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Статті в журналах з теми "Laser powder bedfusion (L-PBF)":
1
Asnafi, Nader. "Application of Laser-Based Powder Bed Fusion for Direct Metal Tooling." Metals 11, no. 3 (March 10, 2021): 458. http://dx.doi.org/10.3390/met11030458.
Анотація:
The journey of production tools in cold working, hot working, and injection molding from rapid tooling to additive manufacturing (AM) by laser-based powder bed fusion (L-PBF) is described. The current machines and their configurations, tool steel powder materials and their properties, and the L-PBF process parameters for these materials are specified. Examples of production tools designed for and made by L-PBF are described. Efficient design, i.e., high tooling efficiency and performance in operation, should be the primary target in tool design. Topology and lattice structure optimization provide additional benefits. Using efficient design, L-PBF exhibits the greatest potential for tooling in hot working and injection molding. L-PBF yields high tooling costs, but competitive total costs in hot working and injection molding. Larger object sizes that can be made by L-PBF, a larger number of powder metals that are designed for different tooling applications, lower feedstock and L-PBF processing costs, further L-PBF productivity improvement, improved surface roughness through L-PBF, and secured quality are some of the targets for the research and development in the future. A system view, e.g., plants with a high degree of automation and eventually with cyber-physically controlled smart L-PBF inclusive manufacturing systems, is also of great significance.
2
Adegoke, Olutayo, Joel Andersson, Håkan Brodin, and Robert Pederson. "Review of Laser Powder Bed Fusion of Gamma-Prime-Strengthened Nickel-Based Superalloys." Metals 10, no. 8 (July 23, 2020): 996. http://dx.doi.org/10.3390/met10080996.
Анотація:
This paper reviews state of the art laser powder bed fusion (L-PBF) manufacturing of γ′ nickel-based superalloys. L-PBF resembles welding; therefore, weld-cracking mechanisms, such as solidification, liquation, strain age, and ductility-dip cracking, may occur during L-PBF manufacturing. Spherical pores and lack-of-fusion voids are other defects that may occur in γ′-strengthened nickel-based superalloys manufactured with L-PBF. There is a correlation between defect formation and the process parameters used in the L-PBF process. Prerequisites for solidification cracking include nonequilibrium solidification due to segregating elements, the presence of liquid film between cells, a wide critical temperature range, and the presence of thermal or residual stress. These prerequisites are present in L-PBF processes. The phases found in L-PBF-manufactured γ′-strengthened superalloys closely resemble those of the equivalent cast materials, where γ, γ′, and γ/γ′ eutectic and carbides are typically present in the microstructure. Additionally, the sizes of the γ′ particles are small in as-built L-PBF materials because of the high cooling rate. Furthermore, the creep performance of L-PBF-manufactured materials is inferior to that of cast material because of the presence of defects and the small grain size in the L-PBF materials; however, some vertically built L-PBF materials have demonstrated creep properties that are close to those of cast materials.
3
Li, Chenguang, Suxia Guo, Zhenxing Zhou, Weiwei Zhou, and Naoyuki Nomura. "Powder Fabrication and Laser Powder Bed Fusion of a MoSiBTiC-La2O3 Alloy." Crystals 13, no. 2 (January 24, 2023): 215. http://dx.doi.org/10.3390/cryst13020215.
Анотація:
In the present work, an approach of freeze-dry pulsated orifice ejection method (FD-POEM) was utilized to fabricate monodispersed MoSiBTiC-La2O3 composite powders for laser powder bed fusion (L-PBF). The FD-POEM powders were spherically shaped, possessing a narrow size range and uniform element distribution. As revealed by the single-track and single-layer experiments, the porous FD-POEM particles were sufficiently fused under laser irradiation, leading to the generation of continuous laser tracks and low surface roughness layers, which proved a feasible L-PBF processability of MoSiBTiC-La2O3 powders. Careful microstructural observations confirmed that the microstructure of the molten pools was primarily composed of Mo solid solution dendrites reinforced with La2O3 nanoparticles. Consequently, the single MoSiBTiC-La2O3 track had a high Martens hardness of 3955 HM. The result of this work reveals that the combination of FD-POEM and L-PBF has a great potential of developing advanced heat-resistant Mo-based alloys with tailored structures for ultrahigh-temperature applications.
4
Lu, Pan, Zhang Cheng-Lin, Liu Tong, Liu Xin-Yu, Liu Jiang-Lin, Liu Shun, Wang Wen-Hao, and Zhang Heng-Hua. "Molten pool structure and temperature flow behavior of green-laser powder bed fusion pure copper." Materials Research Express 9, no. 1 (January 1, 2022): 016504. http://dx.doi.org/10.1088/2053-1591/ac327a.
Анотація:
Abstract Additive Manufacturing(AM) is an advanced direct-manufacturing technology, based on the discrete-stacking principle. Laser Powder Bed Fusion (L-PBF) is one of the most promising technologies in the field of metal AM, with the characteristics of fabricating parts with complex shapes directly. For L-PBF equipment , the core device is lasers, and almost all L-PBF printers are currently equipped with infrared laser. However, due to too low absorption rate of the pure copper surface to infrared laser and high thermal conductivity between pure copper, it is extremely challenging to fabricate pure copper by traditional infrared-laser powder bed fusion(IR L-PFB). In this work, green-laser was applied to replace traditional infrared laser during L-PBF process, molten pool structure and temperature flow behavior of Green-Laser powder bed additive manufacturing pure copper was studied by mesoscopic simulation. Here we show that green-laser greatly improved the absorption rate of the pure copper surface, and the result showed that with lower cost laser process parameters (lower laser power 300W and larger hatching space 0.08 mm), pure copper parts with smoother surface, no-remelting and no obvious defects could be fabricated successfully.
5
Jayasinghe, Sarini, Paolo Paoletti, Chris Sutcliffe, John Dardis, Nick Jones, and Peter L. Green. "Automatic quality assessments of laser powder bed fusion builds from photodiode sensor measurements." Progress in Additive Manufacturing 7, no. 2 (October 7, 2021): 143–60. http://dx.doi.org/10.1007/s40964-021-00219-w.
Анотація:
AbstractWhile Laser powder bed fusion (L-PBF) machines have greatly improved in recent years, the L-PBF process is still susceptible to several types of defect formation. Among the monitoring methods that have been explored to detect these defects, camera-based systems are the most prevalent. However, using only photodiode measurements to monitor the build process has potential benefits, as photodiode sensors are cost-efficient and typically have a higher sample rate compared to cameras. This study evaluates whether a combination of photodiode sensor measurements, taken during L-PBF builds, can be used to predict measures of the resulting build quality via a purely data-based approach. Using several unsupervised clustering approaches build density is classified with up to 93.54% accuracy using features extracted from three different photodiodes, as well as observations relating to the energy transferred to the material. Subsequently, a supervised learning method (Gaussian Process regression) is used to directly predict build density with a RMS error of 3.65%. The study, therefore, shows the potential for machine-learning algorithms to predict indicators of L-PBF build quality from photodiode build measurements only. This study also shows that, relative to the L-PBF process parameters, photodiode measurements can contribute to additional information regarding L-PBF part quality. Moreover, the work herein describes approaches that are predominantly probabilistic, thus facilitating uncertainty quantification in machine-learnt predictions of L-PBF build quality.
6
Asnafi, Nader. "Tool and Die Making, Surface Treatment, and Repair by Laser-based Additive Processes." BHM Berg- und Hüttenmännische Monatshefte 166, no. 5 (May 2021): 225–36. http://dx.doi.org/10.1007/s00501-021-01113-2.
Анотація:
AbstractThis paper explores the possibilities to use laser-based additive processes to make, surface treat and repair/remanufacture tools, dies and molds for cold working, hot working, and injection molding. The failures encountered in these applications are described. The materials used conventionally and in the laser additive processes are accounted for. The properties of the tools, dies and molds made by Laser-based Powder Bed Fusion (L-PBF) are as good as and in some cases better than the properties of those made in wrought materials. Shorter cycle time, reduced friction, smaller abrasive wear, and longer life cycle are some of the benefits of L‑PBF and Directed Energy Deposition with powder (DED-p) (or Laser Metal Deposition with powder, LMD‑p, or Laser Cladding, LC). L‑PBF leads to higher toolmaking costs and shorter toolmaking lead time. Based on a review of conducted investigations, this paper shows that it is possible to design and make tools, dies and molds for and by L‑PBF, surface functionalize them by DED-p (LMD‑p, LC), and repair/remanufacture them by DED-p (LMD‑p, LC). With efficient operational performance as the target for the whole tool life cycle, this combination of L‑PBF and DED-p (LMD‑p, LC) has the greatest potential for hot working and injection molding tools and the smallest for cold working tools (due to the current high L‑PBF and DED-p (LMD‑p, LC) costs).
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Uhlmann, Eckart, and Alexander Mühlenweg. "Parameterentwicklung im L-PBF-Prozess/Parameter development for laser powder bed fusion." wt Werkstattstechnik online 111, no. 07-08 (2021): 507–12. http://dx.doi.org/10.37544/1436-4980-2021-07-08-39.
Анотація:
Die aktuelle Literatur zum Thema Laser Powder Bed Fusion (L-PBF) beschäftigt sich größtenteils mit Dauerstrich- (continuous-wave, cw) Laser-Anlagen, die kontinuierlich strahlend das Pulverbett scannen. Zusätzlich gibt es Anlagen mit gepulsten (quasi-continuous-wave, qcw) Lasern, die einen Puls bestimmter Dauer auf einen Punkt abgeben und dann zum nächsten Punkt springen. Die Parametersätze sind nicht ohne Weiteres zwischen den Anlagentypen übertragbar. Diese Arbeit behandelt die Parameterentwicklung für den Werkstoff Haynes 282 auf einer qcw-L-PBF-Anlage. Current literature on Laser Powder Bed Fusion (L-PBF) mainly focuses on continuous-wave (cw) laser systems to scan the powder bed while continuously emitting laser light. Also, there are systems with pulsed (quasi-continuous-wave, qcw) lasers to scan one point in the powder bed for a set duration and then jump to the next point. The parameter sets for one system are not easy to transfer to a different type of laser system. This work describes the development of a parameter set for Haynes 282 on a system with a qcw laser.
8
Lu, Pan, Zhang Cheng-Lin, Liu Tong, Liu Jiang-Lin, Xie Chun-Lin, and Zhang Heng-Hua. "Mesoscopic numerical simulation and experimental investigation of laser powder bed fusion AlCu5MnCdVA alloys." Materials Research Express 8, no. 12 (December 1, 2021): 126525. http://dx.doi.org/10.1088/2053-1591/ac2b56.
Анотація:
Abstract AlCu5MnCdVA alloys had high specific strength, good machining and fatigue properties, outstanding electroplating and excellent corrosion resistance. However, due to wide crystallization temperature range, it is hard to realize sequential solidification for AlCu5MnCdVA alloy by traditional casting process. Laser Powder Bed Fusion (L-PBF) has become one of the most promising technology in Metal Additive Manufacturing (MAM). In this study, L-PBF was employed to fabricate AlCu5MnCdVA parts, and both mesoscopic numerical element model and experimental printing were applied to study the feasibility of L-PBF Additive Manufacturing AlCu5MnCdVA alloy. Relative densities, phase analysis and micromorphology were investigated systematically by SEM, EDS and XRD. The laser process parameters window for AlCu5MnCdVA were obtained: volumetric energy density 41–51 J mm−3, laser power 230–240W, laser scanning speed 1200–1325 mm s−1. And the relative density of parts fabricated by L-PBF reached 96.1%. Besides, AlCu5MnCdVA alloy fabricated by L-PBF was mainly consist of α-Al, little other phase such as Al2Cu or Al2Mn3 was detected.
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Quinn, Paul, Sinéad M. Uí Mhurchadha, Jim Lawlor, and Ramesh Raghavendra. "Development and Validation of Empirical Models to Predict Metal Additively Manufactured Part Density and Surface Roughness from Powder Characteristics." Materials 15, no. 13 (July 5, 2022): 4707. http://dx.doi.org/10.3390/ma15134707.
Анотація:
Metal additive manufacturing (AM) processes, viz laser powder bed fusion (L-PBF), are becoming an increasingly popular manufacturing tool for a range of industries. The powder material used in L-PBF is costly, and it is rare for a single batch of powder to be used in a single L-PBF build. The un-melted powder material can be sieved and recycled for further builds, significantly increasing its utilisation. Previous studies conducted by the authors have tracked the effect of both powder recycling and powder rejuvenation processes on the powder characteristics and L-PBF part properties. This paper investigates the use of multiple linear regression to build empirical models to predict the part density and surface roughness of 316L stainless steel parts manufactured using recycled and rejuvenated powder based on the powder characteristics. The developed models built on the understanding of the effect of powder characteristics on the part properties. The developed models were found to be capable of predicting the part density and surface roughness to within ±0.02% and ±0.5 Ra, respectively. The models developed enable L-PBF operators to input powder characteristics and predict the expected part density and surface roughness.
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Li, Zheng, Hao Li, Jie Yin, Yan Li, Zhenguo Nie, Xiangyou Li, Deyong You, et al. "A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures." Micromachines 13, no. 8 (August 22, 2022): 1366. http://dx.doi.org/10.3390/mi13081366.
Анотація:
Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems.
Дисертації з теми "Laser powder bedfusion (L-PBF)":
1
Ty, Anthony. "Étude d'un alliage base nickel obtenu par L-PBF et par fonderie pour applications à haute température : relations procédés - microstructures - propriétés mécaniques." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP045.
Анотація:
Ces travaux de thèse visent à la compréhension des liens entre les paramètres du procédé de fabrication additive L-PBF, la santé matière, la microstructure et les propriétés mécaniques de pièces en alliage NiCrBSi. Pour ce faire, nous étudions la microstructure complexe de ces alliages, tant dans le cas d’une structure à l’équilibre générée par le procédé de fonderie, que hors équilibre générée par le procédé L-PBF. Pour le premier cas, la genèse de la microstructure est déterminée par l’analyse des transformations liquide-solide et solide-solide à l’équilibre. Pour le second cas, le domaine de fabricabilité ainsi que les liens entre les paramètres de fabrication, la santé matière, la microstructure et la dureté sont décrits. Par ailleurs, les transformations microstructurales engendrées par les traitements thermiques sont aussi étudiées pour les deux types de microstructures. La fabrication additive d’un tel alliage amène des problèmes de santé matière, dont la fissuration, qui n’a pas pu être évitée. Néanmoins une dureté élevée à haute température ainsi qu’une grande stabilité microstructurale, ont été validéesThis thesis aims to understand the relationships between the parameters of the Laser Powder Bed Fusion (L-PBF) additive manufacturing process, the material health, the microstructure, and the mechanical properties of NiCrBSi alloy components. To achieve this, the complex microstructure of these alloys is investigated both in the case of an equilibrium structure generated by the casting process and an out-of-equilibrium structure generated by the L-PBF process. For the former case, liquid-solid and solid-solid transformations at equilibrium are analyzed. For the latter case, the manufacturability domain, as well as the relationships between manufacturing parameters, material health, microstructure, and hardness, are described. Additionally, microstructural transformations induced by heat treatments are also studied for both types of microstructures. The additive manufacturing of such an alloy introduces material health issues, including cracking, which could not be avoided. Nevertheless, a high hardness at high temperature and excellent microstructural stability, have been validated
2
Eriksson, Philip. "Evaluation of mechanical and microstructural properties for laser powder-bed fusion 316L." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355882.
Анотація:
This thesis work was done to get a fundamental knowledge of the mechanical and microstructural properties of 316L stainless steel fabricated with the additive manufacturing technique, laser powder-bed fusion (L-PBF). The aims of the thesis were to study the mechanical and microstructural properties in two different building orientations for samples built in two different machines, and to summarize mechanical data from previous research on additive manufactured 316L. Additive manufacturing (AM) or 3D-printing, is a manufacturing technique that in recent years has been adopted by the industry due to the complexity of parts that can be built and the wide range of materials that can be used. This have made it important to understand the behaviour and properties of the material, since the material differs from conventionally produced material. This also adds to 316L, which is an austenitic stainless steel used in corrosive environments. To study the effect of the building orientation, samples of 316L were built in different orientations on the build plate. The density and amount of pores were also measured. Tensile testing and Charpy-V testing were made at room temperature. Vickers hardness was also measured. Microstructure and fracture surfaces were examined using light optical microscope (LOM) and scanning electron microscope (SEM). The microstructure of the 316L made with L-PBF was found to have meltpools with coarser grains inside them, sometime spanning over several meltpools. Inside these coarser grains was a finer cellular/columnar sub-grain structure. The tensile properties were found to be anisotropic with higher strength values in the orientation perpendicular to the building direction. Also high dense samples had higher tensile properties than low dense samples. The impact toughness was found to be influenced negatively by high porosity. Hardness was similar in different orientations, but lower for less dense samples. Defects due to lack of fusing of particles were found on both the microstructure sample surfaces and fracture surfaces. The values from this study compare well with previous reported research findings.
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SIVO, ANTONIO. "On the Laser Powder Bed Fusion based processing route for hard to weld Nickel Superalloys." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971609.
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Högman, Carl. "The effect of stripe width, stripe overlap, gas flow, and scan angle on process stability in Laser Powder Bed Fusion (L-PBF)." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-86140.
Анотація:
It is known that altering different processing parameters will yield completely different results in additive manufacturing. Some of the most common ones to alter to increase material quality or to increase productivity are laser power, hatch distance, layer thickness and scan speed. These parameters directly affect the material quality and are well understood. This study investigates how the process for additive manufacturing is being affected by the more unexplored minor process parameters stripe width, stripe overlap, and gas flow, with a goal to increase to knowledge of the process stability in additive manufacturing. Density measurements and investigations in optical tomography were made to determine the minor process parameters effect on the material density and process stability. The density is measured using white light interferometry and the results from the density analysis showed that the minor process parameters does not affect the density of the produced material within the interval used in this study. The minor process parameters effect on the process stability were investigated using the measured gray value obtained from optical tomography. A higher gray value means that the process is kept at a higher temperature for a longer period of time. A decrease in stripe width increased the measured gray value, while an increase of the stripe overlap increased the measured gray value. To understand what the measured gray value means for the process, the spatter area was measured using ImageJ, and a strong correlation between measured spatter area and measured gray value was found, showing that a larger spatter area will be visible as higher measured gray value. The effect of the scan angle was investigated in optical tomography, comparing the mean gray value to the scan angle. Results showed that the mean gray value increases when the angle is close to perpendicular to the gas flow at higher stripe widths and higher stripe overlaps.Det är känt att olika processparametrar erhåller olika materialkvalitéter när de ändras. Några av de vanligaste att variera för att öka materialkvalitén eller öka produktiviteten är lasereffekten, hatch-avståndet, lagertjocklek and skannhastighet. Dessa parametrar påverkar materialkvalitén och är väl undersökta. Denna studie undersöker hur processen påverkas av de mer okända parametrarna skannbredd, överlapp och gasflödet, med målet att utöka kunskapen kring processtabiliteten i additiv tillverkning. Densitetsmätningar och undersökningar i optisk tomografi gjordes för att bestämma påverkan av de sekundära processparametrarnas påverkan på materialdensiteten och processtabiliteten. Densiteten mäts med en vit-ljus interferometer och resultatet från densitetsanalysen visade att de sekundära parametrarna inte påverkade densiteten av de producerade materialet inom intervallen som användes i denna studie. Påverkan av de sekundära parametrarna på processtabiliteten undersöktes med det uppmätta gråvärdet från optisk tomografi. Ett högra gråvärde innebär att temperaturen är högre under en längre period. En ökning av skannbredden sänkte det uppmätta gråvärdet och en ökning av överlappet ökade de uppmätta gråvärdet. För att förstå vad gråvärdet innebär för processen så mättes arean av stänk i ImageJ. En stark korrelation mellan uppmätt area av stänk och uppmätt gråvärde upptäcktes, vilket visades i att det uppmätta gråvärdet var högre när arean av stänk var större. Påverkan av skannvinkeln undersöktes också i optisk tomografi där jämföranden mellan gråvärdet och skannvinkeln gjordes. Resultatet visade att gråvärdet ökar när skannvinkeln är nära vinkelrät mot gasflödets vid höga värden på skannbredden och överlappet.
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Lee, Jiwon. "Novel fabrication of Alloy 625 and MCrAlY bond coat by laser powder bed fusion and microstructure control A novel approach to the production of NiCrAlY bond coat onto IN625 superalloy by selective laser melting Influence of heat treatments on microstructure evolution and mechanical properties of Inconel 625 processed by laser powder bed fusion A new observation of strain-induced grain boundary serration and its underlying mechanism in a Ni–20Cr binary model alloy Heat treatments design for superior high-temperature tensile properties of Alloy 625 produced by selective laser melting High temperature oxidation of NiCrAlY coated Alloy 625 manufactured by selective laser melting." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2020. http://www.theses.fr/2020EMAC0008.
Анотація:
Dans cette étude, l'alliage 625 a été élaboré par l'une des méthodes de fabrication additive (AM) les plus couramment utilisées, la fusion laser sélective sur lit de poudre (L-PBF), et ses propriétés mécaniques ont été évaluées à différentes températures. L'alliage 625 fabriqué par L-PBF a montré une résistance élevée et un allongement à la rupture médiocre. Ainsi, des traitements thermiques ont été appliqués pour améliorer ses performances. Un traitement thermique de mise en solution à une température supérieure à 1000 °C a été appliquée à l'alliage L-PBF 625, ce qui a entraîné une recristallisation en raison de l’énergie stockée par le matériau attribuée à la forte densité de dislocations présentes dans l’alliage. Cette microstructure modifiée a montré une résistance satisfaisante lors des essais de traction à température ambiante (résistance plus élevée que l'alliage corroyé 625 et allongement supérieur à l'alliage L-PBF brut de fabrication). À l'étape suivante, l'alliage L-PBF 625 recristallisé a été soumis à un traitement thermique de Grain Boundary Serration (GBS, dentelure des joints de grains) pour améliorer ses propriétés mécaniques à haute température. Comme il s'agissait de la première tentative pour générer la GBS d'un alliage à haute teneur en Nb, il était d'abord important de comprendre le mécanisme GBS. Pour induire le GBS, il est nécessaire que les larges atomes de soluté se déplacent près des joints de grains (GB). Par conséquent, le traitement thermique GBS a été modifié pour être appliqué à l'alliage L-PBF 625. Le traitement thermique de GBS spécialement conçu a réussi à induire pour la première fois les motifs en zigzag des GB dentelés. Cet alliage GB-L-PBF dentelé 625 a montré des propriétés mécaniques améliorées à haute température en termes de ductilité accrue et d'élimination de l'effet de vieillissement dynamique (DSA). Pour améliorer davantage les propriétés à haute température de l'alliage L-PBF 625, un revêtement de liaison NiCrAlY a été nouvellement appliqué au substrat en alliage 625 par la même méthode (L-PBF) pour améliorer l'efficacité du processus de production et augmenter la résistance à l'oxydation/corrosion à haute température. Bien que leurs différentes propriétés thermiques aient conduit à de nombreux essais et erreurs dans la fabrication du matériau, les paramètres optimaux ont été définis et vérifiés pour évaluer le potentiel de commercialisation du procédé. La caractéristique de refusion du L-PBF a induit une bonne liaison entre le substrat et le revêtement, ce qui indique une bonne stabilité. Le comportement à l'oxydation de l'alliage 625 revêtu de NiCrAlY a été caractérisé par analyse thermo-gravimétrique (TGA) et des tests de chocs thermiques ; les résultats ont indiqué que le nouveau matériau avait une résistance à l'oxydation plus élevée que l'alliage 625 brut de fabrication. Par conséquent, le traitement thermique de GBS associé à un revêtement NiCrAlY efficace peut améliorer considérablement les propriétés mécaniques à haute température de l'alliage 625 fabriqué par L-PBFIn this study, Alloy 625 was fabricated by one of the most commonly used additive manufacturing (AM) methods, laser powder bed fusion (L-PBF), and its mechanical properties were evaluated at various temperatures. The L-PBF fabricated Alloy 625 showed high strength and relatively poor elongation. Thus, some heat treatments were applied to improve its performance. A solid-solution heat treatment with a temperature of more than 1000 °C was applied to the L-PBF Alloy 625, resulting in recrystallization because of high energy stored within the alloy attributed by high density of dislocations. This modified microstructure of the L-PBF Alloy 625 sample showed the required strength under tensile testing at room temperature (higher strength than wrought Alloy 625 and greater elongation than L-PBF as-built alloy). In view of enhancing mechanical properties at high temperature, a grain boundary serration (GBS) heat treatment was specifically designed for L-PBF Alloy 625. Because this was the first attempt to produce GBS in a high-Nb-content alloy, it was necessary to understand its mechanism first. To induce GBS, it is necessary for large solute atoms to move near the grain boundaries (GBs). Therefore, the GBS heat treatment was modified for application to the L-PBF Alloy 625. The specially designed GBS heat treatment successfully induced the zigzag patterns of serrated GBs for the first time. This GBS L-PBF Alloy 625 showed improved high-temperature mechanical properties in terms of increased ductility and elimination of the dynamic strain aging (DSA) effect at elevated temperatures. To further improve the high-temperature property of the L-PBF Alloy 625, NiCrAlY bond coat was applied to the Alloy 625 substrate by the same method (L-PBF) for the first time to improve the efficiency of the production process and increase the resistance to oxidation. Although their different thermal properties led to many trials and errors in the manufacturing of the material, the optimal parameters for applying NiCrAlY bond coat deposition by L-PBF were set and verified to assess the potential for the process to be commercialized. The remelting characteristic of L-PBF induced good metallurgical bonding between the substrate and coating, which indicates good stability. The oxidation behavior of the NiCrAlY-coated Alloy 625 was characterized by thermal gravimetric analysis (TGA) and thermal shock testing; the results indicated that the novel coated material had higher resistance to oxidation than bulk Alloy 625. Therefore, the GBS heat treatment together with efficient NiCrAlY coating can greatly improve the high-temperature mechanical properties of L-PBF manufactured Alloy 625
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Massard, Quentin. "Compréhension et maîtrise de la mise en oeuvre en fabrication additive d’aciers à haute teneur en carbone tel que le 100Cr6 par fusion sélective par laser sur lit de poudre." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2022. http://www.theses.fr/2022ECDL0024.
Анотація:
De nos jours, la production de pièces en acier par fabrication additive (FA) est un sujet central dans le monde de l’industrie, y compris l’automobile. En effet, les possibilités qu’offrent la fabrication additive sont diverses et nombreuses (allègement, formes complexes, …). Le 100Cr6 est un acier à hautes performances mécaniques, principalement utilisé pour la production de roulements à billes, en raison de son importante dureté et résistance à la fatigue. Une étude de processabilité de l’acier 100Cr6 par fusion selective par laser sur lit de poudre a tout d’abord été réalisée. Après avoir caractérisé les propriétés physiques et chimiques du matériau, des échantillons denses et non fissurés ont pu être produits au travers d’une optimisation paramétrique. Un cycle de post-traitement a pu être défini et des essais de traction plane et de fatigue par flexion rotative ont pu être réalisés.Afin de comprendre et maîtriser le phénomène de fissuration du 100Cr6 lors de son emploi par L-PBF une étude métallurgique approfondie (microdureté, imagerie optique, MEB, DRX, EBSD) a pu être menée. L’influence de l’emploi du plateau chauffant quant à la formation de Bainite et de Martensite et leur impacte sur la fissuration a pu être mis en évidence.Enfin, une étude de recyclabilité de la poudre de 100Cr6 oxydée a pu être réalisée à travers l’utilisation d’une machine de sphéroïdisation par plasma radiofréquence. Un débit d’alimentation de poudre dans le plasma permettant de régénérer les propriétés physiques et rhéologiques de la poudre a pu être défini. Une méthode de nettoyage permettant d’améliorer les propriétés chimiques de la poudre a également été proposéNowadays, the production of steel parts by additive manufacturing (AM) is a central topic in the world of industry, including automotive. Indeed, the possibilities offered by additive manufacturing are diverse and numerous (weight reduction, complex shapes, ...). 100Cr6 is a high mechanical performance steel, mainly used for the production of ball bearings, due to its high hardness and fatigue resistance. A processability study of 100Cr6 steel produced by selective laser melting on powder bed was first performed. After having characterized the physical and chemical properties of the material, dense and non-cracked samples were produced through a parametric optimization. A post-treatment cycle was defined and plane tensile tests and rotary bending fatigue tests were performed.In order to understand and control the cracking phenomenon of 100Cr6 when used in L-PBF, a thorough metallurgical study (microhardness, optical imaging, SEM, XRD, EBSD) was conducted. The influence of the use of the heating plate on the formation of Bainite and Martensite and their impact on cracking was highlighted.Finally, a recyclability study of the oxidized 100Cr6 powder was carried out through the use of a radiofrequency plasma spheroidization machine. A powder feed rate in the plasma allowing to regenerate the physical and rheological properties of the powder was defined. A cleaning method to improve the chemical properties of the powder was also proposed
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Santos, Gonçalo Edgar Bento dos. "Propagação de fendas por fadiga em titânio Ti6Al4V produzido por SLM para solicitações em modo misto I+II." Master's thesis, 2020. http://hdl.handle.net/10316/92219.
Анотація:
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaEste estudo revela-se particularmente interessante devido à variedade de indústrias que utiliza este tipo da liga de titânio Ti6Al4V, desde a indústria aeroespacial, à biomédica e a outras aplicações de engenharia de alto desempenho. Para que esta liga de titânio seja utilizada de forma segura e consciente, é necessário o conhecimento de todas as suas propriedades e comportamentos nas mais diversas situações de aplicação.Este trabalho teve como principal tema a propagação de fendas por fadiga em provetes de titânio Ti6Al4V produzidos por SLM para solicitações em modo I+II. Para o efeito, usaram-se provetes CTS e diferentes ângulos de carregamento, começando no modo I puro para ângulo de carregamento α=0º e passando pelo modo misto I+II para ângulos α=15º, 30º e 45º. Neste estudo foram realizados ensaios de propagação de fendas por fadiga para R=0, de onde resultaram curvas da/dN-K, a análise do fenómeno do fecho de fenda, a comparação de modelos para o cálculo do fator de intensidade de tensões e o estudo da fratografia. Dos ensaios realizados para o modo I puro e para modo misto I+II foi possível aplicar dois métodos diferentes para o cálculo de ∆K_I e ∆K_II em cada um dos casos estudados (α=0º, α=15º, α=30º, α=45º), obtendo-se uma boa correlação entre ambos os métodos. O método proposto nesta dissertação demostrou ser um método válido e com maior simplicidade quando comparado a outros já existentes. Foi possível também verificar que o fecho de fenda foi diminuindo com o aumento do ângulo de carregamento (α), devido à diminuição da componente do carregamento que provoca o modo I de propagação com o aumento do ângulo α. A análise da superfície de fratura revelou poucas diferenças entre os provetes ensaiados, onde foram encontrados defeitos típicos do processo L-PBF (SLM) tais como: porosidade, partículas por fundir e inclusão por contaminação.
This study proves to be particularly interesting due to the variety of industries that use this type of titanium alloy Ti6Al4V, from the aerospace industry, to biomedical and other high performance engineering applications. For this titanium alloy to be used safely and consciously, it is necessary to know all of its properties and behaviors in the most diverse application conditions.This work had as a main theme fatigue crack propagation in titanium Ti6Al4V produced by SLM for loads in mixed mode I+II and its main purpose was the study of fatigue crack propagation in CTS test pieces for diferente loading angles, starting with pure mode I for loading angle α=0º and passing through the mixed mode I+II for loading angles α=15º, 30º e 45º. In this study, fatigue crack propagation tests were performed for R=0, resulting in da/dN-K curves, the analysis of crack closure phenomenom, the models’ comparison for the calulation of the stress intensity factor and the study of fractography. From the tests performed for pure mode I and mixed mode I+II, it was possible to apply two diferent methods for the calculation of ∆K_I e ∆K_II in each of the studied cases (α=0º, α=15º, α=30º, α=45º), obtaining a good correlation between both methods. The proposed method in this dissertation proved to be a valid and simpler method when compared to existing ones. It was also possible to verify that the crack closure was decreasing with the increase of the loading angle (α), due to the decrease of the loading component that causes mode I of propagation with the increase of the angle α. The analysis of the crack surface revealed few diferences between the test specimens, where typical defects of the L-PBF (SLM) process were found, such as: porosity, unmelted particles and contamination inclusion.
Outro - O autor agradece o apoio financeiro fornecido pelo Fundo Europeu de Desenvolvimento Regional (FEDER), através do programa PT2020, no âmbito do Programa Operacional Regional do Centro (CENTRO-01-0145-FEDER-028789) e pela Fundação para a Ciência e a Tecnologia IP/MCTES, através de fundos nacionais (PIDDAC), para a elaboração do presente documento.
Частини книг з теми "Laser powder bedfusion (L-PBF)":
1
Haase, Fabian, Carsten Siemers, Maximilian Goldapp, and Joachim Rösler. "Si-Containing Titanium Alloys for Laser Powder Bed Fusion (PBF-L)." In Proceedings of the 61st Conference of Metallurgists, COM 2022, 343–54. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-17425-4_46.
2
Hoppe, Birk, and Sebastian Enk. "Schlieren- und Schattengrafie zur Visualisierung der Schutzgasdynamik im Laser Powder Bed Fusion (L-PBF)." In Rapid.Tech + FabCon 3.D International Hub for Additive Manufacturing: Exhibition + Conference + Networking, 197–210. München: Carl Hanser Verlag GmbH & Co. KG, 2019. http://dx.doi.org/10.3139/9783446462441.015.
3
Hoppe, Birk, and Sebastian Enk. "Schlieren- und Schattengrafie zur Visualisierung der Schutzgasdynamik im Laser Powder Bed Fusion (L-PBF)." In Rapid.Tech + FabCon 3.D International Hub for Additive Manufacturing: Exhibition + Conference + Networking, 197–210. München, Germany: Carl Hanser Verlag GmbH & Co. KG, 2019. http://dx.doi.org/10.1007/978-3-446-46244-1_15.
4
Krakhmalev, Pavel, and Nataliya Kazantseva. "Microstructure of L-PBF alloys." In Fundamentals of Laser Powder Bed Fusion of Metals, 215–43. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-824090-8.00018-4.
5
Yakout, Mostafa, and M. A. Elbestawi. "Insights on Laser Additive Manufacturing of Invar 36." In Advances in Civil and Industrial Engineering, 71–93. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-4054-1.ch004.
Анотація:
Recently, additive manufacturing (AM) became a promising technology to manufacture complex structures with acceptable mechanical properties. The laser powder-bed fusion (L-PBF) process is one of the most common AM processes that has been used for producing a wide variety of metals and composites. Invar 36 is an austenite iron-nickel alloy that has a very low coefficient of thermal expansion; therefore, it is a good candidate for the L-PBF process. This chapter covers the state-of-the-art for producing Invar 36 using the L-PBF process. The chapter aims at describing research insights of using metal AM techniques in producing Invar 36 components. Like most of nickel-based alloys, Invar 36 is weldable but hard-to-machine. However, there are some challenges while processing these alloys by laser. This chapter also covers the challenges of using the L-PBF process for producing nickel-based alloys. In addition, it reports the L-PBF conditions that could be used to produce fully dense Invar 36 components with mechanical properties comparable to the wrought Invar 36.
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Thompson, Scott M., and Nathan B. Crane. "Process Defects in Metal Additive Manufacturing." In Additive Manufacturing Design and Applications, 1–23. ASM International, 2023. http://dx.doi.org/10.31399/asm.hb.v24a.a0006972.
Анотація:
Abstract This article presents a general understanding of causes and possible solutions for defects in the most common metal additive manufacturing (AM) processes: laser powder-bed fusion (L-PBF), laser directed-energy deposition (DED-L), and binder jetting (BJ).
7
Yadroitsev, Igor, and Ina Yadroitsava. "A step-by-step guide to the L-PBF process." In Fundamentals of Laser Powder Bed Fusion of Metals, 39–77. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-824090-8.00026-3.
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Yeung, Ho. "Methodologies and Implementation of Laser Powder-Bed Fusion Process Control." In Additive Manufacturing Design and Applications, 1–9. ASM International, 2023. http://dx.doi.org/10.31399/asm.hb.v24a.a0006955.
Анотація:
Abstract Part quality in additive manufacturing (AM) is highly dependent on process control, but there is a lack of adequate AM control methods and standards. Laser powder-bed fusion (L-PBF) is one of the most-used metal AM techniques. This article focuses on the following laser control parameters: laser focus, laser power, laser position, and laser power-position synchronization. It then provides a discussion on laser scan strategies. The article also provides an overview of the AM control framework, the two major sections of which are software and hardware.
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Lane, Brandon, and David Deisenroth. "In-Process Thermography of Metal Additive Manufacturing Processes." In Additive Manufacturing Design and Applications, 1–14. ASM International, 2023. http://dx.doi.org/10.31399/asm.hb.v24a.a0006954.
Анотація:
Abstract This article provides readers with a brief review of the applications of thermography in additive manufacturing (AM), which still is largely a research and development (R&D) effort. There is a particular focus on metals-based laser powder-bed fusion (L-PBF), although applications in directed-energy deposition (DED) and electron beam PBF (E-PBF) also are mentioned. The metrological basis of thermography is discussed in the article. Background information on radiation thermometry is provided, including how the various equations are applied. Finally, specific examples and lessons learned from various AM thermographic studies at the National Institute of Standards and Technology (NIST) are provided.
10
Mogale, Ntebogeng, Wallace Matizamhuka, and Prince Cobbinah. "Hot Corrosion and Oxidation Behaviour of TiAl Alloys during Fabrication by Laser Powder Bed Additive Manufacturing Process." In Corrosion [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100345.
Анотація:
This research paper summarises the practical relevance of additive manufacturing with particular attention to the latest laser powder bed fusion (L-PBF) technology. L-PBF is a promising processing technique, integrating intelligent and advanced manufacturing systems for aerospace gas turbine components. Some of the added benefits of implementing such technologies compared to traditional processing methods include the freedom to customise high complexity components and rapid prototyping. Titanium aluminide (TiAl) alloys used in harsh environmental settings of turbomachinery, such as low-pressure turbine blades, have gained much interest. TiAl alloys are deemed by researchers as replacement candidates for the heavier Ni-based superalloys due to attractive properties like high strength, creep resistance, excellent resistance to corrosion and wear at elevated temperatures. Several conventional processing technologies such as ingot metallurgy, casting, and solid-state powder sintering can also be utilised to manufacture TiAl alloys employed in high-temperature applications. This chapter focuses on compositional variations, microstructure, and processing of TiAl alloys via L-PBF. Afterward, the hot corrosion aspects of TiAl alloys, including classification, characteristics, mechanisms and preventative measures, are discussed. Oxidation behaviour, kinetics and prevention control measures such as surface and alloy modifications of TiAl alloys at high temperature are assessed. Development trends for improving the hot corrosion and oxidation resistance of TiAl alloys possibly affecting future use of TiAl alloys are identified.
Тези доповідей конференцій з теми "Laser powder bedfusion (L-PBF)":
1
Batalha, Rodolfo, André Carvalho, Piter Gargarella, Ana Cabral, Paulo Morais, and Guiomar Evans. "Laser-Powder Bed Fusion Of Ti-Based Alloys For Biomedical Applications." In Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235765159.
Анотація:
The focus of this work is to process new biocompatible Ti alloys solely constituted of non-toxic elements by laser-powder bed fusion (L-PBF), a metal additive manufacturing (AM) technology. The main L-PBF processing parameters such as laser power and scanning speed were defined to obtain highly dense samples. The effects of the addition of ceramic particles and the influence of the scanning strategy on the microstructure of the Ti-based alloys were investigated, showing the possibility for in-situ tailoring the material properties in the L-PBF process. Finally, some prototypes were manufactured proving the feasibility of manufacturing parts of Ti-based biocompatible alloys with complex geometry by L-PBF.
2
Sperry, McKay, Annie Busath, Michael Ottesen, Jacob Heslington, and Nathan Crane. "Post-Processing and Material Properties of Nylon 12 Prepared by Laser-Powder Bed Fusion." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69053.
Анотація:
Abstract Laser Powder Bed Fusion (L-PBF) is a fabrication process in the Powder Bed Fusion (PBF) family of additive manufacturing. The key advantage to L-PBF over other manufacturing methods is design flexibility. Additional design flexibility, however, has previously come at the cost of reduced material properties. Polyamide 12 (PA12, Nylon 12) is a semicrystalline polymer with thermophysical properties that make it ideal for L-PBF. Although L-PBF PA12 has tensile strength comparable to injection molded PA12, it has substantially reduced ductility. This paper reports on a series of post-processing treatment for L-PBF of PA12 and measures their impact on strength, ductility, and density. These include annealing, cooling, and pressure treatments. The treatments resulted in PA12 parts with a wide range of properties, which could be tailored according to end-use application with up to 11% increase in strength or 19% increase in ductility.
3
Greco, Sebastian, Kevin Gutzeit, Hendrik Hotz, Marc Schmidt, Marco Zimmermann, Benjamin Kirsch, and Jan C. Aurich. "Influence of Machine Type and Powder Batch During Laser-Based Powder Bed Fusion (L-PBF) of AISI 316L." In ASME 2021 16th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/msec2021-60448.
Анотація:
Abstract The use of additive manufacturing (AM) in industrial applications is steadily increasing due to its near net shape production and high design-freedom. For metallic components, laser-based powder bed fusion (L-PBF) is currently one of the most widely used AM processes. During L-PBF, a component is manufactured layer by layer from a powdery raw material. The process is controlled by a multitude of parameters like the laser power, scanning speed and layer thickness, whose combination significantly influences the properties of the components. In this study, the influence of the L-PBF machine type and the influence of the powder batch are investigated by means of relative density, microhardness and microstructure of the components. For this purpose, three setups are defined, differing in the powder batch and machine type used. By comparing the process results of the additive manufacturing of different setups, the influence of the machine type and powder batch are determined. The considered material is stainless steel AISI 316L. The results revealed significant differences between all investigated properties of the additively manufactured components. Consequently, process parameter combinations cannot be transferred between different machine types and powder batches without verification of the component properties and, if necessary, special adaption of the process.
4
Lopez, Felipe, Paul Witherell, and Brandon Lane. "Identifying Uncertainty in Laser Powder Bed Fusion Models." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8692.
Анотація:
A limitation frequently encountered in additive manufacturing (AM) models is a lack of indication about their precision and accuracy. Often overlooked, information on model uncertainty is required for validation of AM models, qualification of AM-produced parts, and uncertainty management. This paper presents a discussion on the origin and propagation of uncertainty in Laser Powder Bed Fusion (L-PBF) models. Four sources of uncertainty are identified: modeling assumptions, unknown simulation parameters, numerical approximations, and measurement error in calibration data. Techniques to quantify uncertainty in each source are presented briefly, along with estimation algorithms to diminish prediction uncertainty with the incorporation of online measurements. The methods are illustrated with a case study based on a transient, stochastic thermal model designed for melt pool width predictions. Model uncertainty is quantified for single track experiments and the effect of online estimation in overhanging structures is studied via simulation. The application of these concepts to estimation and control of the L-PBF process is suggested.
5
Papy, K., A. Sova, A. Borbely, J. M. Staerk, J. Favre, Z. Roulon, J. Sijobert, and P. Bertrand. "Additive Manufacturing Feasibility of WC-17Co Cermet Parts by Laser Powder Bed Fusion." In ITSC2022. DVS Media GmbH, 2022. http://dx.doi.org/10.31399/asm.cp.itsc2022p0951.
Анотація:
Abstract Cermets are composite materials consisting of a ceramic reinforcement and a metal matrix. Conventional tungsten carbide cermet parts containing a cobalt matrix phase are mainly produced by powder sintering. Laser Powder Bed Fusion (L-PBF) is an additive manufacturing technology widely applied for direct fabrication of metal functional parts with complex geometry. The present paper deals with the feasibility study of additive manufacturing of cermet parts by L-PBF using WC-17Co powder. The results showed that parametric optimisation of the L-PBF process allowed the production of solid WC-17Co part. Structural analysis revealed the presence of significant porosity (1.41%) and small-scale cracks in the as-built samples. Post-processing, such as HIP (Hot Isostatic Pressure) significantly improved the structure of manufactured parts. The porosity after HIP was very low (0.01%) and phase analysis revealed that the samples after HIP did not contain the fragile W2C phase. Abrasive wear tests showed that the wear resistance performance of additively manufactured parts was comparable to a reference produced by powder sintering. High values of hardness (around 1100 HV30) were observed for the as-built and HIP samples. The study successfully demonstrated the possibility of manufacturing wear-resistant cermet parts by L-PBF.
6
Deirmina, Faraz, Lorenzo Quarzago, Eleonora Bettini, Matthew Ritche, Daniel Butcher, Shahin Mehraban, Nicholas Lavery, and Massimo Pellizzari. "Hot Work Tool Steel Tailored for the Laser Powder Bed Fusion Processing." In Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235765264.
Анотація:
Hot work tool steels with medium C contents are known to be difficult to process by laser powder bed fusion (L-PBF). Cold and, to a lesser extent, hot cracking occurs in these alloys. Cold cracks are attributed to the low ductility and large residual stresses due to the complex thermal profiles. These can be avoided by platform preheating, which may introduce additional costs and side-effects on microstructure and properties. Therefore, the market trend is to develop new steel grades with improved 3D-printabilty. In this work, a prototype alloy with a leaner C content is proposed. To compensate for the negative effect of reduced C, computational thermodynamics was used to define chemistries with an optimized balance of carbide forming elements, and Si. The prototype tool steel shows enhanced L-PBF processability, and properties meeting and/or exceeding those of wrought AISI H13 in terms of hot strength, tempering and thermal fatigue resistance.
7
Zhang, Shanshan, Brandon Lane, and Kevin Chou. "Powder Thermal Conductivity Measurements in L-PBF Using Powder-Included Build Specimens: Internal Geometry Effect." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8475.
Анотація:
Abstract This study investigates the thermal conductivity of 17-4PH stainless steel powder that was encapsulated within specimens with different internal geometries in laser powder bed fusion (L-PBF) additive manufacturing (AM). The objective is to evaluate the effect of the internal geometry of the specimens on the measurement of the powder thermal conductivity and to compare the thermal properties amongst the 17-4PH and two additional powder materials used in L-PBF. Continued from the previous work [1], three new cone configurations in the hollow specimens were designed and fabricated in an L-PBF system. The thermal conductivity of the internal powder was indirectly measured using an experimental-numerical approach, combined with laser-flash testing, finite element (FE) heat transfer modeling and multivariate inverse method. The results reveal that the thermal conductivity of 17-4PH powder ranges from 0.67 W/(m·K) to 1.34 W/(m·K) at 100 °C to 500 °C, and varies with the internal geometry of the specimens. In addition, the measurement of the hollow specimen with a convex cone seems to be a more reliable evaluation. Further, the thermal conductivity ratio of the powder to the solid counterpart of 17-4PH approximately ranges from 3.9 % to 5.5 % at tested temperatures, which is similar to the results obtained from the nickel-based super alloy 625 (IN625) and Ti-6Al-4V (Ti64) powders measured in a previous study.
8
Aminzadeh, Masoumeh, and Thomas Kurfess. "Layerwise Automated Visual Inspection in Laser Powder-Bed Additive Manufacturing." In ASME 2015 International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/msec2015-9393.
Анотація:
Laser powder-bed fusion (L-PBF) is an additive manufacturing (AM) process that enables fabrication of functional metal parts with near-net-shape geometries. The drawback to L-PBF is its lack of precision as well as the formation of defects due to process randomness and irregularities associated with laser powder fusion. Over the past two decades much research has been conducted to control laser powder fusion in order to provide parts of higher quality. This paper addresses online quality monitoring in AM by in-situ automated visual inspection of each layer which is aimed to geometric objects and defects from high-resolution visual images. A scheme for online defect detection system is presented that consists of three levels of processing: low-level, intermediate-level, and high-level processing. Each level is described and appropriately divided to several stages, when insightful. Techniques that are feasible in each level for successful defect detection and classification are identified and described. Requirements and specifications of the measurement data to achieve desired performance of the online defect detection system are stated. Image processing algorithms are developed for first level of processing and implemented for segmentation of geometric objects. Due to the large variation of intensities within the powder region and fused regions, and also the non-multi-modal nature of the image, the basic segmentation algorithms such as thresholding do not produce appropriate results. In this work, morphological operations are effectively designed and implemented following thresholding to achieve the desired object segmentation. Examples of implementations are given. The paper provides the results of object segmentation which is the initial stage of development of an in-situ automated visual inspection for L-PBF process.
9
Yan, Dongqing, Eddie Taewan Lee, Somayeh Pasebani, and Zhaoyan Fan. "A Study of the Laser Powder Bed Fusion Manufactured Surface Roughness Prediction and Optimization Based on Artificial Neural Network." In ASME 2023 18th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/msec2023-102011.
Анотація:
Abstract Laser powder bed fusion (L-PBF) is one of the most popular additive manufacturing methods in metal additive manufacturing. The surface roughness of the L-PBF manufactured parts is significantly influenced by major process parameters adopted, such as laser power, laser scanning speed, laser hatch space, and layer thickness of powder. This paper presented a machine-learning approach to determine the control parameters for reducing the surface roughness of the L-PBF products. In this study, a three-level full factorial experiment was designed with four major process parameters to examine the corresponding influence of surface roughness. The roughness of the fabricated samples was acquired by a laser profilometer. An artificial neural network model was trained to establish the relationship between the controllable parameters and finished surface roughness. The trained model was validated through additional experiments. The study provided an effective model for predicting the surface quality of L-PBF fabricated parts and a guideline for the process parameter selection.
10
Moges, Tesfaye, Paul Witherell, and Gaurav Ameta. "On Characterizing Uncertainty Sources in Laser Powder Bed Fusion Additive Manufacturing Models." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11727.
Анотація:
Abstract Tremendous effort has been dedicated to computational models and simulations of Additive Manufacturing (AM) processes to better understand process complexities and better realize high-quality parts. However, understanding whether a model is an acceptable representation for a given scenario is a difficult proposition. With metals, the laser powder bed fusion (L-PBF) process involves complex physical phenomena such as powder packing, heat transfer, phase transformation, and fluid flow. Models based on these phenomena will possess different degrees of fidelity as they often rely on assumptions that may neglect or simplify process physics, resulting in uncertainty in their prediction accuracy. Predictive uncertainty and its characterization can vary greatly between models. This paper characterizes sources of L-PBF model uncertainty, including those due to modeling assumptions (model form uncertainty), numerical approximation (numerical uncertainty), and model input parameters (input parameter uncertainty) for low and high-fidelity models. The characterization of input uncertainty in terms of probability density function (PDF) and its propagation through L-PBF models, is discussed in detail. The systematic representation of such uncertainty sources is achieved by leveraging the Web Ontology Language (OWL) to capture relevant knowledge used for interoperability and reusability. The topology and mapping of the uncertainty sources establish fundamental requirements for measuring model fidelity and guiding the selection of a model suitable for its intended purpose.
Звіти організацій з теми "Laser powder bedfusion (L-PBF)":
1
Slattery, Kevin, and Kirk A. Rogers. Internal Boundaries of Metal Additive Manufacturing: Future Process Selection. SAE International, March 2022. http://dx.doi.org/10.4271/epr2022006.
Анотація:
In the early days, there were significant limitations to the build size of laser powder bed fusion (L-PBF) additive manufacturing (AM) machines. However, machine builders have addressed that drawback by introducing larger L-PBF machines with expansive build volumes. As these machines grow, their size capability approaches that of directed energy deposition (DED) machines. Concurrently, DED machines have gained additional axes of motion which enable increasingly complex part geometries—resulting in near-overlap in capabilities at the large end of the L-PBF build size. Additionally, competing technologies, such as binder jet AM and metal material extrusion, have also increased in capability, albeit with different starting points. As a result, the lines of demarcation between different processes are becoming blurred. Internal Boundaries of Metal Additive Manufacturing: Future Process Selection examines the overlap between three prominent powder-based technologies and outlines an approach that a product team can follow to determine the most appropriate process for current and future applications.