Nickel-based superalloy (DZ411) is widely used in the manufacture of high-temperature components in the aerospace field due to its excellent physical and mechanical properties, such as high-temperature resistance, oxidation resistance, and corrosion resistance. Laser polishing can improve the surface quality and service performance of nickel-based superalloy materials. In this paper, a new type of multi-beam coupling laser based conventional laser is used to process the nickelbased superalloy materials. The processing experiments of nickel-based superalloy were carried out by changing laser power, scanning speed, and scanning pitch. Then the polished surfaces were observed and detected by laser confocal microscope. The results show that the surface of nickel-based superalloy materials has certain regularity with the variations of process parameters. Under these experimental parameters, surface roughness (Ra) decreases first and then increases with the increase of laser power, scanning speed, and scanning pitch. The minimum Ra of the polished surface is 1.06 μm under the process parameter combinations of laser power of 1W, scanning speed of 400 mm/s, and scanning pitch of 20 μm. The maximum valley depth (Rv) and the maximum height (Rz) of profile first decrease and then increase with the increase of laser power or scanning speed. However, Rv and Rz had a little rate of fluctuation with the increase of scanning pitch. The laser polishing process involves the dynamic time-varying absorption mechanism of the coupled laser energy by polymorphic materials, and it is accompanied by complex physical processes such as material melting, gasification, and re-condensation. When Ra is relatively low, a clear corrugated structure appears on the machined surface. This research work can provide process data support for optimizing the polishing process parameters of nickel-based superalloys and expand the laser processing types.
Due to the characteristics of high hardness, wear resistance, corrosion resistance, excellent thermal shock resistance, and low thermal expansion coefficient, Si3N4 ceramics are widely used in aerospace, national defense, electronic and electrical, mechanical, chemical, and other fields. In this paper, the grooving experiments of Si3N4 ceramics were carried out by using a novel dual-beam coupled nanosecond pulse laser, and the influence of laser power and scanning speed on the surface morphology and geometric size of grooves were studied. The results show that the laser power has a significant effect on the surface morphology and geometric size of grooves. With the increase of laser power, the laser power density augments, and the width and depth of grooves increase. The groove width and groove depth first increase and then decrease with the increase of scanning speed, and both the groove width and depth reach the maximum value at scanning speed of 800 mm/min.
The coupled nanosecond laser processing system was used for processing 6061 aluminum alloy in this paper. At first, we explored the relationship between laser processing parameters, such as laser power, laser repetition frequency, as well as scanning speed, and the processed surface quality for 6061 aluminum alloy plate sample. The optimal laser parameters were determined by the experiment of the flat plate sample processing, and then the paths of laser processing were designed and planned on the aluminum alloy with curved surface to explore the influence of curvature on the surface quality. The results show that the new processing technology of coupled nanosecond laser polishing could obtain good surface quality. The optimal laser processing parameters are average laser power of 5W, scanning speed of 500mm/min, and repetition frequency of 10kHz, which could reduce the surface roughness by 43%. In addition, the surface quality of the aluminum alloy is closer to the original surface as the curvature increased. And the convex surface has a lower surface roughness than the concave surface because the spot shape is different at different curvature positions. The coupled laser polishing process provides theoretical and technological support for the high-quality machining of 6061 aluminum alloy in this study.
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