| SUN Xiaoguang,GUO Xiaoyu,XIANG Li,LI Bowen,MA Maishou.Effect of Structural Gap Width on Corrosion Behavior of 6A01-T5 Aluminum Alloy[J],53(20):61-68 |
| Effect of Structural Gap Width on Corrosion Behavior of 6A01-T5 Aluminum Alloy |
| Received:March 27, 2024 Revised:June 07, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.20.005 |
| KeyWord:crevice corrosion aluminum alloy alkaline environment gap width |
| Author | Institution |
| SUN Xiaoguang |
CRRC Qingdao Sifang Co., Ltd., Shandong Qingdao , China;State Key Laboratory of Environmental Adaptability for Industrial Products, China National Electric Apparatus Research Institute Co., Ltd., Guangzhou , China |
| GUO Xiaoyu |
CRRC Qingdao Sifang Co., Ltd., Shandong Qingdao , China |
| XIANG Li |
State Key Laboratory of Environmental Adaptability for Industrial Products, China National Electric Apparatus Research Institute Co., Ltd., Guangzhou , China |
| LI Bowen |
Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
| MA Maishou |
CRRC Qingdao Sifang Co., Ltd., Shandong Qingdao , China |
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| Abstract: |
| There are a large number of riveted and bolted connections in engineering applications, which creates many structural gaps. These gaps can easily cause crevice corrosion and structural failure. Therefore, the work aims to provide guidance for the prevention and optimization on the gap structure to study the crevice corrosion behavior of 6A01-T5 aluminum alloy. The specimens of 6A01-T5 aluminum alloy with constant gap depth and different gap widths were subject to corrosion tests in alkaline NaCl solution for different time by immersion method at room temperature and atmospheric pressure. Optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyze the morphology and composition of corrosion products. The white light interferometer was used to detect the surface microstructure and depth of corrosion pit after the removal of corrosion products, and the electronic balance was used to detect the corrosion weight loss. After 4 d of corrosion, there was obvious discoloration on the surface of the specimen. After 18 d, there was an obvious discoloration band along the direction of the gap. At the same time, there was white product adhered to the gap. After 45 d, the surface corrosion of the specimen was further aggravated, and the white corrosion products in the gap and the gap width increased significantly. The main corrosion products were Al(OH)3, Al2O3 and AlO(OH). According to the microscopic profile detection of the specimens, the specimens with gap widths of 0.15 mm and 0.3 mm produced a concave channel in the direction of the slit, and local thinning and corrosion pits were generated in the slit. After 45 d of corrosion, for the specimen with a gap width of 0.15 mm, the width of the sunken channel was about 2 500 μm, the depth was about 3-4 μm, and the deepest corrosion pit was about 60 μm. For the specimen with a gap width of 0.3 mm, the width of the sunken channel was about 1 200 μm, the depth was about 3-4 μm, and the deepest corrosion pit was about 80 μm. However, for the specimen with a gap width of 0.5 mm, no obvious sunken channel was detected at the gap, only local thinning zone and corrosion pit existed at the gap, and the deepest corrosion pit was about 40 μm after 45 d of corrosion. The corrosion weight loss test showed that the corrosion weight loss of the specimen increased with the corrosion time, and the corrosion weight loss of the specimen with a gap width of 0.3 mm was the largest, followed by specimen with a gap width of 0.15 mm and the specimen with a gap width of 0.5 mm had the smallest corrosion weight loss. In alkaline NaCl solution, the gap corrosion degree of 6A01-T5 aluminum alloy increases firstly and then decreases with the increase of gap width, and gradually increases with the extension of corrosion time. The crevice corrosion will produce a concave channel along the direction of the slot opening, and with the increase of the gap width, the incubation period of the concave channel will prolong, and the width of the concave channel will decrease. When the gap width reaches 0.5 mm, no obvious corrosion concave channel will be produced. |
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