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Mesoscopic-scale simulation of pore evolution during laser powder bed fusion process
摘要： Laser powder bed fusion (LPBF) is an advanced manufacturing technology that uses data-driven, layer-by-layer accumulation of materials to form metal components and has been widely applied in aerospace and other fields. Effectively controlling pore defects is a key scientific problem and technical difficulty in LPBF industrial production. Based on the open-source discrete element method code Yade, the particle distribution of the powder bed was obtained. Based on the open-source computational fluid dynamics code OpenFOAM, the pore evolution during the LPBF formation process at the mesoscopic scale was predicted. The thermal–force factors affecting the molten pool included the surface tension, Marangoni effect, gasification recoil force, and mushy drag force. The laser energy model used a body heat source based on interface tracking. First, dimensionless analysis of the molten pool evolution in the case of LPBF single-track formation was carried out. The molten pool evolution was mainly influenced by the gasification recoil force, Marangoni effect and surface tension, and the main influencing factors on different zones of the molten pool were different. To examine the influences of the laser power, scanning speed, powder bed thickness, and hatch space on the pore defect in the LPBF formation process, simulations were carried out and compared with experimental results. When the volumetric energy density was too small, pore defects occurred due to insufficient fusion of metal particles, and when the volumetric energy density was too large to cause the “keyhole” effect, pore defects occurred because the entrained gas could not escape in time. This paper is expected to provide theoretical guidance for the scientific regulation of pore defects in LPBF production.
关键词： OpenFOAM,Volumetric energy density,Dimensionless analysis,Pore defect,Laser powder bed fusion,Numerical simulation
更新于2025-09-19 17:13:59
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Benchmarking of Laser Powder Bed Fusion Machines
摘要： This paper presents the methodology and results of an extensive benchmarking of laser powder bed fusion (LPBF) machines conducted across five top machine producers and two end users. The objective was to understand the influence of the individual machine on the final quality of predesigned specimens, given a specific material and from multiple perspectives, in order to assess the current capabilities and limitations of the technology and compare them with the capabilities of an 11-year-old machine belonging to one of the end users participating in this investigation. The collected results give a clear representation of the status of LPBF technology considering its maturity in terms of process capabilities and potential applications in a production environment.
关键词： laser powder bed fusion,technology evaluation,benchmarking,additive manufacturing,repeatability,selective laser melting,accuracy
更新于2025-09-16 10:30:52
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Processability of Atypical WC-Co Composite Feedstock by Laser Powder-Bed Fusion
摘要： Processing of tool materials for cutting applications presents challenges in additive manufacturing (AM). Processes must be carefully managed in order to promote the formation of In this study, for the ?rst time, a satelliting process is used to prepare a WCM-Co (12 wt.% Co) composite. Melting trials were undertaken to evaluate the consolidation behaviour of single tracks within a single layer. Tracks with continuous and relatively uniform surface morphology were obtained. These features are essential for high-quality AM builds in order to encourage good bonding between subsequent tracks within a layer which may reduce porosity within a 3D deposition. This study elucidates the formation of track irregularities, melting modes, crack sensitivity, and balling as a function of laser scanning speed and provides guidelines for future production of WCM-Co by laser powder-bed fusion.
关键词： WCM-Co,satelliting,melt mode,single tracks,laser-powder bed fusion (L-PBF)
更新于2025-09-16 10:30:52
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A Review on Laser Powder Bed Fusion of Inconel 625 Nickel-Based Alloy
摘要： The Inconel 625 (IN625) superalloy has a high strength, excellent fatigue, and creep resistance under high-temperature and high-pressure conditions, and is one of the critical materials used for manufacturing high-temperature bearing parts of aeroengines. However, the poor workability of IN625 alloy prevents IN625 superalloy to be used in wider applications, especially in applications requiring high geometrical complexity. Laser powder bed fusion (LPBF) is a powerful additive manufacturing process which can produce metal parts with high geometrical complexity and freedom. This paper reviews the studies that have been done on LPBF of IN625 focusing on the microstructure, mechanical properties, the development of residual stresses, and the mechanism of defect formation. Mechanical properties such as microhardness, tensile properties, and fatigue properties reported by di?erent researchers are systematically summarized and analyzed. Finally, the remaining issues and suggestions on future research on LPBF of IN625 alloy parts are put forward.
关键词： additive manufacturing,heat treatment,Inconel 625,laser powder bed fusion,mechanical properties
更新于2025-09-16 10:30:52
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Determining the feasible conditions for processing lunar regolith simulant via Laser Powder Bed Fusion
摘要： Additive manufacturing shows an intrinsic compatibility with building in extra-terrestrial colonization. The use of raw materials found in situ can drastically reduce the complexity of the material supply chain. Laser Powder Bed Fusion (LPBF) is a flexible option for producing components starting from powder feedstock. However, further understanding of the technological capabilities is required to resolve both deposition issues and process applicability in space. This work addresses the processability of lunar highlands regolith simulant NU-LHT-2M by Laser Powder Bed Fusion on an open prototypal system. The investigation into the influence of process parameters and different base plate materials (carbon steel, self-supporting deposition and refractory clay) was enabled by the in-house developed LPBF machine. The process feasibility window for multi-layer deposition was determined on the refractory clay base plate which ensured stable deposition. Finally, process parameters were studied to produce multi-layer cubical samples which were further analysed for their mechanical properties. Specimens presented compressive yield stress values in excess of 31.4 MPa and micro hardness values in excess of 680 HV, showing the potential of the technology for the deposition of lunar regolith components. The results were also interpreted to assess the technological feasibility of future LPBF machines which may operate in micro gravity conditions.
关键词： space manufacturing,Laser Powder Bed Fusion,process development,regolith
更新于2025-09-16 10:30:52
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Thermal expansion behavior of CNT reinforced AlSi10Mg composite fabricated via laser powder bed fusion
摘要： Carbon nanotube (CNT) reinforced Al matrix composite exhibit good dimensional stability and can be a promising material with low coef?cient of thermal expansion (CTE). The thermal expansion behavior of CNT/AlSi10Mg composite with the CNTs content from 0 wt% to 2 wt% fabricated via laser powder bed fusion (LPBF) was investigated in this research. The CTE of all samples increased generally as the temperature increasing. At the same temperature, the CTE of the samples was smaller when CNTs content is lower. The best dimensional stability was reached as CNTs content was 2 wt%. The CTE deceased to 29.08 × 10?6 °C?1, as much as 16% reduction compared with unreinforced AlSi10Mg at 300 °C. The solid solution and precipitation behavior of Si in matrix and the interruptions of Si network resulted in the ?uctuation during dimension increase. With the CNTs distributed along the cell boundary, the Si network was consolidated. Hence, the microstructure of the composite became more stable and the CTE got lower with the addition of CNTs increasing. Moreover, the experimental results were similar to the predicted value of the thermoelastic model.
关键词： laser powder bed fusion,CNTs,coef?cient of thermal expansion,network
更新于2025-09-16 10:30:52
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Processing of X65MoCrWV3a??2 Cold Work Tool Steel by Laser Powder Bed Fusion
摘要： Laser powder bed fusion (L-PBF) of forming tools has become of major interest in the tooling industry because of the high geometrical flexibility of this process. During L-PBF, a metallic powder bed is melted selectively by a laser beam, enabling the layer-wise manufacturing of parts from 3D computer-aided design data. The process is characterized by a locally and temporally unsteady heat flow in the solidified part and in the melt pool, causing nonequilibrium solidification and phase transformations. In addition, rapid heating and cooling occur, promoting the formation of microstructural defects, cold cracks, and distortion. Because of the high tendency to form cold cracks, processing of martensitic tool steels is still a challenging task. Tool steel X65MoCrWV3-2 is processed by L-PBF and the resulting microstructure and the associated local properties are investigated by microhardness measurements, nanoindentation, and scanning electron microscopy. It is gathered from the investigations that regions of different microstructures and mechanical properties on both micro- and macroscale are present in the L-PBF-densified steel. The different microstructures and properties are the result of the alternating heat insert at different temperature regimes, forming heat-affected zones in which the tempering processes are triggered and strongly varying properties are generated.
关键词： additive manufacturing,martensite,microstructure formation,laser powder bed fusion,tool steels
更新于2025-09-16 10:30:52
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Influence of particle morphology and size distribution on the powder flowability and laser powder bed fusion manufacturability of Ti-6Al-4V alloy
摘要： Laser powder bed fusion (LPBF) additive manufacturing technology is sensitive to variations in powder particle morphology and size distribution. However, the absence of a clear link between the powder characteristics and the LPBF performances complicates the development, selection and quality control of LPBF powder feedstock. In this work, three Ti-6Al-4V powder lots produced by two different techniques, namely, plasma atomization and gas atomization, were selected and characterized. Following the micro-computed tomography analysis of the powder particles’ morphology, size and density, the flowability of these powder lots was concurrently evaluated using Hall and Gustavsson flowmeters and an FT4 powder rheometer. Using established rheology-based criteria, a figure of merit was proposed to quantify the overall powder suitability for the LPBF process. Next, the same three powder lots were used to 3D-print and post-process a series of testing specimens with different layer thicknesses and build orientations, in order to establish a correlation between the powder characteristics and the geometric and mechanical properties of a final product. This study demonstrates that the use of highly spherical powders with a limited amount of fine particles promotes their flowability and yields LPBF components with improved mechanical and geometric characteristics.
关键词： sphericity,powder flowability,particle size distribution,Laser powder bed fusion,layer thickness,Ti-6Al-4V
更新于2025-09-12 10:27:22
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Multi-physical analysis of thermo-optical effects for different Selective Laser Melting (SLM) scanning strategies
摘要： In this paper, transient thermo-optical effects in protective windows for selective laser melting are analyzed by means of a multi-physical analysis. The temperature distribution of the window is simulated for different scanning strategies and orders of exposure. Therefore, cubic test specimens are virtually built and the resulting axial and lateral focus shift is analyzed. Furthermore, the impact of the distance between the laser scanner and the protective window is analyzed. The simulations predict that spreading the thermal load on the window both spatially and temporally reduces the focus shift. Consequently, the focus shift is reduced if the window is placed further away from the laser scanner.
关键词： thermal lensing,Selective laser melting,protective window,finite element analysis,laser-powder bed fusion,additive manufacturing
更新于2025-09-12 10:27:22
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In-situ characterization of tungsten microcracking in Selective Laser Melting
摘要： Additive Manufacturing is a promising way of processing tungsten, with opportunities to create more complex parts than are possible using other powder metallurgical routes. This may lead to extended applications such as collimators, in fusion reactors, or in other structurally loaded, high temperature environments. The poor thermal shock resistance and ductile-to-brittle transition that occurs in tungsten above room temperature are challenges that hinder production of fully dense and crack free parts. This research employs high speed in-situ monitoring of Selective Laser Melting of single tracks to visualize crack initiation and propagation. The circumstances that lead to cracking are correlated with microstructural morphology and processing conditions.
关键词： In-situ monitoring,Additive Manufacturing,Microcracking,Laser powder bed fusion,Tungsten,Selective Laser Melting
更新于2025-09-12 10:27:22