Journal articles on the topic 'Additively manufactured (AM) steel'
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1
Balan, Arunachalam S. S., Kannan Chidambaram, Arun V. Kumar, Hariharan Krishnaswamy, Danil Yurievich Pimenov, Khaled Giasin, and Krzysztof Nadolny. "Effect of Cryogenic Grinding on Fatigue Life of Additively Manufactured Maraging Steel." Materials 14, no. 5 (March 5, 2021): 1245. http://dx.doi.org/10.3390/ma14051245.
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Additive manufacturing (AM) is replacing conventional manufacturing techniques due to its ability to manufacture complex structures with near-net shape and reduced material wastage. However, the poor surface integrity of the AM parts deteriorates the service life of the components. The AM parts should be subjected to post-processing treatment for improving surface integrity and fatigue life. In this research, maraging steel is printed using direct metal laser sintering (DMLS) process and the influence of grinding on the fatigue life of this additively manufactured material was investigated. For this purpose, the grinding experiments were performed under two different grinding environments such as dry and cryogenic conditions using a cubic boron nitride (CBN) grinding wheel. The results revealed that surface roughness could be reduced by about 87% under cryogenic condition over dry grinding. The fatigue tests carried out on the additive manufactured materials exposed a substantial increase of about 170% in their fatigue life when subjected to cryogenic grinding.
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Avanzini, Andrea. "Fatigue Behavior of Additively Manufactured Stainless Steel 316L." Materials 16, no. 1 (December 21, 2022): 65. http://dx.doi.org/10.3390/ma16010065.
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316L stainless steel is the material of choice for several critical applications in which a combination of mechanical strength and resistance to corrosion is required, as in the biomedical field. Additive Manufacturing (AM) technologies can pave the way to new design solutions, but microstructure, defect types, and surface characteristics are substantially different in comparison to traditional processing routes, making the assessment of the long-term durability of AM materials and components a crucial aspect. In this paper a thorough review is presented of the relatively large body of recent literature devoted to investigations on fatigue of AM 316L, focusing on the comparison between different AM technologies and conventional processes and on the influence of processing and post-processing aspects in terms of fatigue strength and lifetime. Overall fatigue data are quite scattered, but the dependency of fatigue performances on surface finish, building orientation, and type of heat treatment can be clearly appreciated, as well as the influence of different printing processes. A critical discussion on the different testing approaches presented in the literature is also provided, highlighting the need for shared experimental test protocols and data presentation in order to better understand the complex correlations between fatigue behavior and processing parameters.
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Kučerová, Ludmila, Andrea Jandová, and Ivana Zetková. "Comparison of Microstructure and Mechanical Properties of Additively Manufactured and Conventional Maraging Steel." Defect and Diffusion Forum 405 (November 2020): 133–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.405.133.
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Maraging steel is an iron-nickel steel alloy, which achieves very good material properties like high toughness, hardness, good weldability, high strength and dimensional stability during heat treatment. In this work, maraging steel 18Ni-300 was manufactured by selective laser melting. It is a method of additive manufacturing (AM) technology, which produces prototypes and functional parts. Sample of additively manufactured and conventional steel with the same chemical composition were tested after in three different states – heat treated (as-built/as-received), solution annealed and precipitation hardened. Resulting microstructures were analysed by light and scanning electron microscopy and mechanical properties were obtained by hardness measurement and tensile test. Cellular martensitic microstructures were observed in additively manufactured samples and conventional maraging steel consisted of lath martensitic microstructures. Very similar mechanical properties were obtained for both steels after the application of the same heat treatment. Ultimate tensile strengths reached 839 – 900 MPa for samples without heat treatment and heat treated by solution annealing, the samples after precipitation hardening had tensile strengths of 1577 – 1711 MPa.
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Thomas, Sarah A., Michelle C. Hawkins, Robert S. Hixson, Ramon M. Martinez, George T. Gray Gray, Darby J. Luscher, and Saryu J. Fensin. "Shock Hugoniot of Forged and Additively Manufactured 304L Stainless Steel." Metals 12, no. 10 (October 2, 2022): 1661. http://dx.doi.org/10.3390/met12101661.
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The purpose of this research was to measure the equation of state for additively manufactured (AM) and forged 304L stainless steel using a novel experimental technique. An understanding of the dynamic behavior of AM metals is integral to their timely adoption into various applications. The Hugoniot of the AM 304L was compared to that of the forged 304L at particle velocities where the material retains a two-wave structure. This comparison enabled us to determine the sensitivity of the equation of state to microstructure as varied due to processing. Our results showed that there was a measurable difference in the measured shock velocity between the AM and forged 304L. The shock wave velocities for the AM 304L were found to be ~3% slower than those for the forged 304L at similar particle velocities. To understand these differences, properties such as densities, sound speeds, and texture were measured and compared between the forged and AM materials. Our results showed that no measurable difference was found in these properties. Additionally, it is possible that differing elastic wave amplitudes may influence shock velocity
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Iliopoulos, Athanasios P., Rhys Jones, John G. Michopoulos, Nam Phan, and Calvin Rans. "Further Studies into Crack Growth in Additively Manufactured Materials." Materials 13, no. 10 (May 12, 2020): 2223. http://dx.doi.org/10.3390/ma13102223.
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Understanding and characterizing crack growth is central to meeting the damage tolerance and durability requirements delineated in USAF Structures Bulletin EZ-SB-19-01 for the utilization of additive manufacturing (AM) in the sustainment of aging aircraft. In this context, the present paper discusses the effect of different AM processes, different build directions, and the variability in the crack growth rates related to AM Ti-6Al-4V, AM Inconel 625, and AM 17-4 PH stainless steel. This study reveals that crack growth in these three AM materials can be captured using the Hartman–Schijve crack growth equation and that the variability in the various da/dN versus ΔK curves can be modeled by allowing the terms ΔKthr and A to vary. It is also shown that for the AM Ti-6AL-4V processes considered, the variability in the cyclic fracture toughness appears to be greatest for specimens manufactured using selective layer melting (SLM).
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Silva, Tiago, Afonso Gregório, Filipe Silva, José Xavier, Ana Reis, Pedro Rosa, and Abílio de Jesus. "Numerical-Experimental Plastic-Damage Characterisation of Additively Manufactured 18Ni300 Maraging Steel by Means of Multiaxial Double-Notched Specimens." Journal of Manufacturing and Materials Processing 5, no. 3 (August 2, 2021): 84. http://dx.doi.org/10.3390/jmmp5030084.
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Additive manufacturing (AM) has become a viable option for producing structural parts with a high degree of geometrical complexity. Despite such trend, accurate material properties, under diversified testing conditions, are scarce or practically non-existent for the most recent additively manufactured (AMed) materials. Such data gap may compromise component performance design, through numerical simulation, especially enhanced by topological optimisation of AMed components. This study aimed at a comprehensive characterisation of laser powder bed fusion as-built 18Ni300 maraging steel and its systematic comparison to the conventional counterpart. Multiaxial double-notched specimens demonstrated a successful depiction of both plastic and damage behaviour under different stress states. Tensile specimens with distinct notch configurations were also used for high stress triaxiality range characterisation. This study demonstrates that the multiaxial double-notched specimens constitute a viable option towards the inverse plastic behaviour calibration of high-strength additively manufactured steels in distinct state of stress conditions. AMed maraging steel exhibited higher strength and lower ductility than the conventional material.
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Iliopoulos, Athanasios, Rhys Jones, John Michopoulos, Nam Phan, and R. Singh Raman. "Crack Growth in a Range of Additively Manufactured Aerospace Structural Materials." Aerospace 5, no. 4 (November 9, 2018): 118. http://dx.doi.org/10.3390/aerospace5040118.
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The aerospace industry is now beginning to adopt Additive Manufacturing (AM), both for new aircraft design and to help improve aircraft availability (aircraft sustainment). However, MIL-STD 1530 highlights that to certify airworthiness, the operational life of the airframe must be determined by a damage tolerance analysis. MIL-STD 1530 also states that in this process, the role of testing is merely to validate or correct the analysis. Consequently, if AM-produced parts are to be used as load-carrying members, it is important that the d a / d N versus ΔK curves be determined and, if possible, a valid mathematical representation determined. The present paper demonstrates that for AM Ti-6Al-4V, AM 316L stainless steel, and AM AerMet 100 steel, the d a / d N versus ΔK curves can be represented reasonably well by the Hartman-Schijve variant of the NASGRO crack growth equation. It is also shown that the variability in the various AM d a / d N versus Δ K curves is captured reasonably well by using the curve determined for conventionally manufactured materials and allowing for changes in the threshold and the cyclic fracture toughness terms.
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Williams, Colin L., Parisa Shokouhi, Matthew H. Lear, Carly Donahue, and Colt J. Montgomery. "Ultrasonic methods for the characterization of additively manufactured 316L stainless steel." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A94. http://dx.doi.org/10.1121/10.0015658.
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This research utilizes linear and nonlinear ultrasonic techniques to establish a linkage between microstructure and macroscale mechanical properties of additively manufactured (AM) stainless steel 316L samples. The specimens are manufactured using two methods: laser-powder bed fusion and traditional wrought manufacturing. Using the nonlinear ultrasonic method of second harmonic generation, the acoustic nonlinearity parameter is estimated in samples with different heat treatment levels intended to alter microstructural and mechanical properties. Linear ultrasonic parameters including wave speed and resonant frequency are additionally measured. Mechanical properties are obtained through tensile testing of coupons corresponding to the test samples. Microstructural information for the samples is obtained using electron backscatter diffraction to help elucidate the relationships between microstructure, mechanical properties, and ultrasonic response. Results indicate correlations between the nonlinearity parameter and both ultimate tensile strength and yield strength, where nonlinearity generally decreases as sample strength increases, particularly in the AM samples. We hypothesize that microstructural evolution of grain characteristics across different heat treatments influences trends in measured nonlinearity, as well as substructures at smaller scales such as dislocations. These results show promising evidence for the feasibility of AM parts qualification using nondestructive nonlinear ultrasonic testing.
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Gonzalez-Nino, David, Timothy Strasser, and Gary S. Prinz. "Ultra Low-Cycle Fatigue Behavior Comparison between Additively Manufactured and Rolled 17-4 PH (AISI 630) Stainless Steels." Metals 11, no. 11 (October 28, 2021): 1726. http://dx.doi.org/10.3390/met11111726.
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This study investigates the mechanical behavior of additively manufactured (AM) 17-4 PH (AISI 630) stainless steels and compares their behavior to traditionally produced wrought counterparts. The goal of this study is to understand the key parameters influencing AM 17-4 PH steel fatigue life under ULCF conditions and to develop simple predictive models for fatigue-life estimation in AM 17-4 steel components. In this study, both AM and traditionally produced (wrought) material samples are fatigue tested under fully reversed (R = −1) strain controlled (2–4% strain) loading and characterized using micro-hardness, x-ray diffraction, and fractography methods. Results indicate decreased fatigue life for AM specimens as compared to wrought 17-4 PH specimens due to fabrication porosity and un-melted particle defect regions which provide a mechanism for internal fracture initiation. Heat treatment processes performed in this work, to both the AM and wrought specimens, had no observable effect on ULCF behavior. Result comparisons with an existing fatigue prediction model (the Coffin–Manson universal slopes equation) demonstrated consistent over-prediction of fatigue life at applied strain amplitudes greater than 3%, likely due to inherent AM fabrication defects. An alternative empirical ULCF capacity equation is proposed herein to aid future fatigue estimations in AM 17-4 PH stainless steel components.
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Hayward, Mason, Gabriela Petculescu, and Erica Murray. "Ultrasonically determined elastic constants of additively manufactured 316L stainless steel." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A131. http://dx.doi.org/10.1121/10.0015783.
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We determined the effect of laser speed on the elastic constants of additively manufactured (AM) 316L stainless steel using resonant ultrasound spectroscopy (RUS). The alloy (316L) has biomechanical applications, such as medical implants. AM disks were manufactured at a constant power of 100 W and varying laser speeds of 800, 1000, and 1200 mm/s. RUS samples were extracted from the disks to determine the effects of fabrication parameters on elastic constants, as well as variations in properties across a single disk. As laser speed increases, the longitudinal (c11) moduli decreases from 284.74 GPa to 226.84 GPa, while the shear (c44) moduli exhibits minimal change. The measurement error in both moduli increases as laser speed decreases, which is attributed to the textured polycrystal nature of the samples built at lower speed. At lower speed, a greater amount of energy is deposited within the volume, allowing grains more time to grow. The grain structure determined by electron backscatter diffraction shows large crystallite formations in the 800 mm/s sample while the 1200 mm/s sample shows more homogenous small-grain distribution, which is expected of an ideal polycrystal. Variations of properties across the disk will also be presented.
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Macatangay, D. A., S. Thomas, N. Birbilis, and R. G. Kelly. "Unexpected Interface Corrosion and Sensitization Susceptibility in Additively Manufactured Austenitic Stainless Steel." Corrosion 74, no. 2 (December 19, 2017): 153–57. http://dx.doi.org/10.5006/2723.
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This communication describes observations of unexpected microstructural interface susceptibility to accelerated dissolution in additively manufactured (AM) Type 316L stainless steel prepared by selective laser melting. Observations include accelerated microstructural interface dissolution in the as-built condition, as well as more rapid sensitization of grain boundaries upon exposure to elevated temperature. Electrolytic etching in persulfate solution was used to evaluate the susceptibility of microstructural interfaces to accelerated dissolution in both wrought and AM 316L. Post-test optical microscopy and profilometry on AM 316L revealed that the melt pool boundaries in the as-built condition were susceptible to accelerated attack, although the small grains within the prior melt pools were not. Furthermore, short, elevated temperature exposure (1 h at 675°C) also induced sensitization of the grain boundaries. Identical testing on as-manufactured wrought 316L confirmed that no microstructural interfaces showed susceptibility to accelerated dissolution, and grain boundaries could be sensitized only by extended periods (24 h) at elevated temperature (675°C). Annealing was capable of removing sensitization in wrought 316L, but activated the surface of the AM 316L, leading to widespread, uniform dissolution.
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Astafurov, Sergey, and Elena Astafurova. "Phase Composition of Austenitic Stainless Steels in Additive Manufacturing: A Review." Metals 11, no. 7 (June 30, 2021): 1052. http://dx.doi.org/10.3390/met11071052.
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Additive manufacturing (AM) is among the novel industrial technologies for fast prototyping of complex parts made from different constructional and functional materials. This review is focused on phase composition of additively manufactured chromium-nickel austenitic stainless steels. Being produced by conventional methods, they typically have single-phase austenitic structure, but phase composition of the steels could vary in AM. Comprehensive analysis of recent studies shows that, depending on AM technique, chemical composition, and AM process parameters, additively manufactured austenitic stainless steels could be characterized by both single-phase austenitic and multiphase structures (austenite, ferrite, σ-phase, and segregations of alloying elements). Presence of ferrite and other phases in AM steels strongly influences their properties, in particular, could increase strength characteristics and decrease ductility and corrosion resistance of the steels. Data in review give a state-of-art in mutual connection of AM method, chemical composition of raw material, and resultant phase composition of AM-fabricated Cr-Ni steels of 300-series. The possible directions for future investigations are discussed as well.
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Melia, Michael A., Jesse G. Duran, Jason M. Taylor, Francisco Presuel-Moreno, Rebecca F. Schaller, and Eric J. Schindelholz. "Marine Atmospheric Corrosion of Additively Manufactured Stainless Steels." Corrosion 77, no. 9 (June 5, 2021): 1003–13. http://dx.doi.org/10.5006/3793.
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Additively manufactured (AM) stainless steels (SSs) exhibit numerous microstructural differences compared to their wrought counterparts, such as Cr-enriched dislocation cell structures. The influence these unique features have on a SSs corrosion resistance are still under investigation with most current works limited to laboratory experiments. The work herein shows the first documented study of AM 304L and 316L exposed to a severe marine environment on the eastern coast of Florida with comparisons made to wrought counterparts. Coupons were exposed for 21 months and resulted in significant pitting corrosion to initiate after 1 month of exposure for all conditions. At all times, the AM coupons exhibited lower average and maximum pit depths than their wrought counterparts. After 21 months, pits on average were 4 μm deep for AM 316L specimen and 8 μm deep for wrought specimen. Pits on the wrought samples tended to be nearly hemispherical and polished with some pits showing crystallographic attack while pits on AM coupons exhibited preferential attack at melt pool boundaries and the cellular microstructure.
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Navarro, Miguel, Amer Matar, Seyid Fehmi Diltemiz, and Mohsen Eshraghi. "Development of a Low-Cost Wire Arc Additive Manufacturing System." Journal of Manufacturing and Materials Processing 6, no. 1 (December 24, 2021): 3. http://dx.doi.org/10.3390/jmmp6010003.
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Due to their unique advantages over traditional manufacturing processes, metal additive manufacturing (AM) technologies have received a great deal of attention over the last few years. Using current powder-bed fusion AM technologies, metal components are very expensive to manufacture, and machines are complex to build and maintain. Wire arc additive manufacturing (WAAM) is a new method of producing metallic components with high efficiency at an affordable cost, which combines welding and 3D printing. In this work, gas tungsten arc welding (GTAW) is incorporated into a gantry system to create a new metal additive manufacturing platform. Design and build of a simple, affordable, and effective WAAM system is explained and the most frequently seen problems are discussed with their suggested solutions. Effect of process parameters on the quality of two additively manufactured alloys including plain carbon steel and Inconel 718 were studied. System design and troubleshooting for the wire arc AM system is presented and discussed.
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Bartels, Dominic, Julian Klaffki, Indra Pitz, Carsten Merklein, Florian Kostrewa, and Michael Schmidt. "Investigation on the Case-Hardening Behavior of Additively Manufactured 16MnCr5." Metals 10, no. 4 (April 21, 2020): 536. http://dx.doi.org/10.3390/met10040536.
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Additive manufacturing (AM) technologies, such as laser-based powder bed fusion of metals (PBF-LB/M), allow for the fabrication of complex parts due to their high freedom of design. PBF-LB/M is already used in several different industrial application fields, especially the automotive and aerospace industries. Nevertheless, the amount of materials being processed using AM technologies is relatively small compared to conventional manufacturing. Due to this, an extension of the material portfolio is necessary for fulfilling the demands of these industries. In this work, the AM of case-hardening steel 16MnCr5 using PBF-LB/M is investigated. In this context, the influences of different processing strategies on the final hardness of the material are studied. This includes, e.g., stress relief heat treatment and microstructure modification to increase the resulting grain size, thus ideally simplifying the carbon diffusion during case hardening. Furthermore, different heat treatment strategies (stress relief heat treatment and grain coarsening annealing) were applied to the as-built samples for modifying the microstructure and the effect on the final hardness of case-hardened specimens. The additively manufactured specimens are compared to conventionally fabricated samples after case hardening. Thus, an increase in both case-hardening depth and maximum hardness is observed for additively manufactured specimens, leading to superior mechanical properties.
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Kučerová, Ludmila, Ivana Zetková, Štěpán Jeníček, and Karolína Burdová. "Production of Hybrid Joints by Selective Laser Melting of Maraging Tool Steel 1.2709 on Conventionally Produced Parts of the Same Steel." Materials 14, no. 9 (April 21, 2021): 2105. http://dx.doi.org/10.3390/ma14092105.
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Joining additively manufactured (AM) complex shaped parts to larger conventionally produced parts can lead to innovative product designs. Another alternative is direct deposition on a conventional semi-product. Therefore, similar joints of maraging tool steel 1.2709 were produced by AM deposition of powder of this steel on a bulk conventionally manufactured steel part. The resulting hybrid parts were solution annealed and precipitation hardened. Solution annealing at 820 °C for 20 min was followed by furnace cooling. Precipitation hardening was performed at 490 °C for 6 h. The mechanical properties of the samples were characterised using tensile testing and hardness measurement across the joint. Metallographic analysis was also carried out. The tensile properties of the AM and conventionally produced steel after equivalent heat treatments were also determined as the reference values. The mechanical properties of the hybrid parts are close to the properties of both steels. The hybrid parts in the as-built condition had a tensile strength of 1029 MPa and a total elongation of 14%. Solution annealing did not change these properties significantly, except for yield strength, which decreased by approximately 150 MPa. After precipitation annealing, the strength was higher, 2011 MPa, and total elongation dropped to 5%.
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Vukkum, Venkata Bhuvaneswari, Ahmed A. Darwish, Jijo Christudasjustus, Steven Storck, and Rajeev Kumar Gupta. "Corrosion Performance of Additively Manufactured 316L Stainless Steel Produced By Feedstock Modification." ECS Meeting Abstracts MA2022-01, no. 16 (July 7, 2022): 1013. http://dx.doi.org/10.1149/ma2022-01161013mtgabs.
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Additive manufacturing (AM) is an emerging technology that can build 3d-component in a single step via the layer-by-layer process. Selective laser melting (SLM) is a popular powder bed fusion (PBF) – AM technique that involves rapid heating and cooling cycles with broad temperature gradients and complex thermal history. Moreover, the SLM components are often reported to have lower build densification due to stochastic porosity. The complex thermal cycles and stochastic porosity can negatively influence the corrosion performance of SLM printed 316L Stainless steel (SLM-316L) alloys. The corrosion performance of SLM-316L can be improved by optimizing the SLM processing parameters to improve the density and/or performing post-processing. However, post-processing increases the cost and time to deliver the components and is desired to avoid. Therefore, modifying the feedstock to increase corrosion resistance and therefore tolerance of the pores would help streamline the workflow and eliminate expensive post-manufacturing steps. In this research, the feedstock modification was conducted using ball milling of various additives and 316L powder. Corrosion performance of the SLM specimen was dependent on the additive used to modify the feedstock. Some of the additives imparted significantly improved corrosion performance, as evident from the high pitting and repassivation potentials and absence of metastable pitting. Observed corrosion performance was correlated with the microstructure which was studied using scanning and transmission electron microscopes. X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry was used to study the surface film. Role of additives on microstructure and corrosion performance will be discussed.
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Wang, Min Shi, Miles Fan, Sam Cruchley, and Yu Lung Chiu. "Effect of Cellular Dislocation Structure on the Strength of Additively Manufactured 316L Stainless Steel." Materials Science Forum 1016 (January 2021): 1576–84. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.1576.
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Additively manufactured (AM) 316L stainless steel (SS) often contains cellular dislocation structure which is a distinct microstructural feature compared with those fabricated traditionally, like casting and forging. The role of this unique cellular dislocation structure on the mechanical properties of the AM 316L SS needs to be determined to guide its further performance improvement. In this study, the effect of cellular dislocation structure on the strength of AM 316L SS was investigated via micro-mechanical compression test. Single crystalline micro-pillars were firstly prepared from both the as-built and annealed AM 316L SS bulk specimens, with and without cellular dislocation structure relatively. The results show a significant increase of the yield strength of the micro-pillars with the cellular dislocation structure. The micro-pillars containing cellular dislocation structure with different sizes and morphologies have been studied to evaluate the effect of cellular dislocation structure on the strength of AM 316L SS.
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Stoner, Brant Edward, Griffin T. Jones, Sanjay Joshi, and Rich Martukanitz. "Optimization of digital radiography for large metallic additively manufactured components." Rapid Prototyping Journal 26, no. 3 (December 19, 2019): 531–37. http://dx.doi.org/10.1108/rpj-04-2018-0107.
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Purpose The continued improvement of additive manufacturing (AM) processing has led to increased part complexity and scale. Processes such as electron beam directed energy deposition (DED) are able to produce metal AM parts several meters in scale. These structures pose a challenge for current inspection techniques because of their large size and thickness. Typically, X-ray computed tomography is used to inspect AM components, but low source energies and small inspection volumes restrict the size of components that can be inspected. This paper aims to develop digital radiography (DR) as a method for inspecting multi-meter-sized AM components and a tool that optimizes the DR inspection process. Design/methodology/approach This tool, SMART DR, provides optimal orientations and the probability of detection for flaw sizes of interest. This information enables design changes to be made prior to manufacturing that improve the inspectabitity of the component and areas of interest. Findings Validation of SMART DR was performed using a 40-mm-thick stainless-steel blade produced by laser-based DED. An optimal orientation was automatically determined to allow radiographic inspection of a thickness of 40 mm with a 70% probability of detecting 0.5 mm diameter flaws. Radiography of the blade using the optimal orientation defined by SMART DR resulted in 0.5-mm diameter pores being detected and indicated good agreement between SMART DR’s predictions and the physical results. Originality/value This paper addresses the need for non-destructive inspection techniques specifically developed for AM components.
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Zohdi, Nima, and Richard (Chunhui) Yang. "Material Anisotropy in Additively Manufactured Polymers and Polymer Composites: A Review." Polymers 13, no. 19 (September 30, 2021): 3368. http://dx.doi.org/10.3390/polym13193368.
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Additive manufacturing (AM) is a sustainable and innovative manufacturing technology to fabricate products with specific properties and complex shapes for additive manufacturable materials including polymers, steels, titanium, copper, ceramics, composites, etc. This technology can well facilitate consumer needs on products with complex geometry and shape, high strength and lightweight. It is sustainable with having a layer-by-layer manufacturing process contrary to the traditional material removal technology—subtractive manufacturing. However, there are still challenges on the AM technologies, which created barriers for their further applications in engineering fields. For example, materials properties including mechanical, electrical, and thermal properties of the additively manufactured products are greatly affected by using different ways of AM methods and it was found as the material anisotropy phenomenon. In this study, a detailed literature review is conducted to investigate research work conducted on the material anisotropy phenomenon of additively manufactured materials. Based on research findings on material anisotropy phenomenon reported in the literature, this review paper aims to understand the nature of this phenomenon, address main factors and parameters influencing its severity on thermal, electrical and mechanical properties of 3D printed parts, and also, explore potential methods to minimise or mitigate this unwanted anisotropy. The outcomes of this study would be able to shed a light on improving additive manufacturing technologies and material properties of additively manufactured materials.
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Warzocha, Krzysztof, Jerzy Szura, Piotr Bąk, Paweł Rzucidło, and Tomasz Rogalski. "Transformative Use of Additive Technology in Design and Manufacture of Hydraulic Actuator for Fly-by-Wire System." Applied Sciences 11, no. 11 (May 22, 2021): 4772. http://dx.doi.org/10.3390/app11114772.
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In this paper, the results of research on additively manufactured aerospace parts made of maraging steel are presented. This state-of-the-art technology seems to have the highest potential for practical use in the field of ultra-light and high-performance aerospace hydraulic parts. The strength properties of representative specimens made with steel 1.2709 were investigated. The researchers conducted static tensile testing, fatigue tensile testing, and pressure impulse testing. A Goodman diagram was plotted to visualize the impact of the building orientation vs. load character on the fatigue strength of the additive manufacturing (AM) specimens. Based on the research carried out on the strength of the AM samples, an aircraft flight control actuator was designed to achieve the highest level of safety integrity along with the greatest simplicity and lowest weight relative to hydraulic actuators manufactured using classical methods. The entire design process was integrated with the manufacturing process to achieve this target.
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Zuback, J. S., and T. DebRoy. "The Hardness of Additively Manufactured Alloys." Materials 11, no. 11 (October 23, 2018): 2070. http://dx.doi.org/10.3390/ma11112070.
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The rapidly evolving field of additive manufacturing requires a periodic assessment of the progress made in understanding the properties of metallic components. Although extensive research has been undertaken by many investigators, the data on properties such as hardness from individual publications are often fragmented. When these published data are critically reviewed, several important insights that cannot be obtained from individual papers become apparent. We examine the role of cooling rate, microstructure, alloy composition and post process heat treatment on the hardness of additively manufactured aluminum, nickel, titanium and iron base components. Hardness data for steels and aluminum alloys processed by additive manufacturing and welding are compared to understand the relative roles of manufacturing processes. Furthermore, the findings are useful to determine if a target hardness is easily attainable either by adjusting AM process variables or through appropriate alloy selection.
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Alam, Md Shafayet, Imran Hossain, Gaurab Dutta, and Erica Murray. "Effects of Different Scan Speeds on Microstructural and Corrosion Properties of Additively Manufactured HSLA Steels in 3.5% NaCl Solution." ECS Meeting Abstracts MA2022-02, no. 10 (October 9, 2022): 696. http://dx.doi.org/10.1149/ma2022-0210696mtgabs.
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In automotive applications, high-strength low alloy (HSLA) steels are providing enhanced material properties, due to the high yield strength, less fragility, and lower weight, which also promotes lower fuel consumption. HSLA steels contain a small amount of carbon (under 0.2%) and also contain small amounts of alloying elements such as copper, nickel, niobium, vanadium, chromium, molybdenum and zirconium. This eliminates the toughness reducing effect of a pearlitic volume fraction, yet maintains and increases the material's strength by refining the grain size. Therefore, HSLA steels are used for structures intended to handle large amounts of stress or that need a good strength-to-weight ratio. Traditional manufacturing methods for steel (e.g., blast furnace or electric arc furnace methods) fail to provide the necessary optimization for best output in terms of performance and application. The quality of molten steel is greatly affected by scrap steel. The smelting period is longer, and the power consumption is large. In addition, these processes allow more impurities into the molten steel, which compromises the quality of the final product. However, additive manufacturing (AM) can can be used to fabricate HSLA steel components without these drawbacks. In addition, AM can provide a relatively faster process with low manufacturing costs, in comparison with traditional processing methods. Although AM has several benefits, studies shows that AM processes can result in HSLA steels with microstructural defects, such as non-homogeneity, internal cavities, inclusions, and impurities. Consequently, these microstructural features have a significant affect on the corrosion properties of AM parts as corrosion tends to initiate in defective regions. The AM processing parameters directly impact the microstructure of the fabricated part. Hence, it is important to understand the relationship between the AM processing parameters on resulting microstructural features. The present work evaluated the electrochemical corrosion properties of HSLA steels fabricated by AM via selective laser melting (SLM) under different processing conditions. The goal of the work was to investigate the role of microstructure on electrochemical corrosion in high-strength low alloy steels due to SLM processing conditions. Two types of HSLA steels, Fe 367 and Fe 398, were fabricated by AM via (SLM). Fe 398 differs from Fe 367 as it contains molybdenum and nickel. Each type was fabricated at a laser power of 100W, and scan speed of 600, 800, 100 and 1200 mm/s. The samples were exposed to 3.5% NaCl for 15 days, individually. To acquire the electrochemical corrosion data and to perform analysis, a Gamry reference 600 potentiostat/galvanostat was used. The electrochemical data were obtained by collecting the impedance spectra, and measuring the polarization resistance every 5 days. On day 15, cyclic polarization data was collected for each sample. These measurements helped to identify the localized corrosion as well as provide detailed information about the corrosion properties, such as passive layer growth, initiation and secession of pitting, and corrosion rate. The topography of the materials was observed by SEM before and after the corrosion tests. Energy Dispersive Spectroscopy (EDS) was performed on the samples to identify the chemical elements. The surface roughness was observed through confocal microscope. The Confocal and SEM images showed the change in surface microstructure and topographical properties of the samples before and after the corrosion testing. The difference in laser power and scan speed affected the microstructure and corrosion properties of the materials. As the samples were manufactured at same laser power, the scan speed was responsible for different topographical and corrosion behavior. Samples manufactured at lower scan speed showed less flaws on the surface of the materials than the samples manufactured at higher scan speed. Therefore, both Fe 398 and Fe 367 showed better surface topography at 600 mm/s and 800 mm/s. They also demonstrated significantly lower corrosion rate than the other samples. EDS identified chemical oxides and chlorides which were formed during the corrosion test. Overall, this work demonstrated that Fe 398 shows better microstructural and corrosion properties than Fe 367 at lower scan speed.
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Pan, Z., V. K. Nadimpalli, T. L. Christiansen, S. A. Andersen, M. B. Kjer, O. V. Mishin, and Y. Zhang. "Influence of shielding gas flow on the uniformity of additively manufactured martensitic stainless steel." IOP Conference Series: Materials Science and Engineering 1249, no. 1 (July 1, 2022): 012026. http://dx.doi.org/10.1088/1757-899x/1249/1/012026.
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Abstract Shielding gas flow is essential to the additive manufacturing (AM) process, and the effects of argon shielding gas flow variation on the macroscopic homogeneity of additive manufactured stainless steel parts have been studied using an open-architecture AM system. Such a variation manifests itself layer-by-layer within one part and part-by-part across the build plate. Within one build, a combination of balling behavior, conduction melting and keyhole melting is observed across the build plate using the same laser parameters. Quantitative characterization of the melt pool shapes show that the melt pool width and the penetration depth exhibit the largest variations. Possible relations between the gas flow condition and macroscopic structure variations are discussed and guidelines for improved design of a gas flow system as well as future research directions are suggested for achieving macroscopically uniform metal AM.
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Church, Philip, Mark Reynolds, Peter Gould, Robin Oakley, Nigel Harrison, Dave Williamson, Chris Braithwaite, and Nick Taylor. "Tensile Properties of AM Maraging steel." EPJ Web of Conferences 183 (2018): 01058. http://dx.doi.org/10.1051/epjconf/201818301058.
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Additively Manufactured (AM) materials have great potential for producing graded materials, embedded structures and near net complex shapes. AM maraging steel properties have been compared with wrought maraging steel. The comparison featured interrupted tensile tests over a range of temperatures and strain rates. In addition a specially designed Tensile Split Hopkinson Pressure Bar (TSHPB) has been built to test very high strength metals at high strain rates. The results showed that the AM maraging steel was much more ductile than expected and exhibited significant necking under all conditions tested. All the samples exhibited ductile fracture. Although not as ductile as the wrought material, the AM material could be cost effective through economies of scale for complex components. The microstructure contained inclusions which derived from either the powder or the AM process and thus there is significant potential to improve these materials further. A modified Armstrong-Zerilli model was also constructed for these materials and shown to predict the raw experimental data within experimental error using DYNA3D simulations.
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Schindelholz, Eric J., Michael A. Melia, and Jeffrey M. Rodelas. "Corrosion of Additively Manufactured Stainless Steels—Process, Structure, Performance: A Review." Corrosion 77, no. 5 (February 6, 2021): 484–503. http://dx.doi.org/10.5006/3741.
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The corrosion of additively manufactured (AM) metallic materials, such as stainless steels (SS), is a critical factor for their qualification and reliable use. This review assesses the emerging knowledgebase of powder-based laser AM SS corrosion and environmentally assisted cracking (EAC). The origins of AM-unique material features and their hierarchal impact on corrosion and EAC are addressed relative to conventionally processed SS. The effects of starting material, heat treatment, and surface finishing are substantively discussed. An assessment of the current status of AM corrosion research, scientific gaps, and research needs with greatest impact for AM SS advancement and qualification is provided.
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Peng, Daren, Andrew S. M. Ang, Alex Michelson, Victor Champagne, Aaron Birt, and Rhys Jones. "Analysis of the Effect of Machining of the Surfaces of WAAM 18Ni 250 Maraging Steel Specimens on Their Durability." Materials 15, no. 24 (December 13, 2022): 8890. http://dx.doi.org/10.3390/ma15248890.
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It is now well-known that the interaction between surface roughness and surface-breaking defects can significantly degrade the fatigue life of additively manufactured (AM) parts. This is also aptly illustrated in the author’s recent study on the durability of wire and arc additively manufactured (WAAM) 18Ni 250 Maraging steel specimens, where it was reported that failure occurred due to fatigue crack growth that arose due to the interaction between the surface roughness and surface-breaking material defects. To improve the durability of an AM part, several papers have suggested the machining of rough surfaces. However, for complex geometries the fully machining of the entire rough surface is not always possible and the effect of the partial machining on durability is unknown. Therefore, this paper investigates if partial machining of WAAM 18Ni 250 Maraging steel surfaces will help to improve the durability of these specimens. Unfortunately, the result of this investigation has shown that partial machining may not significantly improve durability of WAAM 18Ni 250 Maraging steel specimens. Due to the order of surface roughness seen in WAAM 250 Maraging steel, the improvement to durability is only realized by full machining to completely remove the remnants of any print artefacts.
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Maicas-Esteve, Héctor, Iman Taji, Marc Wilms, Yaiza Gonzalez-Garcia, and Roy Johnsen. "Corrosion and Microstructural Investigation on Additively Manufactured 316L Stainless Steel: Experimental and Statistical Approach." Materials 15, no. 4 (February 21, 2022): 1605. http://dx.doi.org/10.3390/ma15041605.
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The use of metal additive manufacturing (AM) has strongly increased in the industry during the last years. More specifically, selective laser melting (SLM) is one of the most used techniques due to its numerous advantages compared to conventional processing methods. The purpose of this study is to investigate the effects of process parameters on the microstructural and corrosion properties of the additively manufactured AISI 316L stainless steel. Porosity, surface roughness, hardness, and grain size were studied for specimens produced with energy densities ranging from 51.17 to 173.91 J/mm3 that resulted from different combinations of processing parameters. Using experimental results and applying the Taguchi model, 99.38 J/mm3 was determined as the optimal energy density needed to produce samples with almost no porosity. The following analysis of variance ANOVA confirmed the scanning speed as the most influential factor in reducing the porosity percentage, which had a 74.9% contribution, followed by the position along the building direction with 22.8%, and finally, the laser energy with 2.3%. The influence on corrosion resistance was obtained by performing cyclic potentiodynamic polarization tests (CPP) in a 3.5 wt % NaCl solution at room temperature for different energy densities and positions (Z axis). The corrosion properties of the AM samples were studied and compared to those obtained from the traditionally manufactured samples. The corrosion resistance of the samples worsened with the increase in the percentage of porosity. The process parameters have consequently been optimized and the database has been extended to improve the quality of the AM-produced parts in which microstructural heterogeneities were observed along the building direction.
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Karasz, Erin, Kasandra Escarcega-Herrera, Jason Taylor, Courtney L. Clark, Jamie A. Stull, and Michael Anthony Melia. "(Digital Presentation) Comparison of Electrochemical Measurements to Atmospheric Corrosion Experiments on Additively Manufactured 316L." ECS Meeting Abstracts MA2022-02, no. 10 (October 9, 2022): 697. http://dx.doi.org/10.1149/ma2022-0210697mtgabs.
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As interest in the commercial implementation of additively manufactured (AM) metal components increases, so does the need to understand the corrosion behavior of these materials. AM metals deviate in microstructure and surface quality from traditionally processed metals which impacts their corrosion properties. Currently there are no studies investigating the variation in corrosion behavior for AM components printed on different machines. This work compares the breakdown potential, an indication of stable pit growth and the loss of passivity, from 316L stainless steel samples printed on several machines. A correlation between breakdown potential and the surface microstructure, unique to parts printed on different machines, will be discussed. Additionally, the electrochemical measurements are correlated with salt fog experiments. Finally, pit morphology from accelerated atmospheric corrosion exposures (salt fog and constant humidity/contamination lab exposures) are compared to a real-world exposure (coastal environment) of AM 316L. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2022-4063 A
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Blinn, Bastian, Marcus Klein, and Tilmann Beck. "Determination of the anisotropic fatigue behaviour of additively manufactured structures with short-time procedure PhyBaLLIT." MATEC Web of Conferences 165 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201816502006.
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Additive Manufacturing techniques provide completely new possibilities in component design and creation of innovative material structures. To utilize the whole potential of Additive Manufacturing, the microstructure, the mechanical properties and their interrelations as well as their relationship to the Additive Manufacturing process parameters are essential. Investigations of the fatigue behaviour of additively manufactured (AM-) metallic materials are still available in limited extent. However, as a prerequisite for efficient and reliable use of AM-components in safety relevant structures, sound knowledge of fatigue behaviour and properties of these structures is indispensable. A central aspect in Additive Manufacturing is the anisotropic mechanical behaviour under monotonic and cyclic loading in dependency on the building direction [1, 2]. In the present work, the microstructure and mechanical properties of Selective Laser Melted (SLM) as well as Laser Deposition Welded (LDW) AISI 316L stainless steel specimens are investigated with special focus on the influence of the building direction. The investigated specimens are built in horizontal and vertical direction, resulting in layer planes oriented parallel and perpendicular to the loading direction, respectively. The fatigue tests have been performed on a servohydraulic testing system with measurement of stress-strain-hysteresis as well as of plastic deformation induced changes in temperature and specific electrical resistance. S-Nf-curves in the HCF-regime of AM-specimens have been determined with the time and material efficient Physically Based Lifetime calculation procedure PhyBaLLIT [3]. Anisotropic fatigue behaviour of the different AM-specimens has been rated with load increase tests (LIT) and the usage of S-Nfcurves calculated by the PhyBaLLIT method.
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Jaskari, Matias, Sumit Ghosh, Ilkka Miettunen, Pentti Karjalainen, and Antti Järvenpää. "Tensile Properties and Deformation of AISI 316L Additively Manufactured with Various Energy Densities." Materials 14, no. 19 (October 4, 2021): 5809. http://dx.doi.org/10.3390/ma14195809.
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Additive manufacturing (AM) is an emerging fabrication technology that offers unprecedented potential for manufacturing end-to-end complex shape customized products. However, building products with high performance by AM presents a technological challenge. Inadequate processing parameters, fabrication environment or changes in powder properties may lead to high defect density in the part and poor mechanical properties. Microstructure, defect structure, and mechanical properties of AISI 316L stainless steel pieces, additively manufactured by the laser powder bed fusion method using three different volume energy densities (VEDs), were investigated and compared with those of a commercial wrought AISI 316L sheet. Scanning and transmission electron microscopies were employed for characterization of grain and defect structures, and mechanical properties were determined by tensile testing. It was found that the number of defects such as pores and lack of fusion in AM specimens did not affect the strength, but they impaired the post-uniform elongation, more significantly when processed with the low VED. Twinning was found to be an active deformation mechanism in the medium and high VED specimens and in the commercially wrought material in the later stage of straining, but it was suppressed in the low VED specimens presumably because the presence of large voids limited the strain attained in the matrix.
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Puichaud, Anne-Helene, Camille Flament, Aziz Chniouel, Fernando Lomello, Elodie Rouesne, Pierre-François Giroux, Hicham Maskrot, Frederic Schuster, and Jean-Luc Béchade. "Microstructure and mechanical properties relationship of additively manufactured 316L stainless steel by selective laser melting." EPJ Nuclear Sciences & Technologies 5 (2019): 23. http://dx.doi.org/10.1051/epjn/2019051.
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Additive manufacturing (AM) is rapidly expanding in many industrial applications because of the versatile possibilities of fast and complex fabrication of added value products. This manufacturing process would significantly reduce manufacturing time and development cost for nuclear components. However, the process leads to materials with complex microstructures, and their structural stability for nuclear application is still uncertain. This study focuses on 316L stainless steel fabricated by selective laser melting (SLM) in the context of nuclear application, and compares with a cold-rolled solution annealed 316L sample. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure and mechanical properties is discussed. It was found that after HT, the material microstructure remains mostly unchanged, while the HIP treatment removes the materials porosity, and partially re-crystallises the microstructure. Finally, the tensile tests showed excellent results, satisfying RCC-MR code requirements for all AM materials.
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Clark, Courtney L., Jamie A. Stull, Timothy Gorey, and Daniel E. Hooks. "(Digital Presentation) Effects of Surface Finish on the Corrosion Performance of Additively Manufactured Metals." ECS Meeting Abstracts MA2022-01, no. 16 (July 7, 2022): 1011. http://dx.doi.org/10.1149/ma2022-01161011mtgabs.
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Metal additive manufacturing (AM) is becoming a transformative technology in the manufacturing industry. The as-built surfaces produced by metal AM are very different compared to wrought material, typically resulting in very rough surfaces that have different corrosion properties. There are a large number of studies that have attempted to understand the corrosion response of metal AM. However, these studies are typically performed on materials that have been printed on a single machine. As a result, there are significant inconsistencies in the literature due to the high variability in the quality of parts manufactured on different machines. We will present work that compares the corrosion response of AM 316L stainless steel (SS) that has been printed on multiple machines. Our results have shown there is significant variability observed in the corrosion performance of metal AM parts built on different machines and within a single build plate. The observed corrosion performance is likely affected by the stability of the passive film, chemical segregation, and microstructure of the surface. We also propose that surface finishing of AM 316L SS reduces the part-to-part variations observed in the corrosion performance of the material printed on different machines and within a single build plate. This talk will discuss the corrosion properties of AM 316L SS, A20x (AM aluminum alloy), and Ti-6Al-4V parts produced by direct metal laser sintering (DMLS). The majority of our work focused on understanding the susceptibility to localized corrosion of metal additively manufactured materials with respect to build machine, surface roughness, and build angle. As a result, we also examined the corrosion performance of 316L SS built on a single instrument as we varied the build parameters. Conventional electrochemical corrosion experiments were used to characterize corrosion performance, including open circuit potential, potentiostatic electrochemical impedance spectroscopy, and potentiodynamic polarization scans. White light interferometry, optical profilometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were utilized to characterize the surface of the samples.
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Guo, W. F., C. Guo, and Qiang Zhu. "Heat Treatment Behavior of the 18Ni300 Maraging Steel Additively Manufactured by Selective Laser Melting." Materials Science Forum 941 (December 2018): 2160–66. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2160.
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The steel 18Ni300 is widely used for tooling of injection moulding and die casting industries. Additive manufacturing (AM) technology is applicable to manufacture dies with “ideal” design without construction of manufacturing reality. Selective laser melting (SLM) processed materials have finer microstructure due to steeper temperature gradient and more rapid cooling conditions than conventional casting process during solidification. This difference may make different heat treatment behavior in obtaining optimal properties of the 18Ni300 maraging steel manufactured by SLM. Heat treatment is one of the most processes to improve microstructure, mechanical properties and performance of tooling dies. This work studies evolution of microstructure and properties during heat treatment, by X-ray diffraction, optical and scanning electron microscopy (SEM). The results show that the SLMed materials with only aging treatment have comparable strengths and hardness to those of conventionally cast materials with both solution and aging treatment. For the SLMed materials, with increase of aging time and/or temperature, the formed reverted austenite (γ-Fe) fraction increases, while aging precipitation hardening decreases. This is more apparent at aging temperatures of higher than 540°C. The combined effects of softening by formation of reverted austenite (γ-Fe) and age hardening induced by precipitation are discussed.
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Černašėjus, Olegas, Jelena Škamat, Vladislav Markovič, Nikolaj Višniakov, and Simonas Indrišiūnas. "Effect of Laser Processing on Surface Properties of Additively Manufactured 18-Percent Nickel Maraging Steel Parts." Coatings 10, no. 6 (June 26, 2020): 600. http://dx.doi.org/10.3390/coatings10060600.
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In the present work, the experimental study on laser processing of additively manufactured (AM) maraging steel part surface was conducted. Nanosecond pulsed laser at ablation mode was used for surface modification in oxidizing atmosphere. The morphology, roughness, elemental and phase composition, microhardness and tribological properties of the processed surfaces were investigated. The obtained results revealed that pulsed laser processing under the ablation mode in air allows obtaining modified surface with uniform micro-texture and insignificant residual undulation, providing 3 times lower roughness as compared with the as-manufactured AM part. The intensive oxidation of surface during laser processing results in formation of the significant oxides amount, which can be controlled by scanning speed. Due to the presence of the oxide phase (such as Fe2CoO4 and Ti0.11Co0.89O0.99), the hardness and wear resistance of the surface were significantly improved, up to 40% and 17 times, respectively. The strong correlation between the roughness parameter Ra and mass loss during the tribological test testifies the significant role of the obtained morphology for the wear resistance of the surface.
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Zhang, Fan, Lyle E. Levine, Andrew J. Allen, Sandra W. Young, Maureen E. Williams, Mark R. Stoudt, Kil-Won Moon, Jarred C. Heigel, and Jan Ilavsky. "Phase Fraction and Evolution of Additively Manufactured (AM) 15-5 Stainless Steel and Inconel 625 AM-Bench Artifacts." Integrating Materials and Manufacturing Innovation 8, no. 3 (August 5, 2019): 362–77. http://dx.doi.org/10.1007/s40192-019-00148-1.
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Knorr, Lukas, Robert Setter, Dominik Rietzel, Katrin Wudy, and Tim Osswald. "Comparative Analysis of the Impact of Additively Manufactured Polymer Tools on the Fiber Configuration of Injection Molded Long-Fiber-Reinforced Thermoplastics." Journal of Composites Science 4, no. 3 (September 15, 2020): 136. http://dx.doi.org/10.3390/jcs4030136.
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Additive tooling (AT) utilizes the advantages of rapid tooling development while minimizing geometrical limitations of conventional tool manufacturing such as complex design of cooling channels. This investigation presents a comparative experimental analysis of long-fiber-reinforced thermoplastic parts (LFTs), which are produced through additively manufactured injection molding polymer tools. After giving a review on the state of the art of AT and LFTs, additive manufacturing (AM) plastic tools are compared to conventionally manufactured steel and aluminum tools toward their qualification for spare part and small series production as well as functional validation. The assessment of the polymer tools focuses on three quality criteria concerning the LFT parts: geometrical accuracy, mechanical properties, and fiber configuration. The analysis of the fiber configuration includes fiber length, fiber concentration, and fiber orientation. The results show that polymer tools are fully capable of manufacturing LFTs with a cycle number within hundreds before showing critical signs of deterioration or tool failure. The produced LFTs moldings provide sufficient quality in geometrical accuracy, mechanical properties, and fiber configuration. Further, specific anomalies of the fiber configuration can be detected for all tool types, which include the occurrence of characteristic zones dependent on the nominal fiber content and melt flow distance. Conclusions toward the improvement of additively manufactured polymer tool life cycles are drawn based on the detected deteriorations and failure modes.
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Vafadar, Ana, Ferdinando Guzzomi, and Kevin Hayward. "Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers." Metals 11, no. 4 (April 1, 2021): 574. http://dx.doi.org/10.3390/met11040574.
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Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.
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Cho, Seongkoo, Steven F. Buchsbaum, Monika M. Biener, Justin T. Jones, and Roger Qiu. "The Importance of Electrochemically Active Surface Area in the Corrosion Behavior of Additively Manufactured 316L Stainless Steel." ECS Meeting Abstracts MA2022-01, no. 16 (July 7, 2022): 1015. http://dx.doi.org/10.1149/ma2022-01161015mtgabs.
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Surfaces of additively manufactured (AM) stainless steel (SS) by fusing metallic powders are known to be much rougher than those produced by conventionally fabrication methods. The measured surface roughness (Sa or Sq) can range from a few to tens of microns depending on the build angle. Recent studies have shown that the large surface roughness associated with printing conditions makes the AM SS surfaces susceptible to localized corrosion and open-circuit corrosion [1, 2]. Sa or Sq have also long been used to characterize the corrosion behavior of traditionally manufactured metals [3]. However, the open-circuit corrosion rate of the traditional metals has been mainly studied in the submicron-scale surface roughness, and some results have showed that changes in the roughness of hundreds of nanometers or more have little effect on the change in the corrosion rate [4]. In addition, when applied to AM materials, no consistent correlation between the pitting breakdown potential (Eb) and surface roughness has been observed. In this study, the dependence of the corrosion behavior on the electrochemically active surface area of AM 316L SS, defined as the total area of the curvilinear surface that is exposed to the electrolyte, has been explored. The localized corrosion susceptibility was evaluated under full immersion in 3.5 wt% NaCl solution through potentiodynamic polarization for testing articles with different surface roughness. While no correlation to Sa or Sq was displayed, the Eb values showed a clear statistical trend with respect to the electrochemically active surface area: the lager the active surface area, the smaller the Eb. The observed correlation fits well with a previously reported stochastic pitting model on metal surfaces [5]. In addition, by normalizing linear polarization resistance and electrochemical impedance spectra with the electrochemically active surface area, it can be confirmed that the as-printed surface roughness of AM 316L SS did not have a significant effect on the change of the open-circuit corrosion phenomenon under static immersion conditions. Our results suggest that electrochemically active surface area is an appropriate parameter to characterize the corrosion behavior of AM metal surfaces. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. References 1. Melia, M.A., et al., How build angle and post-processing impact roughness and corrosion of additively manufactured 316L stainless steel. Npj Materials Degradation, 2020. 4(1). 2. Ni, C., Y. Shi, and J. Liu, Effects of inclination angle on surface roughness and corrosion properties of selective laser melted 316L stainless steel. Materials Research Express, 2019. 6(3). 3. Walter, R. and M.B. Kannan, Influence of surface roughness on the corrosion behaviour of magnesium alloy. Materials & Design, 2011. 32(4): p. 2350-2354. 4. Li, W. and D.Y. Li, Influence of surface morphology on corrosion and electronic behavior. Acta Materialia, 2006. 54(2): p. 445-452. 5. Shibata, T., 1996 W R Whitney Award lecture: Statistical and stochastic approaches to localized corrosion. Corrosion, 1996. 52(11): p. 813-830.
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Mohd Yusuf, Shahir Mohd, Ying Chen, and Nong Gao. "Influence of High-Pressure Torsion on the Microstructure and Microhardness of Additively Manufactured 316L Stainless Steel." Metals 11, no. 10 (September 29, 2021): 1553. http://dx.doi.org/10.3390/met11101553.
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High-pressure torsion (HPT) is known as an effective severe plastic deformation (SPD) technique to produce bulk ultrafine-grained (UFG) metals and alloys by the application of combined compressive force and torsional shear strains on thin disk samples. In this study, the microstructures and microhardness evolution of an additively manufactured (AM) 316L stainless steel (316L SS) processed through 5 HPT revolutions are evaluated at the central disk area, where the effective shear strains are relatively low compared to the peripheral regions. Scanning electron microscopy (SEM) analysis showed that the cellular network sub-structures in AM 316L SS were destroyed after 5 HPT revolutions. Transmission electron microscopy (TEM) observations revealed non-equilibrium ultrafine grained (UFG) microstructures (average grain size: ~115 nm) after 5 revolutions. Furthermore, energy dispersive x-ray spectroscopy (EDX) analysis suggested that spherical Cr-based nano-silicates are also found in the as-received condition, which are retained even after HPT processing. Vickers microhardness (HV) measurements indicated significant increase in average hardness values from ~220 HV before HPT processing to ~560 HV after 5 revolutions. Quantitative X-ray diffraction (XRD) patterns exhibit a considerable increase in dislocation density from ~0.7 × 1013 m−2 to ~1.04 × 1015 m−2. The super-high average hardness increment after 5 HPT revolutions is predicted to be attributed to the UFG grain refinement, significant increase in dislocation densities and the presence of the Cr-based nano-silicates, according to the model established based on the linear additive theory.
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Kizer, Nathan, Edward Reutzel, Corey Dickman, and Christopher M. Kube. "In-process volumetric sensing of defects in multiple parts during powder bed fusion using acoustics." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A94. http://dx.doi.org/10.1121/10.0015659.
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Additively manufactured (AM) metals have been gaining popularity due to their advantages over traditionally manufactured metals. AM processes can produce complex geometries unachievable in other methods. However, AM metals remain susceptible to traditional defects such as delaminations during manufacturing. Such defects can cause to build failure or loss of part integrity making them unsuitable for many structural applications. These defects often result from incorrect selections of process parameters for particular parts. In-situ monitoring systems using ultrasonic inspection have been proposed to sense and mitigate defects. This presentation describes experimental efforts to integrate a plurality of ultrasonic transducers into powder bed fusion AM. Nine 9Cr-1Mo stainless steel parts with identical dimensions were produced using powder bed fusion. Each part was printed with various laser power and speeds to produce a range of build qualities. Nine ultrasonic transducers were integrated into the build substrate to simultaneously monitor the nine AM parts during the build. Results of these measurements will be highlighted. This demonstration indicates the potential for using ultrasound to help determine optimal process parameters for reducing defects in AM parts. Additionally, this work supports progress toward closed-loop feedback for on-the-fly corrections.
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BURES, MARTIN, MAX-JONATHAN KLEEFOOT, YUSUF BAKIR, and MIROSLAV ZETEK. "LASER MACROPOLISHING OF ADDITIVELY MANUFACTURED PARTS OF MARAGING STEEL WITH RESPECT TO SURFACE PROPERTIES." MM Science Journal 2022, no. 3 (September 27, 2022): 5918–25. http://dx.doi.org/10.17973/mmsj.2022_10_2022125.
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This article is focused on the laser macro polishing of additively manufactured (AM) parts. The material that is being processed is maraging steel (MS1). The main part of the study is to find suitable parameters to significantly reduce the surface roughness of 3 surfaces with completely different topologies. The investigated parameters are scanning speed, defocussed laser and laser power. However, other material properties are also tested. Fatigue life, tensile and hardness testing were carried out for 3 different sets of laser macro polishing parameters. It was found that surface roughness reduction of Ra by over 90 % is possible. Interestingly, tensile testing of parameters 1 and 2 showed more brittle-like behaviour in comparison to parameter 3. This was further supported by hardness testing, which showed increased hardness in the centre of the samples.
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Langer, Lukas, Matthias Schmitt, Jaime Cuesta Aguirre, Georg Schlick, and Johannes Schilp. "Hybrid additive manufacturing of hot working tool steel H13 with dissimilar base bodies using Laser-based Powder Bed Fusion." IOP Conference Series: Materials Science and Engineering 1135, no. 1 (November 1, 2021): 012012. http://dx.doi.org/10.1088/1757-899x/1135/1/012012.
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Abstract Hybrid additive manufacturing (HAM) describes the combination of additively built structures onto a conventionally manufactured base body. The advantages of both manufacturing processes are combined in one process chain. As a result, new applications can be achieved with higher cost-effectiveness. With the Additive Manufacturing (AM) process a bonding zone is created that is comparable to a welded joint. In order to evaluate the quality and mechanical properties of the bonding zone, two steels (42CrMo4 and 25CrMo4) are investigated as base body materials with the hot working tool steel X40CrMoV5-1 (AISI H13) for the AM structure. Process parameters for Laser-based Powder Bed Fusion of X40CrMo4V5-1 are developed to achieve a crack and defect free structure as well as an optimized bonding zone in dependency of the base body material. Furthermore, the chemical and mechanical properties are examined in the as-built and heat-treated state. It is observed that a crack-free material bonding is possible and samples with relative densities above 99.5% are obtained. The size of the bonding zone depends on the material of the base body as well as post-process heat treatment. An average hardness of 600 HV1 can be achieved in the “as-built” state.
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Müller, Johanna, Marcel Grabowski, Christoph Müller, Jonas Hensel, Julian Unglaub, Klaus Thiele, Harald Kloft, and Klaus Dilger. "Design and Parameter Identification of Wire and Arc Additively Manufactured (WAAM) Steel Bars for Use in Construction." Metals 9, no. 7 (June 27, 2019): 725. http://dx.doi.org/10.3390/met9070725.
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Additive manufacturing (AM) in industrial applications benefits from increasing interest due to its automation potential and its flexibility in manufacturing complex structures. The construction and architecture sector sees the potential of AM especially in the free form design of steel components, such as force flow optimized nodes or bionic-inspired spaceframes. Robot-guided wire and arc additive manufacturing (WAAM) is capable of combining a high degree of automation and geometric freedom with high process efficiency. The build-up strategy (layer by layer) and the corresponding heat input influence the mechanical properties of the WAAM products. This study investigates the WAAM process by welding a bar regarding the build-up geometry, surface topography, and material properties. For tensile testing, an advanced testing procedure is applied to determine the strain fields and mechanical properties of the bars on the component and material scale.
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Souza, Andrews, Paulina Capela, Vítor Lopes, Filipe Prior, Hélder Puga, Delfim Soares, and José Teixeira. "Thermal Contact Resistance between Mold Steel and Additively Manufactured Insert for Designing Conformal Channels: An Experimental Study." Journal of Manufacturing and Materials Processing 6, no. 5 (September 13, 2022): 99. http://dx.doi.org/10.3390/jmmp6050099.
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The focus of this research is on thermal contact resistance between a mold and its insert, specifically inserts made by additive manufacturing (AM). Using a thermal steady-state system and varying contact pressures (0, 50, 75, and 100 bars), we present experimental results of the thermal contact resistance at the contact interface between steel A (1.2344), obtained from an extruded rod, and steel B (1.2709), produced by laser powder bed fusion. Thermal tests were performed for unbonded and bonded configurations. Results showed that increasing the contact pressure allows the system equilibrium to be reached at lower temperatures. Furthermore, thermal tests showed that in the transition zone of the bonded configuration, a well-defined resistance is not formed between the two steel samples as it occurs in the unbonded configuration. For the unbonded configuration, the thermal contact resistance values decrease with increasing applied contact pressure, improving the system’s heat transfer.
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Hoosain, Shaik E., Lerato C. Tshabalala, Samuel Skhosana, Christopher Freemantle, and N. Mndebele. "INVESTIGATION OF THE PROPERTIES OF DIRECT ENERGY DEPOSITION ADDITIVE MANUFACTURED 304 STAINLESS STEEL." South African Journal of Industrial Engineering 32, no. 3 (2021): 258–63. http://dx.doi.org/10.7166/32-3-2661.
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One of the main considerations in adopting the additive manufacturing (AM) technology is whether the material properties of the AM-produced part are comparable with the wrought material. This study compared the properties of AM-produced 304 stainless steel via the direct energy deposition (DED) AM process with wrought 304 stainless steel. The samples were studied in their as-built or as-received condition; and the characterisation analysis included micro-structural evaluation, hardness tests, Charpy impact testing, tensile testing, and X-ray diffraction. The results demonstrated that, in general, the strength characteristics of the AM sample exceeded those of the wrought material other than for toughness.
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Mazur, Maciej, Martin Leary, Matthew McMillan, Joe Elambasseril, and Milan Brandt. "SLM additive manufacture of H13 tool steel with conformal cooling and structural lattices." Rapid Prototyping Journal 22, no. 3 (April 18, 2016): 504–18. http://dx.doi.org/10.1108/rpj-06-2014-0075.
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Purpose Additive manufacture (AM) such as selective laser melting (SLM) provides significant geometric design freedom in comparison with traditional manufacturing methods. Such freedom enables the construction of injection moulding tools with conformal cooling channels that optimize heat transfer while incorporating efficient internal lattice structures that can ground loads and provide thermal insulation. Despite the opportunities enabled by AM, there remain a number of design and processing uncertainties associated with the application of SLM to injection mould tool manufacture, in particular from H13/DIN 1.2344 steel as commonly used in injection moulds. This paper aims to address several associated uncertainties. Design/methodology/approach A number of physical and numerical experimental studies are conducted to quantify SLM-manufactured H13 material properties, part manufacturability and part characteristics. Findings Findings are presented which quantify the effect of SLM processing parameters on the density of H13 steel components; the manufacturability of standard and self-supporting conformal cooling channels, as well as structural lattices in H13; the surface roughness of SLM-manufactured cooling channels; the effect of cooling channel layout on the associated stress concentration factor and cooling uniformity; and the structural and thermal insulating properties of a number of structural lattices. Originality/value The contributions of this work with regards to SLM manufacture of H13 of injection mould tooling can be applied in the design of conformal cooling channels and lattice structures for increased thermal performance.
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Lin, Zidong, Kaijie Song, Wei Ya, and Xinghua Yu. "Parametric and Metallurgical Investigation of Modified 3D AM 80 HD Steel for Wire and Arc Additive Manufacturing." Journal of Physics: Conference Series 2101, no. 1 (November 1, 2021): 012049. http://dx.doi.org/10.1088/1742-6596/2101/1/012049.
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Abstract Wire and arc additive manufacturing (WAAM) is an advanced 3D printing method for metallic materials on the foundation of traditional arc welding processes. WAAM is regarded as a proper way to manufacture large-dimensional metallic parts with the combination of high deposition rate and low cost. In this research, a specifically designed and manufactured low carbon high strength steel (Grade 3D AM 80 HD) wire, equivalent to a composition of AWS ER 110S-1 wire, was deposited using WAAM to print a muti-beads wall aiming to explore its feasibility for heavily loaded marine applications. A parametric investigation was proceeded to find the optimal deposition voltage and overlap ratio. A vertical position compensation method was adopted to optimize the step-up distance for welding torch between neighboring layers. Microstructure of the deposited component was characterized and also indicated by Thermal-Calc Software, followed by the measurement of hardness and prediction of tensile strength. Furthermore, a comparison of tensile strength of the WAAMed 3D AM 80 HD wall, 3D AM 80 HD wire, AWS ER 110S-1 wire, and a WAAMed wall produced by wire manufacturer (Voestalpine Böhler Welding Corporation) was conducted.
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Beltrán, Natalia, David Blanco, Braulio José Álvarez, Álvaro Noriega, and Pedro Fernández. "Dimensional and Geometrical Quality Enhancement in Additively Manufactured Parts: Systematic Framework and A Case Study." Materials 12, no. 23 (November 28, 2019): 3937. http://dx.doi.org/10.3390/ma12233937.
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In order to compete with traditional manufacturing processes, Additive Manufacturing (AM) should be capable of producing medium to large batches at industrial-degree quality and competitive cost-per-unit. This paper proposes a systematic framework approach to the problem of fulfilling dimensional and geometric requirements for medium batch sizes of AM parts, which has been structured as a three-step optimization methodology. Firstly, specific work characteristics are analyzed so that information is arranged according to an Operation Space (factors that could have an influence upon quality) and a Verification Space (formed by quality indicators and requirements). Standard process configuration leads to characterization of the standard achievable quality. Secondly, controllable factors are analyzed to determine their relative influence upon quality indicators and the optimal process configuration. Thirdly, optimization of part dimensional and/or geometric definition at the design level is performed in order to improve part quality and meet quality requirements. To evaluate the usefulness of the proposed framework under quasi-industrial condition, a case study is presented here which is focused on the dimensional and geometric optimization of surgical-steel tibia resection guides manufactured by Laser-Power Bed Fusion (L-PBF). The results show that the proposed approach allows for part quality improvement to a degree that matches the initial requirements.
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Fatemi, Ali, Reza Molaei, and Nam Phan. "Multiaxial Fatigue of Additive Manufactured Metals." MATEC Web of Conferences 300 (2019): 01003. http://dx.doi.org/10.1051/matecconf/201930001003.
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Additive manufacturing (AM) has recently gained much interest from researchers and industry practitioners due to the many advantages it offers as compared to the traditional subtractive manufacturing methods. These include the ability to fabricate net shaped complex geometries, integration of multiple parts, on-demand fabrication, and efficient raw material usage, among other benefits. Some of distinguishing features of AM metals, as compared to traditional subtractive manufacturing methods, include surface roughness, porosity and lack of fusion defects, residual stresses due to the thermal history of the part during the fabrication process, and anisotropy of the properties. Most components made of AM processes are subjected to cyclic loads, therefore, fatigue performance is an important consideration in their usage for safety critical applications. In addition, the state of stress at fatigue critical locations are often multiaxial. Considering the fact that many of the distinguishing features of AM metals are directional, the subject of multiaxial fatigue presents an important study area for a better understanding of their fatigue performance. This paper presents an overview of the aforementioned issues using recent data generated using AM Ti-6Al-4V and 17-4 PH stainless steel. Specimens were made by laser-based powder bed fusion and subjected to axial, torsion, and in-phase as well as out-of-phase loadings. A variety of conditions such as surface roughness, thermo-mechanical treatment, and notch effects are included. Many aspects are considered including damage mechanisms and crack paths, cyclic deformation, fatigue crack nucleation and growth, and stress concentration effects.