Repair by laser cladding on vertical surfaces differs from conventional flat-position cladding because the laser spot, powder stream, shielding gas, gravity, and molten-pool flow are no longer symmetrically coupled. The work aims to develop a multi-angle laser cladding strategy for vertical 38CrMoAl steel substrates to determine suitable repair postures for narrow inner-wall and large-component repair. Ni60B nickel-based alloy powder was deposited in single-pass tracks by changing only the angle between the cladding head and the substrate normal, while the laser power, scanning speed, powder feeding rate, and shielding gas flow were kept at 250 W, 2 mm/s, 4.22 g/min, and 6 L/min, respectively. Downward-angle cladding was conducted at 0°-70°, and upward-angle cladding was conducted at 10°-40°. The surface morphology, cross- sectional dimensions, cross-sectional area, dilution ratio, microstructure, interfacial element distribution, and microhardness were characterized by optical observation, ImageJ analysis, metallography, SEM, EDS line scanning, and Vickers hardness testing. The results showed that the cladding angle strongly controlled the projected laser energy density and the effective powder capture behavior. In downward-angle cladding, increasing the angle elongated the laser spot reduced the local energy density, and enhanced the downward movement of incompletely solidified molten metal under the combined action of gravity and gas flow. As a result, the coating cross-section evolved from a fish-shaped profile to a flattened and elongated profile. The bead width increased from 1.25 mm at 0° to 2.50 mm at 70°, whereas the penetration depth generally decreased and the apex offset increased to 0.14 mm. Excessive downward angles, especially 60° and 70°, caused more asymmetric powder adhesion and poorer surface quality. Among the downward-angle conditions, 30° produced the most favorable combination of forming quality and material utilization, with a maximum cross-sectional area of 0.662 mm2, the lowest dilution ratio of 32.1%, and the highest microhardness of (597.42±4.52)HV. In upward-angle cladding, the upward component of the powder/gas flow partially counteracted gravity, weakened the downward flow of the molten pool, and produced a more elliptical cross-section. The reinforcement height decreased with the increasing upward angle, while the width, penetration depth, and apex offset changed non-monotonically. The coating formed at an upward angle of 10° showed the best overall performance in this group, with a cross-sectional area of 0.398 mm2, a dilution ratio of 42.9%, and a microhardness of (371.36±4.38)HV. Microstructural analysis revealed that the cladding angle did not substantially change the spatial distribution of grains: columnar dendrites were mainly observed near the fusion boundary, whereas equiaxed grains dominated the middle and upper regions of the molten pool. Nevertheless, the angle markedly affected grain size. The top-region grains formed under normal incidence were coarser than those formed at the downward angle of 30° and the upward angle of 30°, which indicated that inclined cladding modified local solidification conditions by changing the coupling among laser energy distribution, gravity, gas-force-driven flow, and Marangoni convection. EDS line scanning showed mutual diffusion of Fe and Ni across the coating/substrate interface, confirming sound metallurgical bonding. These findings demonstrate that the cladding angle simultaneously regulates geometry formation, dilution, grain growth, and hardness in vertical-surface laser cladding. Considering forming quality, powder utilization, dilution ratio, and microhardness, a downward angle of 30° and an upward angle of 10° are recommended as preferred repair postures for vertical 38CrMoAl substrates.
Key words
vertical substrate /
variable angle /
laser cladding /
38CrMoAl steel /
microstructure
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References
[1] WENG F, CHEN C Z, YU H J.Research Status of Laser Cladding on Titanium and Its Alloys: A Review[J]. Materials & Design, 2014, 58: 412-425.
[2] KUSINSKI J, KAC S, KOPIA A, et al.Laser Modification of the Materials Surface Layer - a Review Paper[J]. Bulletin of the Polish Academy of Sciences: Technical Sciences, 2012, 60(4): 711-728.
[3] BAO G, SHINOZAKI K, IGURO S, et al.Stress Corrosion Cracking Sealing in Overlaying of Inconel 182 by Laser Surface Melting[J]. Journal of Materials Processing Technology, 2006, 173(3): 330-336.
[4] LEE C M, WOO W S, ROH Y H.Remanufacturing: Trends and Issues[J]. International Journal of Precision Engineering and Manufacturing-Green Technology, 2017, 4(1): 113-125.
[5] THOMPSON S M, BIAN L K, SHAMSAEI N, et al.An Overview of Direct Laser Deposition for Additive Manufacturing; Part I: Transport Phenomena, Modeling and Diagnostics[J]. Additive Manufacturing, 2015, 8: 36-62.
[6] KATTIRE P, PAUL S, SINGH R, et al.Experimental Characterization of Laser Cladding of CPM 9V on H13 Tool Steel for Die Repair Applications[J]. Journal of Manufacturing Processes, 2015, 20: 492-499.
[7] TAMANNA N, CROUCH R, NAHER S.Progress in Numerical Simulation of the Laser Cladding Process[J]. Optics and Lasers in Engineering, 2019, 122: 151-163.
[8] HAJIAHMADI M, KHORRAM A, GHOREISHI M.Statistical Modeling and Optimization of Clad Geometry in Laser Cladding of Amdry 961 on Inconel 713LC Superalloy with Response Surface Methodology[J]. Journal of Laser Applications, 2024, 36(2): 022023.
[9] HAO J B, MENG Q D, LI C C, et al.Effects of Tilt Angle between Laser Nozzle and Substrate on Bead Morphology in Multi-Axis Laser Cladding[J]. Journal of Manufacturing Processes, 2019, 43: 311-322.
[10] 王鹏飞, 杨坤, 陈明智, 等. 倾斜基板激光熔覆GH3536熔池形貌的仿真与实验研究[J]. 中国激光, 2021, 48(10): 1002121.
WANG P F, YANG K, CHEN M Z, et al.Simulation and Experimental Research on the GH3536 Molten Pool Laser Cladding on Inclined Substrate[J]. Chinese Journal of Lasers, 2021, 48(10): 1002121.
[11] 李天奕, 石拓, 李宽, 等. 变倾角激光熔覆成形层高和层宽模型研究[J]. 中国激光, 2023, 50(8): 0802102.
LI T Y, SHI T, LI K, et al.Height and Width Model of Cladding Layer Formed by Laser Cladding with Variable Angle[J]. Chinese Journal of Lasers, 2023, 50(8): 0802102.
[12] 尹一君. 基体倾斜和熔覆头偏转对激光熔覆层形貌与粉末利用率影响的研究[J]. 应用激光, 2020, 40(5): : 800-805.
YIN Y J.The Effects of Substrate Tilt and Coaxial Nozzle Deflection on Laser Cladding Morphology and Powder Utilization Rate[J]. Applied Laser, 2020, 40(5): 800-805.
[13] 姜付兵, 石世宏, 傅戈雁. 光内送粉喷头空间变姿态粉气流场数值模拟[J]. 激光技术, 2015, 39(2): 145-151.
JIANG F B, SHI S H, FU G Y.Numerical Simulation of Powder-Gas Flow Field of Inside-Beam Powder Feeding Nozzle with Changing Attitude[J]. Laser Technology, 2015, 39(2): 145-151.
[14] 李向波, 李涛, 石博文, 等. 基于齿面缺陷激光修复几何数学模型的齿轮修复[J]. 中国表面工程, 2020, 33(3): 129-136.
LI X B, LI T, SHI B W, et al.Gear Repairing Based on Geometric Mathematical Model of Tooth Surface Defects by Laser[J]. China Surface Engineering, 2020, 33(3): 129-136.
[15] LIN J, HWANG B C.Coaxial Laser Cladding on an Inclined Substrate[J]. Optics & Laser Technology, 1999, 31(8): 571-578.
[16] 朱刚贤, 石世宏, 傅戈雁, 等. 基于激光加工机器人的光内送粉变基面熔覆研究[J]. 中国激光, 2015, 42(3): 106-111.
ZHU G X, SHI S H, FU G Y, et al.Research on Variable Reference Plane Cladding Based on Laser Processing Robot with Inside-Laser Powder Feeding[J]. Chinese Journal of Lasers, 2015, 42(3): 106-111.
[17] ZHANG G, SUN W L, ZHAO D M, et al.Effect of Laser Beam Incidence Angle on Cladding Morphology in Laser Cladding Process[J]. Journal of Mechanical Science and Technology, 2020, 34(4): 1531-1537.
[18] WANG K Y, YIN X Q, LU H R, et al.Enhancing the Wear Resistance of AlSi9Mg Alloys Using Rotatable Inner- Surface Laser Cladding Method[J]. Journal of Thermal Spray Technology, 2025, 34(5): 1747-1762.
[19] HUANG H L, ZHOU L, LUO S M.Laser Cladding Path Planning for Gear Repair Based on Area Division and Trajectory Correction[J]. The International Journal of Advanced Manufacturing Technology, 2024, 134(7): 3719-3732.
[20] ZHU C Y, ZHU H, ZHONG S J, et al.Laser Cladding Path Planning Algorithm Based on Surface Point Cloud Data[C]//2024 7th International Conference on Data Science and Information Technology (DSIT). Nanjing, China. IEEE, 2024: 1-6.
[21] LIU J D, BA Z Y, SHU D.Laser Cladding Path Planning for Curved Metal Parts[J]. Metals, 2024, 14(9): 1055.
[22] ZHAO K, CHEN M Z, WANG Z D, et al.Investigation of Thermal and Fluid Dynamics Behaviors of Melt Pool during Laser Direct Metal Deposition on Inclined Substrates[J]. Materials Today Communications, 2024, 41: 110953.
[23] XUE Z W, XU L Y, CHEN Z, et al.Formation Optimization of Downward Overlaid Inconel 625 on Curved Surface of X65 Pipeline Basing on Dynamic Behavior of Molten Pool[J]. Journal of Materials Research and Technology, 2023, 25: 6356-6368.
[24] YAO J H, YANG L J, LI B, et al.Characteristics and Performance of Hard Ni60 Alloy Coating Produced with Supersonic Laser Deposition Technique[J]. Materials & Design, 2015, 83: 26-35.
[25] CONDE A, ZUBIRI F, DE DAMBORENEA Y J. Cladding of Ni-Cr-B-Si Coatings with a High Power Diode Laser[J]. Materials Science and Engineering: A, 2002, 334(1/2): 233-238.
[26] SIREDEY-SCHWALLER N, HAMEL-AKRÉ J, PELTIER L, et al.Solidification Sequence of Ni-Si-Cr ~3wt% B Brazing Alloys[J]. Welding in the World, 2017, 61(6): 1253-1265.
[27] NIU F Y, BI W M, LIU Z H, et al.304-Ni60B (NiCrBSi) Composite Components Using WAAM-LC Integrated Hybrid Manufacturing[J]. The International Journal of Advanced Manufacturing Technology, 2024, 132(1): 463-474.
[28] ZHAO Y, YU T B, SUN J Y, et al.Effect of Laser Cladding on Forming Qualities of YCF101 Alloy Powder in the Different Lap Joint Modes[J]. The International Journal of Advanced Manufacturing Technology, 2018, 96(5): 1991-2001.
[29] LIAN G F, LI Y, CAO Q, et al.The Forming Quality of Tungsten-Carbide Coatings Synthesized in Situ by Laser Remelting[J]. Optics & Laser Technology, 2024, 170: 110177.
[30] SHANG X F, WANG Z J, HAN D X, et al. Research on Defects of Titanium Alloy Laser Rapid Forming[J]. Advanced Materials Research, 2011, 189/190/191/192/193: 3726-3730.
[31] 褚梦雅, 练国富, 姚明浦, 等. 斜面激光熔覆粉末流场及光粉耦合机理研究[J]. 表面技术, 2023, 52(7): 369-383.
CHU M Y, LIAN G F, YAO M P, et al.Powder Flow Field and Light-Powder Coupling Mechanism of Inclined Plane Laser Cladding[J]. Surface Technology, 2023, 52(7): 369-383.
[32] MENG X K, JIANG Y L, WANG H, et al.Effect of Variable Laser Incident Angles on Microstructure and Mechanical Properties of Laser-Cladded Inconel 718[J]. Surface and Coatings Technology, 2024, 477: 130310.
[33] 李海波, 李涛, 王鑫林, 等. 倾斜基体对激光熔覆能量分布的影响研究[J]. 应用激光, 2017, 37(3): 333.
LI H B, LI T, WANG X L, et al.Study on the Influence of the Inclined Substrate to the Energy Distribution of Laser Cladding[J]. Applied Laser, 2017, 37(3): 333.
[34] LI X B, LI T, SHI B W, et al.The Influence of Substrate Tilt Angle on the Morphology of Laser Cladding Layer[J]. Surface and Coatings Technology, 2020, 391: 125706.
[35] LIAN G F, CHU M Y, FENG M Y, et al.The Inclined Morphology and Molten Pool of Laser Cladding under Different Cladding Methods[J]. Optics & Laser Technology, 2025, 180: 111445.
[36] CHEN L Y, YU T B, XU P F, et al.In-Situ NbC Reinforced Fe-Based Coating by Laser Cladding: Simulation and Experiment[J]. Surface and Coatings Technology, 2021, 412: 127027.
[37] LIU Y N, DING Y, YANG L J, et al.Research and Progress of Laser Cladding on Engineering Alloys: A Review[J]. Journal of Manufacturing Processes, 2021, 66: 341-363.
[38] ZHANG Y C, LI Z G, NIE P L, et al.Carbide and Nitride Precipitation during Laser Cladding of Inconel 718 Alloy Coatings[J]. Optics & Laser Technology, 2013, 52: 30-36.
[39] ZHOU S F, DAI X G, ZENG X Y.Effects of Processing Parameters on Structure of Ni-Based WC Composite Coatings during Laser Induction Hybrid Rapid Cladding[J]. Applied Surface Science, 2009, 255(20): 8494-8500.
[40] ZHOU S F, DAI X Q, ZHENG H Z.Analytical Modeling and Experimental Investigation of Laser Induction Hybrid Rapid Cladding for Ni-Based WC Composite Coatings[J]. Optics & Laser Technology, 2011, 43(3): 613-621.
[41] WANG H, ZHANG X F, WANG Y F, et al.Forming and Microstructure Evolution Mechanism of Asymmetric Molten Pool in Laser Cladding[J]. Metals, 2023, 13(12): 1970.
[42] 张洋, 宋博瀚, 薛峰. 稀释率对镍基合金激光熔覆层组织和性能的影响[J]. 应用激光, 2016, 36(3): 259-264.
ZHANG Y, SONG B H, XUE F.Influence of DILUTION on Microstructure and Properties in Ni Based Laser Clad Coating[J]. Applied Laser, 2016, 36(3): 259-264.
[43] HEMMATI I, OCELÍK V, DE HOSSON J T M. Dilution Effects in Laser Cladding of Ni-Cr-B-Si-C Hardfacing Alloys[J]. Materials Letters, 2012, 84: 69-72.
Funding
The Liaoning Provincial Major Science and Technology Project (2025JH1/11700009); The Science and Technology Program of Xinjiang Production and Construction Corps (2025AB071, 2025YD004)
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