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This study investigates the in situ alloying of a Ni-based superalloy processed by means of laser powder bed fusion (LPBF). For this purpose, Inconel 625 powder is mixed with 1 wt.% of Ti6Al4V powder. The modified alloy is characterized by densification levels similar to the base alloy, with relative density superior to 99.8%. The material exhibits Ti-rich segregations along the melt pool contours. Moreover, Ti tends to be entrapped in the interdendritic areas during solidification in the as-built state. After heat treatments, the modified Inconel 625 version presents greater hardness and tensile strengths than the base alloy in the same heat-treated conditions. For the solution annealed state, this is mainly attributed to the elimination of the segregations into the interdendritic structures, thus triggering solute strengthening. Finally, for the aged state, the further increment of mechanical properties can be attributed to a more intense formation of phases than the base alloy, due to elevated precipitation strengthening ability under heat treatments. It is interesting to note how slight chemical composition modification can directly develop new alloys by the LPBF process.
Giulio Marchese; Margherita Beretta; Alberta Aversa; Sara Biamino. In Situ Alloying of a Modified Inconel 625 via Laser Powder Bed Fusion: Microstructure and Mechanical Properties. Metals 2021, 11, 988 .
AMA StyleGiulio Marchese, Margherita Beretta, Alberta Aversa, Sara Biamino. In Situ Alloying of a Modified Inconel 625 via Laser Powder Bed Fusion: Microstructure and Mechanical Properties. Metals. 2021; 11 (6):988.
Chicago/Turabian StyleGiulio Marchese; Margherita Beretta; Alberta Aversa; Sara Biamino. 2021. "In Situ Alloying of a Modified Inconel 625 via Laser Powder Bed Fusion: Microstructure and Mechanical Properties." Metals 11, no. 6: 988.
Laser Powder Bed Fusion (LPBF) is an additive manufacturing technology which has been the subject of thorough research and successfully adopted in several industrial sectors. Among all the processable classes of materials, titanium alloys are especially interesting due to their favourable combination of mechanical properties and corrosion resistance. Most of the literature focuses on Ti-6Al-4V, although there are other alloys which are widely applied in fields that can benefit from the advantages of LPBF techniques, such as Ti-6Al-2Sn-4Zr-6Mo, thus far not investigated for this technology. This alloy is generally preferred to Ti-6Al-4V for the production of some components in the aerospace industry, mostly due to its superior strength. In this work, the most suitable process window for this alloy was investigated. Samples produced with two different combinations of process parameters, located in the selected process window, were then thoroughly studied in order to assess the effect of building conditions on the microstructure, phases and mechanical properties of the as-built and heat-treated material. To do so, an X-ray diffraction analysis was conducted with the aim of determining the phase composition and lattice parameters. Moreover, microstructural features, such as α” needles and α lath widths, were analysed in order to correlate the thermal history of the process to the final microstructure of the specimens. Furthermore, the hardness and the tensile properties of the alloy processed by LPBF were quantified and compared with the data available in the literature relative to conventional manufacturing technologies.
Alessandro Carrozza; Alberta Aversa; Paolo Fino; Mariangela Lombardi. A study on the microstructure and mechanical properties of the Ti-6Al-2Sn-4Zr-6Mo alloy produced via Laser Powder Bed Fusion. Journal of Alloys and Compounds 2021, 870, 159329 .
AMA StyleAlessandro Carrozza, Alberta Aversa, Paolo Fino, Mariangela Lombardi. A study on the microstructure and mechanical properties of the Ti-6Al-2Sn-4Zr-6Mo alloy produced via Laser Powder Bed Fusion. Journal of Alloys and Compounds. 2021; 870 ():159329.
Chicago/Turabian StyleAlessandro Carrozza; Alberta Aversa; Paolo Fino; Mariangela Lombardi. 2021. "A study on the microstructure and mechanical properties of the Ti-6Al-2Sn-4Zr-6Mo alloy produced via Laser Powder Bed Fusion." Journal of Alloys and Compounds 870, no. : 159329.
Perfluoroalkyl substances (PFAS) represent one of the most recalcitrant class of compounds of emerging concern and their removal from water is a challenging goal. In this study, we investigated the removal efficiency of three selected PFAS from water, namely, perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and pefluorooctanesulfonic acid (PFOS) using a custom-built non-thermal plasma generator. A modified full factorial design (with 2 levels, 3 variables and the central point in which both quadratic terms and interactions between couple of variables were considered) was used to investigate the effect of plasma discharge frequency, distance between the electrodes and water conductivity on treatment efficiency. Then, the plasma treatment running on optimized conditions was used to degrade PFAS at ppb level both individually and in mixture, in ultrapure and groundwater matrices. PFOS 1 ppb exhibited the best degradation reaching complete removal after 30 min of treatment in both water matrices (first order rate constant 0.107 min−1 in ultrapure water and 0.0633 min−1 in groundwater), while the degradation rate of PFOA and PFHxA was slower of around 65% and 83%, respectively. During plasma treatment, the production of reactive species in the liquid phase (hydroxyl radical, hydrogen peroxide) and in the gas phase (ozone, NOx) was investigated. Particular attention was dedicated to the nitrogen balance in solution where, following to NOx hydrolysis, total nitrogen (TN) was accumulated at the rate of up to 40 mgN L−1 h−1.
Davide Palma; Dimitra Papagiannaki; Manuel Lai; Rita Binetti; Mohamad Sleiman; Marco Minella; Claire Richard. PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma. Molecules 2021, 26, 924 .
AMA StyleDavide Palma, Dimitra Papagiannaki, Manuel Lai, Rita Binetti, Mohamad Sleiman, Marco Minella, Claire Richard. PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma. Molecules. 2021; 26 (4):924.
Chicago/Turabian StyleDavide Palma; Dimitra Papagiannaki; Manuel Lai; Rita Binetti; Mohamad Sleiman; Marco Minella; Claire Richard. 2021. "PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma." Molecules 26, no. 4: 924.
Directed energy deposition is an additive manufacturing technology which usually relies on prototype machines or hybrid systems, assembled with parts from different producers. Because of this lack of standardization, the optimization of the process parameters is often a mandatory step in order to develop an efficient building process. Although, this preliminary phase is usually expensive both in terms of time and cost. The single scan approach allows to drastically reduce deposition time and material usage, as in fact only a stripe per parameters combination is deposited. These specimens can then be investigated, for example in terms of geometrical features (e.g. growth, width) and microstructure to assess the most suitable process window. In this work, Ti-6Al-4V single scans, produced by means of directed energy deposition, corresponding to a total of 50 different parameters combinations, were analyzed, focusing on several geometrical features and relative parameters correlations. Moreover, considering the susceptibility of the material to oxygen pick-up, the necessity of an additional shielding gas system was also evaluated, by comparing the specimens obtained with and without using a supplementary argon flow. A process window, which varies according to the user needs, was found together with a relationship between microstructure and process parameters, in both shielding scenarios. Graphic Abstract
Alessandro Carrozza; Federico Mazzucato; Alberta Aversa; Mariangela Lombardi; Federica Bondioli; Sara Biamino; Anna Valente; Paolo Fino. Single Scans of Ti-6Al-4V by Directed Energy Deposition: A Cost and Time Effective Methodology to Assess the Proper Process Window. Metals and Materials International 2021, 1 -13.
AMA StyleAlessandro Carrozza, Federico Mazzucato, Alberta Aversa, Mariangela Lombardi, Federica Bondioli, Sara Biamino, Anna Valente, Paolo Fino. Single Scans of Ti-6Al-4V by Directed Energy Deposition: A Cost and Time Effective Methodology to Assess the Proper Process Window. Metals and Materials International. 2021; ():1-13.
Chicago/Turabian StyleAlessandro Carrozza; Federico Mazzucato; Alberta Aversa; Mariangela Lombardi; Federica Bondioli; Sara Biamino; Anna Valente; Paolo Fino. 2021. "Single Scans of Ti-6Al-4V by Directed Energy Deposition: A Cost and Time Effective Methodology to Assess the Proper Process Window." Metals and Materials International , no. : 1-13.
Additive manufacturing (AM) is one of the processes with the most potential for producing components used in internal combustion engines and features high efficiency due to the possibility of building very complex shapes. Several drawbacks of parts produced using AM are still unresolved, like poor surface quality, the presence of internal defects and anisotropic mechanical behaviour, which all contribute to decreasing the fatigue strength compared with the material produced using conventional processes. The effect of building direction on both the macroscopic mechanical behaviour and the crack propagation mechanism of Ni‐base superalloy Inconel718 produced using AM was investigated under the combined effect of low cycle fatigue (LCF) and high temperature. The different crack growth mechanisms investigated using compact tension (CT) specimens, tested at high temperature, showed a significant difference between the two building directions. The LCF fatigue experiments also showed a significant difference in the ε‐N curves from the two directions together with a high level of scatter due to the dispersion of the defect size at the fracture origin. The dimensions of the defects (as measured using the parameter) were analysed by means of extreme value statistics and showed a significant difference between the two orientations investigated. The aim of this work is to propose a simplified approach (based on ΔJeff concepts) to estimate the fatigue life of a component produced using AM that takes into account the material variability due to the combined effect of mechanical anisotropic behaviour and the presence of defects at high‐temperature conditions.
Francesco Sausto; G. Marchese; E. Bassini; M. Calandri; S. Biamino; D. Ugues; S. Foletti; S. Beretta. Anisotropic mechanical and fatigue behaviour of Inconel718 produced by SLM in LCF and high‐temperature conditions. Fatigue & Fracture of Engineering Materials & Structures 2020, 44, 271 -292.
AMA StyleFrancesco Sausto, G. Marchese, E. Bassini, M. Calandri, S. Biamino, D. Ugues, S. Foletti, S. Beretta. Anisotropic mechanical and fatigue behaviour of Inconel718 produced by SLM in LCF and high‐temperature conditions. Fatigue & Fracture of Engineering Materials & Structures. 2020; 44 (1):271-292.
Chicago/Turabian StyleFrancesco Sausto; G. Marchese; E. Bassini; M. Calandri; S. Biamino; D. Ugues; S. Foletti; S. Beretta. 2020. "Anisotropic mechanical and fatigue behaviour of Inconel718 produced by SLM in LCF and high‐temperature conditions." Fatigue & Fracture of Engineering Materials & Structures 44, no. 1: 271-292.
Metal Additive Manufacturing and Laser Powder Bed Fusion (LPBF), in particular, have come forth in recent years as an outstanding innovative manufacturing approach. The LPBF process is notably characterized by very high solidification and cooling rates, as well as repeated abrupt heating and cooling cycles, which generate the build-up of anisotropic microstructure and residual stresses. Post-processing stress-relieving heat treatments at elevated temperatures are often required in order to release some of these stresses. The effects of 1 h–hold heat treatments at different specific temperatures (solutionizing, annealing, stress-relieve and low-temperature stress-relieve) on residual stress levels together with microstructure characterization were therefore investigated for the popular Alloy 625 produced by LPBF. The build-up of residual stress is accommodated by the formation of dislocations that produce local crystallographic misorientation within grains. Electron backscattered diffraction (EBSD) was used to investigate local misorientation by means of orientation imaging, thereby assessing misorientation or strain levels, in turn representing residual stress levels within the material. The heavily constrained as-built material was found to experience full recrystallization of equiaxed grains after solutionizing at 1150 °C, accompanied by significant drop of residual stress levels due to this grains reconfiguration. Heat treatments at lower temperatures however, even as high as the annealing temperature of 980 °C, were found to be insufficient to promote recrystallization though effective to some extent to release residual stress through apparently dislocations recovery. Average misorientation data obtained by EBSD were found valuable to evaluate qualitatively residual stress levels. The effects of the different heat treatments are discussed and suggest that the peculiar microstructure of alloys produced by LPBF can possibly be transformed to suit specific applications.
Mathieu Terner; Jiwon Lee; Giulio Marchese; Sara Biamino; Hyun-Uk Hong. Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments. Materials 2020, 13, 4643 .
AMA StyleMathieu Terner, Jiwon Lee, Giulio Marchese, Sara Biamino, Hyun-Uk Hong. Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments. Materials. 2020; 13 (20):4643.
Chicago/Turabian StyleMathieu Terner; Jiwon Lee; Giulio Marchese; Sara Biamino; Hyun-Uk Hong. 2020. "Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments." Materials 13, no. 20: 4643.
AISI 316L stainless steel samples were produced by means of laser powder-directed energy deposition using optimized building conditions with two different deposition strategies. The samples, in the as-built state, were at first characterized in terms of microstructure, hardness and residual stresses by the incremental hole-drilling strain-gauge method. The results highlighted that the deposition strategy mainly affects the residual stress values, while the material hardness value is not strongly varied. The distribution of the residual stresses along the sample height was also evaluated by measuring the stress at different distances from the building platform. Furthermore, some samples underwent a homogenizing heat treatment for 2 h at 600 and 800 °C and were characterized and compared with the as-built ones. The results showed that the suggested heat treatments allow not only a reduction in residual stresses but also the homogenization of the microstructure confirmed by comparing the variations of the Vickers hardness values along the building direction. Tensile tests were also performed on the as-built and heat-treated samples in order to investigate the effect of the heat treatment on the tensile properties of the material.
Alberta Aversa; Gabriele Piscopo; Alessandro Salmi; Mariangela Lombardi. Effect of Heat Treatments on Residual Stress and Properties of AISI 316L Steel Processed by Directed Energy Deposition. Journal of Materials Engineering and Performance 2020, 29, 6002 -6013.
AMA StyleAlberta Aversa, Gabriele Piscopo, Alessandro Salmi, Mariangela Lombardi. Effect of Heat Treatments on Residual Stress and Properties of AISI 316L Steel Processed by Directed Energy Deposition. Journal of Materials Engineering and Performance. 2020; 29 (9):6002-6013.
Chicago/Turabian StyleAlberta Aversa; Gabriele Piscopo; Alessandro Salmi; Mariangela Lombardi. 2020. "Effect of Heat Treatments on Residual Stress and Properties of AISI 316L Steel Processed by Directed Energy Deposition." Journal of Materials Engineering and Performance 29, no. 9: 6002-6013.
Ni-based superalloy components for high-temperature applications rely on the long term stability of the microstructure and mechanical properties at service temperatures. Nowadays, the production of such types of components is frequently performed via Additive Manufacturing (AM) technologies. Nevertheless, few studies are dedicated to understanding the behavior of AM Ni-based superalloys upon prolonged exposure to high temperatures. This work aims at studying the effect of prolonged thermal exposures on the microstructure and mechanical properties of Inconel 625 processed by laser powder bed fusion. Thermal exposures within the range of 600 °C and 900 °C for 200 h were performed on this material. The as-built and solution annealed Inconel 625 conditions were selected. The solution annealed state implies a complete chemical homogenization, typically recommended for working at high temperatures, whereas the initial as-built state is characterized by segregations and fine dendritic structures. Upon the studied prolonged thermal exposures, the peculiar as-built microstructure formed a higher quantity of phases with smaller dimensions with respect to the solution annealed condition under thermal exposures. The smaller phases of the as-built state resulted in similar mechanical properties evolution under different temperatures. Differently, the prolonged heat-treated solution annealed conditions exhibited more marked mechanical properties variations due to coarser phases.
Giulio Marchese; Emilio Bassini; Simone Parizia; Diego Manfredi; Daniele Ugues; Mariangela Lombardi; Paolo Fino; Sara Biamino. Role of the chemical homogenization on the microstructural and mechanical evolution of prolonged heat-treated laser powder bed fused Inconel 625. Materials Science and Engineering: A 2020, 796, 140007 .
AMA StyleGiulio Marchese, Emilio Bassini, Simone Parizia, Diego Manfredi, Daniele Ugues, Mariangela Lombardi, Paolo Fino, Sara Biamino. Role of the chemical homogenization on the microstructural and mechanical evolution of prolonged heat-treated laser powder bed fused Inconel 625. Materials Science and Engineering: A. 2020; 796 ():140007.
Chicago/Turabian StyleGiulio Marchese; Emilio Bassini; Simone Parizia; Diego Manfredi; Daniele Ugues; Mariangela Lombardi; Paolo Fino; Sara Biamino. 2020. "Role of the chemical homogenization on the microstructural and mechanical evolution of prolonged heat-treated laser powder bed fused Inconel 625." Materials Science and Engineering: A 796, no. : 140007.
This paper presents a study of the microstructure evolution due to oxidation exposure of Inconel 625 (IN625) alloy produced by Laser Powder Bed Fusion (LPBF). IN625 is a nickel-based superalloy characterized by good mechanical properties, excellent oxidation, and corrosion resistance from cryogenic temperatures up to 980 °C, allowing its wide use in various harsh environments. In order to enable the application of LPBF IN625 components at high temperatures, the oxidation properties and microstructure of as-built and post-heat treated LPBF IN625 alloy must be carefully investigated. For this reason, an extensive characterization of the oxidation behavior of the alloy in the as-built condition and after solution treatment was performed. For both these conditions, the oxidation treatments were performed at 900 °C up to 96 h. The characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and scratch test analysis. The characteristics of the oxide layer and formed phases were investigated. The as-built IN625 state presented greater oxidation resistance compared to the solutionized IN625 one. The latter condition showed a defected oxide layer with the presence of Nb and Ni oxides inside the Cr oxide layer.
Simone Parizia; Giulio Marchese; Masoud Rashidi; Massimo Lorusso; Eduard Hryha; Diego Manfredi; Sara Biamino. Effect of heat treatment on microstructure and oxidation properties of Inconel 625 processed by LPBF. Journal of Alloys and Compounds 2020, 846, 156418 .
AMA StyleSimone Parizia, Giulio Marchese, Masoud Rashidi, Massimo Lorusso, Eduard Hryha, Diego Manfredi, Sara Biamino. Effect of heat treatment on microstructure and oxidation properties of Inconel 625 processed by LPBF. Journal of Alloys and Compounds. 2020; 846 ():156418.
Chicago/Turabian StyleSimone Parizia; Giulio Marchese; Masoud Rashidi; Massimo Lorusso; Eduard Hryha; Diego Manfredi; Sara Biamino. 2020. "Effect of heat treatment on microstructure and oxidation properties of Inconel 625 processed by LPBF." Journal of Alloys and Compounds 846, no. : 156418.
This work aims to investigate the effect of the process parameters on the densification and microstructure of Inconel 939 (IN939) alloy processed by laser powder bed fusion (LPBF). IN939 is a Ni-based superalloy with high creep and corrosion resistance that can be used up to around 850 °C under load, resulting in higher operative temperatures than the ones commonly allowed for Inconel 718 and Inconel 625 alloys (around 650 °C). However, this alloy can suffer from poor weldability involving possible crack formation. In order to minimize the residual porosity and the cracking density, specific process parameters were investigated. The parameters to generate IN939 samples almost pores-free (porosity ≤0.22%) with a cracking density ≤1.36 mm/mm2 as well as samples almost crack-free (≤0.10 mm/mm2) with limited residual porosity (≤0.89%) were determined. The microstructure revealed fine dendritic/cellular structures with the formation of sub-micrometric phases. A high concentration of these phases was also found along the intergranular cracks, suggesting that their presence, coupled to the high thermal stresses, can be the primary reason for crack formation during the LPBF process.
Giulio Marchese; Simone Parizia; Abdollah Saboori; Diego Manfredi; Mariangela Lombardi; Paolo Fino; Daniele Ugues; Sara Biamino. The Influence of the Process Parameters on the Densification and Microstructure Development of Laser Powder Bed Fused Inconel 939. Metals 2020, 10, 882 .
AMA StyleGiulio Marchese, Simone Parizia, Abdollah Saboori, Diego Manfredi, Mariangela Lombardi, Paolo Fino, Daniele Ugues, Sara Biamino. The Influence of the Process Parameters on the Densification and Microstructure Development of Laser Powder Bed Fused Inconel 939. Metals. 2020; 10 (7):882.
Chicago/Turabian StyleGiulio Marchese; Simone Parizia; Abdollah Saboori; Diego Manfredi; Mariangela Lombardi; Paolo Fino; Daniele Ugues; Sara Biamino. 2020. "The Influence of the Process Parameters on the Densification and Microstructure Development of Laser Powder Bed Fused Inconel 939." Metals 10, no. 7: 882.
The hot working behaviour of additively manufactured Ti–6Al–4V pre-forms by Electron Beam Melting (EBM) has been studied at temperatures of 1000–1200 °C and strain rates of 0.001–1 s−1. As a reference, a wrought Ti–6Al–4V alloy was also analyzed as same as the EBM one. In order to investigate the hot working behaviour of these samples, all the data evaluations were carried out step by step, and the stepwise procedure was discussed. No localized strain as a consequence of shear band formation was found in the samples after the hot compression. The flow stress curves of all the samples showed peak stress at low strains, followed by a regime of flow softening with a near-steady-state flow at large strains. Interestingly, it is found that the initial microstructure and porosity content as well as the chemistry of material (e.g. oxygen content) as being possible contributors to the lower level of flow stress that could be beneficial from the industrial point of view. The flow softening mechanism(s) were discussed in detail using the microstructure of the specimens before and after the hot deformation. Dynamic Recrystalization (DRX) could also explain the gentle oscillation in the appearance of the flow softening curves of the EBM samples. Moreover, the hot working analysis indicated that the activation energy for hot deformation of as-built EBM Ti–6Al–4V alloy was calculated as ~193.25 kJ/mol, which was much lower than the wrought alloy (229.34 kJ/mol). These findings can shed lights on a new integration of metal Additive Manufacturing (AM) and thermomechanical processing. It is very interesting to highlight that through this new integration, it would be possible to reduce the forging steps and save more energy and materials with respect to the conventional routes.
Abdollah Saboori; Ata Abdi; Seyed Ali Fatemi; Giulio Marchese; Sara Biamino; Hamed Mirzadeh. Hot deformation behavior and flow stress modeling of Ti–6Al–4V alloy produced via electron beam melting additive manufacturing technology in single β-phase field. Materials Science and Engineering: A 2020, 792, 139822 .
AMA StyleAbdollah Saboori, Ata Abdi, Seyed Ali Fatemi, Giulio Marchese, Sara Biamino, Hamed Mirzadeh. Hot deformation behavior and flow stress modeling of Ti–6Al–4V alloy produced via electron beam melting additive manufacturing technology in single β-phase field. Materials Science and Engineering: A. 2020; 792 ():139822.
Chicago/Turabian StyleAbdollah Saboori; Ata Abdi; Seyed Ali Fatemi; Giulio Marchese; Sara Biamino; Hamed Mirzadeh. 2020. "Hot deformation behavior and flow stress modeling of Ti–6Al–4V alloy produced via electron beam melting additive manufacturing technology in single β-phase field." Materials Science and Engineering: A 792, no. : 139822.
Blown powder additive manufacturing technologies are not restricted to the use of a process chamber. This feature allows to build larger components with respect to conventional powder bed processes. This peculiarity is mostly promising for manufacturing large components or repairing/rebuilding parts of large systems. The main downside of using an open environment, even if a protective shielding gas system is adopted, is the lack of control of process atmosphere. This is particularly critical for titanium alloys which are very sensitive to oxygen/nitrogen pick-up; they have a detrimental effect on ductility, by causing embrittlement and possibly leading to the formation of cracks. It is then important to address how environmental factors, such as process atmosphere and platform temperature, impact not only on the processability but also on the final component properties, both from a compositional and mechanical point of view. The correlations between these environmental factors and microstructure, interstitials content, grain size, and hardness were investigated. Moreover, the Hall–Petch equation was then adopted to additive manufacturing microstructures, characterized by a columnar grain morphology, and used to further investigate the relationship intercurring between grains and hardness and how different microstructures might influence this correlation.
Alessandro Carrozza; Alberta Aversa; Federico Mazzucato; Mariangela Lombardi; Sara Biamino; Anna Valente; Paolo Fino. An Innovative Approach on Directed Energy Deposition Optimization: A Study of the Process Environment’s Influence on the Quality of Ti-6Al-4V Samples. Applied Sciences 2020, 10, 4212 .
AMA StyleAlessandro Carrozza, Alberta Aversa, Federico Mazzucato, Mariangela Lombardi, Sara Biamino, Anna Valente, Paolo Fino. An Innovative Approach on Directed Energy Deposition Optimization: A Study of the Process Environment’s Influence on the Quality of Ti-6Al-4V Samples. Applied Sciences. 2020; 10 (12):4212.
Chicago/Turabian StyleAlessandro Carrozza; Alberta Aversa; Federico Mazzucato; Mariangela Lombardi; Sara Biamino; Anna Valente; Paolo Fino. 2020. "An Innovative Approach on Directed Energy Deposition Optimization: A Study of the Process Environment’s Influence on the Quality of Ti-6Al-4V Samples." Applied Sciences 10, no. 12: 4212.
Additive manufacturing (AM) processes allow producing the complex components in a layerwise fashion. The complexity includes the design of lighter and stronger components by using lattice structures that can be quickly realized through AM technologies. However, the mechanical behaviour of lattice structures is not completely known, especially in the post-treated state. Thus, this work aims to explore the effect of post-treatment on the compressive strength of specimens with lattice structures. The samples are produced using Ti-6Al-4V powder processed by Electron Beam Melting (EBM). The outcomes of this work confirm the correlation between the heat treatment and final mechanical properties.
Manuela Galati; Abdollah Saboori; Sara Biamino; Flaviana Calignano; Mariangela Lombardi; Giovanni Marchiandi; Paolo Minetola; Paolo Fino; Luca Iuliano. Ti-6Al-4V lattice structures produced by EBM: Heat treatment and mechanical properties. Procedia CIRP 2020, 88, 411 -416.
AMA StyleManuela Galati, Abdollah Saboori, Sara Biamino, Flaviana Calignano, Mariangela Lombardi, Giovanni Marchiandi, Paolo Minetola, Paolo Fino, Luca Iuliano. Ti-6Al-4V lattice structures produced by EBM: Heat treatment and mechanical properties. Procedia CIRP. 2020; 88 ():411-416.
Chicago/Turabian StyleManuela Galati; Abdollah Saboori; Sara Biamino; Flaviana Calignano; Mariangela Lombardi; Giovanni Marchiandi; Paolo Minetola; Paolo Fino; Luca Iuliano. 2020. "Ti-6Al-4V lattice structures produced by EBM: Heat treatment and mechanical properties." Procedia CIRP 88, no. : 411-416.
Directed energy deposition (DED) as a metal additive manufacturing technology can be used to produce or repair complex shape parts in a layer-wise process using powder or wire. Thanks to its advantages in the fabrication of net-shape and functionally graded components, DED could attract significant interest in the production of high-value parts for different engineering applications. Nevertheless, the industrialization of this technology remains challenging, mainly because of the lack of knowledge regarding the microstructure and mechanical characteristics of as-built parts, as well as the trustworthiness/durability of engineering parts produced by the DED process. Hence, this paper reviews the published data about the microstructure and mechanical performance of DED AISI 316L stainless steel. The data show that building conditions play key roles in the determination of the microstructure and mechanical characteristics of the final components produced via DED. Moreover, this review article sheds light on the major advancements and challenges in the production of AISI 316L parts by the DED process. In addition, it is found that in spite of different investigations carried out on the optimization of process parameters, further research efforts into the production of AISI 316L components via DED technology is required.
Abdollah Saboori; Alberta Aversa; Giulio Marchese; Sara Biamino; Mariangela Lombardi; Paolo Fino. Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review. Applied Sciences 2020, 10, 3310 .
AMA StyleAbdollah Saboori, Alberta Aversa, Giulio Marchese, Sara Biamino, Mariangela Lombardi, Paolo Fino. Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review. Applied Sciences. 2020; 10 (9):3310.
Chicago/Turabian StyleAbdollah Saboori; Alberta Aversa; Giulio Marchese; Sara Biamino; Mariangela Lombardi; Paolo Fino. 2020. "Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review." Applied Sciences 10, no. 9: 3310.
Laser-Directed Energy Deposition was used to produce AISI 316 L stainless steel samples. The effect of the protective atmosphere on the microstructure and mechanical performance of AISI 316 L deposited parts was investigated by building samples using a simple nitrogen shielding gas or using a nitrogen-filled build chamber. The effect of the different processing conditions on the microstructure was evaluated by X-ray analysis, optical and scanning electron microscopy. Only slight differences in the cellular dendrites morphology of samples built under different protective atmosphere conditions were observed. However, the presence of oxides was monitored too: the oxides composition and area fraction were analysed and compared by image analyses, and it was demonstrated that the protective atmosphere mainly affects the oxides dimensions. The effect of the oxides and nitrogen pick-up on the mechanical performance of the samples was evaluated by tensile tests. The results revealed that the nitrogen-filled build chamber allowed the achievement of slightly higher tensile strength and elongation with respect to the other processing conditions as a consequence of the reduced size of the oxide inclusions.
Alberta Aversa; Abdollah Saboori; Erica Librera; Michele de Chirico; Sara Biamino; Mariangela Lombardi; Paolo Fino. The role of Directed Energy Deposition atmosphere mode on the microstructure and mechanical properties of 316L samples. Additive Manufacturing 2020, 34, 101274 .
AMA StyleAlberta Aversa, Abdollah Saboori, Erica Librera, Michele de Chirico, Sara Biamino, Mariangela Lombardi, Paolo Fino. The role of Directed Energy Deposition atmosphere mode on the microstructure and mechanical properties of 316L samples. Additive Manufacturing. 2020; 34 ():101274.
Chicago/Turabian StyleAlberta Aversa; Abdollah Saboori; Erica Librera; Michele de Chirico; Sara Biamino; Mariangela Lombardi; Paolo Fino. 2020. "The role of Directed Energy Deposition atmosphere mode on the microstructure and mechanical properties of 316L samples." Additive Manufacturing 34, no. : 101274.
The authors wish to make the following correction to the paper
Emilio Bassini; Giulio Cattano; Giulio Marchese; Sara Biamino; Daniele Ugues; Mariangela Lombardi; Gianfranco Vallillo; Benjamin Picqué. Correction: Bassini, E.; et al. Study of the Effects of Aging Treatment on Astroloy Processed via Hot Isostatic Pressing. Materials 2019, 12, 1517. Materials 2020, 13, 1831 .
AMA StyleEmilio Bassini, Giulio Cattano, Giulio Marchese, Sara Biamino, Daniele Ugues, Mariangela Lombardi, Gianfranco Vallillo, Benjamin Picqué. Correction: Bassini, E.; et al. Study of the Effects of Aging Treatment on Astroloy Processed via Hot Isostatic Pressing. Materials 2019, 12, 1517. Materials. 2020; 13 (8):1831.
Chicago/Turabian StyleEmilio Bassini; Giulio Cattano; Giulio Marchese; Sara Biamino; Daniele Ugues; Mariangela Lombardi; Gianfranco Vallillo; Benjamin Picqué. 2020. "Correction: Bassini, E.; et al. Study of the Effects of Aging Treatment on Astroloy Processed via Hot Isostatic Pressing. Materials 2019, 12, 1517." Materials 13, no. 8: 1831.
The aim of this study is to define the process parameters to build components for industrial applications in A357 alloy by Laser Powder Bed Fusion (LPBF) and to evaluate the effects of post-processing heat treatments on the microstructure and mechanical properties in order to obtain the highest hardness and strength. First, process parameters values were defined to obtain full dense components with highest productivity. Then samples were built for microstructural, hardness, and tensile strength investigation in different conditions: as-built, after a stress-relieving treatment, and after a T6 precipitation hardening treatment. For this latest treatment, different time and temperatures for solution and ageing were investigated to find the best in terms of final hardness achievable. It is demonstrated that samples in A357 alloy can be successfully fabricated by LPBF with a density of 99.9% and a mean hardness value achievable of 116 HV0.1, in as-built condition. However, for production purposes, it is fundamental to reduce the residual stresses typical of LPBF. It was shown that a similar hardness value could be obtained after a stress-relieving treatment followed by a proper T6 treatment, together with a coarser but more isotropic microstructure.
Massimo Lorusso; Francesco Trevisan; Flaviana Calignano; Mariangela Lombardi; Diego Manfredi. A357 Alloy by LPBF for Industry Applications. Materials 2020, 13, 1488 .
AMA StyleMassimo Lorusso, Francesco Trevisan, Flaviana Calignano, Mariangela Lombardi, Diego Manfredi. A357 Alloy by LPBF for Industry Applications. Materials. 2020; 13 (7):1488.
Chicago/Turabian StyleMassimo Lorusso; Francesco Trevisan; Flaviana Calignano; Mariangela Lombardi; Diego Manfredi. 2020. "A357 Alloy by LPBF for Industry Applications." Materials 13, no. 7: 1488.
In this work, 316L cubes were produced by Directed Energy Deposition (DED) process. To evaluate the effect of deposition patterns on the microstructure, mechanical performance and residual stress of 316L samples, two different deposition strategies are selected (67° and 90°). The general microstructure is revealed, and then the effect of deposition pattern on the microstructure of 316L alloy is evaluated through the Primary Cellular Arm Spacing (PCAS) analysis. The cooling rate in each sample is estimated according to the PCAS values. Interestingly, it is found that by increasing the rotation angle per layer, the PCAS value decreases as a consequence of increment in the cooling rate. On the other hand, in both cases, by increasing the distance from the substrate, due to the changes in cooling mechanisms, the cooling rate at first decreases and then at the last layers increases again. The phase composition analysis of 316L samples confirms the predictions that suggested the presence of residual δ-ferrite in the final microstructure. In fact, the final microstructure of samples is characterized by austenitic dendrites together with some residual δ-ferrite in the interdendritic regions. Moreover, the microstructural evaluations exhibit that during the DED process, some metallic inclusions are formed within the 316L samples that consequently deteriorates their mechanical properties. Tensile results show that the samples with 90° rotation per layer have a better mechanical performance such as slightly higher ultimate tensile strength and almost 35% higher elongation to fracture, mainly owing to their finer microstructure and slightly less oxide content. However, in both cases, the elongation of the 316L samples is lower than the typical elongation of this material produced via DED. This discrepancy is found to be as a result of higher inclusions contents in the samples produced in this work with respect to those of literature. Lastly, it is found that the residual stresses on the top surfaces are similar for both deposition patterns, although higher stress values are observed on the lateral surfaces of the cubes produce using the 90° rotation per layer.
Abdollah Saboori; Gabriele Piscopo; Manuel Lai; Alessandro Salmi; Sara Biamino. An investigation on the effect of deposition pattern on the microstructure, mechanical properties and residual stress of 316L produced by Directed Energy Deposition. Materials Science and Engineering: A 2020, 780, 139179 .
AMA StyleAbdollah Saboori, Gabriele Piscopo, Manuel Lai, Alessandro Salmi, Sara Biamino. An investigation on the effect of deposition pattern on the microstructure, mechanical properties and residual stress of 316L produced by Directed Energy Deposition. Materials Science and Engineering: A. 2020; 780 ():139179.
Chicago/Turabian StyleAbdollah Saboori; Gabriele Piscopo; Manuel Lai; Alessandro Salmi; Sara Biamino. 2020. "An investigation on the effect of deposition pattern on the microstructure, mechanical properties and residual stress of 316L produced by Directed Energy Deposition." Materials Science and Engineering: A 780, no. : 139179.
Post-processing treatments of metallic materials play a key role in the achievement of high mechanical and surface properties of the final components and in the optimization of their behavior in service conditions
Mariangela Lombardi. Post-Processing Improvements for Mechanical, Microstructure, and Surface Properties of Steel. Metals 2020, 10, 230 .
AMA StyleMariangela Lombardi. Post-Processing Improvements for Mechanical, Microstructure, and Surface Properties of Steel. Metals. 2020; 10 (2):230.
Chicago/Turabian StyleMariangela Lombardi. 2020. "Post-Processing Improvements for Mechanical, Microstructure, and Surface Properties of Steel." Metals 10, no. 2: 230.
Banded and discontinuous eutectic microstructures were found in melt quenched ribbons and laser melted single tracks of an Al-3%wt Er alloy, respectively. The bands occurring in ribbons are made of alternate primary α-Al phase and eutectic. Their formation is well described by the Han-Trivedi model for banding in alloy solidification. Microstructure fluctuations between fibrous and discontinuous eutectic are seen in laser melted single tracks on the same length scale of bands due to change in local temperature gradient. Overall, various transitions in phase morphology are found in thin zones of material constituting a valuable guideline for interpretation of the solidification mechanism. Nano-indentation tests show that the fine microstructures induce substantial hardening.
Dario Gianoglio; Silvia Marola; Livio Battezzati; Alberta Aversa; Federico Bosio; Mariangela Lombardi; Diego Manfredi; Massimo Lorusso. Banded microstructures in rapidly solidified Al-3 wt% Er. Intermetallics 2020, 119, 106724 .
AMA StyleDario Gianoglio, Silvia Marola, Livio Battezzati, Alberta Aversa, Federico Bosio, Mariangela Lombardi, Diego Manfredi, Massimo Lorusso. Banded microstructures in rapidly solidified Al-3 wt% Er. Intermetallics. 2020; 119 ():106724.
Chicago/Turabian StyleDario Gianoglio; Silvia Marola; Livio Battezzati; Alberta Aversa; Federico Bosio; Mariangela Lombardi; Diego Manfredi; Massimo Lorusso. 2020. "Banded microstructures in rapidly solidified Al-3 wt% Er." Intermetallics 119, no. : 106724.