Effect of Scanning Parameters on the Surface Roughness of Ti-6Al-4V Processed by Laser Powder Bed Fusion

WANG Mengda; DING Jiaming; JI Xia; Steven Y. Liang

doi:10.16490/j.cnki.issn.1001-3660.2025.19.012

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Surface Technology ›› 2025, Vol. 54 ›› Issue (19) : 143-152. DOI: 10.16490/j.cnki.issn.1001-3660.2025.19.012

Laser Surface Modification Technology

Effect of Scanning Parameters on the Surface Roughness of Ti-6Al-4V Processed by Laser Powder Bed Fusion

WANG Mengda¹, DING Jiaming¹, JI Xia^1,*, Steven Y. Liang²

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Abstract

The work aims to systematically investigate the effect of scanning strategy and hatch spacing on the surface roughness and microstructural evolution of Ti-6Al-4V alloy fabricated with Laser Powder Bed Fusion (LPBF), to provide theoretical guidance for process optimization. Ti-6Al-4V samples with dimensions of 5 mm×5 mm×1 mm were manufactured with an EOS M280 LPBF system under various processing conditions. The resulting microstructure and surface quality were quantitatively characterized through electron backscatter diffraction (EBSD) and white-light three-dimensional optical profilometry. The experimental design incorporated two distinct scanning strategies, namely stripe and chessboard patterns, in combination with two different hatch spacing. The hatch spacing of 0.14 mm represented a commonly recommended value, while 0.11 mm corresponded to a higher overlap ratio, aiming to explore the impact of varying overlap on melt pool stability and surface roughness. To further investigate the interaction between scanning strategy and localized thermal behavior, a multi-factorial approach was employed by introducing two chessboard unit sizes of 3 mm and 1 mm. This setup allowed for a comprehensive evaluation of the combined effects of scanning parameters on grain morphology and surface characteristics.
Compared with the stripe scanning pattern, the chessboard strategy significantly improved the uniformity of heat input distribution. This improvement facilitated grain refinement and enhanced the randomness of grain orientation. Under stripe scanning conditions, the average grain size was measured at 2.236 µm. When the chessboard strategy was applied, the average grain size decreased to 1.995 µm, indicating a reduction of 10.78 percent. Additionally, the peak of the grain aspect ratio probability density curve shifted from 1.743 to 1.616, corresponding to a 7.29 percent decrease. These changes collectively suggested effective suppression of columnar grain growth through the chessboard pattern. In terms of crystallographic texture, the peak grain orientation spread (GOS) increased from 0.66° under stripe scanning to 0.68° with the chessboard pattern, indicating an increase of 3.03 percent. A further reduction in chessboard unit size from 3 mm to 1 mm led to a continued increase in GOS to 0.8°, reflecting a 17.65 percent enhancement in grain orientation uniformity. However, this change also resulted in a rise in average grain size to 2.357 µm, representing an 18.15 percent increase, and the grain aspect ratio reached 1.648, marking a slight increase of 1.98 percent. These observations indicated that excessive local heat accumulation began to offset the benefits of refinement and texture weakening, leading to a saturation effect. With respect to surface roughness, the stripe scanning strategy resulted in the highest S_a value of (71.978±3.02) µm due to pronounced thermal accumulation. In contrast, the chessboard strategy significantly improved melt pool homogeneity, reducing the Sa value to (46.325±2.85) µm, which corresponded to a 35.65 percent reduction in surface roughness. Further reduction of the chessboard unit size to 1 mm led to a S_a value of (45.131±2.10) µm, with a marginal additional improvement of 2.58 percent. When the hatch spacing decreased from 0.14 mm to 0.11 mm under stripe scanning conditions, the S_a value was reduced to (52.515±2.54) µm, reflecting a 27.05 percent improvement. However, this enhancement was still less significant than that achieved with the chessboard strategy. Although reducing hatch spacing can promote grain refinement to a certain extent, it also intensified thermal accumulation, which favored directional grain growth and limited further improvements in surface quality.
The findings indicate that optimizing the scanning strategy effectively regulates melt pool behavior and grain evolution, thereby reducing the surface roughness and improving the surface quality of Ti-6Al-4V components manufactured by LPBF.

Key words

laser powder bed fusion / scanning parameters / Ti-6Al-4V / surface roughness / grain orientation / grain size

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WANG Mengda, DING Jiaming, JI Xia, Steven Y. Liang. Effect of Scanning Parameters on the Surface Roughness of Ti-6Al-4V Processed by Laser Powder Bed Fusion[J]. Surface Technology. 2025, 54(19): 143-152 https://doi.org/10.16490/j.cnki.issn.1001-3660.2025.19.012

References

[1] 张蕾涛, 刘德鑫, 张伟樯, 等. 钛合金表面激光熔覆涂层的研究进展[J]. 表面技术, 2020, 49(8): 97-104.
ZHANG L T, LIU D X, ZHANG W Q, et al.Research Progress of Laser Cladding Coating on Titanium Alloy Surface[J]. Surface Technology, 2020, 49(8): 97-104.
[2] 赵秦阳, 陈永楠, 徐义库, 等. 钛合金材料低成本化制备技术进展与展望[J]. 中国有色金属学报, 2021, 31(11): 3127-3140.
ZHAO Q Y, CHEN Y N, XU Y K, et al.Progress and Prospects of Cost-Effective Manufacturing Technologies for Titanium Alloys[J]. The Chinese Journal of Nonferrous Metals, 2021, 31(11): 3127-3140.
[3] SONG J W, HAN Y F, FANG M H, et al.Temperature Sensitivity of Mechanical Properties and Microstructure during Moderate Temperature Deformation of Selective Laser Melted Ti-6Al-4V Alloy[J]. Materials Characterization, 2020, 165: 110342.
[4] SUN D S, GU D D, LIN K J, et al.Selective Laser Melting of Titanium Parts: Influence of Laser Process Parameters on Macro- and Microstructures and Tensile Property[J]. Powder Technology, 2019, 342: 371-379.
[5] KAN W H, GAO M, ZHANG X, et al.The Influence of Porosity on Ti-6Al-4V Parts Fabricated by Laser Powder Bed Fusion in the Pursuit of Process Efficiency[J]. The International Journal of Advanced Manufacturing Technology, 2022, 119(7): 5417-5438.
[6] URIONDO A, ESPERON-MIGUEZ M, PERINPANAYAGAM S.The Present and Future of Additive Manufacturing in the Aerospace Sector: A Review of Important Aspects[J]. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2015, 229(11): 2132-2147.
[7] KAHLIN M, ANSELL H, MOVERARE J J.Fatigue Behaviour of Notched Additive Manufactured Ti₆Al₄V with As-Built Surfaces[J]. International Journal of Fatigue, 2017, 101: 51-60.
[8] 朱莉娜, 邓彩艳, 王东坡, 等. 表面粗糙度对Ti-6Al-4V合金超高周疲劳性能的影响[J]. 金属学报, 2016, 52(5): 583-591.
ZHU L N, DENG C Y, WANG D P, et al.Effect of Surface Roughness on very High Cycle Fatigue Behavior of Ti-6Al-4V Alloy[J]. Acta Metallurgica Sinica, 2016, 52(5): 583-591.
[9] 孙智, 任耀剑, 隋艳伟. 失效分析:基础与应用[M]. 2版. 北京: 机械工业出版社, 2017: 230-233.
SUN Z, REN Y J, SUI Y W.Failure Analysis[M]. 2nd ed. Beijing: China Machine Press, 2017: 230-233.
[10] 王俊卿, 仲建军. 减小零件表面粗糙度值的对策与研究[J]. 装备制造技术, 2017(1): 160-162.
WANG J Q, ZHONG J J.Countermeasure and Research on Reducing Surface Roughness Value of Parts[J]. Equipment Manufacturing Technology, 2017(1): 160-162.
[11] MA H Y, WANG J C, QIN P, et al.Advances in Additively Manufactured Titanium Alloys by Powder Bed Fusion and Directed Energy Deposition: Microstructure, Defects, and Mechanical Behavior[J]. Journal of Materials Science & Technology, 2024, 183: 32-62.
[12] 徐戊矫, 龙江, 章磊, 等. Al6061板在不同应变路径下粗糙度演变的有限元模拟及实验[J]. 中国有色金属学报, 2015, 25(10): 2844-2853.
XU W J, LONG J, ZHANG L, et al.Finite Element Simulation and Experiment of Surface Roughness Evolution for Al6061 Sheet under Different Strain Routes[J]. The Chinese Journal of Nonferrous Metals, 2015, 25(10): 2844-2853.
[13] MATSUZAWA M, ITO A, KOMATSU T, et al.Effect of Grain Size on Change in Surface Roughness of Carbon Steels through Polishing Processes[J]. International Journal of Automation Technology, 2022, 16(1): 95-103.
[14] LU J Z, DENG W W, LUO K Y, et al.Surface EBSD Analysis and Strengthening Mechanism of AISI304 Stainless Steel Subjected to Massive LSP Treatment with Different Pulse Energies[J]. Materials Characterization, 2017, 125: 99-107.
[15] KÓNYA J, JABER H, KOVÁCS T A, et al. Effects of Selective Laser Melting Building Directions and Surface Modifications on Surface Roughness of Ti₆Al₄V Alloy[J]. Discover Applied Sciences, 2024, 6(1): 5.
[16] 冯恩昊, 王小齐, 韩潇, 等. 激光选区熔化Ti₆Al₄V合金的工艺参数优化[J]. 粉末冶金技术, 2022, 40(6): 555-563.
FENG E H, WANG X Q, HAN X, et al.Process Parameters Optimization of Ti₆Al₄V Fabricated by Selective Laser Melting[J]. Powder Metallurgy Technology, 2022, 40(6): 555-563.
[17] 李颖, 彭霜, 张婷, 等. 选区激光熔化制备Ti-6Al-4V合金的热处理工艺及力学性能[J]. 金属热处理, 2022, 47(9): 175-181.
LI Y, PENG S, ZHANG T, et al.Heat Treatment Process and Mechanical Properties of Selective Laser Melted Ti-6Al-4V Alloy[J]. Heat Treatment of Metals, 2022, 47(9): 175-181.
[18] 胡全栋, 孙帆, 李怀学, 等. 扫描方式对激光选区熔化成形316不锈钢性能的影响[J]. 航空制造技术, 2016, 59(增刊1): 124-127.
HU Q D, SUN F, LI H X, et al.Effects of Scanning Patterns on the Defects and Microstructure of 316 Stainless Steel Fabricated by Selective Laser Melting (SLM)[J]. Aeronautical Manufacturing Technology, 2016, 59(Sup. 1): 124-127.
[19] 陈德宁, 刘婷婷, 廖文和, 等. 扫描策略对金属粉末选区激光熔化温度场的影响[J]. 中国激光, 2016, 43(4): 403003.
CHEN D N, LIU T T, LIAO W H, et al.Temperature Field during Selective Laser Melting of Metal Powder under Different Scanning Strategies[J]. Chinese Journal of Lasers, 2016, 43(4): 403003.
[20] THIJS L, VERHAEGHE F, CRAEGHS T, et al.A Study of the Microstructural Evolution during Selective Laser Melting of Ti-6Al-4V[J]. Acta Materialia, 2010, 58(9): 3303-3312.
[21] RICKMAN J M, LAWRENCE A, ROLLETT A D, et al.Calculating Probability Densities Associated with Grain- Size Distributions[J]. Computational Materials Science, 2015, 101: 211-215.
[22] PELEVIN I.Surface morphology investigations of nanocrystalline R₂Fe₁₄B (R=Y, Nd, Gd, Er) by atomic force microscopy[C]// Modern Trends in Manufacturing Technologies and Equipment. Cheboksary: Materials Research Forum LLC, 2022: 81.
[23] BIAN P Y, SHI J, LIU Y, et al.Influence of Laser Power and Scanning Strategy on Residual Stress Distribution in Additively Manufactured 316L Steel[J]. Optics & Laser Technology, 2020, 132: 106477.
[24] LIZZUL L, BERTOLINI R, GHIOTTI A, et al.Turning of Additively Manufactured Ti₆Al₄V: Effect of the Highly Oriented Microstructure on the Surface Integrity[J]. Materials, 2021, 14(11): 2842.
[25] 刘飞, 马晓桐, 刘战伟, 等. 电子背散射衍射技术及其在微观力学行为研究中的应用[J]. 力学与实践, 2023, 45(6): 1321-1330.
LIU F, MA X T, LIU Z W, et al.Electron Backscatter Diffraction Technique and Its Application in the Study of Micromechanics Behavior[J]. Mechanics in Engineering, 2023, 45(6): 1321-1330.
[26] FIDDER H.Structure-Property Relationships in Laser Assisted and Mechanically Deformed Advanced Materials [D]. Groningen: University of Groningen Press, 2020.
[1] LI W, WANG Y Z, ZHOU X G, et al.Measurement of the Pattern Shifts for HR-EBSD with Larger Lattice Rotations[J]. Ultramicroscopy, 2023, 247: 113697.
[27] LIANG H Q, ZENG Y P, ZUO K H, et al.Mechanical Properties and Thermal Conductivity of Si₃N₄ Ceramics with YF₃ and MgO as Sintering Additives[J]. Ceramics International, 2016, 42(14): 15679-15686.
[28] 王祥, 张林杰, 李森, 等. 增材制造Ti-6Al-4V组织的演化与拉伸性能的差异[J]. 航空制造技术, 2019, 62(17): 88-94.
WANG X, ZHANG L J, LI S, et al.Evolution of Microstructure and Properties of Ti-6Al-4V in Additive Manufacturing[J]. Aeronautical Manufacturing Technology, 2019, 62(17): 88-94.
[29] 李宏伟, 向治宇, 张昕, 等. 脉冲电流作用下GH4738合金不均匀变形组织的均匀化机理与规律[J]. 塑性工程学报, 2023, 30(6): 102-110.
LI H W, XIANG Z Y, ZHANG X, et al.Mechanism and Rules of Microstructure Homogenization in Non-Uniform Deformed GH4738 under Pulsed Current[J]. Journal of Plasticity Engineering, 2023, 30(6): 102-110.
[30] ALVI M H.Recrystallization Kinetics and Microstructural Evolution in Hot Rolled Aluminum Alloys[M]. Pittsburgh: Carnegie Mellon University, 2005: 61-72.
[31] CHOLKAR A, MCCANN R, KINAHAN D, et al.Fabrication of Anti-Icing Surface Structures on Aluminum Alloy for Aerospace Applications[J]. Key Engineering Materials, 2022, 926: 1643-1649.
[32] SLABEJOVÁ S, HOLUBJAK J, CZÁNOVÁ T, et al. Surface Quality of a Groove after Trochoidal Milling with a Monolithic Ceramic Milling Cutter[J]. Manufacturing Technology, 2022, 22(3): 334-341.
[33] XIAO W J, XU Y X, SONG L J.Phase-Field Study on the Evolution of Microstructure of the Molten Pool for Additive Manufacturing[J]. Chinese Journal of Theoretical and Applied Mechanics, 2021, 53(12): 3252-3262.