| HU Zhong-yao,SHI Wei,XIANG Song.Effect of Ultrasonic Rolling on Intergranular Corrosion Behavior of 6061 Aluminum Alloy[J],52(10):194-205 |
| Effect of Ultrasonic Rolling on Intergranular Corrosion Behavior of 6061 Aluminum Alloy |
| Received:September 21, 2022 Revised:February 06, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.10.015 |
| KeyWord:6061 aluminum alloy ultrasonic rolling microstructure deformation AlFeSi phase intergranular corrosion |
| Author | Institution |
| HU Zhong-yao |
College of Materials and Metallurgy, Guizhou University, Guiyang , China |
| SHI Wei |
College of Materials and Metallurgy, Guizhou University, Guiyang , China;Guizhou Key Laboratory of Materials Mechanical Behavior and Microstructure, Guiyang , China;National & Local Joint Engineering Laboratory for High-Performance Metal Structure Material and Advanced Manufacturing Technology, Guiyang , China |
| XIANG Song |
College of Materials and Metallurgy, Guizhou University, Guiyang , China;Guizhou Key Laboratory of Materials Mechanical Behavior and Microstructure, Guiyang , China;National & Local Joint Engineering Laboratory for High-Performance Metal Structure Material and Advanced Manufacturing Technology, Guiyang , China |
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| Abstract: |
| The work aims to study the effect of the deformed layer on intergranular corrosion of 6061 aluminum alloys under three static pressure conditions. In this paper, USRP (ultrasonic surface rolling processing) was adopted to strengthen the surface layer of 6061 aluminum alloys, which was characterized with a scanning electron microscopy, a laser confocal microscopy, X-ray diffraction, et al. Under three kinds of static pressures, the results showed that after ultrasonic surface rolling processing (USRP), the cross section generated deformed layer which refined and elongated grains on the top surface, the length of deformed layer extended to three hundreds microns, and the corrosion channel was blocked and the expansion depth was reduced to fifty percent under the accelerated corrosion condition with the acidified NaCl solution. The intergranular corrosion susceptibility was reduced by ultrasonic surface rolling processing. However, the characterization results performed that the material hardness decreased gradually with the increase of depth which stayed away from the surface. It was worth noting that the region of hardness was not in consistent with the deformed layer by optical microscope. So, it was concluded that the intergranular corrosion propagation path did not have a primary relationship with surface roughness, which was mainly related to the dispersion distribution of AlFeSi phase in the deformed layer. The fined level depended on the pressure, which was a positive correlation. The results suggested that the corrosion path of untreated samples extended along a certain grain boundary which was filled the second phase as the cathode phase. The grains of the cross section fell off, and the corrosion behavior transformed from the intergranular corrosion to exfoliation corrosion, which presented a deep corrosion path from the top surface and a narrow corrosion width by the scanning electron microscope and the laser confocal microscope. That because the dispersed second phase broke off the continuity of the electrochemical micro couples in the treated alloy eventually, which made the corrosion depth shorter and the corrosion path wider than those of the untreated sample. Moreover, when the AlFeSi phase was refined under different pressures in the matrix, after the ultrasonic surface rolling processing, the damage mode did not change from intergranular corrosion to exfoliation corrosion with the increase of pressure. The corrosion scope of the matrix became smaller, and the decrease intergranular corrosion susceptibility of the alloy was significantly increased. The brittle phase of AlFeSi phase was elongated and broken along the rolling direction. Compared with the untreated samples, after the intergranular corrosion test time of three hours, the AlFeSi phase affected corrosion processing, and the dispersion distribution of the AlFeSi phase destroyed the galvanic corrosion with the surrounding matrix. These results show that USRP can improve the intergranular corrosion resistance of 6061 aluminum alloy. The surface roughness is not the main factors to improve the intergranular corrosion resistance. However, refining and dispersing the AlFeSi phase in 6061 aluminum alloy through USRP is the key factor to inhibit the intergranular corrosion extension. |
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