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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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Influence of Process Parameters on the Porosity, Accuracy, Roughness, and Support Structures of Hastelloy X Produced by Laser Powder Bed Fusion
摘要： The manufacture of highly complex components from nickel-based superalloys with laser powder bed fusion (L-PBF) technology can reduce the production costs parts with comparable microstructural and mechanical properties when compared to casting. The purpose of this study was to investigate the characteristics of samples produced in commercial Hastelloy X (with w% composition of 21Cr-18Fe-9Mo-0.7W-1.5Co-0.1C-1Si-1Mn-0.5Al-0.15Ti-bal.Ni) with an L-PBF process in terms of build density, accuracy, surface roughness, and interface area between the part and the support structures. Samples were obtained with a high density (99.88%), without cracks and with low surface roughness. From the analysis of the support structures, it emerged that the choice of the parameters between support structures, the lower face of the part (down-skin) and the internal area of the part (in-skin) is fundamental to the correct realization of these structures in order to avoid deformation of the components that is induced by thermal stresses during part building.
关键词： process parameters,nickel super-alloys,additive manufacturing,selective laser melting,Hastelloy X
更新于2025-09-16 10:30:52
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Microstructurea??Texturea??Mechanical Property Relationship in Alloys Produced by Additive Manufacturing Following Selective Laser Melting (SLM) Technique
摘要： Additively manufactured alloys produced by selective laser melting (SLM) exhibit different microstructure, texture and mechanical properties compared to their conventionally processed counterparts. The reason for this difference has been attributed to unique conditions that are met during processing through SLM. The differences are specific to the alloy system. Most influencing variable of SLM processing has been found to be the scanning strategy which comprises interlayer hatch rotation, build orientation, printing pattern (unidirectional, meander or checker board), etc. These variants lead to alteration of microstructure and crystallographic texture. Among the properties, yield strength of SLM-processed alloys has been found to be higher compared to their conventionally processed counterparts, which has been attributed to the finer microstructure and high defect density resulting from the process. On the other hand, ductility is on the lower side due to voids and porosity. The texture of SLM-processed materials shows characteristic features, which is dependent on materials and processing strategies. This further influences the properties. This paper deals with the evolution of microstructure, texture and mechanical properties for selected alloy systems, namely the alloys of iron, aluminium, and titanium, which have been most extensively studied after SLM processing.
关键词： Mechanical properties,Crystallographic texture,Additive manufacturing,Microstructure,Selective laser melting
更新于2025-09-16 10:30:52
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Laser beam melting of Cr3C2-NiCr
摘要： Due to the high temperature wear resistance, low friction coefficient and corrosion resistance, chromium carbides are widely used for coating applications and commonly processed through thermal spraying. In contrast to classical processing, additive manufacturing technologies such as Laser Beam Melting (LBM) offer significant geometrical flexibility in design. Relying on the use of this advantage for manufacturing innovative products, the present study focuses on the qualification of Cr3C2-NiCr for the LBM process. Experiments are carried out with composite thermal spray powder through variation of the main LBM process parameters and pre-heating temperatures up to 800 °C. Specimens are generated and evaluated with respect to material microstructure and mechanical properties. The results indicate that pre-heating can significantly improve the material quality. It prevents thermal cracking and substantially reduces porosity, in particular for low laser energy inputs. An impact of the LBM process parameters and pre-heating on the balance between the binder and the carbide phase is detected only for high laser energy inputs above 1000 J/mm3. Measurements of the micro-hardness of the laser molten material indicate a hardness close to the specifications of thermally sprayed material. A maximum transverse rupture strength around 600 MPa is achieved for specimens generated with pre-heating and medium laser energy inputs. For high laser energy inputs, secondary carbide and graphite phases occur inside the material microstructure.
关键词： Cutting tools,Additive manufacturing,Laser beam melting,Chromium carbide,Cr3C2-NiCr,LBM,Cermet
更新于2025-09-16 10:30:52
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[IEEE 2019 Far East NDT New Technology & Application Forum (FENDT) - Qingdao, Shandong province, China (2019.6.24-2019.6.27)] 2019 Far East NDT New Technology & Application Forum (FENDT) - Visual Detection of AM Surface Defects Based on Laser Ultrasound Technology
摘要： Selective Laser Melting (SLM) process is a kind of Additive Manufacturing (AM) method, which can process parts with arbitrary complex geometry. However, macro-defects will destroy the mechanical properties of metal materials manufactured by SLM. Laser ultrasound can excite broadband surface waves and realize non-contact nondestructive testing of surface defects. In this paper, 316L stainless steel samples are prepared by SLM process are used for laser ultrasonic detection. According to the diffraction phenomenon of surface wave at the defect, a laser ultrasonic B-scan detection platform is built. The B-scan images of different length defects on the sample surface are obtained, and the quantitative detection of surface defects is realized quickly. In order to further improve the signal-to-noise ratio and the accuracy of imaging detection, EEMD (Ensemble Empirical Mode Decomposition) denoising is applied to the collected ultrasonic signal, which improves the accuracy of imaging, makes the signal more stable and realizes the visual detection of surface length defects clearly and intuitively.
关键词： b-scan,additive manufacturing,laser ultrasound technology,EEMD
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE/MTT-S International Microwave Symposium - IMS 2019 - Boston, MA, USA (2019.6.2-2019.6.7)] 2019 IEEE MTT-S International Microwave Symposium (IMS) - 3D Printed Slotted Rectangular Hollow Waveguides
摘要： This work proposes an approach to generate high performance rectangular hollow waveguides for applications in E- and W-Band by stereolithography 3D plastic printing and subsequent copper electroplating. In order to improve the metal deposition process, large and densely positioned sidewall gaps are identified as a key parameter in the design for manufacturing of such transmission lines with the proposed fabrication strategy. Measurements of fabricated prototypes achieve an overall attenuation of about 8 to 10 dB/m over wide bandwidths and thus, perform in similar ranges as compared to conventionally manufactured waveguides. Despite the large sidewall gaps, radiation leakage has been measured in an order of -50 dB, suggesting feasibility to many practical applications. The proposed approach offers fundamental contributions to the design for manufacturing of 3D printed waveguide systems and increases the applicability of conventional electro-plating processes.
关键词： rectangular waveguides,3D printing,electroplating,Additive manufacturing
更新于2025-09-16 10:30:52
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Topographic Measurement of Individual Laser Tracks in Alloy 625 Bare Plates
摘要： Additive manufacturing (AM) combines all of the complexities of materials processing and manufacturing into a single process. The digital revolution made this combination possible, but the commercial viability of these technologies for critical parts may depend on digital process simulations to guide process development, product design, and part qualification. For laser powder bed fusion, one must be able to model the behavior of a melt pool produced by a laser moving at a constant velocity over a smooth bare metal surface before taking on the additional complexities of this process. To provide data on this behavior for model evaluations, samples of a single-phase nickel-based alloy were polished smooth and exposed to a laser beam at three different power and speed settings in the National Institute of Standards and Technology Additive Manufacturing Metrology Testbed and a commercial AM machine. The solidified track remaining in the metal surface after the passing of the laser is a physical record of the position of the air–liquid–solid interface of the melt pool trailing behind the laser. The surface topography of these tracks was measured and quantified using confocal laser scanning microscopy for use as benchmarks in AM model development and validation. These measurements are part of the Additive Manufacturing Benchmark Test Series.
关键词： Additive manufacturing,Welding,Nickel-based superalloys,Topography data,Laser melt pool,Metals
更新于2025-09-16 10:30:52
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The Influence of Iron in Minimizing the Microstructural Anisotropy of Ti-6Al-4V Produced by Laser Powder-Bed Fusion
摘要： There remains a significant challenge in adapting alloys for metal-based additive manufacturing (AM). Adjusting alloy composition to suit the process, particularly under regimes close to industrial practice, is therefore a potential solution. With the aim of designing new Ti-based alloys of superior mechanical properties for use in laser powder-bed fusion, this research investigates the influence of Fe on the microstructural development of Ti-6Al-4V. The operating mechanisms that govern the relationship between the alloy composition (and Fe in particular) and the grain size are explored using EBSD, TEM, and in situ high-energy synchrotron X-ray diffraction. It was found that Fe additions up to 3 wt pct lead to a progressive refinement of the microstructure. By exploiting the cooling rates of AM and suitable amount of Fe additions, it was possible to obtain microstructures that can be optimized by heat treatment without obvious precipitation of detrimental brittle phases. The resulting microstructure consists of a desirable and well-studied fully laminar a + b structure in refined prior-b grains.
关键词： iron,grain refinement,additive manufacturing,microstructure,Ti-6Al-4V
更新于2025-09-16 10:30:52
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Biofunctionalization of selective laser melted porous titanium using silver and zinc nanoparticles to prevent infections by antibiotic-resistant bacteria
摘要： Antibiotic-resistant bacteria are frequently involved in implant-associated infections (IAIs), making the treatment of these infections even more challenging. Therefore, multifunctional implant surfaces that simultaneously possess antibacterial activity and induce osseointegration are highly desired in order to prevent IAIs. The incorporation of multiple inorganic antibacterial agents onto the implant surface may aid in generating synergistic antibacterial behavior against a wide microbial spectrum while reducing the occurrence of bacterial resistance. In this study, porous titanium implants synthesized by selective laser melting (SLM) were biofunctionalized with plasma electrolytic oxidation (PEO) using electrolytes based on Ca/P species as well as silver and zinc nanoparticles in ratios from 0 to 100% that were tightly embedded into the growing titanium oxide layer. After the surface bio-functionalization process, silver and zinc ions were released from the implant surfaces for at least 28 days resulting in antibacterial leaching activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the biofunctionalized implants generated reactive oxygen species, thereby contributing to antibacterial contact-killing. While implant surfaces containing up to 75% silver and 25% zinc nanoparticles fully eradicated both adherent and planktonic bacteria in vitro as well as in an ex vivo experiment performed using murine femora, solely zinc-bearing surfaces did not. The minimum inhibitory and bactericidal concentrations determined for different combinations of both types of ions confirmed the presence of a strong synergistic antibacterial behavior, which could be exploited to reduce the amount of required silver ions by two orders of magnitude (i.e., 120 folds). At the same time, the zinc bearing surfaces enhanced the metabolic activity of pre-osteoblasts after 3, 7, and 11 days. Altogether, implant biofunctionalization by PEO with silver and zinc nanoparticles is a fruitful strategy for the synthesis of multifunctional surfaces on orthopedic implants and the prevention of IAIs caused by antibiotic-resistant bacteria.
关键词： Multifunctional biomaterials,silver and zinc nanoparticles,implant-associated infections,plasma electrolytic oxidation,additive manufacturing,MRSA
更新于2025-09-16 10:30:52
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Powder Bed Based Laser Additive Manufacturing Process of Stainless Steel: A Review
摘要： This study presents a review on powder bed laser additive manufacturing of stainless steel. The powder bed laser additive manufacturing processes that are presented in this paper are the selective laser sintering and selective laser melting. The powder bed laser additive manufacturing process of stainless steel are reviewed in this paper. The process parameters was found to plat an important role in the evolving properties of the powder bed based laser additive manufacturing process. The paper ends with the perspective of future research directions.
关键词： Materials characterization,laser additive manufacturing,selective laser sintering,Additive manufacturing,selective laser melting
更新于2025-09-12 10:27:22