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Finite element prediction and validation of residual stress profiles in 316L samples manufactured by laser powder bed fusion
摘要： Laser powder bed fusion (LPBF) processes continue to grow in popularity and much progress has been made in recent years. However, due to the extreme thermal gradients present, significant residual stresses are inevitable and can be detrimental during component service. Critical to mitigating these stresses effectively is the ability to model the thermo-mechanical process accurately and efficiently. A simplified FE modelling methodology has been developed and applied to a cylindrical component built in both the horizontal and vertical orientations. The resulting distortion of the parts following a slitting process was compared with those predicted by the model and good agreement to within 5% was found. The final stress fields in the components were predicted by the model and then examined to assess the principal stresses driving the distortion and the causes of difference in results between the two build orientations.
关键词： LPBF,residual stress,finite element modelling,Laser powder bed fusion,distortion
更新于2025-09-12 10:27:22
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Process Design of Laser Powder Bed Fusion of Stainless Steel Using a Gaussian Process-Based Machine Learning Model
摘要： In this work, a Gaussian process (GP)-based machine learning model is developed to predict the remelted depth of single tracks, as a function of combined laser power and laser scan speed in a laser powder bed fusion process. The GP model is trained by both simulation and experimental data from the literature. The mean absolute prediction error magni?ed by the GP model is only 0.6 lm for a powder bed with layer thickness of 30 lm, suggesting the adequacy of the GP model. Then, the process design maps of two metals, 316L and 17-4 PH stainless steels, are developed using the trained model. The normalized enthalpy criterion of identifying keyhole mode is evaluated for both stainless steels. For 316L, the result suggests that the DH (cid:2) 30 criterion hs should be related to the powder layer thickness. For 17-4 PH, the criterion should be revised to DH hs (cid:2) 25.
关键词： stainless steel,process design,Gaussian process,machine learning,laser powder bed fusion
更新于2025-09-12 10:27:22
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Fracture Toughness of a Hot Work Tool Steel Fabricated by Laser‐Powder Bed Fusion Additive Manufacturing
摘要： The fracture toughness of AISI H13 tool steel, additively manufactured by laser powder bed fusion (L-PBF) technique was studied. The influence of the building direction on fracture toughness was investigated on small notched bending samples heat treated according to two different thermal cycles, namely quenching and tempering (QT) and only tempering (T). The notch was electro discharge machined parallel (P//), perpendicular (P┴) and longitudinal (L) to the building direction. Both heat treatments, even if to a different extent, delete the as-built microstructure, producing secondary carbides precipitation in the martensitic matrix. The microstructure of the directly tempered parts is finer than the quenched and tempered ones. The fracture toughness increases moving from P┴ to P//. The T samples show a higher apparent fracture toughness in the P//, despite the higher hardness. Secondary cracks formation allows toughness in P// samples. This effect is more pronounced in T samples where the stronger precipitation of carbides at the prior melt boundaries promotes secondary cracks. Moreover, in P// samples the laser tracks act as barriers to crack propagation and as stress dissipators.
关键词： Laser powder bed fusion,hot work tool steel,fracture toughness,microstructure
更新于2025-09-12 10:27:22
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Titanium for Consumer Applications || Bone regeneration on implants of titanium alloys produced by laser powder bed fusion: A review
摘要： Bone regeneration on biomaterials is a topic of increased interest due to the possibility of creating implants that existing bone can attach to. Titanium alloys are very suitable for this purpose and have been proven to be biocompatible, while also having suitable mechanical properties [1]. Moreover, titanium alloys are one of the most widely investigated materials for metal additive manufacturing (AM), which means that custom-designed implants can be manufactured reliably by AM. The AM technology best suited to this is powder bed fusion; laser powder bed fusion (LPBF) in particular holds some advantages. In this chapter, we investigate the current state of the art for the production of pure Ti and Ti6Al4V implants by LPBF, focusing on the requirements and capabilities for osseointegration. The first section discusses bone architecture and requirements for bone implants in general, identifying different requirements for different types of implants, and describing the various bone growth processes in more detail. This is followed by a section on surface structuring; the surface morphology and chemistry strongly influence the initial stages of bone growth, making it critical to the success of such implants. The next section describes porous structures, also known as lattice structures, which allow bone in-growth and attachment. This section describes various requirements for such lattices (pore size, lattice design, etc.) in terms of bone growth and summarizes what has been achieved thus far. The following section describes the mechanical properties of titanium lattice structures of various types that have been produced by LPBF. The next two sections describe in detail successful in vitro and in vivo experiments, respectively, for bone growth on LPBF titanium alloys. Finally, a discussion section summarizes the current state of the art and highlights requirements for future research efforts.
关键词： Bone regeneration,Titanium alloys,Laser powder bed fusion,Additive manufacturing,Osseointegration
更新于2025-09-12 10:27:22
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Temperature Profile, Bead Geometry, and Elemental Evaporation in Laser Powder Bed Fusion Additive Manufacturing Process
摘要： Powder bed fusion processes have been a focus of research in recent years. Computational models of this process have been extensively investigated. In most cases, the distribution of heat intensity over the powder bed during the laser–powder interaction is assumed to follow a Gaussian beam pattern. However, the heat distribution over the surface is a complicated process that depends on several factors such as beam quality factor, laser wavelength, etc. and must be considered to present the laser–material interaction in a way that represents the actual beam. This work presents a process in which a non-Gaussian laser beam model is used to model the temperature pro?le, bead geometry, and elemental evaporation in the powder bed process. The results are compared against those of a Gaussian beam model and also an experiment using Inconel 718 alloy. The model offers good predictions of the temperature, bead shape, and concentration of alloying elements.
关键词： Additive manufacturing,Temperature profile,Powder bed fusion,Laser powder bed fusion,Bead geometry,Non-Gaussian beam,Elemental evaporation
更新于2025-09-11 14:15:04
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Effect of powder characteristics on production of oxide dispersion strengthened Fe 14Cr steel by laser powder bed fusion
摘要： In order to assess the potentialities of additive manufacturing in nuclear industry, Oxide Dispersion Strengthened (ODS) Fe\14Cr steels are produced by laser powder bed fusion (L-PBF). Such materials are currently manufactured by milling a Fe\14Cr atomized powder with Y2O3 and TiH2 powders. The resulting powder has a non-spherical shape being coarser than powders typically used in L-PBF equipment. The influence of powder characteristics on the processability of ODS Fe\14Cr by L-PBF are studied in details. Four different powders are used. These powders differ from size, morphology and chemical composition. Finer is the powder; wider is the process range to obtain dense samples. This phenomenon could be mitigated by transferring an amount of energy superior to 110 J.mm?3. The presence of yttrium and titanium gives columnar microstructure for ODS samples, whereas Fe\14Cr samples have stirred microstructure. Titanium and yttrium form oxides, which enlarge the melt pool and induce columnar growth.
关键词： Additive manufacturing,Powder flowability,Metal Matrix Composites (MMCs),Chemical composition,Laser Powder Bed Fusion (L-PBF),Particle size distribution
更新于2025-09-11 14:15:04
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Pore Closure Effect of Laser Shock Peening of Additively Manufactured AlSi10Mg
摘要： This article reports on an exceptional insight provided by nondestructive X-ray tomography of the same samples before and after laser shock peening (LSP). The porosity in two additively manufactured aluminum alloy (AlSi10Mg) tensile samples before and after LSP was imaged using identical X-ray tomography settings and overlap of the data was performed for direct comparison. The results indicate clearly that near-surface pores are closed by the process, while internal pores remain unaffected. LSP has become well known as a method to improve the fatigue properties of materials, including those of additively manufactured aluminum alloys. This improvement is usually attributed to the compressive residual stress induced by the process. The additional effect of closure of near-surface pores that is illustrated in this work is of interest for additive manufacturing because additive manufacturing is not yet able to produce completely pore-free components. Since the critical pore initiating fatigue cracks are always attributed to surface or subsurface pores, the closure of these pores may play an additional role in improving the fatigue properties. While more work remains to unravel the relative importance of near-surface porosity compared to the compressive residual stress effect, this work clearly shows the effect of LSP—closing of pores near the surface. For the processing conditions demonstrated here, all pores up to 0.7 mm from the surface are closed without damaging the surface, while higher peening power results in surface damage.
关键词： additive manufacturing,laser shock peening,X-ray tomography,aluminum alloys,laser powder bed fusion
更新于2025-09-11 14:15:04
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A cybermanufacturing and AI framework for laser powder bed fusion (LPBF) additive manufacturing process
摘要： In Laser Powder Bed Fusion (LPBF) along, more than 50 process parameters are known to affect print quality. The current state-of-the-art practice in process control only considers a small fraction of them – mainly on laser power and scanning speed affecting temperature gradient and geometry of a melting pool. This letter proposes a system-wide platform involving various machine learning principles and leveraging production data stored in the cloud. The proposed framework aims to identify process parameters that may affect print quality so that a viable process control strategy can be formulated.
关键词： Laser powder bed fusion,Metal 3D printing,Machine learning,Process monitoring
更新于2025-09-11 14:15:04
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Scalable laser powder bed fusion processing of nitinol shape memory alloy
摘要： The authors report on pulsed laser powder bed fusion fabrication of nitinol (NiTi) shape memory materials. The authors ?rst performed single-track laser parameter sweeps to assess melt pool stability and determine energy parameters and hatch spacing for larger builds. The authors then assessed the melt pool chemistry as a function of laser energy density and build plate composition. Brittle intermetallics were found to form at the part/build plate interface for both N200 and Ti-6-4 substrates. The intermetallic formation was reduced by building on a 50Ni–50Ti substrate, but delamination still occurred due to thermal stresses upon cooling. The authors were able to overcome delamination on all substrates and fabricate macroscopic parts by building a lattice support structure, which is both compliant and controls heat transfer into the build plate. This approach will enable scalable fabrication of complex NiTi parts.
关键词： additive manufacturing,shape memory alloy,nitinol,scalable fabrication,laser powder bed fusion
更新于2025-09-11 14:15:04
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Variation of Surface Topography in Laser Powder Bed Fusion Additive Manufacturing of Nickel Super Alloy 625
摘要： This document provides details on the files available for download in the dataset “Variation of Surface Topography in Laser Powder Bed Fusion of Nickel Super Alloy 625.” The following sections provide details on the experiments, methods, and data files. The experiment detailed in this document methodically varies part position and surface orientation relative to the build plate and relative to the recoater blade. This dataset provides surface height data for analysis and development of correlations by the greater research community.
关键词： additive manufacturing,focus variation,IN625,surface texture,surface topography,nickel super alloy 625,laser powder bed fusion
更新于2025-09-11 14:15:04