, indicating a pronounced recovery phenomenon. At large temperature differences and high average temperatures, the accumulation of dislocation tangles at grain boundaries and the formation of dislocation cell structures lead to severe incoherence in plastic deformation and the accumulation of damage. Furthermore, the introduction of thermal cycling and an increase in temperature differences also induce severe creep damage. It is observed that the dominant crack initiation mode changes from fatigue-dominated transgranular cracking to oxidation-induced intergranular cracking as the average temperature increases. Finally, a modified life prediction model is developed by incorporating thermal plastic strain energy to reflect the effect of thermal cycling on TMF behaviour.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.