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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).
7
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.
9
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.
10
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.
11
Brown, Ben, Joseph Newkirk, and Frank Liou. "Absorption of Nitrogen during Pulsed Wave L-PBF of 17-4 PH Steel." Materials 14, no. 3 (January 25, 2021): 560. http://dx.doi.org/10.3390/ma14030560.
Анотація:
In the fabrication of 17-4 PH by laser powder bed fusion (L-PBF) the well-documented occurrence of large amounts of retained austenite can be attributed to an elevated concentration of nitrogen present in the material. While the effects of continuous wave (CW) laser processing on in-situ nitrogen absorption characteristics have been evaluated, power modulated pulsed wave (PW) laser processing effects have not. In this study the effects of PW L-PBF processing of 17-4 PH on nitrogen absorption, phase composition, and mechanical performance are explored using commercially available PW L-PBF equipment and compared to samples produced by CW L-PBF. PW L-PBF samples fabricated in cover gas conditions with varying amounts of nitrogen demonstrated reduced absorption levels compared to those produced by CW L-PBF with no effects on phase composition and minimal effects on mechanical performance.
12
Liović, David, Marina Franulović, Ervin Kamenar, and Dražan Kozak. "Nano-Mechanical Behavior of Ti6Al4V Alloy Manufactured Using Laser Powder Bed Fusion." Materials 16, no. 12 (June 12, 2023): 4341. http://dx.doi.org/10.3390/ma16124341.
Анотація:
The microstructure of Ti6Al4V alloy, manufactured using laser powder bed fusion (L-PBF), is affected by process parameters and heat treatment. However, their influence on the nano-mechanical behavior of this widely applicable alloy is still unknown and scarcely reported. This study aims to investigate the influence of the frequently used annealing heat treatment on mechanical properties, strain-rate sensitivity, and creep behavior of L-PBF Ti6Al4V alloy. Furthermore, the influence of different utilized L-PBF laser power–scanning speed combinations on mechanical properties of annealed specimens has been studied as well. It has been found that the effect of high laser power remains present in the microstructure even after annealing, resulting in increase in nano-hardness. Moreover, the linear relation between the Young’s modulus and the nano-hardness after annealing has been established. Thorough creep analysis revealed dislocation motion as a dominant deformation mechanism, both for as-built and annealed conditions of the specimens. Although annealing heat treatment is beneficial and widely recommended, it reduces the creep resistance of Ti6Al4V alloy manufactured using L-PBF. The results presented within this research article contribute to the L-PBF process parameter selection, as well as to understanding the creep behavior of these novel and widely applicable materials.
13
Oyedeji, Ayodeji, Natasha Sacks, Andrew Venter, and Johannes Pötschke. "Numerical methods in predicting residual stresses in laser powder bed fusion developed parts – a scoping review." MATEC Web of Conferences 388 (2023): 02003. http://dx.doi.org/10.1051/matecconf/202338802003.
Анотація:
The study reviews the numerical methods for predicting residual stresses in parts manufactured with additive manufacturing (AM) technique, such as laser powder bed fusion (L-PBF). L-PBF is a fast-growing technology with enormous potential for creating complex geometries with improved properties as compared to conventional processes. However, parts produced with L-PBF are susceptible to higher magnitudes of residual stresses, particularly tensile stresses as compared to compressive stresses, leading to geometrical distortions. While newly developed materials offer excellent properties and benefits to the industrial sector, the residual stresses that develop when parts are produced using the L-PBF process remain unexplored. The study evaluates three numerical simulation methods, such as thermomechanical modelling (TMM), inherent strain method (ISM), and multi-scale modelling (MSM) used to predict residual stresses in L-PBF parts. Each method has its advantages and limitations, and the best method depends on the specific application and available resources. The review highlights the potential benefits of numerical simulation methods for predicting residual stresses in L-PBF parts and compared to experimental results. Thus, the study recommends that future research should focus on improving the accuracy of numerical simulation methods for predicting residual stresses in L-PBF parts through refinement processes and exploring the impact of residual stresses on the L-PBF parts through detailed characterization.
14
Baqerzadeh Chehreh, Abootorab, Anna Strauch, Felix Großwendt, Arne Röttger, Rainer Fechte-Heinen, Werner Theisen, and Frank Walther. "Influence of Different Alloying Strategies on the Mechanical Behavior of Tool Steel Produced by Laser-Powder Bed Fusion." Materials 14, no. 12 (June 17, 2021): 3344. http://dx.doi.org/10.3390/ma14123344.
Анотація:
Additive manufacturing is a high-potential technique that allows the production of components with almost no limitation in complexity. However, one of the main factors that still limits the laser-based additive manufacturing is a lack of processable alloys such as carbon martensitic hardenable tool steels, which are rarely investigated due to their susceptibility to cold cracking. Therefore, this study aimed to expand the variety of steels for laser powder bed fusion (L-PBF) by investigating an alternative alloying strategy for hot work tool steel powder. In this study, a comprehensive investigation was performed on the powder and L-PBF processed specimen properties and their correlation with the existing defects. Cubical specimens were created using the following two alloying strategies by means of L-PBF: conventional pre-alloyed gas-atomized powder and a mixture of gas-atomized powder with mechanically crushed pure elements and ferroalloys. The influence of the particle parameters such as morphology were correlated to the defect density and resulting quasi-static mechanical properties. Micromechanical behavior and damage evolution of the processed specimens were investigated using in situ computed tomography. It was shown that the properties of the L-PBF processed specimens obtained from the powder mixture performs equal or better compared to the specimens produced from conventional powder.
15
Wang, Wenyuan, Naoki Takata, Asuka Suzuki, Makoto Kobashi, and Masaki Kato. "Processability and Optimization of Laser Parameters for Densification of Hypereutectic Al–Fe Binary Alloy Manufactured by Laser Powder Bed Fusion." Crystals 11, no. 3 (March 23, 2021): 320. http://dx.doi.org/10.3390/cryst11030320.
Анотація:
Centimeter-sized samples of hypereutectic Al–15 mass% Fe alloy were manufactured by a laser powder bed fusion (L-PBF) process while systematically varying laser power (P) and scan speed (v). The effects on relative density and melt pool depth of L-PBF-manufactured samples were investigated. In comparison with other Al alloys, a small laser process window of P = 77–128 W and v = 0.4–0.8 ms−1 was found for manufacturing macroscopically crack-free samples. A higher v and P led to the creation of macroscopic cracks propagating parallel to the powder-bed plane. These cracks preferentially propagated along the melt pool boundaries decorated with brittle θ-Al13Fe4 phase, resulting in low L-PBF processability of Al–15%Fe alloy. The deposited energy density model (using P·v−1/2) would be useful for identifying the optimum L-PBF process conditions towards densification of Al–15%Fe alloy samples, in comparison with the volumetric energy density (using P·v−1), however, the validity of the model was reduced for this alloy in comparison with other alloys with high thermal conductivities. This is likely due to inhomogeneous microstructures having numerous coarsened θ–Al13Fe4 phases localized at melt pool boundaries. These results provide insights into achieving sufficient L-PBF processability for manufacturing dense Al–Fe binary alloy samples.
16
Semikolenov, Anton, Pavel Kuznetsov, Tatyana Bobkova, Svetlana Shalnova, Olga Klimova-Korsmik, Viktor Klinkov, Ilya Kobykhno, Tatyana Larionova, and Oleg Tolochko. "Microstructure Evolution of FeNiCoCrAl1.3Mo0.5 High Entropy Alloy during Powder Preparation, Laser Powder Bed Fusion, and Microplasma Spraying." Materials 14, no. 24 (December 19, 2021): 7870. http://dx.doi.org/10.3390/ma14247870.
Анотація:
In the present study, powder of FeCoCrNiMo0.5Al1.3 HEA was manufactured by gas atomization process, and then used for laser powder bed fusion (L-PBF) and microplasma spraying (MPS) technologies. The processes of phase composition and microstructure transformation during above mentioned processes and subsequent heat treatment were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and differential thermal analysis (DTA) methods. It was found that gas atomization leads to a formation of dendrites of body centered cubic (BCC) supersaturated solid solution with insignificant Mo-rich segregations on the peripheries of the dendrites. Annealing leads to an increase of element segregations till to decomposition of the BCC solid solution and formation of σ-phase and B2 phase. Microstructure and phase composition of L-PBF sample are very similar to those of the powder. The MPS coating has a little fraction of face centered cubic (FCC) phase because of Al oxidation during spraying and formation of regions depleted in Al, in which FCC structure becomes more stable. Maximum hardness (950 HV) is achieved in the powder and L-PBF samples after annealing at 600 °C. Elastic modulus of the L-PBF sample, determined by nanoindentation, is 165 GPa, that is 12% lower than that of the cast alloy (186 GPa).
17
Lindström, Viktor, Oleksii Liashenko, Kai Zweiacker, Serhii Derevianko, Vladyslav Morozovych, Yurij Lyashenko, and Christian Leinenbach. "Laser Powder Bed Fusion of Metal Coated Copper Powders." Materials 13, no. 16 (August 7, 2020): 3493. http://dx.doi.org/10.3390/ma13163493.
Анотація:
Laser powder bed fusion (L-PBF) of copper alloys with high copper content is difficult due to the high infrared reflectivity and thermal conductivity of these alloys. In this study a simple and scalable method for coating copper powder with tin and nickel is presented, and suggested as an alloying strategy for such alloys. The coated powders were processed in a commercial L-PBF-machine at various scanning speeds. The samples made from coated powders show a lower amount of porosity compared to samples made from in-situ alloyed powders of similar composition.
18
Akwaboa, Stephen, Congyuan Zeng, Nigel Amoafo-Yeboah, Samuel Ibekwe, and Patrick Mensah. "Thermophysical Properties of Laser Powder Bed Fused Ti-6Al-4V and AlSi10Mg Alloys Made with Varying Laser Parameters." Materials 16, no. 14 (July 10, 2023): 4920. http://dx.doi.org/10.3390/ma16144920.
Анотація:
This study investigated the influence of diverse laser processing parameters on the thermophysical properties of Ti-6Al-4V and AlSi10Mg alloys manufactured via laser powder bed fusion. During fabrication, the laser power (50 W, 75 W, 100 W) and laser scanning speed (0.2 m/s, 0.4 m/s, 0.6 m/s) were adjusted while keeping other processing parameters constant. Besides laser processing parameters, this study also explored the impact of test temperatures on the thermophysical properties of the alloys. It was found that the thermophysical properties of L-PBF Ti-6Al-4V alloy samples were sensitive to laser processing parameters, while L-PBF AlSi10Mg alloy showed less sensitivity. In general, for the L-PBF Ti-6Al-4V alloy, as the laser power increased and laser scan speed decreased, both thermal diffusivity and conductivity increased. Both L-PBF Ti-6Al-4V and L-PBF AlSi10Mg alloys demonstrated similar dependence on test temperatures, with thermal diffusivity and conductivity increasing as the test temperature rose. The CALPHAD software Thermo-Calc (2023b), applied in Scheil Solidification Mode, was utilized to calculate the quantity of solution atoms, thus enhancing our understanding of observed thermal conductivity variations. A detailed analysis revealed how variations in laser processing parameters and test temperatures significantly influence the alloy’s resulting density, specific heat, thermal diffusivity, and thermal conductivity. This research not only highlights the importance of processing parameters but also enriches comprehension of the mechanisms influencing these effects in the domain of laser powder bed fusion.
19
Wong, H., K. Dawson, G. A. Ravi, L. Howlett, R. O. Jones, and C. J. Sutcliffe. "Multi-Laser Powder Bed Fusion Benchmarking—Initial Trials with Inconel 625." International Journal of Advanced Manufacturing Technology 105, no. 7-8 (November 9, 2019): 2891–906. http://dx.doi.org/10.1007/s00170-019-04417-3.
Анотація:
Abstract Production rate is an increasingly important factor in the deployment of metal additive manufacturing (AM) throughout industry. To address the perceived low production rate of metal AM systems based on single-laser powder bed fusion (L-PBF), several companies now offer systems in which melting has been parallelised by the introduction of multiple, independently controlled laser beams. Nevertheless, a full set of studies is yet to be conducted to benchmark the efficiency of multi-laser systems and, at the same time, to verify if the mechanical properties of components are compromised due to the increase in build rate. This study addresses the described technology gaps and presents a 4-beam L-PBF system operating in “single multi” (SM) mode (SM-L-PBF) where each of the four lasers is controlled so that it melts all of a particular components’ layers and produces specimens for comparison with standard L-PBF specimens from the same machine. That is all four lasers making all of some of the parts were compared to a single-laser manufacturing all of the parts. Build parameters were kept constant throughout the manufacturing process and the material used was Inconel 625 (IN625). Stress-relieving heat treatment was conducted on As-built (AB) specimens. Both AB and heat-treated (HT) specimen sets were tested for density, microstructure, tensile strength and hardness. Results indicate that the stress-relieving heat treatment increases specimen ductility without compromising other mechanical properties. SM-L-PBF has achieved a build rate of 14 cm3/h when four 200 W lasers were used to process IN625 at a layer thickness of 30 μm. An increase in the build rate of 2.74 times (build time reduction: 63%) has been demonstrated when compared to that of L-PBF, with little to no compromises in specimen mechanical properties. The observed tensile properties exceed the American Society for Testing Materials (ASTM) requirements for IN625 (by a margin of 22 to 26% in the 0.2% offset yield strength). Average specimen hardness and grain size are in the same order as that reported in literatures. The study has demonstrated that a multi-laser AM system opens up opportunities to tackle the impasse of low build rate in L-PBF in an industrial setting and that at least when operating in single mode there is no detectable degradation in the mechanical and crystallographic characteristics of the components produced.
20
Shakirov, Ivan, Pavel Kuznetsov, Mikhail Staritsyn, Anton Zhukov, and Vitaliy Bobyr. "The study of the regularities of structure formation and properties of the L-PBF metal as a set of processes on the way to create a controlled structure." MATEC Web of Conferences 315 (2020): 13001. http://dx.doi.org/10.1051/matecconf/202031513001.
Анотація:
In this work, to study the effect of laser powder bed fusion (L-PBF) parameters on the microstructure and mechanical properties of 321 austenitic steel, a series of samples were created combining various combinations of L-PBF technological modes, such as: laser spot diameter, scanning speed, laser power, scanning strategy. The possibility of controlling the structure formation of steel in the L-PBF process with the aim of obtaining a given crystallographic texture, grain size and morphology is estimated. The relationship between the resulting anisotropic structure and mechanical properties is investigated.
21
van der Walt, Jacobus, and Miranda Fateri. "Recycling PA12 powder from laser powder bed fusion through producing filament for fused deposition modelling." MATEC Web of Conferences 388 (2023): 03001. http://dx.doi.org/10.1051/matecconf/202338803001.
Анотація:
The laser-powder bed fusion (L-PBF) process presents advantages over other polymer additive manufacturing processes in terms of part strength and high production rate possible with the technology. The high cost and limited re-use of nylon powder used in the process however limit the large-scale adoption of the technology in industry. This paper investigated the re-use of PA12 powder that is no longer suitable for the L-PBF process through producing filament for the fused deposition modelling (FDM) process. Results from the study showed that parts with good mechanical strength and reasonable dimensional accuracy can be produced using FDM.
22
De Terris, Thibaut, Olivier Castelnau, Zehoua Hadjem-Hamouche, Halim Haddadi, Vincent Michel, and Patrice Peyre. "Analysis of As-Built Microstructures and Recrystallization Phenomena on Inconel 625 Alloy Obtained via Laser Powder Bed Fusion (L-PBF)." Metals 11, no. 4 (April 12, 2021): 619. http://dx.doi.org/10.3390/met11040619.
Анотація:
The microstructures induced by the laser-powder bed fusion (L-PBF) process have been widely investigated over the last decade, especially on austenitic stainless steels (AISI 316L) and nickel-based superalloys (Inconel 718, Inconel 625). However, the conditions required to initiate recrystallization of L-PBF samples at high temperatures require further investigation, especially regarding the physical origins of substructures (dislocation densities) induced by the L-PBF process. Indeed, the recrystallization widely depends on the specimen substructure, and in the case of the L-PBF process, the substructure is obtained during rapid solidification. In this paper, a comparison is presented between Inconel 625 specimens obtained with different laser-powder bed fusion (L-PBF) conditions. The effects of the energy density (VED) values on as-built and heat-under microstructures are also investigated. It is first shown that L-PBF specimens created with high-energy conditions recrystallize earlier due to a larger density of geometrically necessary dislocations. Moreover, it is shown that lower energy densities offers better tensile properties for as-built specimens. However, an appropriate heat treatment makes it possible to homogenize the tensile properties.
23
Akilan, Arulselvan Arumugham, Swapnil Kumar, Mohammad Qasim Shaikh, Ravi K. Enneti, and Sundar V. Atre. "Effects of Powder Characteristics and Chemical Composition on the Properties of 25Cr7Ni Stainless Steel Fabricated by Laser-Powder Bed Fusion and Evaluation of Process Simulation." Metals 13, no. 8 (August 16, 2023): 1476. http://dx.doi.org/10.3390/met13081476.
Анотація:
The 25Cr7Ni stainless steel alloy system is gaining increasing interest in the oil and gas industry because of its combination of high strength and corrosion resistance properties. However, very few studies on the effects of starting powder attributes and chemical composition on the as-printed properties of 25Cr7Ni stainless steel fabricated through laser-powder bed fusion (L-PBF) exist in the literature. This study examined the influence of powder attributes and chemical composition on the samples from gas atomized and water atomized 25Cr7Ni stainless steel powders, fabricated through L-PBF, on their as-printed microstructure and properties. The mechanical properties that were examined included ultimate tensile strength (UTS), elongation (%), and hardness. The corrosion behavior was also studied using linear sweep voltammetry in 3.5 wt.% NaCl solution. The evolved phases were characterized using optical and scanning electron microscopy, as well as through X-ray diffraction. The gas atomized powders, with their spherical and uniform morphology, yielded as-printed parts of higher relative densities when compared to water atomized powders, with irregular morphology due to better powder bed compaction. The higher densification obtained in the L-PBF samples from gas atomized powders translated into the highest UTS, hardness, and yield strength among the L-PBF samples from water atomized powders and wrought–annealed 25Cr7Ni stainless steel. The presence of higher amounts of N and Mn in the chemical composition of the gas atomized powders over water atomized powders promoted the presence of retained austenite in the corresponding L-PBF samples. Higher amounts of Mo, combined with austenite content, yielded a higher corrosion resistance in the L-PBF samples from the gas atomized powder than in the L-PBF samples from the water atomized powders. The latter part of the work is focused on the evaluation of simulation parameters for analyzing the fabrication procedure for the L-PBF process using Simufact software. For a given set of process parameters, Simufact provides the distortion and internal stresses developed in the printed parts as output. The present study sought to evaluate the process simulation by comparing the experimental observations in terms of the part distortion achieved in a stainless steel cube fabricated through L-PBF with Simufact process simulation obtained using the same set of process parameters.
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Mohr, Gunther, Susanna Nowakowski, Simon J. Altenburg, Christiane Maierhofer, and Kai Hilgenberg. "Experimental Determination of the Emissivity of Powder Layers and Bulk Material in Laser Powder Bed Fusion Using Infrared Thermography and Thermocouples." Metals 10, no. 11 (November 20, 2020): 1546. http://dx.doi.org/10.3390/met10111546.
Анотація:
Recording the temperature distribution of the layer under construction during laser powder bed fusion (L-PBF) is of utmost interest for a deep process understanding as well as for quality assurance and in situ monitoring means. While having a notable number of thermal monitoring approaches in additive manufacturing (AM), attempts at temperature calibration and emissivity determination are relatively rare. This study aims for the experimental temperature adjustment of an off-axis infrared (IR) thermography setup used for in situ thermal data acquisition in L-PBF processes. The temperature adjustment was conducted by means of the so-called contact method using thermocouples at two different surface conditions and two different materials: AISI 316L L-PBF bulk surface, AISI 316L powder surface, and IN718 powder surface. The apparent emissivity values for the particular setup were determined. For the first time, also corrected, closer to real emissivity values of the bulk or powder surface condition are published. In the temperature region from approximately 150 °C to 580 °C, the corrected emissivity was determined in a range from 0.2 to 0.25 for a 316L L-PBF bulk surface, in a range from 0.37 to 0.45 for 316L powder layer, and in a range from 0.37 to 0.4 for IN718 powder layer.
25
Dareh Baghi, Alireza, Shahrooz Nafisi, Heike Ebendorff-Heidepriem, and Reza Ghomashchi. "Microstructural Development of Ti-6Al-4V Alloy via Powder Metallurgy and Laser Powder Bed Fusion." Metals 12, no. 9 (August 31, 2022): 1462. http://dx.doi.org/10.3390/met12091462.
Анотація:
A detailed study was carried out to gain a better understanding of the microstructural differences between Ti-6Al-4V parts fabricated via the conventional powder metallurgy (PM) and the laser powder bed fusion (L-PBF) 3D printing routes. The parts were compared in terms of the constituent phases in the microstructure and their effects on the micro- and nano-hardness. In L-PBF parts, the microstructure has a single phase of martensitic α′ with hcp crystal structure and acicular laths morphology, transformed from prior parent phase β formed upon solidification of the melt pool. However, for the sintered parts via powder metallurgy, two phases of α and β are noticeable and the microstructure is composed of α grains and α + β Lamellae. The microhardness of L-PBF processed Ti-6Al-4V samples is remarkably higher than that of the PM samples but, surprisingly, the nano-hardness of the bulk martensitic phase α′ (6.3 GPa) is almost the same as α (i.e., 6.2 GPa) in PM samples. This confirms the rapid cooling of the β phase does not have any effect on the hardening of the bulk martensitic hcp α′. The high microhardness of L-PBF parts is due to the fine lath morphology of α′, with a large concentration of low angle boundaries of α′. Furthermore, it is revealed that for the α phase in PM samples, a higher level of vanadium concentration lowers the nano-hardness of the α phase. In addition, as expected, the compacting pressure and sintering temperature during the PM process led to variations in the porosity level as well as the microstructural morphology of the fabricated specimens, which will in turn have a significant effect on the mechanical properties.
26
Jain, Srishti, James Hyder, Mike Corliss, and Wayne NP Hung. "Electrochemical Polishing of Extruded and Laser Powder-Bed-Fused Inconel 718." International Journal of Engineering Materials and Manufacture 6, no. 4 (October 1, 2021): 284–98. http://dx.doi.org/10.26776/ijemm.06.04.2021.04.
Анотація:
ABSTRACT Electro-chemical polishing (ECP) was utilized to produce sub-micron surface finish on Inconel 718 parts manufactured by Laser Powder-Bed-Fusion (L-PBF) and extrusion methods. The L-PBF parts had very rough surfaces due to semi-welded powder particles, surface defects, and difference layer steps that were generally not found on surfaces of extruded and machined components. This study compared the results of electro-polishing of these differently manufactured parts under the same conditions. Titanium electrode was used with an acid-based electrolyte to polish both the specimens at different combinations of pulsed current density, duty cycle, and polishing time. Digital 3D optical profiler was used to assess the surface finish, while optical and scanning electron microscopy was utilized to observe the microstructure of polished specimens. At optimal condition, the ECP successfully reduced the surface of L-PBF part from 17 µm to 0.25 µm; further polishing did not improve the surface finish due to different removal rates of micro-leveled pores, cracks, nonconductive phases, and carbide particles in 3D-printed Inconel 718. The microstructure of extruded materials was uniform and free of processing defects, therefore can be polished consistently to 0.20 µm. Over-polishing of extruded material could improve its surface finish, but not for the L-PBF material due to defects and the surrounding micro-strain.
27
Ninpetch, Patiparn, Pruet Kowitwarangkul, Prasert Chalermkarnnon, Patcharapit Promoppatum, Piyapat Chuchuay, and Phadungsak Rattanadecho. "Numerical Modeling of Distortion of Ti-6Al-4V Components Manufactured Using Laser Powder Bed Fusion." Metals 12, no. 9 (September 8, 2022): 1484. http://dx.doi.org/10.3390/met12091484.
Анотація:
The laser powder bed fusion (L-PBF) process is a powder-based additive manufacturing process that can manufacture complex metallic components. However, when the metallic components are fabricated with the L-PBF process, they frequently encounter the residual stress and distortion that occurs due to the cyclic of rapid heating and cooling. The distortion detrimentally impacts the dimensional and geometrical accuracy of final built parts in the L-PBF process. The purpose of this research was to explore and predict the distortion of Ti-6Al-4V components manufactured using the L-PBF process by using numerical modeling in Simufact Additive 2020 FP1 software. Firstly, the numerical model validation was conducted with the twin-cantilever beam part. Later, studies were carried out to examine the effect of component sizes and support-structure designs on the distortion of tibial component produced by the L-PBF process. The results of this research revealed a good agreement between the numerical model and experiment data. In addition, the platform was extended to predict the distortion in the tibial component. Large distortion arose near the interface between the tibial tray and support structure due to the different stiffness between the solid bulk and support structure. The distortion of the tibial component increased with increasing component size according to the surface area of the tibial tray, and with increasing thickness of the tibial tray. Furthermore, the support-structure design plays an important role in distortion reduction in the L-PBF process. For example, the maximum distortion of the tibial component was minimized up to 44% when a block support-structure design with a height of 2.5 mm was used instead of the lattice-based support. The present study provides useful information to help the medical sector to manufacture effective medical components and reduce the chance of part failure from cracking in the L-PBF process.
28
Riipinen, Tuomas, Sini Metsä-Kortelainen, Tomi Lindroos, Janne Sami Keränen, Aino Manninen, and Jenni Pippuri-Mäkeläinen. "Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion." Rapid Prototyping Journal 25, no. 4 (May 13, 2019): 699–707. http://dx.doi.org/10.1108/rpj-06-2018-0136.
Анотація:
Purpose The purpose of this paper is to report on the developments in manufacturing soft magnetic materials using laser powder bed fusion (L-PBF). Design/methodology/approach Ternary soft magnetic Fe-49Co-2V powder was produced by gas atomization and used in an L-PBF machine to produce samples for material characterization. The L-PBF process parameters were optimized for the material, using a design of experiments approach. The printed samples were exposed to different heat treatment cycles to improve the magnetic properties. The magnetic properties were measured with quasi-static direct current and alternating current measurements at different frequencies and magnetic flux densities. The mechanical properties were characterized with tensile tests. Electrical resistivity of the material was measured. Findings The optimized L-PBF process parameters resulted in very low porosity. The magnetic properties improved greatly after the heat treatments because of changes in microstructure. Based on the quasi-static DC measurement results, one of the heat treatment cycles led to magnetic saturation, permeability and coercivity values comparable to a commercial Fe-Co-V alloy. The other heat treatments resulted in abnormal grain growth and poor magnetic performance. The AC measurement results showed that the magnetic losses were relatively high in the samples owing to formation of eddy currents. Research limitations/implications The influence of L-PBF process parameters on the microstructure was not investigated; hence, understanding the relationship between process parameters, heat treatments and magnetic properties would require more research. Originality/value The relationship between microstructure, chemical composition, heat treatments, resistivity and magnetic/mechanical properties of L-PBF processed Fe-Co-V alloy has not been reported previously.
29
Wu, Po-Kuan, Wei-Ting Lin, Jia-Wei Lin, Hong-Chuong Tran, Tsung-Yuan Kuo, Chi-Sheng Chien, Vi-Long Vo, and Ru-Li Lin. "Mechanical Properties of Titanium/Nano-Fluorapatite Parts Produced by Laser Powder Bed Fusion." Materials 16, no. 4 (February 10, 2023): 1502. http://dx.doi.org/10.3390/ma16041502.
Анотація:
Laser powder bed fusion (L-PBF) has attracted great interest in recent years due to its ability to produce intricate parts beyond the capabilities of traditional manufacturing processes. L-PBF processed biomedical implants are usually made of commercial pure titanium (CP-Ti) or its alloys. However, both alloys are naturally bio-inert, and thus reduce the formation of apatite as implants are put into the human body. Accordingly, in an attempt to improve the bioactivity of the materials used for making orthopedic implants, the present study decomposed fluorapatite material (FA, (Ca10(PO4)6F2)) into the form of nano-powder and mixed this powder with CP-Ti powder in two different ratios (99%Ti + 1%FA (Ti-1%FA) and 98%Ti + 2%FA (Ti-2%FA)) to form powder material for the L-PBF process. Experimental trials were conducted to establish the optimal processing conditions (i.e., laser power, scanning speed and hatching space) of the L-PBF process for the two powder mixtures and the original CP-Ti powder with no FA addition. The optimal parameters were then used to produce tensile test specimens in order to evaluate the mechanical properties of the different samples. The hardness of the various samples was also examined by micro-Vickers hardness tests. The tensile strength of the Ti-1%FA sample (850 MPa) was found to be far higher than that of the CP-Ti sample (513 MPa). Furthermore, the yield strength of the Ti-1%FA sample (785 MPa) was also much higher than that of the CP-Ti sample (472 MPa). However, the elongation of the Ti-1%FA sample (6.27 %) was significantly lower than that of the CP-Ti sample (16.17%). Finally, the hardness values of the Ti-1%FA and Ti-2%FA samples were around 63.8% and 109.4%, respectively, higher than that of the CP-Ti sample.
30
Han, Yicheng, Lu Wang, Ke Liu, and Wentao Yan. "Numerical modeling of laser powder bed fusion of metallic glasses: Prediction of crystallization." Journal of Micromechanics and Molecular Physics 05, no. 04 (December 2020): 2050013. http://dx.doi.org/10.1142/s2424913020500137.
Анотація:
Laser powder bed fusion (L-PBF) is promising for producing metallic glasses (MGs) for its extremely high cooling rate and ability to manufacture complex geometrical components. However, the crystallization of MGs under different L-PBF parameters is not fully investigated, which has influences on the mechanical properties. In this study, we develop a multi-physics thermal-fluid flow model for the L-PBF process of MGs, run simulation cases for single tracks, and then analyze the molten pool morphology and crystallization behavior in the center and edge of the track, as well as the heat affected zone. The simulation results are validated against the experimental results in the literature and have provided deeper insight into the crystallization phenomenon observed in the experiments.
31
Abdelwahed, Marawan, Riccardo Casati, Sven Bengtsson, Anna Larsson, Martina Riccio, and Maurizio Vedani. "Effects of Powder Atomisation on Microstructural and Mechanical Behaviour of L-PBF Processed Steels." Metals 10, no. 11 (November 5, 2020): 1474. http://dx.doi.org/10.3390/met10111474.
Анотація:
In this research, steel alloys based on the Fe-Cr-Mo, Fe-Cr-Mn and Fe-Cr-Mo-Mn-Ni systems have been designed, produced by different atomisation techniques, and processed by laser powder bed fusion (L-PBF) to investigate their microstructural and mechanical behaviour. Both gas atomisation and water atomisation were considered for powder preparation. The resulting different flowability of powders, hence a different densification behaviour during processing, could be compensated by tuning the L-PBF parameters and by the application of a post treatment to improve flowability of the water atomised powders. In agreement with thermodynamic calculations, small-size oxide-based nonmetallic inclusions of the type SiO2, MnO-SiO2, Cr2O3-SiO2 were found within the steel matrix and on the fracture surfaces of the water atomised L-PBF alloys, featuring higher amounts of oxygen than the gas-atomised steels. Analyses on microstructure and hardness of the hardenable as-built steels suggested that during laser processing, the multilayer L-PBF structure undergoes an in-situ tempering treatment. Furthermore, the mechanical properties of the L-PBF steels could be widely tuned depending on the post-thermal treatment conditions.
32
Otani, Yuki, Naoki Takata, Asuka Suzuki, Makoto Kobashi, and Masaki Kato. "Processability and Solidification Microstructure of Al-10Si-4.5Mg Alloy Fabricated by Laser Powder Bed Fusion." Key Engineering Materials 964 (November 23, 2023): 53–58. http://dx.doi.org/10.4028/p-n2qg2g.
Анотація:
With the aim of developing a high-strength aluminum alloy for laser powder bed fusion (L-PBF), an Al–10Si–4.5Mg alloy with the a-Al/Si/Mg2Si three-phase microstructure was investigated. The Al–10Si–4.5Mg alloy processed by L-PBF exhibited a fine cellular microstructure including fine granular Mg2Si phases, and therefore exhibited a higher hardness of 187 HV0.1 than those of the conventional Al–Si–Mg alloy. However, cracks were macroscopically propagated between the internal fabrication voids along the melt pool boundaries in the L-PBF processed samples, resulting in a limited relative density below 95.5%. The cracking could be attributed to the relatively coarse Mg2Si particles decorated with the eutectic network. Although the improved strength suggests the advantage of strengthening by the Mg2Si phase, further optimization of the processing conditions will be required to manufacture the intact L-PBF parts.
33
Guo, Suxia, Weiwei Zhou, Zhenxing Zhou, Yuchi Fan, Wei Luo, and Naoyuki Nomura. "In-Situ Reduction of Mo-Based Composite Particles during Laser Powder Bed Fusion." Crystals 11, no. 6 (June 18, 2021): 702. http://dx.doi.org/10.3390/cryst11060702.
Анотація:
Raw powders are processed in water during the freeze-dry pulsated orifice ejection method (FD-POEM), leading to the inclusion of oxygen impurities. This study proposes a strategy for removing the oxygen content and enhancing the mechanical performance of laser powder bed fusion (L-PBF) builds from powders using carbon nanotubes (CNTs) and H2 reduction. Spherical 1.5 wt.% CNT/Mo composite powders with uniform dispersion were fabricated via FD-POEM. The quantity of MoO2 decreased significantly, and a hexagonally structured Mo2C phase was simultaneously formed in the L-PBF build. The Mo2C with network structure was distributed along the boundaries of equiaxed Mo grains, leading to an increased Vickers hardness of the matrix. This study demonstrates the feasibility of fabricating oxygen-free and high-strength refractory parts during L-PBF for ultrahigh-temperature applications.
34
Manfredi, Diego, and Róbert Bidulský. "Laser powder bed fusion of aluminum alloys." Acta Metallurgica Slovaca 23, no. 3 (September 27, 2017): 276. http://dx.doi.org/10.12776/ams.v23i3.988.
Анотація:
<p class="AMSmaintext">The aim of this study is to analyze and to summarize the results of the processing of aluminum alloys, and in particular of the Al-Si-Mg alloys, by means of the Additive Manufacturing (AM) technique defined as Laser Powder Bed Fusion (L-PBF). This process is gaining interest worldwide thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical strength and hardness related to a very fine microstructure. L-PBF is very complex from a physical point of view, due to the extremely rapid interaction between a concentrated laser source and micrometric metallic powders. This generate very fast melting and subsequent solidification on each layer and on the previously consolidated substrate. The effects of the main process variables on the microstructure and mechanical properties of the final parts are analyzed: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power, scanning speed and scanning strategy. Furthermore, some examples of applications for the AlSi10Mg alloy are illustrated.</p>
35
Depboylu, F. N., E. Yasa, Ö. Poyraz, and F. Korkusuz. "COMMERCIALLY PURE (CP-TI) TITANIUM MEDICAL IMPLANT PRODUCTION USING LASER POWDER BED FUSION (L-PBF) TECHNOLOGY." Orthopaedic Proceedings 106-B, SUPP_2 (January 2, 2024): 32. http://dx.doi.org/10.1302/1358-992x.2024.2.032.
Анотація:
Decreasing the bulk weight without losing the biomechanical properties of commercial pure titanium (Cp-Ti) medical implants is now possible by using Laser Powder Bed Fusion (L-PBF) technology. Gyroid lattice structures that have precious mechanical and biological advantages because of similarity to trabecular bone. The aim of the study was to design and develop L-PBF process parameter optimization for manufacturing gyroid lattice Cp-Ti structures. The cleaning process was then optimized to remove the non-melted powder from the gyroid surface without mechanical loss.Gyroid cubic designs were created with various relative densities by nTopology. L-PBF process parameter optimization was progressed using with Cp-Ti (EOS TiCP Grade2) powder in the EOS M290 machine to achieve parts that have almost full dense and dimensional accuracy. The metallography method was made for density. Dimensional accuracy at gyroid wall thicknesses was investigated between designed and manufactured via stereomicroscope, also mechanical tests were applied with real time experiment and numerical analysis (ANSYS). Mass loss and strut thickness loss were investigated for chemical etching cleaning process.Gyroid parts had 99,5% density. High dimensional accuracy was achieved during L-PBF process parameters optimization. Final L-PBF parameters gave the highest 19% elongation and 427 MPa yield strength values at tensile test. Mechanical properties of gyroid were controlled with changing relative density. A minute chemical etching provided to remove non-melted powders.Compression test results of gyroids at numerical and real-time analysis gave unrelated while deformation behaviors were compatible with each other. Gyroid Cp-Ti osteosynthesis mini plates will be produced with final L-PBF process parameters. MTT cytotoxicity test will be characterized for cell viability.Acknowledgements This project is granted by TUBITAK (120N943). Feza Korkusuz MD is a member of the Turkish Academy of Sciences (TÜBA).
36
Montero, Joaquin, Sebastian Weber, Christoph Petroll, Stefan Brenner, Matthias Bleckmann, Kristin Paetzold, and Vesna Nedeljkovic-Groha. "GEOMETRICAL BENCHMARKING OF LASER POWDER BED FUSION SYSTEMS BASED ON DESIGNER NEEDS." Proceedings of the Design Society 1 (July 27, 2021): 1657–66. http://dx.doi.org/10.1017/pds.2021.427.
Анотація:
AbstractCommercially available metal Laser Powder Bed Fusion (L-PBF) systems are steadily evolving. Thus, design limitations narrow and the diversity of achievable geometries widens. This progress leads researchers to create innovative benchmarks to understand the new system capabilities. Thereby, designers can update their knowledge base in design for additive manufacturing (DfAM). To date, there are plenty of geometrical benchmarks that seek to develop generic test artefacts. Still, they are often complex to measure, and the information they deliver may not be relevant to some designers. This article proposes a geometrical benchmarking approach for metal L-PBF systems based on the designer needs. Furthermore, Geometric Dimensioning and Tolerancing (GD&T) characteristics enhance the approach. A practical use-case is presented, consisting of developing, manufacturing, and measuring a meaningful and straightforward geometric test artefact. Moreover, optical measuring systems are used to create a tailored uncertainty map for benchmarking two different L-PBF systems.
37
Kusoglu, Ihsan Murat, Carlos Doñate-Buendía, Stephan Barcikowski, and Bilal Gökce. "Laser Powder Bed Fusion of Polymers: Quantitative Research Direction Indices." Materials 14, no. 5 (March 2, 2021): 1169. http://dx.doi.org/10.3390/ma14051169.
Анотація:
Research on Laser Powder Bed Fusion (L-PBF) of polymer powder feedstocks has raised over the last decade due to the increased utilization of the fabricated parts in aerospace, automotive, electronics, and healthcare applications. A total of 600 Science Citation Indexed articles were published on the topic of L-PBF of polymer powder feedstocks in the last decade, being cited more than 10,000 times leading to an h-index of 46. This study statistically evaluates the 100 most cited articles to extract reported material, process, and as-built part properties to analyze the research trends. PA12, PEEK, and TPU are the most employed polymer powder feedstocks, while size, flowability, and thermal behavior are the standardly reported material properties. Likewise, process properties such as laser power, scanning speed, hatch spacing, powder layer thickness, volumetric energy density, and areal energy density are extracted and evaluated. In addition, material and process properties of the as-built parts such as tensile test, flexural test, and volumetric porosity contents are analyzed. The incorporation of additives is found to be an effective route to enhance mechanical and functional properties. Carbon-based additives are typically employed in applications where mechanical properties are essential. Carbon fibers, Ca-phosphates, and SiO2 are the most reported additives in the evaluated SCI-expanded articles for L-PBF of polymer powder feedstocks. A comprehensive data matrix is extracted from the evaluated SCI-index publications, and a principal component analysis (PCA) is performed to explore correlations between reported material, process, and as-built parts.
38
Nyamekye, Patricia, Anna Unt, Antti Salminen, and Heidi Piili. "Integration of Simulation Driven DfAM and LCC Analysis for Decision Making in L-PBF." Metals 10, no. 9 (September 2, 2020): 1179. http://dx.doi.org/10.3390/met10091179.
Анотація:
Laser based powder bed fusion (L-PBF) is used to manufacture parts layer by layer with the energy of laser beam. The use of L-PBF for building functional parts originates from the design freedom, flexibility, customizability, and energy efficiency of products applied in dynamic application fields such as aerospace and automotive. There are challenges and drawbacks that need to be defined and overcome before its adaptation next to rivaling traditional manufacturing methods. Factors such as high cost of L-PBF machines, metal powder, post-preprocessing, and low productivity may deter its acceptance as a mainstream manufacturing technique. Understanding the key cost drivers of L-PBF that influence productivity throughout the whole lifespan of products will facilitate the decision-making process. Functional and operational decisions can yield profitability and increase competitiveness among advanced manufacturing sectors. Identifying the relationships between the phases of the life cycle of products influences cost-effectiveness. The aim of the study is to investigate the life cycle cost (LCC) and the impact of design to it in additive manufacturing (AM) with L-PBF. The article provides a review of simulation driven design for additive manufacturing (simulation driven DfAM) and LCC for metallic L-PBF processes and examines the state of the art to outline the merits, demerits, design rules, and life cycle models of L-PBF. Practical case studies of L-PBF are discussed and analysis of the interrelating factors of the different life phases are presented. This study shows that simulation driven DfAM in the design phase increases the productivity throughout the whole production and life span of L-PBF parts. The LCC model covers the whole holistic lifecycle engineering of products and offers guidelines for decision making.
39
Polozov, Igor, Anna Gracheva, and Anatoly Popovich. "Processing, Microstructure, and Mechanical Properties of Laser Additive Manufactured Ti2AlNb-Based Alloy with Carbon, Boron, and Yttrium Microalloying." Metals 12, no. 8 (August 3, 2022): 1304. http://dx.doi.org/10.3390/met12081304.
Анотація:
In this work, Ti-22Al-23Nb-0.8Mo-0.3Si-0.4C-0.1B-0.2Y (at. %) alloy powder was used to fabricate the Ti2AlNb-based alloy samples using Laser powder bed fusion (L-PBF) Additive Manufacturing with a high-temperature substrate preheating. L-PBF process parameters, including laser power, scan speed, hatching distance, and preheating temperature, allowing for obtaining fully dense (99.9% relative density) crack-free samples, were determined. The effects of substrate preheating temperature during the L-PBF process on microstructure, phase composition, and properties of the obtained Ti2AlNb-based alloy were investigated using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction analysis, and microhardness testing. The results obtained for the material with C, B, and Y microalloying were compared to the Ti2AlNb-based alloy fabricated by L-PBF from the powder not alloyed with C, B, and Y. The results revealed that the microalloying reduced the number of solidification cracks; however, no significant microstructural changes were observed, and high-temperature substrate preheating was still necessary to suppress cold cracking of the alloy. The microstructure of the alloy varied from fully-β/B2, B2 + O, to fully-O depending on the preheating temperature. Effects of hot isostatic pressing and heat treatment conditions on microstructure and mechanical properties were investigated.
40
Liović, David, Marina Franulović, Luka Ferlič, and Nenad Gubeljak. "SURFACE ROUGHNESS OF Ti6Al4V ALLOY PRODUCED BY LASER POWDER BED FUSION." Facta Universitatis, Series: Mechanical Engineering 22, no. 1 (April 1, 2024): 063. http://dx.doi.org/10.22190/fume230719030l.
Анотація:
Controlling the surface roughness of materials manufactured by laser powder bed fusion (L-PBF) is critical for achieving functional performance of components and improving their mechanical properties. This is important for components whose surfaces cannot be post-treated using subtractive methods. In this study, the surface roughness has been investigated by applying different laser power and scanning speed combinations. Furthermore, potential effects of different locations on the build platform have been considered as well. The regression models have been developed using significant predictor variables, with their levels defined using face-centered central composite design. The analysis of variance (ANOVA) procedure has been used to evaluate the statistical significance of factors and model performances for each prediction variable. It has been found that the average surface roughness of L-PBF Ti6Al4V alloy can be described with high fitting accuracy using laser power and scanning speed as predictor variables. The position of specimens on the build platform showed no statistically significant effect on the average surface roughness. The experimental research and statistical analysis reported in this paper will contribute to a better understanding of how position, laser power, and scanning speed influence the average surface roughness of L-PBF Ti6Al4V alloy.
41
Defanti, Silvio, Camilla Cappelletti, Andrea Gatto, Emanuele Tognoli, and Fabrizio Fabbri. "Boosting Productivity of Laser Powder Bed Fusion for AlSi10Mg." Journal of Manufacturing and Materials Processing 6, no. 5 (September 30, 2022): 112. http://dx.doi.org/10.3390/jmmp6050112.
Анотація:
The Laser Powder Bed Fusion (L-PBF) process is recognized for high-end industrial applications due to its ability to produce parts with high geometric complexity. If lightweighting is one of the main strengths of L-PBF, a weakness is still the trade-off between high mechanical properties and competitive productivity. This objective can be targeted through a fine tuning of the process parameters within the manufacturing window. The paper pursues the combined optimization of part quality and process productivity for AlSi10Mg by going beyond the commonly used approach based solely on volumetric energy density. The effects of hatch distance and scan speed on the two targets were analyzed in detail. The best results were achieved by the adoption of a high scan speed and a low hatch distance, with notably different outcomes for nearly the same energy density.
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Gao, Lin, Yikai Wang, Xiao Qin, Naixin Lv, Zhiqiang Tong, Changning Sun, and Dichen Li. "Optimization of Laser Powder Bed Fusion Process for Forming Porous Ta Scaffold." Metals 13, no. 10 (October 17, 2023): 1764. http://dx.doi.org/10.3390/met13101764.
Анотація:
To improve the performance of porous tantalum (Ta) manufactured by laser powder bed fusion (L-PBF) and meet its application requirements in medicine, the authors of this paper studied the influence of L-PBF process parameters on the strut surface morphology and mechanical performance. It was found that the powder layer thickness had a significant influence on the microstructure and mechanical properties based on statistical analysis. We proposed optimal process parameters of laser power of 150 W, scanning speed of 270 mm/s, thickness of 0.05 mm, and scanning spacing of 0.07 mm. After parameter optimization, we successfully obtained Ta samples with an elastic modulus of 1.352 ± 0.007 GPa and yield strength of 53.217 ± 0.114 MPa. The results show that the elastic modulus and yield strength of porous Ta samples with a porosity of 80% under the optimal process parameters are significantly superior to previous studies. The porous Ta scaffolds with higher mechanical properties fabricated with the optimized process parameters of L-PBF have significant value for applications in medicine.
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Zouhri, W., J. Y. Dantan, B. Häfner, N. Eschner, L. Homri, G. Lanza, O. Theile, and M. Schäfer. "Optical process monitoring for Laser-Powder Bed Fusion (L-PBF)." CIRP Journal of Manufacturing Science and Technology 31 (November 2020): 607–17. http://dx.doi.org/10.1016/j.cirpj.2020.09.001.
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Tepponen, V., S. Westman, P. Nyamekye, and I. Poutiainen. "Optimized Inconel 718 pressure vessel manufactured with laser powder bed fusion." IOP Conference Series: Materials Science and Engineering 1296, no. 1 (December 1, 2023): 012019. http://dx.doi.org/10.1088/1757-899x/1296/1/012019.
Анотація:
Abstract Laser powder bed fusion (L-PBF) is one of the most novel additive manufacturing methods used for a wide range of industrial grade metallic materials. The process can produce end-use metal parts with desirable qualities and mechanical properties. L-PBF however, remains a complicated and expensive manufacturing method. Design for additive manufacturing (DfAM) is a key aspect leveraging the uptake of advantages and possibilities offered by AM in augmenting its competitiveness against conventional manufacturing (CM) methods. Inconel 718 (IN718) is a nickel-based superalloy boasting high temperature strength, good oxidation, and corrosion resistance at elevated temperatures. IN718 is commonly used for high performance applications, such as power and process industry parts, and gas turbine components. High inherent toughness, hardness, work hardening, and low thermal conductivity properties make the material difficult to manufacture through conventional machining methods. The layer-by-layer building of powder metals via L-PBF makes it possible to build different geometrical intricacy. The offered manufacturing flexibility for complex high-end metal structures for variety of applications makes L-PBF an alternative manufacturing method for high performance metals. This study investigates use of DfAM for a small-scale pressure vessel with predefined geometry, dimensions, design space and load condition. The aim is to introduce and exploit contemporary design optimization methods and their feasibility with AM. Structures, such as lattices and stress field driven geometries based on finite element analysis are investigated in this study. The designs are virtually tested under predefined pressure load of 50 bar. All four design options are manufactured on EOS M290 and IN718 powder. The result of the study shows the different optimizations decrease weight and improve material savings without compromising the linear load capacity. Optimized designs could also be made in such a way that it does not increase the manufacturing duration or add additional steps to it.
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Stornelli, Giulia, Damiano Gaggia, Marco Rallini, and Andrea Di Schino. "HEAT TREATMENT EFFECT ON MARAGING STEEL MANUFACTURED BY LASER POWDER BED FUSION TECHNOLOGY: MICROSTRUCTURE AND MECHANICAL PROPERTIES." Acta Metallurgica Slovaca 27, no. 3 (September 13, 2021): 122–26. http://dx.doi.org/10.36547/ams.27.3.973.
Анотація:
Laser Powder Bed Fusion (L-PBF) is a widespread additive manufacturing technology in industrial applications, for metal components manufacturing. Maraging steel is a special class of Fe-Ni alloys, typically used in the aerospace and tooling sectors due to their good combination of mechanical strength and toughness. This work analyses the heat treatment effect on the microstructure and hardness value of 300-grade maraging steel manufactured by the L-PBF process. The considered heat treatment consists of a solution annealing treatment followed by quenching and ageing hardening treatment. The effect of ageing temperature is reported, in a wide temperature range. Results show that solution annealing treatment fully dissolves the solidification structure caused by the L-PBF process. Moreover, the ageing hardening treatment has a significant impact on the hardness, hence on strength, of L-PBF maraging steel. The optimal ageing conditions for the L-PBF maraging steel are identified and reported: in particular, results show that the hardness of 583 HV is achieved following ageing treatment at 490 °C for 6 hours. A higher treatment temperature leads to over-ageing resulting in a decrease of hardness. Conversely, an excessive ageing time does not seem to affect the hardness value, for the ageing temperature of 490 °C.
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Konečná, Radomila, Tibor Varmus, Gianni Nicoletto, and Federico Uriati. "Microstructure and Fatigue Behavior of High-Performance Aluminum Alloy Al2024 Produced by Laser Powder Bed Fusion." Defect and Diffusion Forum 422 (March 24, 2023): 3–8. http://dx.doi.org/10.4028/p-l37k22.
Анотація:
Aluminum-based alloys are widely used in high-performance structural applications. Therefore, the opportunity to fabricate aluminum components using Laser Powder Bed Fusion (L-PBF) is a matter of great interest. In particular, the Al2024 alloy is extensively used for conventional part production but its processability by L-PBF remains a challenge because of its hot cracking sensitivity upon solidification. The new Reactive Additive Manufacturing (RAM) technology by Elementum 3D enables the production of innovative powders characterized by metal matrix and nanoceramic particles that can be processed using L-PBF. The ceramic nanoparticles of 2 % by weight improves properties and prevents Al2024-RAM2 alloy cracking during solidification. The present study investigates the fatigue performance of Al2024-RAM2 alloy manufactured by L-PBF using an SLM 280 HL equipment with a nominal layer thickness of 60 µm. A set of miniature vertical fatigue specimens were manufactured then underwent to a heat treatment T6. The specimens were tested in the as-built state (i.e., without any surface post-processing) under cyclic plane bending at a load ratio R = 0 at a frequency of 25 Hz. The fatigue performance was determined and compared to that of another Al-alloy produced by L-PBF. Specimens were examined by using optical microscopy and SEM analysis to determine the microstructure. The fracture surfaces of vertical specimens were investigated in the SEM to determine the mechanisms of crack initiation.
47
Liu, Decheng, Wen Yue, Jiajie Kang, and Chengbiao Wang. "Effect of Laser Remelting Strategy on the Forming Ability of Cemented Carbide Fabricated by Laser Powder Bed Fusion (L-PBF)." Materials 15, no. 7 (March 23, 2022): 2380. http://dx.doi.org/10.3390/ma15072380.
Анотація:
Due to the high degree of design freedom and rapid prototyping, laser powder bed fusion (L-PBF) presents a great advantage in the super-hard cemented carbide compared with conventional methods. However, optimizing processing parameters to improve the relative density and surface roughness is still a challenge for cemented carbide fabricated by L-PBF. For this, the effect of the remelting strategy on the forming quality of the L-PBF processed cemented carbide was studied in this article, aiming to explore a suitable process window. The surface quality, relative density, microstructure, and microhardness of the cemented carbide parts fabricated under a single melting and remelting strategy were compared. The results showed that the remelting strategy could efficiently improve the specimens’ surface quality and relative density. Besides, the cracks were not obviously aggravated, and the WC grains could distribute more homogeneously on the binder matrix under the remelting strategy. Therefore, the microhardness showed an improvement compared to the single melting strategy.
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Harkin, Ryan, Hao Wu, Sagar Nikam, Justin Quinn, and Shaun McFadden. "Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process." Metals 10, no. 12 (December 21, 2020): 1700. http://dx.doi.org/10.3390/met10121700.
Анотація:
Titanium alloy powder used for laser-based powder bed fusion (L-PBF) process is costly. One of the solutions is the inclusion of a powder recycling strategy, allowing unused or exposed powder particles to be recuperated post manufacture, replenished and used for future builds. However, during a L-PBF process, powder particles are exposed to high levels of concentrated energy from the laser. Particularly those in close proximity to the melt pool, leading to the formation of spatter and agglomerated particles. These particles can settle onto the powder bed, which can then influence the particle size distribution and layer uniformity. This study analysed extra-low interstitial (ELI) Ti6Al4V (Grade 23) powder when subjected to nine recycle iterations, tracking powder property variation across the successive recycling stages. Characterisation included chemical composition focusing upon O, N, and H content, particle size distribution, morphology and tapped and bulk densities. On review of the compositional analysis, the oxygen content exceeded the 0.13% limit for the ELI grade after 8 recycles, resulting in the degradation from Grade 23 level.
49
Fotovvati, Behzad, Madhusudhanan Balasubramanian, and Ebrahim Asadi. "Modeling and Optimization Approaches of Laser-Based Powder-Bed Fusion Process for Ti-6Al-4V Alloy." Coatings 10, no. 11 (November 18, 2020): 1104. http://dx.doi.org/10.3390/coatings10111104.
Анотація:
Laser-based powder-bed fusion (L-PBF) is a widely used additive manufacturing technology that contains several variables (processing parameters), which makes it challenging to correlate them with the desired properties (responses) when optimizing the responses. In this study, the influence of the five most influential L-PBF processing parameters of Ti-6Al-4V alloy—laser power, scanning speed, hatch spacing, layer thickness, and stripe width—on the relative density, microhardness, and various line and surface roughness parameters for the top, upskin, and downskin surfaces are thoroughly investigated. Two design of experiment (DoE) methods, including Taguchi L25 orthogonal arrays and fractional factorial DoE for the response surface method (RSM), are employed to account for the five L-PBF processing parameters at five levels each. The significance and contribution of the individual processing parameters on each response are analyzed using the Taguchi method. Then, the simultaneous contribution of two processing parameters on various responses is presented using RSM quadratic modeling. A multi-objective RSM model is developed to optimize the L-PBF processing parameters considering all the responses with equal weights. Furthermore, an artificial neural network (ANN) model is designed and trained based on the samples used for the Taguchi method and validated based on the samples used for the RSM. The Taguchi, RSM, and ANN models are used to predict the responses of unseen data. The results show that with the same amount of available experimental data, the proposed ANN model can most accurately predict the response of various properties of L-PBF components.
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Takase, Aya, Takuya Ishimoto, Naotaka Morita, Naoko Ikeo, and Takayoshi Nakano. "Comparison of Phase Characteristics and Residual Stresses in Ti-6Al-4V Alloy Manufactured by Laser Powder Bed Fusion (L-PBF) and Electron Beam Powder Bed Fusion (EB-PBF) Techniques." Crystals 11, no. 7 (July 8, 2021): 796. http://dx.doi.org/10.3390/cryst11070796.
Анотація:
Ti-6Al-4V alloy fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF) techniques have been studied for applications ranging from medicine to aviation. The fabrication technique is often selected based on the part size and fabrication speed, while less attention is paid to the differences in the physicochemical properties. Especially, the relationship between the evolution of α, α’, and β phases in as-grown parts and the fabrication techniques is unclear. This work systematically and quantitatively investigates how L-PBF and EB-PBF and their process parameters affect the phase evolution of Ti-6Al-4V and residual stresses in the final parts. This is the first report demonstrating the correlations among measured parameters, indicating the lattice strain reduces, and c/a increases, shifting from an α’ to α+β or α structure as the crystallite size of the α or α’ phase increases. The experimental results combined with heat-transfer simulation indicate the cooling rate near the β transus temperature dictates the resulting phase characteristics, whereas the residual stress depends on the cooling rate immediately below the solidification temperature. This study provides new insights into the previously unknown differences in the α, α’, and β phase evolution between L-PBF and EB-PBF and their process parameters.