Establishment of unified creep–fatigue life prediction under various temperatures and investigation of failure physical mechanism for Type 304 stainless steel

Abstract

AbstractInvestigations into creep–fatigue life and the corresponding failure physical mechanism are crucial for guaranteeing the structural integrity of components. In this work, a series of strain‐controlled fatigue and creep–fatigue tests were performed at different temperatures. Then, the EBSD‐TEM combinative analysis was performed to reveal the microstructure evolution. The creep failure parameter dependence derived from standard creep experimental data and their importance in further creep–fatigue employment were discussed. Results show that strain energy density has better relevance than ductility in connecting with creep failure. The temperature‐dependent critical strain energy density and an equivalent failure strain energy density, considering geometric effect, were incorporated with the current energy‐based model, which enables creep–fatigue life scatter within a factor of 1.5. Moreover, multi‐slip activations and severe slip interactions under creep–fatigue conditions were responsible for the ultimately lifetime reductions based on microstructure observations.