Ultra-high Cycle Fatigue Characterization and Ultra-slow Crack Growth of Titanium Alloys

钛合金超高周疲劳表征和超慢裂纹扩展

• 批准号: 19F19730
• 负责人: 陳 強
• 金额: $ 1.47万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for JSPS Fellows
• 财政年份: 2019
• 资助国家: 日本
• 起止时间: 2019-07-24 至 2021-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-19F19730/
• 关键词: Titanium Alloy; Ultra-High Cycle Fatigue; Crack Initiation; Crack Growth; Bimodal Structure; Fatigue; Titanium Alloys; Bimodal Microstructure; Ultrasonic Fatigue

In ultra-high cycle fatigue failure, ultra-slow crack growth of small cracks has great contribution to fatigue life. Micron-sized notches were prefabricated on the specimen surface by focused ion beam (FIB) technology. Ultrasonic fatigue tests (20 kHz) were suspended at specific life intervals and field emission scanning electron microscope (SEM) was used to carefully observe the fatigue crack growth behavior at end of the notches. Two types of bimodal microstructures and different cyclic stress amplitudes were employed to investigate the ultra-slow crack growth behavior of the alloys. The path of small fatigue cracks is relatively straight at the primary alpha grain, whilst it is more tortuous at the colony. The colony has a higher resistant to the growth of small fatigue cracks than the primary alpha grain in the bimodal microstructure. If small fatigue cracks pass through very few colonies, fatigue crack growth rate will be higher, even if a lower cyclic stress was applied. Owing to the difference in local microstructure characteristics, the growth rate data of small fatigue cracks show obvious dispersity. The higher volume fraction of colonies should be beneficial to improve the growth resistance of small fatigue cracks. In addition, we also found that deformation twins that were induced by the laser shock peening, can retard the growth of small fatigue cracks. These results may provide insightful ideas for the anti-fatigue microstructure design of titanium alloys.

在超高周疲劳破坏中，小裂纹的超慢裂纹扩展对疲劳寿命有很大贡献。采用聚焦离子束（FIB）技术在试样表面预制了100 μ m大小的缺口。在特定的寿命间隔内暂停超声疲劳试验（20 kHz），并使用场发射扫描电子显微镜（SEM）仔细观察缺口端部的疲劳裂纹扩展行为。采用两种双峰组织和不同的循环应力幅研究了合金的超慢裂纹扩展行为。小疲劳裂纹的路径在初级α晶粒处相对较直，而在殖民地处则较为曲折。在双态组织中，殖民地比初生α晶粒具有更高的抗疲劳小裂纹扩展能力。如果小的疲劳裂纹穿过非常少的菌落，则即使施加较低的循环应力，疲劳裂纹扩展速率也将较高。由于局部组织特征的差异，疲劳小裂纹扩展速率数据表现出明显的分散性。较高的菌落体积分数有利于提高疲劳小裂纹的扩展抗力。此外，我们还发现激光冲击强化诱发的形变孪晶可以延缓疲劳小裂纹的扩展。这些结果可为钛合金抗疲劳组织设计提供参考。

项目成果

Ultra-high cycle fatigue crack initiation and growth in titanium alloy

钛合金超高周疲劳裂纹萌生和扩展

• 发表时间: 2021
• 作者: Kun Yang;Qiang Chen;Qing-Yuan Wang
• 通讯作者: Qing-Yuan Wang

Vacuum retarding and air accelerating effect on the high-cycle and very-high-cycle fatigue behavior of a ZK60 magnesium alloy

真空缓速和空气加速对ZK60镁合金高周和甚高周疲劳行为的影响

• DOI: 10.1016/j.matdes.2020.109310
• 发表时间: 2021-01-15
• 期刊: MATERIALS & DESIGN
• 影响因子: 8.4
• 作者: Liu, Yongjie;Chen, Yao;Wang, Qingyuan
• 通讯作者: Wang, Qingyuan

Sichuan University/Chengdu University/Shanghai Jiao Tong University(中国)

四川大学/成都大学/上海交通大学（中国）

Competing crack initiation behaviors of a laser additively manufactured nickel-based superalloy in high and very high cycle fatigue regimes

激光增材制造的镍基高温合金在高循环和极高循环疲劳状态下的竞争裂纹萌生行为

• DOI: 10.1016/j.ijfatigue.2020.105580
• 发表时间: 2020-07-01
• 期刊: INTERNATIONAL JOURNAL OF FATIGUE
• 影响因子: 6
• 作者: Yang, Kun;Huang, Qi;Chen, Qiang
• 通讯作者: Chen, Qiang

Sichuan university/Chengdu university(中国)

四川大学/成都大学（中国）