激光冲击光整对2024铝合金铣削平面表面质量的影响  

Effect of Laser Shock Finishing on the Surface Quality of 2024 Aluminum Alloy with Milled Plane

作　　者：李海洋 赵喆 郑超[1] 季忠[1] 赵国群[1] LI Hai-yang;ZHAO Zhe;ZHENG Chao;JI Zhong;ZHAO Guo-qun(School of Materials Science and Engineering,Shandong University,Jinan 250061,China)

机构地区：[1]山东大学材料科学与工程学院,济南250061

出　　处：《表面技术》2023年第9期388-396,共9页Surface Technology

基　　金：国家自然科学基金(52075299,52075298);山东省自然科学基金(ZR2020ME149);山东省重点研发计划(2021ZLGX01)。

摘　　要：目的减小铝合金铣削平面的表面粗糙度,满足工程应用中对构件高质量表面的需求。方法通过铣削加工获得3种具有不同初始表面粗糙度的平面试样,试样的Ra分别为1.439、0.614、0.220μm。采用短脉冲、高功率密度激光对表面进行光整处理,利用激光共聚焦显微镜观察光整后试样的表面形貌,采用粗糙度仪检测试样的表面轮廓和表面粗糙度,分析光斑搭接率和激光能量对铝合金铣削平面表面质量的作用规律。结果在脉冲宽度为12 ns、波长为1064 nm、工作频率为1 Hz、光斑直径为2 mm的平顶光束作用下,试样的表面形貌发生重塑。当光斑搭接率为30%、50%、70%时,对于Ra=1.439μm的试样,在冲击后其表面轮廓变化幅值分别为6.88、6.71、6.20μm,表面粗糙度变化率分别为−70.8%、−72.9%、−73.2%;对于Ra=0.614μm的试样,在冲击后其表面粗糙度变化率分别为−58.0%、−58.8%、−66.1%。当激光能量为1.5、2.5、3.5、4.5 J时,对于Ra=1.439μm的试样,在冲击后其表面轮廓变化幅值分别为6.92、6.71、5.22、6.18μm,表面粗糙度变化率分别为−68.1%、−72.9%、−74.6%、−73.8%;对于Ra=0.614μm的试样,在冲击后其表面粗糙度变化率分别为−49.2%、−58.8%、−54.4%、−58.1%。结论合理增大光斑搭接率和增强激光能量,能够有效去除铣削刀痕,改善试样表面形貌的均匀性。光斑搭接率和激光能量对表面粗糙度的影响与试样的初始表面粗糙度有关。对于Ra=1.439μm和Ra=0.614μm的试样,增大光斑搭接率和增强激光能量均能显著降低其表面粗糙度;对于Ra=0.220μm的试样,在文中的激光冲击参数范围内均不能有效提高其表面质量。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 0.220μm 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 1064 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�

关 键 词：激光冲击 2024铝合金 表面形貌 表面粗糙度 光斑搭接率 激光能量 

分 类 号：TN249[电子电信—物理电子学]