Femtosecond Laser Removal Process and Structural Disturbance Effect of Selective Laser Melting GH4169 Additive Micro-defects

FAN Lisha; KAN Xingpu; YU Dengyu; ZHANG Shuowen; WU Ling; WANG Tingbin; ZHAO Tianzhen; ZHANG Di; XIANG Yihou; YAO Jianhua

doi:10.16490/j.cnki.issn.1001-3660.2025.24.005

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Surface Technology ›› 2025, Vol. 54 ›› Issue (24) : 79-89. DOI: 10.16490/j.cnki.issn.1001-3660.2025.24.005

Special Topic—Ultrafast Laser Surface Processing

Femtosecond Laser Removal Process and Structural Disturbance Effect of Selective Laser Melting GH4169 Additive Micro-defects

FAN Lisha^1,2, KAN Xingpu^1,2, YU Dengyu^1,2, ZHANG Shuowen^1,2, WU Ling^1,2, WANG Tingbin^1,2, ZHAO Tianzhen^1,2, ZHANG Di^1,2, XIANG Yihou^1,2, YAO Jianhua^1,2,*

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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.

Key words

GH4169 alloy / spheroidization defects / femtosecond laser removal / light field disturbance / additive manufacturing

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FAN Lisha, KAN Xingpu, YU Dengyu, ZHANG Shuowen, WU Ling, WANG Tingbin, ZHAO Tianzhen, ZHANG Di, XIANG Yihou, YAO Jianhua. Femtosecond Laser Removal Process and Structural Disturbance Effect of Selective Laser Melting GH4169 Additive Micro-defects[J]. Surface Technology. 2025, 54(24): 79-89

References

[1] 冯星涛, 李健民, 耿硕, 等. 热处理对激光选区熔化IN718合金室温低周疲劳性能的影响[J]. 中国激光, 2023, 50(16): 211-220.
FENG X T, LI J M, GENG S, et al.Effect of Heat Treatment on Low-Cycle Fatigue Properties of Selective Laser Melted IN718 at Room Temperature[J]. Chinese Journal of Lasers, 2023, 50(16): 211-220.
[2] 李建军, 杨小红, 王忠堂. GH4169高温合金热变形力学性能研究[J]. 热加工工艺, 2020, 49(12): 49-52.
LI J J, YANG X H, WANG Z T.Research on Mechanical Properties of GH4169 Supper Alloy during Thermal Deformation[J]. Hot Working Technology, 2020, 49(12): 49-52.
[3] 宋润华, 秦海龙, 毕中南, 等. GH4169合金高温动态应变时效实验及模拟[J]. 哈尔滨工业大学学报, 2020, 52(12): 21-26.
SONG R H, QIN H L, BI Z N, et al.Experimental and Modeling Investigations of High Temperature DSA Behaviour for GH4169 Superalloy[J]. Journal of Harbin Institute of Technology, 2020, 52(12): 21-26.
[4] 王哲, 李磊, 沈雪红. GH4169高温合金切削仿真分析及工艺参数优化[J]. 工具技术, 2020, 54(1): 59-62.
WANG Z, LI L, SHEN X H.Cutting Simulation Analysis and Machining Parameters Optimization of GH4169 Superalloy[J]. Tool Engineering, 2020, 54(1): 59-62.
[5] 吴楷, 张敬霖, 吴滨, 等. 激光增材制造镍基高温合金研究进展[J]. 钢铁研究学报, 2017, 29(12): 953-959.
WU K, ZHANG J L, WU B, et al.Research and Development of Ni-Based Superalloy Fabricated by Laser Additive Manufacturing Technology[J]. Journal of Iron and Steel Research, 2017, 29(12): 953-959.
[6] WANG M, LIN X, HUANG W.Laser Additive Manufacture of Titanium Alloys[J]. Materials Technology, 2016: 1-8.
[7] 姚燕生, 汪俊, 陈庆波, 等. 激光增材制造产品缺陷及其处理技术研究现状[J]. 激光与光电子学进展, 2019, 56(10): 45-56.
YAO Y S, WANG J, CHEN Q B, et al.Research Status of Defects and Defect Treatment Technology for Laser Additive Manufactured Products[J]. Laser & Optoelectronics Progress, 2019, 56(10): 45-56.
[8] DEMIR A G, PREVITALI B.Investigation of Remelting and Preheating in SLM of 18Ni300 Maraging Steel as Corrective and Preventive Measures for Porosity Reduction[J]. The International Journal of Advanced Manufacturing Technology, 2017, 93(5): 2697-2709.
[9] 邵玉呈, 陈长军, 张敏, 等. 关于Deloro 40镍基合金粉末激光增材制造成型件裂纹问题研究[J]. 应用激光, 2016, 36(4): 397-402.
SHAO Y C, CHEN C J, ZHANG M, et al.Research on Crack Issue of Deloro 40Ni Alloys Prototype Fabricated by Laser Additive Manufacturing[J]. Applied Laser, 2016, 36(4): 397-402.
[10] WEI Y, FANG X L, QU N S, et al.Effects of Electrolyte Flushing and Surface State on Electropolishing TB2 Titanium Alloy[J]. The International Journal of Advanced Manufacturing Technology, 2022, 119(11): 7865-7874.
[11] 孙晓宇, 魏修亭, 李志永, 等. 电解抛光提高镍钛合金心血管支架表面性能[J]. 中国表面工程, 2021, 34(1): 70-75.
SUN X Y, WEI X T, LI Z Y, et al.Improving Surface Properties of Nitinol Cardiovascular Stent by Electropolishing[J]. China Surface Engineering, 2021, 34(1): 70-75.
[12] HARRISON N J.Selective Laser Melting of Nickel Superalloys: Solidification, Microstructure and Material Response[D]. Sheffield: University of Sheffield, 2016.
[13] 张升, 桂睿智, 魏青松, 等. 选择性激光熔化成形TC4钛合金开裂行为及其机理研究[J]. 机械工程学报, 2013, 49(23): 21-27.
ZHANG S, GUI R Z, WEI Q S, et al.Cracking Behavior and Formation Mechanism of TC4 Alloy Formed by Selective Laser Melting[J]. Journal of Mechanical Engineering, 2013, 49(23): 21-27.
[14] 蔡明, 巩亚东, 冯耀利, 等. 镍基高温合金磨削表面工艺性能试验研究[J]. 东北大学学报(自然科学版), 2019, 40(2): 234-238.
CAI M, GONG Y D, FENG Y L, et al.Experimental Study on Grinding Surface Processing Property of Nickel- Based Superalloy[J]. Journal of Northeastern University (Natural Science), 2019, 40(2): 234-238.
[15] 黄新春, 张定华, 姚倡锋, 等. 镍基高温合金GH4169磨削参数对表面完整性影响[J]. 航空动力学报, 2013, 28(3): 621-628.
HUANG X C, ZHANG D H, YAO C F, et al.Effects of Grinding Parameters on Surface Integrity of GH4169 Nickel-Based Superalloy[J]. Journal of Aerospace Power, 2013, 28(3): 621-628.
[16] CHICHKOV B N, MOMMA C, NOLTE S, et al.Femtosecond, Picosecond and Nanosecond Laser Ablation of Solids[J]. Applied Physics A, 1996, 63(2): 109-115.
[17] PADMANABHAM G, BATHE R.Laser Materials Processing for Industrial Applications[J]. Proceedings of the National Academy of Sciences, India Section A: Physical Sciences, 2018, 88(3): 359-374.
[18] SATO Y, TSUKAMOTO M, SHINONAGA T, et al.Femtosecond Laser-Induced Periodic Nanostructure Creation on PET Surface for Controlling of Cell Spreading[J]. Applied Physics A, 2016, 122(3): 184.
[19] 杨青, 成扬, 方政, 等. 仿生超滑表面的飞秒激光微纳制造及应用[J]. 光电工程, 2022, 49(1): 210326.
YANG Q, CHENG Y, FANG Z, et al.The Preparation and Applications of Bio-Inspired Slippery Surface by Femtosecond Laser Micro-Nano Manufacturing[J]. Opto-Electronic Engineering, 2022, 49(1): 210326.
[20] 杨肖康, 李朋, 王自, 等. 飞秒激光抛光金属钛表面研究[J]. 光电工程, 2025, 52(6): 250056.
YANG X K, LI P, WANG Z, et al.Femtosecond Laser Polishing of Titanium Surfaces[J]. Opto-Electronic Engineering, 2025, 52(6): 250056.
[21] 侯杰, 董建新, 姚志浩. GH4169合金高温疲劳裂纹扩展的微观损伤机制[J]. 工程科学学报, 2018, 40(7): 822-832.
HOU J, DONG J X, YAO Z H.Microscopic Damage Mechanisms during Fatigue Crack Propagation at High Temperature in GH4169 Superalloy[J]. Chinese Journal of Engineering, 2018, 40(7): 822-832.
[22] ZHOU H, ZHOU H M, ZHAO Z Y, et al.Numerical Simulation and Verification of Laser-Polishing Free Surface of S136D Die Steel[J]. Metals, 2021, 11(3): 400.
[23] SHAO T M, HUA M, TAM H Y, et al.An Approach to Modelling of Laser Polishing of Metals[J]. Surface and Coatings Technology, 2005, 197(1): 77-84.
[24] SCHNELL G, DUENOW U, SEITZ H.Effect of Laser Pulse Overlap and Scanning Line Overlap on Femtosecond Laser-Structured Ti₆Al₄V Surfaces[J]. Materials, 2020, 13(4): 969.
[25] 方菊, 刘壮, 李元成, 等. 光斑及线重合度对飞秒激光环形刻蚀SiC/SiC复合材料的影响[J]. 机械制造与自动化, 2023, 52(3): 7-10.
FANG J, LIU Z, LI Y C, et al.Effect of Spot and Line Overlap on Femtosecond Laser Ablation of SiC/SiC Composite[J]. Machine Building & Automation, 2023, 52(3): 7-10.
[26] 潘鹏晖, 吉鹏飞, 林根, 等. 飞秒激光加工熔融石英的理论和实验研究[J]. 物理学报, 2022, 71(24): 414-425.
PAN P H, JI P F, LIN G, et al.Theoretical and Experimental Research of Femtosecond Laser Processing Fused Silica[J]. Acta Physica Sinica, 2022, 71(24): 414-425.
[27] GRBČIĆ L, PARK M, ELZOUKA M, et al. Inverse Design of Photonic Surfaces via Multi Fidelity Ensemble Framework and Femtosecond Laser Processing[J]. NPJ Computational Materials, 2025, 11: 35.
[28] WANG C, LUO Z, DUAN J A, et al.Adjustable Annular Rings of Periodic Surface Structures Induced by Spatially Shaped Femtosecond Laser[J]. Laser Physics Letters, 2015, 12(5): 056001.
[29] 王文泉, 崔宇, 薛蕴鹏, 等. 潮湿空气中应力耦合固态NaCl作用下GH4169合金的中温腐蚀行为研究[J]. 中国腐蚀与防护学报, 2024, 44(6): 1399-1411.
WANG W Q, CUI Y, XUE Y P, et al.Corrosion Behavior of GH4169 Alloy under Flexural Tensile Stress and beneath a NaCl Deposit Film in Water Vapor Containing Air at 600 ℃[J]. Journal of Chinese Society for Corrosion and Protection, 2024, 44(6): 1399-1411.
[30] ALARDAH A H S, ALRASHEED A M, AHMAD ALEMADI F, et al. Effect of Alumina as an Anti-Soiling Nanomaterial for Enhancing Photovoltaic Performance[J]. Materials Proceedings, 2024, 18(1): 2.
[31] PYKA G, KERCKHOFS G, PAPANTONIOU I, et al.Surface Roughness and Morphology Customization of Additive Manufactured Open Porous Ti₆Al₄V Structures[J]. Materials, 2013, 6(10): 4737-4757.

Funding

The National Key Research and Development Program of China (2023YFB4606000); The "Pioneer" and "Leading Goose" R&D Program of Zhejiang (2023C01051); The Fundamental Research Funds for the Provincial Universities of Zhejiang (RF-C2022001)