Abstract
The ratcheting behaviour of a bainite 2.25Cr1MoV steel was studied with various hold periods at 455°C. Particular attention was paid to the effect of stress hold on whole-life ratcheting deformation, fatigue life, and failure mechanism. Results indicate that longer peak hold periods stimulate a faster accumulation of ratcheting strain by contribution of creep strain, while double hold at peak and valley stress has an even stronger influence. Creep strains produced in peak and valley hold periods are noticeable and result in higher cyclic strain amplitudes. Dimples and acquired defects are found in failed specimen by microstructure observation, and their number and size increase under creep-fatigue loading. Enlarged cyclic strain amplitude and material deterioration caused by creep lead to fatigue life reduction under creep-fatigue loading. A life prediction model suitable for asymmetric cycling is proposed based on the linear damage summation rule.
| Original language | English |
|---|---|
| Pages (from-to) | 1937-1949 |
| Number of pages | 13 |
| Journal | Fatigue and Fracture of Engineering Materials and Structures |
| Volume | 42 |
| Issue number | 9 |
| DOIs | |
| State | Published - 2019 |
| Externally published | Yes |
Funding
The authors gratefully acknowledge financial support for this work from the National Natural Science Foundation of China (No. 51435012) and PhD Programs Foundation of Ministry of Education of China (No. 20130032110018).
Keywords
- creep-fatigue loading
- failure mechanism
- life prediction
- ratcheting strain