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| Corrosion Damage Morphology Evolution of 2A12 Aluminum Alloy in EXCO Solution |
| Received:March 21, 2019 Revised:April 17, 2019 |
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| DOI：10.7643/issn.1672-9242.2019.08.0015 |
| KeyWord:2A12 aluminum alloy corrosion damage surface roughness morphology evolution |
| Author | Institution |
| LI Zhi |
School of Mechanical Engineering, Shaanxi Institute of Technology, Xi¢an , China;National Key Laboratoryof Science and Technology on UAV, Northwestern Polytechnical University, Xi¢an , China |
| LYU Sheng-li |
National Key Laboratoryof Science and Technology on UAV, Northwestern Polytechnical University, Xi¢an , China |
| LIU Zhuan-e |
AVIC The First Aircraft Institute, Xi’an , China |
| MA Jun-feng |
Aircraft Strength Research Institute of China, Xi¢an , China |
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| Abstract: |
| Objective To explore the evolution of corrosion damage morphology of 2A12 aluminum alloy in EXCO solution. Methods Accelerated corrosion experiments of 2A12 aluminum alloy were carried out in laboratory. To quantitatively study the correlation between surface roughness and corrosion damage, a 3D scanning imaging instrument was used to scan the specimens to obtain the micro-geometric characteristics of them and have digital quantitative characterization of surface roughness. The occurrence and development of corrosion damage and the evolution of corrosion morphology in EXCO corrosion solution were observed. The pits depth of the specimens was measured and the effect of surface roughness on corrosion damage was analyzed. Results It was found that when the corrosion time did not exceed 6h, the corrosion type of 2A12 aluminum alloy specimens in EXCO solution was mainly pitting corrosion, which would develop toward general corrosion with the extension of time. There were some deep textures formed by grinding on the surface of specimen with high roughness value. These textures restricted the expansion of pit, and made the pit develop along the direction of the texture, which may evolve into micro cracks. Micro crack may also occur at the irregular boundary of pit. Specimens with lower surface roughness had less corrosion damage, but the effect of roughness on corrosion damage diminished over time. Conclusion At room temperature, 2A12 aluminum alloy firstly has pitting in EXCO solution, and the corrosion type evolves from pitting to general corrosion due to faster expansion of the pits to periphery than to depth. Surface roughness plays an important role in the evolution of corrosion damage morphology of 2A12 aluminum alloy specimens. Micro-geometric characteristics of the surface change the corrosion behavior of the specimens and cause obvious differences in corrosion damage by restricting the propagation direction of corrosion pits. With the extension of corrosion time, the material gradually loses its original surface micro-geometric characteristics, and the influence of surface roughness on corrosion behavior decreases. |
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