Abstract
Ratcheting fatigue behavior of bainitic 2.25Cr1MoV forged steel was investigated at 455 oC with various hold periods at peak and valley stress. The incorporation of peak stress holding widened stress-strain hysteresis loop, and this enlargement was more significant under peak/valley hold due to the created creep strain. Fatigue life was greatly shortened with the increase of mean stress or stress amplitude, and this reduction was accelerated when stress holding was involved. The extension of stress holding resulted in shorter fatigue life, but the fatigue lives were quite close when the sum of holding period was equal, regardless of the holding direction. Fatigue damage and creep damage in creep-ratcheting fatigue tests were estimated by the time fraction rule, and creep damage became dominant at long hold period, which was closely related to shortened fatigue lives with stress holding. The linear damage summation rule was used for fatigue life prediction, and it gave satisfactory predictions for peak holding mode. A new model was proposed by introducing stress ratio to consider the influence of asymmetric cycling, and estimates for peak/valley holding were greatly improved.
Original language | English |
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Pages (from-to) | 555-561 |
Number of pages | 7 |
Journal | Procedia Structural Integrity |
Volume | 17 |
DOIs | |
State | Published - 2019 |
Externally published | Yes |
Event | 3rd International Conference on Structural Integrity, ICSI 2019 - Funchal, Madeira, Portugal Duration: Sep 2 2019 → Sep 5 2019 |
Funding
The authors gratefully acknowledge financial support for this work from the National Natural Science Foundation of China (No. 51435012) and Ph.D. Programs Foundation of Ministry of Education of China (No. 20130032110018).