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Ti4822 钛铝合金超声疲劳尺寸效应研究
Study of the Size Effect of Ultrasonic Fatigue in Ti4822 TiAl Alloy
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- DOI:
- 作者:
- 郑严 1, 2, 3, 4，梅金娜 1, 2，朱斌 1，蔡振 1
ZHENG Yan1, 2, 3, 4,MEI Jinna1, 2,ZHU Bin1,CAI Zhen1
- 作者单位:
- 1. 苏州热工研究院有限公司，江苏 苏州 215004；2. 国家核电厂安全及可靠性工程技术研究中心，江苏 苏州 215004；3. 天津 大学化工学院，天津 300350；4. 广西防城港核电有限公司，广西 防城港 538001
1. Suzhou Nuclear Power Research Institute Co., Ltd., Suzhou 215004,China; 2. National Engineering Research Center of Nuclear Power Plant Safety & Reliability, Suzhou 215004,China; 3. School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350,China; 4. Guangxi Fangchenggang Nuclear Power Co., Ltd., Fangchenggang 538001,China
- 关键词:
- 钛铝合金；超声疲劳；尺寸效应；Ti4822
TiAl alloy; ultrasonic fatigue; size effect; Ti4822 alloy
- 摘要:
- 通过 3 种不同尺寸试样(平行段直径 2、3 和 5mm)的高温超声疲劳试验，研究了 Ti4822 合金典型服役温度(650 ℃)下的疲劳尺寸效应，并基于高应力体积理论，提出了 Ti4822 合金高温超高周疲劳(VHCF)极限的预测方法，分析了 Ti4822 合金的裂纹萌生起裂机制。 研究表明，Ti4822 高温 VHCF 极限受到尺寸效应的影响，疲劳极限随试样平行段直径的增大而减小； 提出的 Ti4822 合金高温 VHCF 极限预测方法可以预测拟合范围内的疲劳极限， 并且可能适用于Ti4822 合金其他温度下 VHCF 极限的预测；Ti4822 合金裂纹起裂机制包含非金属夹杂物滑移起裂和晶界滑移起裂两种，裂纹起裂点随应力的减小从试样表面向内部移动。The effect of the fatigue size of a Ti4822 alloy under typical service temperatures (650 ℃)was investigated through high-temperature ultrasonic fatigue experiments on three types of samples with different parallel segment diameters (2, 3, and 5 mm). A method for predicting the high-temperature very high cycle fatigue (VHCF) limit of Ti4822 alloy was proposed on the basis of the highly stressed volume theory. The crack initiation mechanisms of typical fatigue samples were also analysed. The results indicate that the high-temperature VHCF limit of Ti4822 is influenced by the size effect, with the diameter of the parallel segment of the sample increasing, leading to a decrease in the VHCF limit. The proposed method for predicting the high-temperature VHCF limit of Ti4822 alloys could predict the fatigue limit within the fitting range andmight be applicable for predicting the VHCF limit of Ti4822 alloys at other temperatures. The crack initiation mechanics of the Ti4822 alloy include two types: nonmetallic inclusion slip initiation and grain boundary slip initiation, and the crack initiation location moves from the surface toward the internal region as the stress decreases.