Affiliation:
1. Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 150001 China
2. National Key Laboratory for Remanufacturing Army Academy of Armored Forces Beijing 100072 China
3. National Engineering Research Center for Remanufacturing Army Academy of Armored Forces Beijing 100072 China
Abstract
Aluminum alloys are ideal lightweight structural materials for spacecraft, but they are susceptible to local corrosion during service. Herein, a systematic investigation is carried out to determine the fatigue behavior of 5B70 aluminum alloy under salt spray precorrosion. The mechanism of salt spray corrosion, fatigue life, crack propagation, and failure fracture mechanism of 5B70 aluminum alloy are studied. Under the salt spray corrosion, 5B70 aluminum alloy mainly undergoes pitting corrosion via a galvanic corrosion mechanism. After precorrosion, the formation of macroscopic fatigue cracks is accelerated, which significantly reduces its fatigue life. Fracture occurs due to single crack initiation and propagation under fatigue conditions. The fatigue crack tip undergoes a mixture of intergranular and transgranular modes, but mainly transgranular mode. Multiple strain localization phenomena occur during precorrosion fatigue, and corrosion pits on the surface provide a tortuous crack propagation path; the fatigue crack tip is mainly transgranular mode.
Funder
National Natural Science Foundation of China