Academic literature on the topic 'L-PBF based processing route'
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Journal articles on the topic "L-PBF based processing route"
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Obasa, Victoria Dumebi, Oludolapo Akanni Olanrewaju, Oluwashina Phillips Gbenebor, Ezenwanyi Fidelia Ochulor, Cletus Chiosa Odili, Yetunde Oyebolaji Abiodun, and Samson Oluropo Adeosun. "A Review on Lignin-Based Carbon Fibres for Carbon Footprint Reduction." Atmosphere 13, no. 10 (September 30, 2022): 1605. http://dx.doi.org/10.3390/atmos13101605.
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Carbon fibers (CFs) are made mostly from a non-environmentally friendly polyacrylonitrile (PAN) and little from rayon. PAN-based CFs, require huge amount of energy for its production aside its contributions to the global CO2 emission. Therefore, there is recourse to a more environmentally friendly sources of CFs biomass. Recently lignin has been recognized as a potential renewable raw material for carbon fibers to replace PAN-based. The magnitude and quality of CO2 emission of lignin-based CFs are dependent on the processing route. On this premise; this review examines the various lignin-based CFs processing route adopted by researcher in the recent past to establish the most viable route with minimum carbon footprint emission. Outcome of the review shows that the major advantages of aromatic polymer (AP) generated precursor over PAN is the presence of higher quantity of guaiacyl units and oxygen content which makes the stabilization phase efficient and faster requiring less energy. Though there are several methods and options for the various stages of conversion of lignocellulosic biomass into CFs as highlighted in the study, establishing an optimum processing route will be a trade-off amongst various issues of concern; carcinogenic risk, carbon footprint emission, CFs Yield and mechanical strength of the CFs. Inferences from the study shows that the L-CF significantly produced reduced climatic impact in terms of CO2 emission.
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Naffakh, Mohammed. "Biopolymer Nanocomposite Materials Based on Poly(L-lactic Acid) and Inorganic Fullerene-like WS2 Nanoparticles." Polymers 13, no. 17 (August 31, 2021): 2947. http://dx.doi.org/10.3390/polym13172947.
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In the current study, inorganic fullerene (IF)-like tungsten disulphide (WS2) nanoparticles from layered transition metal dichalcogenides (TMDCs) were introduced into a poly(L-lactic acid) (PLLA) polymer matrix to generate novel bionanocomposite materials through an advantageous melt-processing route. The effectiveness of employing IF-WS2 on the morphology and property enhancement of the resulting hybrid nanocomposites was evaluated. The non-isothermal melt–crystallization and melting measurements revealed that the crystallization and melting temperature as well as the crystallinity of PLLA were controlled by the cooling rate and composition. The crystallization behaviour and kinetics were examined by using the Lui model. Moreover, the nucleating effect of IF-WS2 was investigated in terms of Gutzow and Dobreva approaches. It was discovered that the incorporation of increasing IF-WS2 contents led to a progressive acceleration of the crystallization rate of PLLA. The morphology and kinetic data demonstrate the high performance of these novel nanocomposites for industrial applications.
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Kaushal, Sarbjeet, Dilkaran Singh, Dheeraj Gupta, and Vivek Jain. "Processing of Ni–WC–Cr3C2-based metal matrix composite cladding on SS-316L substrate through microwave irradiation." Journal of Composite Materials 53, no. 8 (August 19, 2018): 1023–32. http://dx.doi.org/10.1177/0021998318794846.
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The present paper reports on the development of metal matrix composite clads of Ni–WC–Cr3C2-based materials through microwave heating route. In this study, metal matrix composite clads were deposited on austenitic stainless steel (SS-316 L) inside a multimode-type domestic microwave oven. Experiment trials were carried out at a microwave power of 900 W and frequency of 2.45 GHz. The optimal exposure time for processing of metal matrix composite clads was varied from 60 to 360 s. The microstructural analysis of processed clads revealed that the metal matrix composite clads of approximately 0.85 mm thickness were free from any type of voids and cracks. The WC and Cr3C2 particles were dispersed inside the Ni matrix. The phase analysis results revealed the formation of Cr7Ni3, NiC, Fe6W6C, Co3W3C4, FeNi3, NiW phases inside the clad layer. The formation of hard carbide phases resulted in higher microhardness of the clad layer. The average value of Vicker’s microhardness was observed to be 503 ± 34 HV, which is almost 1.6 times that of the substrate.
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Varvara, Simona, Sorin-Aurel Dorneanu, Alexandru Okos, Liana Maria Muresan, Roxana Bostan, Maria Popa, Daniel Marconi, and Petru Ilea. "Dissolution of Metals in Different Bromide-Based Systems: Electrochemical Measurements and Spectroscopic Investigations." Materials 13, no. 16 (August 17, 2020): 3630. http://dx.doi.org/10.3390/ma13163630.
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The dissolution of the main metals (Cu, Zn, Sn, Pb and Fe) found in waste printed circuit boards (WPCBs) was investigated by electrochemical corrosion measurements (potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)) in different bromide-based systems that could be used as lixiviants in hydrometallurgical route of metals recovery. The analysis of the corrosion products was carried out by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. All measurements showed that the addition of bromine in the electrolyte favors to great extents the dissolution process of all studied metals as compared to bromine-free electrolytes. In the investigated experimental conditions, the highest dissolution rates of the metals were obtained in acidic KBr solution containing 0.01 mol/L bromine and they decreased in the following order: Zn >> Sn > Pb > Fe > Cu. The XRD and XPS chemical assessment allowed the identification of the dissolution products formed on the metallic surfaces after exposure to the electrolytes. They consisted mainly of oxides in the case of Cu, Zn, Sn and Fe, while the presence of PbBr2 was also noticed on the lead surface. Based on the results of EIS and surface investigations, several models explaining the corrosion behavior of the metals were proposed and discussed. The obtained results demonstrate that all studied metals could be successfully leached using brominated solutions, providing a viable alternative for the selective and efficient recovery of the base metals from WPCBs through a multi-step hydrometallurgical processing route.
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Naffakh, Mohammed. "Nanocomposite Materials Based on TMDCs WS2 Modified Poly(l-Lactic Acid)/Poly(Vinylidene Fluoride) Polymer Blends." Polymers 13, no. 13 (June 30, 2021): 2179. http://dx.doi.org/10.3390/polym13132179.
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Novel multifunctional biopolymer blend nanocomposites composed of poly(vinylidene fluoride)(PVDF) and tungsten disulfide nanotubes (INT-WS2) that are layered transition metal dichalcogenides (TMDCs) were easily prepared by applying an economical, scalable, and versatile melt processing route. Furthermore, their synergistic effect to enhance the properties of poly(L-lactic acid) (PLLA) matrix was investigated. From morphological analysis, it was shown that the incorporation of 1D (INT)-WS2 into the immiscible PLLA/PVDF mixtures (weight ratios: 80/20, 60/40, 40/60, and 20/80) led to an improvement in the dispersibility of the PVDF phase, a reduction in its average domain size, and consequently a larger interfacial area. In addition, the nanoparticles INT-WS2 can act as effective nucleating agents and reinforcing fillers in PLLA/PVDF blends, and as such, greatly improve their thermal and dynamic-mechanical properties. The improvements are more pronounced in the ternary blend nanocomposites with the lowest PVDF content, likely due to a synergistic effect of both highly crystalline PVDF and 1D-TMDCs nano-additives on the matrix performance. Considering the promising properties of the developed materials, the inexpensive synthetic process, and the extraordinary properties of environmentally friendly and biocompatibe 1D-TMDCs WS2, this work may open up opportunities to produce new PLLA/PVDF hybrid nanocomposites that show great potential for biomedical applications.
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Nagy, Ildikó, and János Tamás. "Optimization of Density of Sugar Beet (Beta vulgaris L.) Production Quotas by Pointwise Geostatistic Methods." Acta Agraria Debreceniensis, no. 18 (March 4, 2005): 46–50. http://dx.doi.org/10.34101/actaagrar/18/3246.
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The regional distribution of the Hungarian sugar beet production quotas was developed by the conventional concurrency relationships. In our research we analyzed 320 sectors of 9 factories with geostatistic methods in a GIS environment. The applied researches of spatial mean, spatial deviation, deviational ellipse have been introduced by us in this speciality. We used two different methods in our optimization inquiries, where the spatial segment of the standard deviational ellipse was based on a more robust preliminary data processing solution, and this is why it is a less parametricable method. The inquiry of the spatial buffer zones in production sectors ensures an obvious optimization possibility. We considered the supply route distances in both cases as a modeling boundary condition. Our results show that we introduced an effective decision making method to the occurent replanning of the production sectors with the pointwise density inquiries and the geometric analogy that was fitted to it.
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Ghosh, S., Júlio C. Viana, Rui L. Reis, and João F. Mano. "Osteochondral Tissue Engineering Constructs with a Cartilage Part Made of Poly(L-lactic Acid) / Starch Blend and a Bioactive Poly(L-Lactic Acid) Composite Layer for Subchondral Bone." Key Engineering Materials 309-311 (May 2006): 1109–12. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.1109.
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Articular cartilage has an inadequate natural rebuilding capacity. Tissue engineering has shown to have potential to provide an effective alternative to engineer the damaged cartilage. In this study, an integrated porous bi-layered scaffold was developed aiming to mimic the requirements of cartilage and underlying subchondral bone. The osteochondral approach explored in this work was to include a common polymeric component in both cartilage and bone components, which maximised the integration at the interface by mean of a melt-based processing route. A blend of starch and poly(Llactic acid),PLLA, was used in the cartilage side, which was found to possess an adequate water uptake capability. For the bone region, to induce bioactivity, PLLA had been reinforced with hydroxyapatite (HA) and bioactive glass (BG). The surfaces of the constructs were investigated as a function of soaking time in a simulated body (SBF) fluid using scanning electron microscopy (SEM) and FTIR. The SEM – FTIR indicated a bone-like apatite formation and the surface coverage by apatite layer increased with increasing soaking time, whereas the cartilage-layer did not exhibit the formation of any apatite like layer.
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Yongvanich, Niti, Bovornrat Emtip, Boonyarit Hengprayoon, and Ekkapot Jankat. "Synthesis of Spinel Color Pigments from Aluminum Dross Waste." Key Engineering Materials 766 (April 2018): 282–87. http://dx.doi.org/10.4028/www.scientific.net/kem.766.282.
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Spinel-based ceramic color pigments were successfully synthesized from utilization of aluminum dross waste and relevant oxide precursors by solid-state processing. Cobalt ions were selected as a chromophore to produce blue pigments. The conventional oxide route was also carried out for comparison purposes. The spinel phase readily formed when fired at 1100 °C; longer duration yielded a higher degree of purity. No preferential orientation of XRD reflection was observed, indicating random crystallographic arrangement. Phase formation was also confirmed by Fourier Transformed Infrared Spectroscopy (FTIR) which displayed both Co-O tetrahedral and Al-O octahedral which are the main framework for a spinel crystal. Slightly sharper FTIR peaks for the dross route compared to those from the oxide route suggest a difference in crystallinity between the two with different precursors. The particle size distribution was relatively wide (5 – 30 micron), possibly due to a crude nature of the dross precursor. The UV-vis spectra showed absorption in the range of 450-550 nm which is associated with the blue color caused by a shift of the 3d7 electrons of Co2+. The obtained dross-route pigments possessed both a and b color parameters (a = -2.3 to-2.6; b = -3.4 to-4.0) in the negative territory, implying greenness and blueness respectively. The L values were in the 20-30 range. When incorporating into practical glazes, the b parameters unexpectedly became more negative, indicating an even deeper blue tone. This result suggested a high potential for utilization of this dross waste as an alternative precursor source for sustainable production of spinel ceramic pigments.
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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.
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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.
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Takushima, Shigeru, Nobuhiro Shinohara, Daiji Morita, Hiroyuki Kawano, Yasuhiro Mizutani, and Yasuhiro Takaya. "In-Process Height Displacement Measurement Using Crossed Line Beams for Process Control of Laser Wire Deposition." International Journal of Automation Technology 15, no. 5 (September 5, 2021): 715–27. http://dx.doi.org/10.20965/ijat.2021.p0715.
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We propose the use of the line section method with crossed line beams for the process control of laser wire deposition. This method could be used to measure the height displacement in front of a laser spot when the processing direction changes. In laser processing, especially laser deposition of metal additive manufacturing, the laser process control technique that controls the processing parameters based on the measured height displacement in front of a laser processing spot is indispensable for high-accuracy processing. However, it was impossible to measure the height displacement in front of a processing laser spot in a processing route in which the processing direction changes as the measurement direction of the conventional light-section method comprising the use of a straight-line beam is restricted although the configuration is simple. In this paper, we present an in-process height displacement measurement system of the light-section method using two crossed line beams. This method could be used to measure the height displacement in a ±90° direction by projecting two crossed line beams from the side of a laser processing head with a simple configuration comprising the addition of one line laser to the conventional light-section method. The height displacement can be calculated from the projected position shift of the line beams irrespective of the measurement direction by changing the longitudinal position on the crossed line beams according to the measurement direction. In addition, the configuration of our proposed system is compact because the imaging system is integrated into the processing head. We could measure the height displacement at 2.8–4 mm in front of a laser processing spot according to the measurement direction by reducing the influence of intense thermal radiation. Moreover, we experimentally evaluated the height displacement measurement accuracy for various measurement directions. Finally, we evaluated continuous deposition in an “L” shape wherein the deposition direction was changed while using a laser wire direct energy deposition machine for the laser process control based on the in-process height displacement measurement result. We achieved highly accurate continuous deposition at the position wherein the processing direction changes despite the acceleration and deceleration of the stage by laser process control.
Book chapters on the topic "L-PBF based processing route"
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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.
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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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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.
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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.
Conference papers on the topic "L-PBF based processing route"
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Beamer, Chad, Derek Denlinger, Suraj Rao, and Christina Dinh. "High Pressure Heat Treatment for L-PBF Hastelloy X." In HT2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.ht2021p0044.
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Abstract Hastelloy X is used in turbomachinery and petrochemical applications as it is designed for excellent oxidation and stress corrosion cracking resistance, strength, and stress rupture behavior. This alloy is now being printed via powder bed fusion processes as many industries have developed interests in the benefits additive manufacturing (AM) offers. However asprinted Hastelloy X suffers from material defect formation such as hot cracking. Hot isostatic pressing (HIP) is often applied to improve performance and reliability. Although the conventional HIP process has been shown to eliminate defects, the equipment is unable to cool at desired rates allowing the formation of excessive carbide precipitation, negatively influencing corrosion resistance and toughness. In turn the product is solution treated at a similar temperature while applying rapid gas cooling for performance requirements. With use of Uniform Rapid Cooling® available in modern HIP equipment, a high-pressure heat treatment can be applied offering the ability to perform both HIP and heat treatment in one piece of equipment. Microstructure and tensile properties are evaluated and compared to the conventional processing routes. The results demonstrate that the novel high pressure heat treatment approach offers a processing route that is equivalent to or better than conventional methods.
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Aminzadeh, Masoumeh, and Thomas Kurfess. "Vision-Based Inspection System for Dimensional Accuracy in Powder-Bed Additive Manufacturing." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8674.
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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 dimensional precision and accuracy. The efficiency of powder fusion process in powder-bed AM processes is highly affected by process errors, powder irregularities as well as geometric factors. Formation of defects such as lack of fusion and over-fusion due to the aforementioned factors causes dimensional errors that significantly damage the precision. This paper addresses the development of an automated in-situ inspection system for powder-bed additive manufacturing processes based on machine vision. The results of the in-situ automated inspection of dimensional accuracy allows for early identification of faulty parts or alternatively in-situ correction of geometric errors by taking appropriate corrective actions. In this inspection system, 2D optical images captured from each layer of the AM part during the build are analyzed and the geometric errors and defects impairing the dimensional accuracy are detected in each layer. To successfully detect geometric errors, fused geometric objects must be detected in the powder layer. Image processing algorithms are effectively designed to detect the geometric objects from images of low contrast captured during the build inside the chamber. The developed algorithms are implemented to a large number of test images and their performance and precision are evaluated quantitatively. The failure probabilities for the algorithms are also determined statistically.
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Krentz, Tim, Paul Korinko, and Anthony McWilliams. "Fracture and Tensile Characterization of Additively Manufactured Type 300 Series Stainless Steel in the Baseline and Hydrogen Charged Conditions." In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84723.
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Abstract Savannah River National Laboratory (SRNL) has characterized powder bed fusion processed Type 304L stainless steel for use as hydrogen storage and process vessels. As part of this characterization, a simple cylinder (C-cylinder) and a “D-cylinder” were fabricated using two different Laser Powder Bed Fusion (L-PBF) machines at two different sites. These four sample cylinders were electrical discharge machined (EDM) into cylindrical blanks and rectangular blanks and subsequently finished machined into tensile samples and single edge notched three-point bend fracture toughness samples, respectively. The microstructures of the cylinders were optically characterized parallel to the build direction and perpendicular to the build direction at three elevations. Samples were hydrogen charged using conditions to generate approximately 70 wppm (3700 appm) hydrogen. The sub-sized cylindrical tensile samples and fracture toughness samples were non-destructively characterized using computed tomography with a voxel size of nominally 80 microns. Metallographic analysis and CT indicated the samples are virtually pore free and exhibit the expected microstructure of L-PBF processing. The mechanical test samples were tested in the baseline and hydrogen charged conditions to determine the tensile and fracture toughness behavior; based on previous results, the baseline tensile and fracture properties are comparable to wrought material and the hydrogen properties exhibit similar characteristics to wrought materials.
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Kemerling, Brandon, and Daniel Ryan. "Development of Production Eddy Current Inspection Process for Additively Manufactured Industrial Gas Turbine Engine Components." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90971.
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Abstract While metal additive manufacturing (AM) promises substantial efficiency gains to the gas turbine manufacturing sector, uncertainty about the quality of parts produced via AM has been a significant hindrance to widespread implementation. Although high fidelity inspection techniques involving computed tomography (CT) and destructive testing have been effective for low volume development activities, new quality assurance solutions are needed that enable rapid, low-cost inspection of serial production AM components. Solar Turbines Incorporated is actively engaged in the development of inspection processes for high production volume AM part acceptance capability of combustion and turbine hot section components. Eddy current inspection (ECI) was identified as a potential non-destructive evaluation (NDE) solution. Based on the principles of electromagnetism, ECI has been successful on conventional materials for surface and near-surface crack detection. However, limited industry data is available regarding the effectiveness of ECI on AM material. The nature of AM-induced discontinuities, specifically for metal laser powder bed fusion (L-PBF) processing, demands high measurement resolution to detect fine features such as bulk porosity, lack of fusion and interlayer discontinuities. Development activities were thus executed to determine the suitability of ECI for detection of AM discontinuities. NDE training sets were printed with intentional variations in key L-PBF processing parameters to simulate the conditions which produce relevant AM material discontinuities. The training sets were then evaluated with a custom ECI system to determine the inspection capability and sensitivity. Inspections were conducted as a function of multiple input frequencies to determine the optimal tradeoff between measurement resolution and depth of penetration. Additional characterization of the training sets was conducted via metallographic analysis to establish correlations between the ECI results and AM material quality. An optimized multi-frequency inspection setting was identified to provide suitable measurement resolution for near surface AM material inspection. Correlations developed between ECI scan data and materials characterization results have enabled the ability to rapidly discriminate between varying discontinuity levels in AM components. Based on these efforts, ECI is considered a suitable inspection technique for materials produced via the L-PBF AM process.
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Totmina, E. V. "Detoxification of Russian texts based on combination of controlled generation using pretrained ruGPT3 and the Delete method." In Dialogue. RSUH, 2022. http://dx.doi.org/10.28995/2075-7182-2022-21-1158-1165.
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This article describes our solution for the RUSSE Detoxification 2022 text automatic detoxification competition held as part of the Dialogue 2022 conference. Our approach consisted in filtering the p rovided training data set, fine-tuning the pretrained ruGPT3 model and selecting examples of detoxified (neutral) sentences generated with its help based on their cosine proximity and ROUGE-L to the input toxic sentence for their subsequent processing using the ruPrompts library for ruGPT-3. The final stage of processing the generated neutral comments was carried out using the Delete method - an uncontrolled detoxification model based on rules, which deleted all the remaining coarse and absentee words stored in the dictionary provided by the organizers. At the Human Evaluation stage, the system received a chrF metric value of 0.455; at the Automatic Evaluation stage - 0.505, and took eighth place at Manual Evaluation. We conducted a review and analysis of examples of detoxified sentences obtained using our model. The analysis showed that some of the generated neutral sentences in most cases lose the meaning of the original toxic sentence, and also retain either a full negative connotation or a partial one.
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Rahman, M. Shafiqur, Jonathan Ciaccio, and Uttam K. Chakravarty. "A Machine Learning Approach for Predicting Melt-Pool Dynamics of Ti-6Al-4V Alloy in the Laser Powder-Bed Fusion Process." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-71348.
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Abstract This paper presents a supervised machine learning (ML) model to predict the melt-pool geometries of Ti-6Al-4V alloy in the laser powder-bed fusion (L-PBF) process. The ML model is developed based on the normalized values of the five key features (i.e., the laser and material parameters) — laser power, scanning speed, spot size, powder layer thickness, and powder porosity. The two target variables are the melt-pool width and depth, which define the melt-pool geometry and strongly correlate the geometry with the melt-pool dynamics. Information about the features and the corresponding target variables are compiled from an extensive literature survey. A trained data set is created with the melt-pool evolution data collected from experiments. The data set is divided into training and testing sets before any feature engineering, visualization, and analysis, to prevent any data leakage. The k-fold cross-validation technique is applied to minimize the error and find the best performance. Multiple regression methods are trained and tested to find the best model to predict the melt-pool geometry data. Extra trees regressor is found to be the model with the least amount of error using the mean absolute error function. The verification of the ML model is performed by comparing its results with the experimental and CFD modeling results for the melt-pool geometry at a given combination of the processing parameters in the L-PBF process. The melt-pool geometry outputs obtained for the ML model are consistent with the experimental and CFD modeling results.
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Denlinger, Derek. "On the Benefits of High-Pressure Heat Treatment Additively Manufactured CoCr." In HT2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.ht2021p0030.
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Abstract Laser Powder Bed Fusion (L-PBF) processes are becoming more viable in place of traditional castings in a variety of industries. To compete, novel material grades are being considered with additive manufacturing (AM). In maximizing performance and manufacturing efficiency through AM, a novel approach to heat treatment and Hot Isostatic Pressing (HIP) processing needs to be considered. It has been shown that combining key heat treatment processes with (HIP) by utilizing fast cooling rates can benefit static properties as well as improve turn-around time for HIP processing [1,2]. Argon pressures up to 207 MPa with cooling rates above 170°C per minute are now available in production sized HIP systems to design ideal HIP cycles for high pressure heat treatment. Additive manufacturing with high pressure heat treatment is in need of further investigation for establishing new qualification standards. This study investigates designed High-Pressure Heat Treatment cycles to consider mechanical performance on LPBF CoCr. The combined cycles investigate possible alternatives to historically accepted two step HIP then heat treat processing by combining densification with homogenization treatment into one step. Tensile, fatigue, hardness, microstructure and Charpy impact performance are explored to seek optimal properties and with streamlined thermal processing. It was found that all trial conditions exceeded Electron Beam Melted (EBM) AM CoCr expectation, but traditional processing provided a slight advantage in ultimate tensile stress. One of the novel processes explored, “common” was found to provide a slight improvement on yield stress and direct hardness. Published fatigue data is rare for CoCr, however data generated from this study showed a slight advantage to the “common” HPHT process primarily for lower applied stress levels. Microstructures were comparable across all trial processes. It is recommended that each novel processing route be considered as viable alternatives to traditional processing, but that the “common” processing may prove advantageous for both mechanical properties and streamlined manufacturing.
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Mirkoohi, Elham, Hong-Chuong Tran, Yu-Lung Lo, You-Cheng Chang, Hung-You Lin, and Steven Y. Liang. "Effect of Powder Layer Thickness on Residual Stress in Laser Powder Bed Fusion of IN718." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85391.
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Abstract Understanding the relationships between the processing factors in laser powder bed fusion (L-PBF) and residual stress formation is critical for improving the final part performance since tensile residual stress has a critical impact on fatigue life performance and final material properties of the manufactured part. Laser powder bed fusion has virtually infinite number of processing factors each can impact the residual stress, among which, layer thickness is one of them. This paper investigates the impact of powder layer thickness on residual stress formation for the Ni-based super-alloy Inconel 718 (IN718). Test coupons with different layer thicknesses are fabricated with the same geometry. Residual stress is determined via X-ray diffraction (XRD) at different locations along the build direction and transverse direction. In addition, the previously developed physics-based analytical model is used to draw a relationship between powder layer thickness and residual stress through the prediction of temperature field and thermal stress using incremental plasticity. The results of computational modeling and experiments are in good agreement and shows that the increase in powder layer thickness increases the residual stress in an additively manufactured part.
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Gong, Xi, and Guha Manogharan. "Machining Behavior and Material Properties in Additive Manufacturing Ti-6Al-4V Parts." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8487.
Full textAbstract:
Abstract Although Additive Manufacturing (AM) has unique advantages in processing complex part designs using superalloys, metal AM parts currently do not meet the part tolerance and surface finish requirements for most mechanical applications. Hence, there is a growing need for integrated metal hybrid manufacturing through both “in-envelope” and “sequential” additive-subtractive manufacturing. Since AM parts are inherently different from traditionally manufactured parts (e.g., anisotropy, residual stress), there is a critical gap in the literature to correlate as-built AM material properties, material characterization, machining parameters with resulting machining behavior such as cutting force and specific cutting energy. This study reports on the machining behavior of Electron Beam Melting (EBM) and Laser Powder Bed Fusion (L-PBF) processed Ti-6Al-4V parts with highly textured microstructure due to build orientation, and heat treatment across different machining conditions. It was found that specific cutting energy of AM parts changes up to 21.6% based on AM processing, cessed parts, build orientation, and heat treatment conditions. The finding from this study can be used to predict machining behavior based on material characterization. In the future, this study will lead to creating a correlation model on AM parts microstructure and correlated machining behavior, surface finish, and tool wear behavior.