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Characterisation of 17-4PH metallic powder recycling to optimise the performance of the selective laser melting process
摘要： The advantages of Additive Manufacturing (AM) processes are well known. Particularly, those AM techniques which are used to manufacture metallic parts are of great interest to industry due to the good mechanical behaviour of metallic alloys. Despite this, the quality of the manufactured parts is still an important issue due to the wide range of parameters that can affect them. In some powder bed fusion techniques, such as Selective Laser Melting (SLM), not all the initially distributed metallic powder is used in the process. There is an unmolten portion that can be recycled to ensure both the economic and environmental viability of the process. Even though this powder is unmolten, it is thermally affected due to the high temperatures attained during the process. This fact affects the powder properties and, consequently, the properties of the manufactured parts. Therefore, an analysis of the recycling effects of SLM metallic powders is an important issue in order to establish good recycling procedures and to optimise the process performance.
关键词： Additive manufacturing,17-4PH stainless steel,Powder bed fusion,Selective laser melting,Laser beam melting
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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On the Effectiveness of Different Surface Finishing Techniques on A357.0 Parts Produced by Laser-Based Powder Bed Fusion: Surface Roughness and Fatigue Strength
摘要： Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technique that uses a computer-controlled laser beam as the energy source to consolidate a metal powder according to a layer-upon-layer strategy in order to manufacture a three dimensional part. This opens the way for an unprecedented freedom in geometry, but the layer-wise build-up strategy typically results in a very poor surface ?nish, which is a?ected by the staircase e?ect and by the presence of partially molten particles. Surface ?nishing treatments are therefore necessary to obtain an adequate surface ?nish, to improve the fatigue behavior and to meet mechanical and aesthetic needs. The present contribution systematically compares numerous surface ?nishing techniques, including laser shock processing, plastic media blasting, sand blasting, ceramic shot peening and metal shot peening with steel particles of di?erent sizes (φ = 0.2 mm and φ = 0.4 mm). The results show that all the proposed methods improve the surface quality and the fatigue life of A357.0 L-PBF parts. However, the achievement of the lowest surface roughness does not necessarily correspond to the best fatigue performance, thus suggesting that multiple mechanisms may be active and that besides surface roughness also residual stresses contribute to increase the fatigue strength.
关键词： laser shock processing,additive manufacturing,fatigue,shot peening,surface ?nishing,plastic media blasting,sand blasting,surface roughness,A357.0,laser-based powder bed fusion
更新于2025-09-16 10:30:52
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On the Effect of Part Orientation on Stress Distribution in AlSi10Mg Specimens Fabricated by Laser Powder Bed Fusion (L-PBF)
摘要： The freedom of design of AM products suffers from some limitations in case of powder bed metal processes, because AM part’s integrity is affected by the residual stress state that is a consequence of the thermal history during part fabrication. Aim of this work is to evaluate the effect of part orientation on stress distribution. Thus, flat samples of AlSi10Mg alloy built along different orientations are produced by means of laser powder bed fusion (L-PBF) process, also known as Selective Laser Melting (SLM). Then, the semi-destructive hole-drilling method is used to evaluate residual stresses beneath the surfaces of samples. The outcomes of the study can be exploited to define design rules in order to both minimize support structures and optimize the orientation of the part in the building volume.
关键词： Powder bed fusion,Residual stresses,Hole-drilling method,AlSi10Mg,Orientation
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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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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Prediction of Selective Laser Melting Part Quality Using Hybrid Bayesian Network
摘要： Additive manufacturing (AM) is gaining popularity because of its ability to manufacture complex parts in less time. Despite recent research involving designs of experiments (DOEs) to characterize the relationships between some AM process parameters and various part quality characteristics, to date, there seems to be no universally accepted comprehensive model that relates process parameters to part quality. In this paper, to support the goal of manufacturing parts right the first time, a Bayesian network in continuous domain is developed which relates four process parameters (laser power, scan speed, hatch spacing, and layer thickness) and five part quality characteristics (density, hardness, top layer surface roughness, ultimate tensile strength in the build direction and ultimate tensile strength perpendicular to the build direction). A machine learning algorithm is used to train the network on a database mined from a large number of publications with experimental data from parts built using 316L with selective laser melting. Using this Bayesian network, the user is able to enter a value for one or more known nodes or variables, and the network provides predictions on all the remaining nodes in the form of probability distributions. A method is developed whereby the user inputs are checked for reasonableness using an ??-dimensional convex hull, and if necessary a recommendation is returned based on user-defined weights. The network is validated by retaining a subset of the training data for testing and comparing the network’s predictions to the known values. Accuracy is optimized by continually re-training the network using parts built with a specific machine of interest. The industrial relevance of this research is outlined with respect to four current challenges in AM, including the length of time to determine optimal process parameters for a new machine, ability to organize relevant knowledge, quantification of machine variability, and transfer of knowledge to new operators.
关键词： Hybrid Bayesian Network,Selective Laser Melting Part Quality,Powder Bed Fusion,??-Dimensional Convex Hull,Predictive Model
更新于2025-09-16 10:30:52
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Spatter formation during laser beam melting of AlSi10Mg and effects on powder quality
摘要： Cost and resource efficiency of Laser Beam Melting (LBM) highly depend on powder recycling procedures. Non-solidified powder can be sieved and reused in subsequent build cycles. However, due to quality concerns, powder recycling is not commonly practiced. One effect, which can impair the powder quality, lies in the formation and insertion of spatter particles during the melting process. In this paper, spatter particles emerging during LBM of AlSi10Mg are characterized regarding geometric (size, morphology), chemical (alloy composition, oxygen content, oxide layer thickness) properties as well as mass. Spatter particles are collected during the process using two isolation methods. Three types of spatter particles can be differentiated by their formation mechanism. It is found that spatter particles can differ significantly in oxide layer thickness and particle size. A significant share of spatter particles can be segregated by sieving. However, a certain fraction of the spatter particles will be included in the recycled powder.
关键词： Laser beam melting,AlSi10Mg,Powder recycling,Powder quality,Powder bed fusion,Powder reuse,Additive manufacturing,Reusability,Oxidation,Spatter
更新于2025-09-12 10:27:22