| LI Hai-yang,ZHAO Zhe,ZHENG Chao,JI Zhong,ZHAO Guo-qun.Effect of Laser Shock Finishing on the Surface Quality of 2024 Aluminum Alloy with Milled Plane[J],52(9):388-396 |
| Effect of Laser Shock Finishing on the Surface Quality of 2024 Aluminum Alloy with Milled Plane |
| Received:July 29, 2022 Revised:March 21, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.09.035 |
| KeyWord:laser shock 2024 aluminum alloy surface morphology surface roughness overlapping rate laser energy |
| Author | Institution |
| LI Hai-yang |
School of Materials Science and Engineering, Shandong University, Jinan , China |
| ZHAO Zhe |
School of Materials Science and Engineering, Shandong University, Jinan , China |
| ZHENG Chao |
School of Materials Science and Engineering, Shandong University, Jinan , China |
| JI Zhong |
School of Materials Science and Engineering, Shandong University, Jinan , China |
| ZHAO Guo-qun |
School of Materials Science and Engineering, Shandong University, Jinan , China |
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| Abstract: |
| Aluminum alloy is widely applied in the field of aeronautics and astronautics because of its light weight, high specific strength and excellent corrosion resistance. The parts made of aluminum alloy are usually processed by milling, and the surface quality after milling is closely associated with the service performance of these parts. Therefore, finishing process is necessary to reduce the roughness and strengthen the mechanical property of milled surface. Laser shock finishing is a novel flexible manufacturing method in which the laser shock wave pressure is employed to cause plastic deformation on the surface and further improve the surface quality. Compared with the traditional finishing process, laser shock finishing takes advantages of superb flexibility, good repeatability, high efficiency and high precision. However, few attempts have been made to study the effect of laser shock finishing on the surface quality of aluminum alloy after milling. In this work, the effect of laser shock parameters on the finishing quality of 2024-T351 aluminum alloy with milled plane was experimentally investigated. The planar milled specimens with three different initial roughness were manufactured through CNC machining center, and the initial Ra was 1.439, 0.614, and 0.220 μm respectively. A laser system with ultrashort pulse and high laser power density was employed to finish the milled plane. After that, a laser scanning confocal microscope was used to observe the surface morphology of specimens after laser shock finishing. Both the surface profile and roughness were measured by a roughmeter. Based on the measurement, the effect of overlapping rate and laser energy on the surface quality of 2024-T351 aluminum alloy with milled plane was evaluated. It was found that the surface morphology of planar milled specimens could be reshaped by the laser in case of pulse width of 12 ns, wavelength of 1 064 nm, working frequency of 1 Hz, spot diameter of 2 mm and flat-topped beam. While the overlapping rate was 30%, 50%, and 70%, for the specimens with Ra of 1.439 μm, the changing amplitude of surface profile after laser shock finishing was 6.88, 6.71, and 6.20 μm, and the changing rate of roughness was −70.8%, −72.9%, and −73.2% respectively. For the specimens with Ra of 0.614 μm the changing rate of roughness after laser shock was −58.0%, −58.8%, and −66.1%. While the laser energy was 1.5, 2.5, 3.5, and 4.5 J, for the specimens with Ra of 1.439 μm the changing amplitude of surface profile after laser shock finishing was 6.92, 6.71, 5.22, and 6.18 μm, and the changing rate of roughness was −68.1%, −72.9%, −74.6%, and −73.8% respectively. For the specimens with Ra of 0.614 μm the changing rate of roughness after laser shock was −49.2%, −58.8%, −54.4%, and −58.1%. It is revealed that both increasing overlapping rate and strengthening laser energy reasonably can effectively remove the milled mark on the surface and improve the uniformity of surface morphology. In addition, the effect of overlapping rate and laser energy on roughness strongly is related to the initial roughness of planar milled specimens. For the specimens with Ra of 1.439 and 0.614 μm, both increasing overlapping rate and strengthening laser energy can significantly reduce the roughness after laser shock. However, for the specimens with initial Ra of 0.220 μm, the surface quality can not be improved under the given laser shock conditions. |
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