Nick Semjatov , Hans-Henrik König , Pidassa M. Bidola , Guilherme Abreu-Faria , Benjamin Wahlmann , Greta Lindwall , Carolin Körner
{"title":"In-situ synchrotron imaging of powder consolidation and melt pool dynamics in electron beam powder bed fusion","authors":"Nick Semjatov , Hans-Henrik König , Pidassa M. Bidola , Guilherme Abreu-Faria , Benjamin Wahlmann , Greta Lindwall , Carolin Körner","doi":"10.1016/j.addma.2025.104943","DOIUrl":"10.1016/j.addma.2025.104943","url":null,"abstract":"<div><div>Electron beam powder bed fusion (PBF-EB) is an additive manufacturing (AM) technology that enables the fabrication of metallic parts with arbitrary geometric complexity within a vacuum environment. Due to its ability to process materials at high temperatures (> 1000 °C), processing of crack and oxidation sensitive materials, as well as refractory alloys is possible. However, due to limited fundamental understanding of the intricate dynamics during powder consolidation and melt pool formation, the development of advanced processing strategies has mainly been limited to experimentally time-consuming parameter studies, as numerical models have mostly been unable to accurately predict processing conditions at the part or even layer scale. In this study, we perform high-speed in-situ X-ray imaging during multi-layer single track powder melting experiments on MiniMelt, a recently developed, custom-built PBF-EB machine for in-situ X-ray investigations. Our experiments reveal several key melt pool formation dynamics, some of which are being identified for the first time. They show how melt pool formation involves the coalescence of molten powder particles into larger droplets and how these droplets either fuse with the melt pool or solidify as balling particles. They also elucidate the origins of melt pool oscillations and spatter formation and demonstrate how the superposition of these mechanisms can lead to chaotic and escalating movement within the melt. We expect our results to improve and extend the phenomenological understanding of the powder consolidation mechanisms during PBF-EB and to aid in the development of new scanning strategies as well as the validation of numerical models.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104943"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144919746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Han Zhang , Boyu Nie , Weijian Qian , Zhe Song , Yao Xiao , Bingqing Chen , Zijun Zhao , Nan Li , Changkui Liu , Chengli Dong , Shengchuan Wu
{"title":"High-temperature strengthening mechanisms of optimized L-PBF IN718 superalloys with interpretable machine learning","authors":"Han Zhang , Boyu Nie , Weijian Qian , Zhe Song , Yao Xiao , Bingqing Chen , Zijun Zhao , Nan Li , Changkui Liu , Chengli Dong , Shengchuan Wu","doi":"10.1016/j.addma.2025.104958","DOIUrl":"10.1016/j.addma.2025.104958","url":null,"abstract":"<div><div>Laser powder bed fusion (L-PBF) fabricated IN718 alloy is subject to a strength-ductility trade-off at elevated temperatures owing to its intrinsic defects and anisotropic microstructure. In this study, the high-temperature strengthening mechanisms of optimized L-PBF-processed IN718 alloy were elucidated through the integration of <em>in situ</em> synchrotron X-ray tomography and interpretable machine learning. Optimization of the volumetric energy density (VED) during L-PBF established a critical processing window (47–60 J/mm<sup>3</sup>) that minimized defects (porosity <1 %) and refined grains. Specimens IN718 fabricated at 230 W/1000 mm/s (VED = 52.27 J/mm<sup>3</sup>) exhibited superior high-temperature tensile properties (YS = 1017 MPa, UTS = 1184 MPa, EL = 21.3 %). <em>In situ</em> X-ray tomography revealed that strain-induced void nucleation, rather than pre-existing defects, was the primary cause of damage at elevated temperatures. Grains oriented along < 111 > with low Schmid factors were found to impede dislocation slip, thereby enhancing strength while simultaneously accelerating defect-driven premature failure. The XGBoost-SHAP model quantitatively assessed the microstructure-property relationships, demonstrating that grain size and Σ3 boundaries predominantly govern strength, whereas porosity constituted a critical limiting factor for ductility. This study presents a causal framework linking process, microstructure, and property relationships, thereby providing fundamental insights into defect-aware grain boundary engineering in additively manufactured superalloys.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104958"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peng He , Xinlei Pan , Wenhe Wang , Zichuan Yu , Wenhua Chen , Mingxin Wang , Hongwei Yang , Yanqing Yu , Liucheng Zhou , Yinghong Li
{"title":"Defect-organized microstructure-stress synergy in laser in-situ forging additive manufacturing (LIF-AM): A pathway to fatigue-resistant Ti-6Al-4V","authors":"Peng He , Xinlei Pan , Wenhe Wang , Zichuan Yu , Wenhua Chen , Mingxin Wang , Hongwei Yang , Yanqing Yu , Liucheng Zhou , Yinghong Li","doi":"10.1016/j.addma.2025.104955","DOIUrl":"10.1016/j.addma.2025.104955","url":null,"abstract":"<div><div>Laser powder bed fusion (LPBF) technology has achieved industrial application in the lightweight manufacturing of aerospace complex components due to its high dimensional accuracy and excellent static mechanical properties. However, the non-steady-state thermal effects during processing induce heterogeneous tensile stresses, coarse grains, and fusion defects, severely degrading the fatigue performance of as-built LPBF components and limiting their structural applications. In this paper, a novel technique, laser in-situ forging additive manufacturing (LIF-AM), is proposed to improve the fatigue endurance of metal by applying in-situ layer-by-layer femtosecond laser shock during the LPBF process. The results show that LIF-AM technology can reduce un-melted defects, refine the grain, and introduce a compressive residual stress field into Ti-6Al-4V alloy. The maximum defect size decreases from 65 μm in LPBF to 27 μm in LIF-AM due to the femtosecond laser surface cleaning. Under the action of the shock wave, β columnar grains transform into equiaxed grains, and a gradient compressive residual stress field with a depth of ∼800 μm forms, contributing to the dynamic recrystallization. Combined with reducing defects, the crack initiation and propagation are suppressed, causing the high fatigue limit in LIF-AM Ti-6Al-4V alloy which is 19.3 % higher than that of conventional LPBF Ti-6Al-4V alloy. The LIF-AM technology will provide a novel and transformative approach for the high-performance manufacturing of aerospace load-bearing components.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104955"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"In situ powder height measurement as process signature for quality control in electron beam powder bed fusion","authors":"Jakob Renner, Timo Berger, Carolin Körner","doi":"10.1016/j.addma.2025.104910","DOIUrl":"10.1016/j.addma.2025.104910","url":null,"abstract":"<div><div>Quality assurance is one of the most important challenges in powder bed fusion. Binding faults are triggered by locally too thick powder layers and consequently insufficient connection to the layers below. Therefore, the knowledge of the local powder height could be one essential aspect in future quality assurance routes. In this work, multi-detector electron optical imaging based build surface topography measurements of the melted surface and the subsequently applied powder layer are combined to determine the local powder height in situ. The local powder height is measured during the build of a complex part, purely from experimentally measured data. Differences to theoretical continuum-based considerations are rationalized and the role of the process-cycle induced temperature evolution on recorded build surface topographies after melting and powder application revealed. The widths of height histograms, originating from segmented part and powder areas, are identified as key elements to assess the quality of the applied powder layer and the melted surfaces. The developed measurement principle and derived process signatures can serve as basis for future quality assurance routines in series production environments.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104910"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexis Burr , Carlos A. Lopez , Jorge Alberto Becerra , Jun Zeng , Denis Vincent , Vincent Bonnefoy
{"title":"A calibration method to predict shape change during sintering: Application to 316L parts made by Metal Binder Jetting","authors":"Alexis Burr , Carlos A. Lopez , Jorge Alberto Becerra , Jun Zeng , Denis Vincent , Vincent Bonnefoy","doi":"10.1016/j.addma.2025.104938","DOIUrl":"10.1016/j.addma.2025.104938","url":null,"abstract":"<div><div>Metal Binder Jetting (MBJ) is a promising sinter-based additive manufacturing technology allowing to produce parts with complex geometries in small to medium series. However, the required sintering step leads to a drastic shrinkage because of the initially low green density of the part (<span><math><mrow><mo>≈</mo><mn>50</mn><mtext>–</mtext><mn>60</mn><mtext>%</mtext></mrow></math></span>) but also to large shape distortions due to gravity sagging. The prediction of those deformations is therefore paramount to reach near-net shape parts. A step-by-step method, relying on both experimental and numerical procedures, is proposed to predict shape changes during the sintering of 316L stainless steel made by MBJ. The anisotropic linear shrinkage is determined thanks to dilatometry while the viscous deformations are numerically fitted thanks to a calibration part. The numerical implementation is performed in the proprietary HP 3D Digital Sintering software and is tested for various sintering cycles. Optimization loops are proposed to fit correctly all the constitutive parameters leading to deviations of the simulated results with experimental parts below 1%. Then, angular sectors exhibiting various angles of overhangs are sintered to assess the performance of the model. It turns out that most predictions exhibit maximum deviations below 5%, with filleted parts exhibiting the better predictions. Beyond the model ability to predict shape, the parts proposed in this work show interesting features that allow to capture complex thermophysical mechanisms though they are of simple design. In this way, those could become standard calibration parts for any model for initial printing stages.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104938"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dylan Agius , Nima Haghdadi , Christos Dionyssopoulos , Benjamin Malkinson , Beau Krieg , Sophie Primig , Chris Wallbrink
{"title":"Computational analysis of the effect of scan strategies on microstructural evolution in Inconel 738 fabricated by electron beam powder bed fusion","authors":"Dylan Agius , Nima Haghdadi , Christos Dionyssopoulos , Benjamin Malkinson , Beau Krieg , Sophie Primig , Chris Wallbrink","doi":"10.1016/j.addma.2025.104942","DOIUrl":"10.1016/j.addma.2025.104942","url":null,"abstract":"<div><div>An area of metal additive manufacturing (AM) that has gained significant traction in the last decade is the control of scan strategies to manipulate thermal gradients and develop desired microstructures. This approach offers the potential for engineering crystallographic and morphological features at specific locations to enhance the quality of the manufactured part. Multi-spot scan strategies used in powder bed fusion (PBF) have emerged as promising techniques to achieve desirable microstructural features. This is due to the flexibility offered by adjusting spot locations to manipulate thermal gradients between melt pools. However, the influence of the newly developed multi-spot scan strategy on microstructure evolution is highly dependent on the geometry of the build. This requires a trial-and-error experimental approach to develop new multi-spot scan strategies. Alternatively, computational tools offer the possibility of investigating and optimising multi-spot scan strategies to ensure targeted experimental investigations. In this work, a cellular automata (CA) tool is used to simulate the microstructure evolution of Inconel 738 during AM. The tool is firstly validated against experimental data and then used to investigate the influence of different multi-spot scan strategies. Through this investigation, a new algorithm is proposed to control the level of randomness applied to a predefined scan strategy, providing more control over the evolving microstructure. The findings highlight the importance of performing computational investigations to engineer the optimal multi-spot scan strategies to achieve the most desirable microstructure and limit the possible occurrence of lack of fusion defects.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104942"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Data-driven multiscale topology optimization of solid-lattice hybrid structures for additive manufacturing","authors":"Zhengtao Shu, Liang Gao, Hao Li","doi":"10.1016/j.addma.2025.104920","DOIUrl":"10.1016/j.addma.2025.104920","url":null,"abstract":"<div><div>Compared to pure solid or lattice structures, solid-lattice hybrid structures offer enhanced mechanical performance, effectively balancing various design requirements. In this paper, a data-driven multiscale topology optimization method is proposed for designing solid-lattice hybrid structures tailored for additive manufacturing. Implicit modeling techniques are employed to construct microstructure models, enabling both mechanical characterization of microstructure unit cells and geometric reconstruction of optimized designs. A sample database and surrogate model are created to accelerate the optimization process. The solid and lattice structures are represented by two sets of density variables, defined on the solid and lattice layer meshes, respectively. Additionally, the Heaviside function is introduced as a projection function for density filtering, removing pseudo-density elements from the solid layer mesh. Two volume constraints are applied to regulate the structural configuration and performance during the optimization process. After optimization, full-scale solid-lattice hybrid structures are reconstructed by combining topologically optimized solid structures with graded lattice structures using the hybrid level set method (HLSM). Several 2D and 3D numerical examples are provided to validate the effectiveness of the proposed method. Finally, the optimized structures are fabricated via additive manufacturing (AM), and their performance is validated through both finite element analysis (FEA) and experimental testing. The results confirm notable improvements in overall mechanical performance, highlighting the effectiveness of the proposed method in designing lightweight, high-performance structures.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104920"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peipei Liu , Yilei Xiong , Subin Shin , Kiyoon Yi , Liu Yang , Hoon Sohn , Zhao-Dong Xu
{"title":"In-situ subsurface defect detection in directed energy deposition using pulse phase thermography and thermal motion magnification","authors":"Peipei Liu , Yilei Xiong , Subin Shin , Kiyoon Yi , Liu Yang , Hoon Sohn , Zhao-Dong Xu","doi":"10.1016/j.addma.2025.104939","DOIUrl":"10.1016/j.addma.2025.104939","url":null,"abstract":"<div><div>This study presents a novel thermal motion magnification technique for in-situ subsurface defect detection in directed energy deposition (DED) processes. The proposed technique integrates pulse phase thermography (PPT) with phase-based motion magnification to enhance thermal signal sensitivity and mitigate noise interference in the challenging DED environment. An in-situ monitoring system, comprising a coaxial infrared (IR) camera and a laser line scanner, is developed to detect subsurface defects in real time with micron-scale precision. Motion magnification is applied to amplify thermal variations at a specific target frequency band in the IR camera's thermal images, while phase differences in PPT are extracted from the same frequency band for defect detection. The target frequency band is determined according to the current deposition layer height measured by the laser line scanner. This technique was validated with simulation signals under different signal-to-noise ratios and experimentally applied to Ti-6Al-4V samples with subsurface defects, demonstrating its potential as a robust solution for real-time defect detection in DED.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104939"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144880396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bianca Brandl , Scarlett Zeiringer , Ludwig Loidl , Anbu Palanisamy , Sarah Heupl , Matthias Katschnig , Thanh Nguyen , Eva Roblegg , Martin Spoerk , Simone Eder
{"title":"Dual-extruder 3D-printing of biodegradable subcutaneous implants for controlled drug delivery","authors":"Bianca Brandl , Scarlett Zeiringer , Ludwig Loidl , Anbu Palanisamy , Sarah Heupl , Matthias Katschnig , Thanh Nguyen , Eva Roblegg , Martin Spoerk , Simone Eder","doi":"10.1016/j.addma.2025.104928","DOIUrl":"10.1016/j.addma.2025.104928","url":null,"abstract":"<div><div>Subcutaneous implantable drug delivery systems (SIDDS) offer significant reduction in administration frequency compared to oral dosage forms, which improves patient adherence. However, current manufacturing methods, such as hot melt extrusion, offer limited flexibility for individualizing product specifications (e.g., changes in drug loading or changes in the daily dose) and for providing on-demand solutions. Here, dual-extruder fused filament fabrication was explored for the first time as an advanced manufacturing method to produce biodegradable, drug-loaded SIDDS with customizable release profiles. Seven advanced implant designs (including monolithic and core-shell type implants) were tested to study the impact of 3D-printing parameters (e.g., the internal porosity or shell thickness) on the drug release profile, confirming the suppression of burst release and the achievement of zero-order or tri-phasic release profiles. The implants were further characterized with respect to quality parameters such as shell continuity, shell thickness, and drug content. Overall, this work provides a fundamental framework to produce SIDDS with adaptable release profiles and release time frames through adjustment of 3D-printing parameters.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104928"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144880394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Linda Ebert , Anne Jüngert , Sven Sewalski , Martin Werz , Stefan Weihe
{"title":"Non-destructive ultrasonic evaluation and metallographic validation of artificial defects in L-PBF additive manufactured specimens using CAD-seeding","authors":"Linda Ebert , Anne Jüngert , Sven Sewalski , Martin Werz , Stefan Weihe","doi":"10.1016/j.addma.2025.104933","DOIUrl":"10.1016/j.addma.2025.104933","url":null,"abstract":"<div><div>This study investigates the feasibility of ultrasonic testing (UT) for detecting internal defects in laser powder bed fusion (L-PBF) manufactured materials. The suitability of a universal reference test specimen designed for multiple non-destructive tests (NDT) proposed by ISO/ASTM is verified using UT. The star-shaped specimen is used to evaluate the detectability and characterization of artificial defects in 316 L. Each star tip contains spherical or cylindrical defects of varying orientations and sizes (100 – 700 µm). Phased Array Ultrasonic Testing (PAUT) and the Total Focusing Method (TFM) are combined to assess defect detectability, sizing and orientation from multiple probe positions. The results are validated using simulation and microscopic imaging. The results show that PAUT and TFM, when used together, enhance defect detection, identifying flaws as small as 0.1 mm. Detection accuracy depends on probe positioning (top or side surface), beam angle, defect type and orientation. The highest accuracy is achieved from the planar top side of the specimen. The spherical and oriented cylindrical defects proved to be the most challenging to detect. Detectability is mainly influenced by the available sound reflection surface, inner surface roughness and defect filling (loose powder or sintered particles). To improve detectability and promote image-based sizing approaches in ultrasonic testing the inner surface roughness has to be improved. These findings provide a foundation for future research into the detectability of inner defects, sizing approaches and precise seeding of artificial internal defects in L-PBF components using ultrasonic testing.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"110 ","pages":"Article 104933"},"PeriodicalIF":11.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144880395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}