# Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy

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## Abstract

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## 1. Introduction

## 2. Materials and Methods

## 3. Results and Discussions

## 4. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 2.**(

**a**) Specimen with circular cross section (in mm) for conventional fatigue test and dwell fatigue test; (

**b**) specimen with square cross section (in mm) for dwell fatigue test.

**Figure 3.**(

**a**) Schematic of loading waveforms for conventional fatigue test; (

**b**) schematic of loading waveforms for dwell fatigue test.

**Figure 4.**Variation of fatigue life with the rise and fall time for both the conventional fatigue test and the dwell fatigue test, in which the lines denote the linear regression results of the fatigue life with the rise and fall time in log–log scale.

**Figure 5.**Fracture surface morphology of failed specimens under dwell fatigue test. A-1 ~ A-3: C-specimen with N

_{f}= 1016 for rise and fall time 2 s; B-1 ~ B-3: C-specimen with N

_{f}= 709 for rise and fall time 2 s; C-1 ~ C-3: S-specimen with N

_{f}= 833 for rise and fall time 2 s; D-1 ~ D-3: S-specimen with N

_{f}= 665 for rise and fall time 2 s. A-2, B-2, C-2, and D-2 are close-ups of A-1, B-1, C-1, and D-1, respectively; A-3, B-3, C-3, and D-3 are close-ups of the crack initiation regions where the arrows point to in A-2, B-2, C-2, and D-2, respectively; the arrows pointing to in A-3 and D-3 denote the facets.

**Figure 6.**Fracture surface morphology of failed specimens under conventional fatigue test. A-1 ~ A-3: Specimen with N

_{f}= 1141 for rise and fall time 2 s; B-1 ~ B-3: Specimen with N

_{f}= 728 for rise and fall time 200 s. A-2 and B-2 are close-ups of A-1 and B-1, respectively; A-3 and B-3 are close-ups of the crack initiation regions where the arrows point to in A-2 and B2, respectively.

**Table 1.**Loading information and the associated fatigue life of specimens in Figure 4.

Specimen No. | Specimen Type | Maximum Stress/MPa | Stress Ratio R | Rise Time/s | Fall Time/s | Dwell Time/s | Fatigue Life/cyc |
---|---|---|---|---|---|---|---|

1 | C−specimen | 929.1 | −1 | 2 | 2 | 60 | 1016 |

2 | C−specimen | 929.1 | −1 | 2 | 2 | 60 | 813 |

3 | C−specimen | 929.1 | −1 | 2 | 2 | 60 | 709 |

4 | C−specimen | 929.1 | −1 | 20 | 20 | 60 | 884 |

5 | C−specimen | 929.1 | −1 | 20 | 20 | 60 | 628 |

6 | C−specimen | 929.1 | −1 | 20 | 20 | 60 | 607 |

7 | C−specimen | 929.1 | −1 | 20 | 20 | 60 | 545 |

8 | C−specimen | 929.1 | −1 | 110 | 110 | 60 | 641 |

9 | C−specimen | 929.1 | −1 | 200 | 200 | 60 | 499 |

10 | C−specimen | 929.1 | −1 | 200 | 200 | 60 | 624 |

11 | C−specimen | 929.1 | −1 | 2 | 2 | 0 | 1141 |

12 | C−specimen | 929.1 | −1 | 2 | 2 | 0 | 1316 |

13 | C−specimen | 929.1 | −1 | 20 | 20 | 0 | 1197 |

14 | C−specimen | 929.1 | −1 | 20 | 20 | 0 | 1163 |

15 | C−specimen | 929.1 | −1 | 20 | 20 | 0 | 838 |

16 | C−specimen | 929.1 | −1 | 200 | 200 | 0 | 832 |

17 | C−specimen | 929.1 | −1 | 200 | 200 | 0 | 728 |

18 | S−specimen | 929.1 | −1 | 2 | 2 | 60 | 665 |

19 | S−specimen | 929.1 | −1 | 2 | 2 | 60 | 833 |

20 | S−specimen | 929.1 | −1 | 2 | 2 | 60 | 737 |

21 | S−specimen | 929.1 | −1 | 20 | 20 | 60 | 656 |

22 | S−specimen | 929.1 | −1 | 20 | 20 | 60 | 524 |

23 | S−specimen | 929.1 | −1 | 20 | 20 | 60 | 580 |

24 | S−specimen | 929.1 | −1 | 200 | 200 | 60 | 479 |

25 | S−specimen | 929.1 | −1 | 200 | 200 | 60 | 478 |

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**MDPI and ACS Style**

Song, Q.; Li, Y.; Wang, L.; Huang, R.; Sun, C.
Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy. *Metals* **2019**, *9*, 914.
https://doi.org/10.3390/met9080914

**AMA Style**

Song Q, Li Y, Wang L, Huang R, Sun C.
Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy. *Metals*. 2019; 9(8):914.
https://doi.org/10.3390/met9080914

**Chicago/Turabian Style**

Song, Qingyuan, Yanqing Li, Lei Wang, Ruxu Huang, and Chengqi Sun.
2019. "Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy" *Metals* 9, no. 8: 914.
https://doi.org/10.3390/met9080914