Microscale crystal slip and macroscopic cold creep transition in dwell fatigue

Within the framework of cold creep and temperature sensitivity, relations between microscopic slip and macroscopic creep were established in dwell fatigue. The local rate dependent responses were found to be log-arithmic creep in high stress state and exponential form in low stress state, respectively. Micromechanical evidences were provided in rationalizing cold creep at room temperature and creep saturation of titanium alloys towards around 200 degrees C. This was supported by the geometrically necessary density (GND) evolution during the stress dwell period. The roles of local rate dependence, material elastic and plastic anisotropy in load shedding were discussed on possible dwell facets nucleation.

Automated summary

This study established the relationship between microscopic slip and macroscopic creep in dwell fatigue within the framework of cold creep and temperature sensitivity, supported by micromechanical evidence. The research demonstrated that the local rate dependent responses vary in form under different stress states, which is crucial in understanding the behavior during dwell fatigue. The roles of local rate dependence, material anisotropy, and other factors in load shedding were discussed in the nucleation of possible dwell facets.