Mechanism of Precipitate Microstructure Affecting Fatigue Behavior of 7020 Aluminum Alloy
1
School of Materials Science and Engineering, Central South University, Changsha 410083, China
2
Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China
3
School of Civil Engineering, Harbin Institute of Technology, Harbin 150001, China
*
Author to whom correspondence should be addressed.
Materials 2020, 13(15), 3248; https://doi.org/10.3390/ma13153248
Received: 7 July 2020
/
Revised: 17 July 2020
/
Accepted: 17 July 2020
/
Published: 22 July 2020
The effect of different precipitate microstructures obtained by different heat treatments on fatigue behavior of 7020 aluminum alloy was investigated. The fine Guinier Preston I (GPI) zones in the under-aged alloy can be repeatedly sheared by dislocations produced in cyclic loading, making the fatigue crack initiate difficultly and fatigue crack path propagate tortuously. Fatigue strength and fatigue crack propagation resistance of the alloy with shearable precipitates are much higher than those of the alloy with unshearable precipitates. The peak-aged alloy with continuous grain boundary precipitate (GBP) and narrow precipitate free zone (PFZ) is prone to initiate fatigue cracks and reduce fatigue strength. With the growth of unshearable precipitates, the fatigue strength of the alloy firstly increases and then decreases. Precipitates with moderate size in the over-aged alloy improve the roughness-induced crack closure (RICC) effect. Soft matrix with appropriate width between the precipitates can promote the slip reversibility and relax the crack tip stress. The fatigue strength of the moderately over-aged alloy reaches to 122.1 MPa at 107 cycles of loading, and the fatigue crack growth rate (FCGR) is 35.6% slower than that of the peak-aged alloy at ΔK of 10 MPa·m1/2.
View Full-Text
Keywords:
7020 aluminum alloy; artificial aging; precipitate; fatigue strength; fatigue crack growth
▼
Show Figures
Figure 1
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
MDPI and ACS Style
Shan, Z.; Liu, S.; Ye, L.; Li, Y.; He, C.; Chen, J.; Tang, J.; Deng, Y.; Zhang, X. Mechanism of Precipitate Microstructure Affecting Fatigue Behavior of 7020 Aluminum Alloy. Materials 2020, 13, 3248. https://doi.org/10.3390/ma13153248
AMA Style
Shan Z, Liu S, Ye L, Li Y, He C, Chen J, Tang J, Deng Y, Zhang X. Mechanism of Precipitate Microstructure Affecting Fatigue Behavior of 7020 Aluminum Alloy. Materials. 2020; 13(15):3248. https://doi.org/10.3390/ma13153248
Chicago/Turabian StyleShan, Zhaojun, Shengdan Liu, Lingying Ye, Yiran Li, Chunhua He, Jin Chen, Jianguo Tang, Yunlai Deng, and Xinming Zhang. 2020. "Mechanism of Precipitate Microstructure Affecting Fatigue Behavior of 7020 Aluminum Alloy" Materials 13, no. 15: 3248. https://doi.org/10.3390/ma13153248
Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.
