Very high cycle fatigue at elevated temperatures: A review on high temperature ultrasonic fatigue

Effects of microstructure on crack initiation in super martensitic stainless steel under very‐high‐cycle fatigue at elevated temperature

“…Thick oxide layer will hinder the formation of the crack, and then the fatigue crack initiation will be dominant by other factors such as microstructure slip or internal inclusion 49,50 . If the oxide layer is thin enough to be broken by the applied cyclic loading, the brittle oxide layer would create stress concentration resulting in crack initiation from the oxide layer 48,51 . In the fracture morphology observation of the failure samples in this experiment, there is nonobvious oxidation, that is, the oxide layer has not been formed or is difficult to observe, and cracks will initiate from the surface or internal microstructure slip or internal inclusion.…”

“…In elevated‐temperature ultrasonic fatigue testing, there exists a competition between internal defects (e.g., microstructural discontinues and including) and surface oxidation‐elated defects concerning VHCF crack initiation. The dominant mechanism depends on the thickness of the oxide layer as well as the microstructure of the studied materials (e.g., absence/presence of inclusion and process‐related defects) 48 . Thick oxide layer will hinder the formation of the crack, and then the fatigue crack initiation will be dominant by other factors such as microstructure slip or internal inclusion 49,50 .…”

“…49,50 If the oxide layer is thin enough to be broken by the applied cyclic loading, the brittle oxide layer would create stress concentration resulting in crack initiation from the oxide layer. 48,51 In the fracture morphology observation of the failure samples in this experiment, there is nonobvious oxidation, that is, the oxide layer has not been formed or is difficult to observe, and cracks will initiate from the surface or internal microstructure slip or internal inclusion. In this study, the fracture morphology of all failed samples show no obvious oxide layer at the source of initiation as seen in other literatures, 51 so the mechanism of surface crack initiation and propagation caused by oxide is no longer applicable in this experiment.…”

“…The dominant mechanism depends on the thickness of the oxide layer as well as the microstructure of the studied materials (e.g., absence/presence of inclusion and process-related defects). 48 Thick oxide layer will hinder the formation of the crack, and then the fatigue crack initiation will be dominant by other factors such as microstructure slip or internal inclusion. 49,50 If the oxide layer is thin enough to be broken by the applied cyclic loading, the brittle oxide layer would create stress concentration resulting in crack initiation from the oxide layer.…”

A review on isothermal rotating bending fatigue failure: Microstructural and lifetime modeling of wrought and additive manufactured alloys

“…Instead, the lifetime might be constrained by a variety of damage mechanisms, such as fatigue, creep, or oxidation, which might operate indecently when combined 9,10 . The majority of technical components, such as car engines, parts of aviation engines, and components of power plants, operate under conditions of mechanical fatigue at high temperatures 11,12 . Material fatigue responses can be categorized into three groups based on how temperature affects them: temperature‐dependent deformation, temperature‐dependent changes in microstructure, and temperature‐dependent environmental effects 11,13,14 .…”