皮秒/纳秒脉冲激光抛光对激光选区熔化TC4表面完整性影响  

Effect of Picosecond/nanosecond Pulsed-laser Polishing on Surface Integrity of Selective Laser Melting TC4

作　　者：李亮亮[1] 牟建伟 刘艳梅[1] 徐继文[1] 李金龙[1] 李鹏飞[2] 黄舒[2] LI Liangliang;MU Jianwei;LIU Yanmei;XU Jiwen;LI Jinlong;LI Pengfei;HUANG Shu(Innovation Research Institute,Shenyang Aircraft Corporation,Shenyang 110000,China;School of Mechanical Engineering,Jiangsu University,Zhenjiang 212013,China)

机构地区：[1]沈阳飞机工业(集团)有限公司创新研究院,沈阳110000 [2]江苏大学机械工程学院,镇江212013

出　　处：《中国表面工程》2024年第3期57-66,共10页China Surface Engineering

基　　金：国家自然科学基金(52305363);基础加强科技计划(A04014);国家重点研发计划(2023YFB4606000)。

摘　　要：以激光选区熔化TC4钛合金薄壁结构件为研究对象,采用皮秒脉冲激光和纳秒脉冲激光进行激光抛光,旨在探究不同激光抛光方式对增材制造的钛合金表面性能的影响。两种激光加工参数均为优化后的工艺参数,且均为高斯光源。对抛光后的表面形貌、表面粗糙度、热影响层深度、元素分布、氧化程度和试样的拉伸性能进行对比分析。结果表明皮秒脉冲激光和纳秒脉冲激光均可以显著改善增材制造TC4钛合金的表面质量,降低表面粗糙度,从原始的3.52μm下降至皮秒抛光的0.71μm或纳秒激光的0.66μm。纳秒脉冲激光具有更高的热积累,表面氧化程度高,热影响层深,约为34.20μm,比皮秒脉冲激光热影响层深度增大约40.9%。拉伸试验结果表明,虽然激光抛光略微降低了激光选区熔化增材制造钛合金的拉伸性能,但是纳秒脉冲激光抛光后试样的拉伸强度和拉伸应变下降更显著。本研究为激光抛光在增材制造中的应用提供了深入的试验分析和理论探讨,为进一步扩展皮秒脉冲激光在高性能金属零件的制备提供了新思路和方法。The TC4 titanium alloy is widely applied in various fields owing to its low density,low thermal conductivity,corrosion resistance,and stable high-temperature mechanical properties.In this study,picosecond and nanosecond pulsed lasers are used in laser polishing to investigate the effects of different laser-polishing methods on the surface properties of additively manufactured titanium alloy.Pulsed-laser polishing,as a novel surface-processing technology,primarily focuses on precision polishing to achieve superior surface roughness and performance while avoiding laser-induced substrate overheating.Researchers have conducted polishing treatments using nanosecond and picosecond pulsed lasers on different materials and confirmed that pulsed-laser polishing significantly reduces surface roughness,refines the grain structure of melted pools,enhances the microhardness of polished surfaces,and alters the mechanical properties of samples.However,comparative studies pertaining to the polishing of the same thin-wall structure material are limited,thus rendering it challenging to analyze the thermal effects of different lasers and their impact on performance.Based on the average surface roughness and depth of the heat-affected zone as targets,after optimizing hundreds of parameter sets,the optimized processing parameters for picosecond pulsed lasers are determined to be as follows:spot diameter,15μm;scanning speed,2000 mm/s;power,16 W;frequency,500 kHz;pulse width,10 ps;and serpentine scanning path.Meanwhile,the optimized processing parameters for nanosecond pulsed lasers are as follows:spot diameter,25μm;scanning speed,2000 mm/s;power,70 W;frequency,200 kHz;scanning spacing,0.08 mm;dot engraving time,0.1 ms;and serpentine scanning path.A comparative study is performed using picosecond and nanosecond pulsed lasers to investigate their effects on the surface morphology,surface roughness,depth of the heat-affected zone,elemental distribution,oxidation degree,and tensile properties of laser-melted TC4 titanium alloy thin-wall

关 键 词：激光抛光 皮秒激光 纳秒激光 增材制造 组织和性能 

分 类 号：TG162[金属学及工艺—热处理]