表面技术2025，Vol.54Issue(24)：79-89,137,12.DOI:10.16490/j.cnki.issn.1001-3660.2025.24.005
选区激光熔融GH4169增材微缺陷的飞秒激光去除工艺及结构扰动影响研究
Femtosecond Laser Removal Process and Structural Disturbance Effect of Selective Laser Melting GH4169 Additive Micro-defects
摘要
Abstract
GH4169 nickel-based superalloy is widely used in aerospace and other high-end fields;however,selective-laser-melted(SLM)parts frequently exhibit spheroidization defects that severely degrade surface quality and service performance.Conventional post-treatments such as mechanical machining or electropolishing suffer from low efficiency and limited adaptability.The work aims to propose a femtosecond laser spot ablation method to eradicate these spheroidization defects on SLM-GH4169 surfaces,systematically investigate the influences of laser power,pulse/track overlap ratios and defocus distance on removal efficiency,and employ multi-scale characterizations in combination with numerical simulations to unveil the light-field disturbance mechanisms induced by defect topography. Specimens were fabricated on an RS450D metal 3D printer under as-built conditions,presenting spheroidization defects with an average height of 78.4 µm.Ablation was performed with an OR-30-IR femtosecond laser under an argon atmosphere.A orthogonal array was employed to optimize laser power,track overlap(LO),pulse overlap(PO)and defocus distance(z),to balance the removal rate against surface quality.Pre-and post-processing topographies,chemistries,hardness and wettability were systematically characterized by laser-scanning confocal microscopy(LSCM),SEM,EDS,XRD,XPS,Vickers micro-indentation and contact-angle goniometry. Optimal removal was achieved at 30 W,LO=50%,PO=80%and defocus≤90 µm,yielding a maximum removal step of 4.65 µm with minimal peripheral trenching.After 20 passes,the defect height decreased from 153.8 µm to 20.5 µm,indicating complete elimination.A circumferential groove of about 9 µm deep was formed simultaneously,attributed to diffraction of the incident light by the spheroidal topography.COMSOL transient-thermal analyses revealed localized energy concentration at the defect periphery,with temperatures exceeding 2 000 K that drove collateral ablation.FDTD simulations further showed a ripple-like,radial intensity distribution within a 50 µm annulus around the defect,creating electromagnetic hot-spots responsible for the observed trench. Compositional analyses indicated that surface oxygen decreased from 6.67wt.%to 5.58wt.%after femtosecond ablation,whereas Ni,Ti and Cr varied by<1wt.%,evidencing minimal alteration of the substrate chemistry.XPS confirmed effective removal of the native Al2O3 scale.Vickers hardness rose from 364HV to 409HV(+12.3%)within the processed zone;concomitant XRD peak shifts of the γ phase toward higher 2θ suggested lattice contraction and/or micro-strain.Wettability measurements showed a decrease in water-contact angle from 96.7° to 82.5°,restoring a hydrophilic surface favorable for subsequent machining or coating adhesion. In summary,femtosecond laser ablation enables efficient and high-precision elimination of spheroidization defects on GH4169 surfaces while concurrently enhancing surface hardness and wettability,with negligible modification of the bulk composition.The structural disturbance of the incident optical field by the defect topography is identified as the primary mechanism driving the formation of the peripheral trench.This approach offers a reliable laser-subtractive route for in-situ repair and performance enhancement of additively manufactured components,exhibiting excellent scalability and industrial applicability.In the future,integrating in-line monitoring and closed-loop control is expected to further enhance repair accuracy and efficiency.The technology also holds promise for defect remediation in other additively manufactured materials such as titanium alloys and tool steels.关键词
GH4169合金/球化缺陷/飞秒激光去除/光场扰动/增材制造Key words
GH4169 alloy/spheroidization defects/femtosecond laser removal/light field disturbance/additive manufacturing分类
矿业与冶金引用本文复制引用
范丽莎,姚建华,阚星普,喻登宇,张硕文,吴岭,王廷斌,赵天真,张迪,项一侯..选区激光熔融GH4169增材微缺陷的飞秒激光去除工艺及结构扰动影响研究[J].表面技术,2025,54(24):79-89,137,12.基金项目
国家重点研发计划项目(2023YFB4606000) （2023YFB4606000）
浙江省"尖兵""领雁"研发攻关项目(2023C01051) （2023C01051）
浙江省属高校基本科研业务费专项资金(RF-C2022001)The National Key Research and Development Program of China(2023YFB4606000) （RF-C2022001）
The"Pioneer"and"Leading Goose"R&D Program of Zhejiang(2023C01051) （2023C01051）
The Fundamental Research Funds for the Provincial Universities of Zhejiang(RF-C2022001) （RF-C2022001）
