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Asymmetric pore distribution in pbf-lb/m In718 thin-walled structures: Contour morphology and welding quality

JOURNAL OF mANUFACTURING PROCESSES 2025年 143卷 294-305页

作者： Zhou, Kai Xie, Deqiao Li, Zansong Wang, Dongsheng Shen, Lida Nanjing Univ Aeronaut & Astronaut Coll Mech & Elect Engn Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Wuxi Res Inst Wuxi 214153 Peoples R China JITRI Inst Precis Mfg Nanjing 211800 Peoples R China Tongling Univ Coll Mech Engn Tongling 244000 Peoples R China

Current research on In718 alloys produced by powder bed fusion-laser beam metals (pbf-lb/m) is mainly focused on the deformation challenges, while porosity has received less attention. This study focused on the porosity of the sub-surface of printed components, which is influenced by thickness, and the need to optimize the contour space to improve the print quality of thin-walled structures. The results illustrated that when the contour space was bigger than 0.04 mm, an asymmetry of contour melt tracks inevitably appeared for thin-walled structures, regardless of the placement angle. It was also found that asymmetric contour melt tracks were caused by the asymmetric hump effect of internal melt tracks. A localized collapse of one side of the internal melt tracks can cause breakage of the contour melt tracks. This is due to the lack of liquid metal at that location during contour melt track formation. meanwhile, the contour melt track on the opposite side remains mostly undamaged. These broken contour melt tracks could cause asymmetric pore defects during the deposition process. Computational Fluid Dynamics (CFD) simulations were used to validate the contour scanning process. The results showed that a 0.04 mm contour space could significantly reduce the one-sided hump of the internal melt tracks and form a plump contour melt track, which would reduce the problem of local overthickness in the subsequent powder layer during powder spreading processes, thereby reducing the lack of fusion. This research provided valuable theoretical insights and practical guidance for optimizing the pbf-lb/m process for thin-walled In718 parts, with significant implications for engineering applications and academic innovation.

关键词： pbf-lb/m In718 Thin-walled structures Hump effect CFD simulation

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Analysis of Building Platform Inhomogeneities in pbf-lb/m Process on Alloy 718

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APPLIED SCIENCES-BASEL 2025年第7期15卷

作者： Baldi, Niccolo Chandrabalan, Lokesh manetti, marco Giorgetti, Alessandro Arcidiacono, Gabriele Citti, Paolo Palladino, marco Guglielmo Marconi Univ Dept Engn Sci I-00193 Rome Italy Baker Hughes Nuovo Pignone Via Felice Matteucci 2 I-50127 Florence Italy Roma Tre Univ Dept Ind Elect & Mech Engn I-00146 Rome Italy

Additive manufacturing (Am) processes, particularly pbf-lb/m, are considered advantageous due to their flexibility, which allows process engineers to design and fabricate intricate structures both in the prototyping and component manufacturing phases. It is well known that the behavior of the process directly impacts the quality of the materials and thereby induces inhomogeneities on the powder bed on the building platform. Several parameters can be tuned to keep the process under control, getting rid of process uncertainty and distinguishing aspects of a specific machine model. Such behavior requires an extended analysis of the powder bed inhomogeneities and the definition of limits in the printing process. In this work, carried out on Alloy 718 specimens printed using an EOS m290 machine, the inhomogeneities of the melt pool stability, density, and material properties were investigated based on three main factors: the amount of area melted or fused, the gas flow speed setpoint, and the location on the building platform. The test results for Track Stability, melt-pool shape, and porosity analysis show that criticality occurs when more than 50% of the building platform is exposed. This can be partly fixed by raising the differential pressure value.

关键词： additive manufacturing pbf-lb/m Alloy 718 building platform melt-pool shape single track analysis

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A training-free machine learning approach for 3D powder bed reconstruction and defect detection in pbf-lb/m

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PROGRESS IN ADDITIVE mANUFACTURING 2025年 1-25页

作者： Tosoratti, Enrico Potthoff, Ugne Bennewitz, Christopher Bambach, markus Inspire AG Innovat Ctr Addit Mfg Switzerland CH-9014 St Gallen Switzerland Swiss Fed Inst Technol Adv Mfg Lab D MAVT Technoparkstr 1 CH-8005 Zurich Switzerland

We introduce a novel in situ quality monitoring approach for the Laser Powder Bed Fusion (pbf-lb/m) process that operates independently of prior experimental data and can be integrated into existing systems. We employ a cost-effective, high-resolution CmOS camera coupled with a bright and darkfield lighting arrangement to acquire data layer-by-layer. Using computer vision techniques, specifically the GrabCut algorithm, we automate the inspection and the virtual reconstruction of fused part geometries. Our results, compared with nominal slice data and computed tomography scan data, indicate a robust accuracy in quantifying geometric deviations (mean deviation of 15.60 mu\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}m and 15.20 mu\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}m respectively, Jaccard scores of 0.99). The proposed training-free framework, unlike traditional machine learning methods, requires no labeled datasets or prior training, offering a cost-effective and adaptable solution. This eliminates the dependency on material, scan strategy, or part geometry, which typically hinders the scalability of conventional approaches. Additionally, our method facilitates automatic defect detection such as recoater strikes, recoater hopping, and powder shortages, with balanced accuracy scores of up to 0.87. These advantages highlight the framework's potential as a practical tool for in situ process monitoring and quality assurance in pbf-lb/m systems.

关键词： pbf-lb/m Powder bed quality inspection Fused part geometry inspection Image segmentation Computer vision GrabCut algorithm

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Quality assurance via a cyber physical system of a pbf-lb/m machine

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PROGRESS IN ADDITIVE mANUFACTURING 2025年第3期10卷 1771-1783页

作者： Poka, Konstantin Ali, Sozol Saeed, Waleed merz, Benjamin Epperlein, martin Hilgenberg, Kai Bundesanstalt Mat Forsch & Prufung BAM Competence Ctr AM Unter Eichen 87 D-12205 Berlin Germany Tech Univ Berlin Inst Machine Tools & Factory Management Pascalstr 8-9 D-10587 Berlin Germany

Powder Bed Fusion with Laser Beam of metals (pbf-lb/m) faces challenges in reproducibility and quality assurance, even for widely applied alloys like AlSi10mg. This work introduces a digital provenance framework for pbf-lb/m, showcased through the EOS m 300-4 multi-laser machine. An Extract, Transform, Load (ETL) pipeline autonomously captures machine data, including scan vectors as well as process signals, and organizes them into a Digital Shadow (DS). The DS is further extended by external data sources, such as melt Pool monitoring (mPm), to enable comprehensive analysis and root cause identification. This approach ensures continuous data representation and facilitates the development of new quality metrics. moreover, the framework enhances quality assurance and traceability, supports compliance with industry standards, and improves productivity. It also enables more precise cost calculations and predictive maintenance. By addressing these challenges, the framework is essential for advancing pbf-lb/m in industrial applications, achieving greater consistency and scalability in production.

关键词： pbf-lb/m Laser data-driven quality assurance Data engineering Digital shadow

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Enhancing mechanical properties and isotropy in ultrasonic assisted powder bed fusion of metals using a laser beam (pbf-lb/m) via Dual Exposure

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Journal of Advanced Joining Processes 2025年 11卷

作者： Platt, Sebastian Wegner, Jan Elspaß, Arno Schönrath, Hanna Kleszczynski, Stefan Institute for Product Engineering University Duisburg–Essen Lotharstr. 1 Duisburg 47057 Germany Center for Nanointegration Duisburg- Essen (CENIDE) Carl-Benz-Str. 199 Duisburg 47057 Germany

Parts produced via powder bed fusion of metal using a laser beam process often exhibit mechanical anisotropy due to the directional solidification, complicating part design. This study explores the use of ultrasonic-assistance to reduce anisotropy by promoting microstructural homogenization through increased nucleation. Specimens were fabricated using a dual exposure strategy, to avoid the challenges that arise with the in-situ ultrasonic excitation of a powder bed. Furthermore, a comprehensive microstructural as well as mechanical analysis was carried out. microstructural analysis revealed increased grain orientation variation in ultrasonically treated specimens. mechanical testing showed improved tensile and yield strength and reduced anisotropy, with tensile and yield strength anisotropy decreasing by 55.4 % and 46.1 %, respectively. Despite increased surface roughness, ultrasonic treatment reduced anisotropy in ductility-related properties, highlighting its potential to improve the performance of additively manufactured parts by reducing anisotropy and simultaneously enhancing mechanical properties. © 2025 The Author(s)

关键词： Additive manufacturing mechanical anisotropy mechanical properties pbf-lb/m Ultrasonic Assisted Ultrasound

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microstructure of conventional/pbf-lb/m 316L stainless steel hybrid joints brazed with nickel-based brazing alloys

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WELDING IN THE WORLD 2024年第9期68卷 2377-2389页

作者： Tillmann, W. Bueltena, J. Wojarski, L. Crasmoller, A. TU Dortmund Univ Inst Mat Engn Dortmund Germany

Due to the additive manufacturing principle, laser-melted materials (pbf-lb/m) such as the austenitic chromium-nickel steel 316L have a different microstructure compared to materials produced by conventional continuous casting. The pbf-lb/m-produced 316L has a thermally metastable, anisotropic microstructure with epitaxially grown grains in which a cellular substructure is located. When brazing hybrid joints from the conventional and additive manufacturing routes with nickel-based brazing alloys, different diffusion mechanisms occur simultaneously in both joining partners. This occurs due to the different microstructural characteristics of the parent materials. The altered diffusion mechanisms lead to a new distinct microstructure in the joining zone, which influences the achievable quality of the brazed joint in a previously unknown way.

关键词： Brazing Additive manufacturing pbf-lb/m Hybrid joints Stainless steel Nickel-based brazing alloy

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Static load-carrying behavior and material properties of additively manufactured gears (pbf-lb/m, 16mnCr5)

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RAPID PROTOTYPING JOURNAL 2023年第11期29卷 117-130页

作者： Brummer, markus Raddatz, Karl Jakob Schmitt, matthias moritz Schlick, Georg Tobie, Thomas Daub, Rudiger Stahl, Karsten Tech Univ Munich Gear Res Ctr FZG Sch Engn & Design Dept Mech Engn Munich Germany McKinsey & Co Inc Munich Germany Fraunhofer Inst Casting Composite & Proc Technol I Augsburg Germany Tech Univ Munich Inst Machine Tools & Ind Management iwb Sch Engn & Design Dept Mech Engn Munich Germany

PurposeNumerous metals can be processed using the additive manufacturing process laser-based powder bed fusion of metals (pbf-lb/m, ISO/ASTm 52900). The main advantages of additive manufacturing technologies are the high degree of design freedom and the cost-effective implementation of lightweight structures. This could be profitable for gears with increased power density, combining reduced mass with considerable material strength. Current research on additively manufactured gears is focused on developing lightweight structures but is seldom accompanied by simulations and even less by mechanical testing. There has been very little research into the mechanical and material properties of additively manufactured gears. The purpose of this study is to investigate the behavior of lightweight structures in additively manufactured gears under static ***/methodology/approachThis research identifies the static load-carrying capacity of helical gears with different lightweight structures produced by pbf-lb/m with the case hardening steel 16mnCr5. A static gear loading test rig with a maximum torque at the pinion of T1 = 1200 Nm is used. Further focus is set on analyzing material properties such as the relative density, microstructure, hardness depth profile and chemical *** additively manufactured gear variants show no failure or plastic deformation at the maximum test load. The shaft hub connection, the lightweight hub designs and the gearing itself are stable and intact regarding their form and function. The identified material characteristics are comparable to conventionally manufactured gears (wrought and machined), but also some particularities were ***/valueThis research demonstrates the mechanical strength of lightweight structures in gears. Future research needs to consider the dynamic load-carrying capacity of additively manufactured gears.

关键词： material properties Additive manufacturing Powder bed fusion Lightweight 16mnCr5 pbf-lb/m Helical gear

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Impact of processing gas composition on process stability and properties of pbf-lb/m processed alloy 718

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JOURNAL OF mANUFACTURING PROCESSES 2024年 120卷 712-718页

作者： Deckers, T. Fardan, A. Kersting, L. Kreutzer, A. Foret, P. Dubiez-Le Goff, S. Witt, G. Kleszczynski, S. Klement, U. Hryha, E. Linde GmbH D-85716 Unterschleissheim Germany Chalmers Univ Technol Dept Ind & Mat Sci S-41296 Gothenburg Sweden Siemens Energy AG D-10553 Berlin Germany Univ Duisburg Essen Dept Mfg Technol D-47057 Duisburg Germany

The almost unlimited design freedom of the laser-based powder bed fusion of metals (pbf-lb/m) makes this technology very attractive for industry. However, as a developing technology, it still faces some challenges when it comes to productivity and robustness, to name some. Whereas numerous studies covered the impact of laserbased parameters on material properties and robustness, the effect of the processing gas received limited attention. The objective of this study was to evaluate the effect of processing gas composition, containing helium (He) and hydrogen (H2), compared to conventionally used argon (Ar), during pbf-lb/m processing of virgin alloy 718 powder, on printing behavior and part properties. The four gases studied were Ar, Ar +30%He, Ar +30%He +2%H2, and Ar +70%He. Optical Tomography (OT) was used to monitor process stability, which unveiled a significant decrease in process-by products (spatters) between 51 % and 89 % using He and H2containing gases. It was also found that the process gas decreased the bulk porosity from an average value of 0.08 % when processed with Ar to 0.04 % when using Ar + 70%He. The oxygen pickup by the spatter particles was reduced from 630 ppm (Ar) to 331 ppm (Ar +70%He). EBSD analysis revealed that there were no evident changes in microstructure with the processing gas. The samples processed also had similar tensile properties with yield and ultimate tensile strength of 1180 mPa and 1395 mPa, respectively. However, there was a slight increase in ductility from 16.5 % to 17.2 %, when processed with pure Ar and Ar + 70%He, respectively. This study shows that utilizing standard Ar processing atmosphere with He addition leads to a more stable process with reduced spatter, porosity and a marginal increase in ductility for Alloy 718.

关键词： pbf-lb/m Process gas Alloy 718 EBSD Optical tomography Helium Hydrogen

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Knowing the spectral directional emissivity of 316L and AlSi10mg pbf-lb/m surfaces: gamechanger for quantitative in situ monitoring

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PROGRESS IN ADDITIVE mANUFACTURING 2024年第3期9卷 695-704页

作者： Becker, Tina Stark, Thomas Arduini, mariacarla manara, Jochen Altenburg, Simon J. Bundesanstalt Mat Forsch & Prufung Dept Thermog Methods 8 3 D-12205 Berlin Germany Ctr Appl Energy Res CAE D-97074 Wurzburg Germany

For a deep process understanding of the laser powder bed fusion process (pbf-lb/m), recording of the occurring surface temperatures is of utmost interest and would help to pave the way for reliable process monitoring and quality assurance. A notable number of approaches for in-process monitoring of the pbf-lb/m process focus on the monitoring of thermal process signatures. However, due to the elaborate calibration effort and the lack of knowledge about the occurring spectral directional emissivity epsilon ' lambda \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\varepsilon }<^>{\prime}}_{\lambda }$$\end{document} , only a few approaches attempt to measure real temperatures. In this study, to gain initial insights into epsilon ' lambda \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\varepsilon }<^>{\prime}}_{\lambda }$$\end{document} occurring in the pbf-lb/m process, measurements on pbf-lb/m specimens and metal powder specimens were performed for higher temperatures up to T = 1290 degrees C by means of the emissivity measurement apparatus (EmmA) of the Center for Applied Energy Research (CAE, Wuerzburg, Germany). Also, measurements at ambient temperatures were performed with a suitable measurement setup. Two different materials-stainless steel 316L and aluminum AlSi10mg-were examined. The investigated wavelength lambda ranges from the visible range ( lambda VIS \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\lambda }_{VIS}$

关键词： pbf-lb/m In situ monitoring Emissivity

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Optimizing energy modeling in pbf-lb/m metal additive manufacturing: a detailed analysis of resource and energy demand based on standard tensile test specimen

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PROGRESS IN ADDITIVE mANUFACTURING 2024年第3期9卷 675-682页

作者： Brinkmann, Joachim Aurich, Jan C. te Heesen, Henrik Trier Univ Appl Sci Environm Campus Birkenfeld D-55761 Birkenfeld Germany RPTU Kaiserslautern Inst Mfg Technol & Prod Syst D-67663 Kaiserslautern Germany

Additive manufacturing is an essential tool in modern production processes. Competitive quality and the increasing importance of local manufacturing have allowed companies to maintain their production despite supply chains disrupted by the pandemic. However, the rising awareness of society towards environmental and climate protection, the increasing demand for resource-efficient products, and recent developments in energy costs are leading to a rethink in manufacturing processes. Additive manufacturing offers great potential for resource saving components. This study uses standard tensile test specimens to analyze Am processes regarding energy and material flows. The results show a high dependence of energy demand on process time and are transformed into a data-based energy model. Compared to previous energy models, the accuracy can be significantly improved using model data in combination with specific and system-oriented approaches. In addition to system-related saving potentials, design-related optimization potentials can be identified. Innovative and highly resource-saving components can be designed with a design methodology adapted to the extended degrees of freedom of Am. Further saving and recycling potentials can be identified along the material flows. A long-term goal is optimizing and predicting of resource demand in additive manufacturing with a view to the entire product lifecycle.

关键词： Additive manufacturing pbf-lb/m SLm Resource efficiency Energy model

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