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Corrosion mechanism and fatigue behavior of 2A70-T6 aluminum alloy under alternating corrosion and fatigue

Lei Fu (College of Mechanical Engineering, Sichuan University of Science and Engineering, Zigong, China) (School of Aeronautics and Astronautics, Sichuan University, Chengdu, China)
Hui Li (Sichuan University of Science and Engineering, Zigong, China)
Li Lin (Sichuan University of Science and Engineering, Zigong, China)
Qingyuan Wang (Sichuan University, Chengdu, China) (Chengdu University, Chengdu, China)
Qi Fan (Sichuan University of Science and Engineering, Zigong, China)
Xinjie Huang (Sichuan University of Science and Engineering, Zigong, China)
XiuLan Li (Sichuan University of Science and Engineering, Zigong, China)
Sheng Lai (Sichuan University of Science and Engineering, Zigong, China)
Lifei Chen (Sichuan University of Science and Engineering, Zigong, China)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 2 September 2021

Issue publication date: 17 September 2021

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Abstract

Purpose

Most supersonic aircraft were manufactured using 2A70 aluminum alloy. The purpose of this paper is to study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue.

Design/methodology/approach

For this purpose, the aluminum alloy samples were subjected to pre-corrosion and alternating corrosion-fatigue experiments. The failure mechanisms of corrosion and corrosion fatigue were analyzed using microscopic characterization methods of electrochemical testing, X-ray diffraction and scanning electron microscopy. Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life.

Findings

The results showed that the corrosion damage caused by the corrosive environment was gradually connected by pitting pits to form denudation pits along grain boundaries. The deep excavation of chloride ions and the presence of intergranular copper-rich phases result in severe intergranular corrosion morphology. During cyclic loading, alternating hardening and softening occurred. The stress concentration caused by surface pitting pits and denudation pits initiated fatigue cracks at intergranular corrosion products. At the same time, the initiation of multiple fatigue crack sources was caused by the corrosion environment and the morphology of the transient fracture zone was also changed, but the crack propagation rate was not basically affected. The polarization curve and impedance analysis results showed that the corrosion rate increases first, decreases and then increases. Fatigue failure behavior was directly related to micro characteristics such as corrosion pits and microcracks.

Originality/value

In this research, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue. To study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, the Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life.

Keywords

Acknowledgements

This work was financially supported by the National Nature Science Foundation of China (No.51701133), the Opening Foundation of Sichuan Province Engineering Center for Powder Metallurgy(SC-FMYJ2019-07), the Project of Key Lab in Sichuan Colleges on Industry Process Equipment and Control Engineering (GK201808, GK201816) and the Opening Project of Sichuan Province University Key Laboratory of Bridge Non-destruction Detecting and Engineering Computing (2018QYJ03, 2018QZY01). Talent Introduction Project of Sichuan University of Science and Engineering(2020RC19).

Author contributions: Lei Fu. conceived and designed the experiments; Hui Li. performed the experiments; Qingyuan Wang and Xiulan Li. analyzed the data; Xinjie Hunag, Qi Fan, Li Lin, Sheng Lai and Lifei Chen contributed reagents/materials/analysis tools; Lei Fu. wrote the paper; Qingyuan Wang. revised the paper.

Conflicts of interest: The authors declare no conflicts of interest.

Citation

Fu, L., Li, H., Lin, L., Wang, Q., Fan, Q., Huang, X., Li, X., Lai, S. and Chen, L. (2021), "Corrosion mechanism and fatigue behavior of 2A70-T6 aluminum alloy under alternating corrosion and fatigue", Anti-Corrosion Methods and Materials, Vol. 68 No. 5, pp. 422-437. https://doi.org/10.1108/ACMM-02-2020-2265

Publisher

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Emerald Publishing Limited

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