| WU Hu-lin,LUO Lai-zheng,LIU Chun-miao,ZHAO Fang-chao,WANG Bin,WANG Jian-kun,LIU Jian-hong,FU Zhao-xu.Comparative Study on Corrosion Damage Behavior of High Strength Aluminum Alloys under Synergistic Effect of Marine Atmospheric Environment and Tensile Fatigue Load[J],52(10):220-228 |
| Comparative Study on Corrosion Damage Behavior of High Strength Aluminum Alloys under Synergistic Effect of Marine Atmospheric Environment and Tensile Fatigue Load |
| Received:October 29, 2022 Revised:December 20, 2022 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.10.017 |
| KeyWord:high strength aluminum alloy synergistic effect marine atmospheric environment tensile fatigue load failure mechanism |
| Author | Institution |
| WU Hu-lin |
Southwest Institute of Technology and Engineering, Chongqing , China |
| LUO Lai-zheng |
Southwest Institute of Technology and Engineering, Chongqing , China;School of Chemistry & Chemical Engineering, Chongqing University, Chongqing , China |
| LIU Chun-miao |
School of Chemistry and Materials Science, Ludong University, Shandong Yantai , China |
| ZHAO Fang-chao |
Southwest Institute of Technology and Engineering, Chongqing , China |
| WANG Bin |
School of Chemistry and Materials Science, Ludong University, Shandong Yantai , China |
| WANG Jian-kun |
Southwest Institute of Technology and Engineering, Chongqing , China |
| LIU Jian-hong |
Southwest Institute of Technology and Engineering, Chongqing , China |
| FU Zhao-xu |
Wanning Atmospheric-Material Corrosion Field-National-Observation and Research Station, Hainan Wanning , China |
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| Abstract: |
| As an ideal structural material in engineering, high strength aluminum alloy during service will suffer atmospheric corrosion, especially in the marine atmospheric environment, which will form a thin electrolyte film on the surface of aluminum alloy, and thin electrolyte film corrosion occurs due to the presence of corrosive media such as Cl−, O2, and SO2. In addition, during the service period, the high strength aluminum alloys as the structural materials are also subject to fatigue load. Thus, under the actual service conditions, the aluminum alloy structural materials endure the combined effects of atmospheric corrosion of thin electrolyte film and fatigue load. This work aims to comparatively study the corrosion damage behavior of 2024 and 7A52 high strength aluminum alloys under the synergistic effect of marine atmospheric environment and tensile fatigue load and to reveal the failure mechanism. The outdoor actual marine atmosphere in Wanning test site was used as the thin electrolyte film corrosion environment for alloy samples, and the self-designed fatigue load test device was utilized to apply tensile fatigue load at the same time. A sinusoidal stress waveform was employed to the sample with a frequency of 10 Hz. The stress ratio of the fatigue load was 0.1 and the maximum stress was 30% of the yield stress. Under such test conditions, the samples were subject to elastic deformation in a tension-tension mode. The fatigue load was applied once per month for 1 800 seconds. The corrosion damage law of the two kinds of alloys under the synergistic effect was comparatively analyzed based on electrochemical performance, corrosion morphology, fatigue performance and fracture morphology. The microstructure of 2024 alloy was characterized by a large number of irregularly shaped second phase particles and their surface distribution was not very homogenous. The grain boundary of 2024 was obvious and the grain was coarse, which was elongated along the rolling direction. Compared with 2024 alloy, the grain boundary of 7A52 alloy was less obvious, and the number and size of the second phase particles were significantly smaller than those of 2024 alloy, and thus the pitting and intergranular corrosion sensitivity of 7A52 alloy was significantly smaller than that of 2024 alloy. The corrosion rate of 2024 aluminum alloy decreased with the increase of exposure time under the synergistic effect. 2024 alloy suffered exfoliation corrosion and the maximum corrosion depth was 236.4 μm. The corrosion rate of 7A52 alloy fluctuated with exposure time. 7A52 alloy suffered pitting corrosion and intergranular corrosion and the maximum corrosion depth was 20.5μm. Compared with 7A52 alloy, 2024 alloy was subject to corrosion fatigue fracture earlier. The fractures of both alloys showed fatigue fracture characteristics. The cracks started from the surface of the alloys and continued to expand into the alloy matrix under the synergistic effect of Cl− and tensile fatigue load, and finally corrosion fatigue fracture occurred. Thus, it can be inferred that the corrosion rate and corrosion damage degree of 2024 alloy under the synergistic effect are significantly greater than those of 7A52 alloy, resulting in that the anti-fatigue property of the former is also weaker than that of the latter. |
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