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1
Chen, Qiguang. "Fatigue and fracture in Inconel 718-copper-Inconel 718 explosion-bonded composites". Thesis, Massachusetts Institute of Technology, 1990. https://hdl.handle.net/1721.1/128798.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1990.Title as it appears in the M.I.T. Graduate List, Feb. 1990: Fatigue and fracture in explosion-bonded Inconel 718-copper-Inconel 718 composites.
Includes bibliographical references.
by Chikuang Chen.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1990.
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Zhao, Mengxiong. "Ultrasonic fatigue study of Inconel 718". Thesis, Paris 10, 2018. http://www.theses.fr/2018PA100063/document.
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L’Inconel 718 est utilisé dans les disques de turbine des moteurs d’avion, de par sa haute résistance à la corrosion, à l’oxydation, au fluage et sa haute résistance mécanique à très haute température. Le nombre total de cycles de ces composants mécaniques s’élève à 109~1010 durant sa vie. Ils subissent des chargements de grande amplitude à faible fréquence, comme les forces centrifuges ou les contraintes thermiques mais aussi des chargements de faibles amplitudes à très haute fréquence, du aux vibrations des pales. Dans ce travail, on se propose d’étudier la fatigue à très grand nombre de cycles (VHCF) de l’Inconel 718 en utilisant des machines de fatigue ultrasonique, fonctionnant à 20KHz. Le système d’acquisition utilise des cartes NI et le logiciel LabView pour superviser la fréquence, la température, les déplacements durant toute la durée des tests. Des capteurs laser Keyence utilisant deux sondes pour les faces supérieure et inférieure de l’éprouvette permettent de capturer la fréquence et les modes de vibration. La différence entre les valeurs moyennes mesurées permet d’accéder à l’allongement de l’éprouvette, dû à l’auto-échauffement.3 types de matériaux avec différents traitements thermiques, AR, DA et DAHQ de l’ONERA et SAFRAN sont comparés. La différence au niveau de la taille de grain, de la phase, des précipités, … est analysée par micrographie métallographique en utilisant un microscope optique (MO) et un microscope électronique à balayage (MEB). Le comportement en traction quasi-statique et sous chargement cyclique contrainte-déformation est aussi proposé. La transition entre durcissement et adoucissement cyclique apparait à l’issue du traitement thermique. Finalement, les surfaces de ruptures sont observées en utilisant des caméras optiques et un MEB afin d’identifier les mécanismes de ruptures de l’Inconel 718 dans le domaine de la fatigue à très grand nombre de cyclesInconel 718 is widely used in turbine disk of aeronautic engines, due to its high resistance to corrosion, oxidation, thermal creep deformation and high mechanical strength at elevated temperature. The total cycle of these mechanical components is up to 109~1010 during its whole lifetime. It endures high-amplitude low-frequency loading including centrifugal force or thermal stress, and also low-amplitude high-frequency loading came from vibration of blade.In this work, the very high cycle fatigue (VHCF) behaviour of Inconel 718 with self-heating phenomenon without any cooling is studied using ultrasonic fatigue system at 20KHz. Acquisition system is improved using NI capture card with LabView for monitoring the frequency, temperature, displacement and so on during all the tests. Keyence laser sensor with two probes at the top and bottom surfaces of the specimens is used to reveal the frequency and vibration mode. The difference of mean values between these two probes is the elongation of the specimen caused by self-heating phenomenon.Three sets of materials with different heat treatment, As-Received (AR), Directly Aged (DA) and Directly Aged High Quality (DAHQ) from ONERA and SAFRAN are compared. The difference of grain size, phase, precipitate particle, etc. is investigated by metallographic micrograph using optical microscope (OM) and scanning electron microscope (SEM). Quasi-static uniaxial tensile property and cyclic stress-strain response is also proposed. The transition from cyclic hardening to cyclic softening appears after aged heat treatment. Finally, fracture surfaces are observed using optical camera and scanning electron microscope in order to identify the mechanism of fracture of Inconel 718 in the VHCF domain
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Knock, Nathaniel Oscar. "CHARACTERIZATION OF INCONEL 718: USING THE GLEEBLE AND VARESTRAINT TESTING METHODS TO DETERMINE THE WELDABILITY OF INCONEL 718". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/396.
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Nickel based superalloys were developed to withstand the severe thermal and mechanical environment associated with rocket propulsion systems and jet engines. In many alloy systems the strength of a component rapidly deteriorates as the operating temperature increases. Nickel based superalloys, however, retain strength over a range of temperatures which includes the operating range for many propulsion systems. This improved performance is accomplished by a combination of solid-solution strengthening, precipitation strengthening and grain-boundary strengthening. Furthermore, super-alloy systems are designed for ease of fabrication, to include machining, welding and heat treating. Inconel 718 was developed to overcome problems with post-weld cracking that were common in precipitation hardened nickel based superalloys strengthened by γ’. Inconel 718 is strengthened by γ’’ and is less sensitive to cracking during post-weld thermal treatment. However, in some cases, compositional changes which improved the behavior of these alloys during stress relief actually led to greater difficulty during the joining process.
Many approaches have been used to determine the hot-cracking sensitivity of Inconel 718. Historically, two approaches have been particularly valuable because of their repeatability, their ability to compare different alloy systems and their verisimilitude to actual fabrication. These are the Gleeble hot-ductility test and the Variable-Restraint (Varestraint) weld test. Varestraint samples were prepared as per standard preparation techniques and tested longitudinally with a GTAW. At a predetermined location a strain was applied perpendicular to weld direction. The applied strain varied from 0.25%, 0.5%, 1.0%, 2.0%, and 4.0%. The Inconel 718 yielded a maximum crack length of 0.6 mm with a saturation strain of 2.0%. Both the total crack length and the number of cracks did not have a saturation strain.
Gleeble samples were prepared from rod stock and tested with standard methodology to determine the characteristic temperatures: nil ductility, nil strength, and ductility recovery temperature of Inconel 718. The samples were tested at various pull temperatures on-heating until the nil strength temperature then tested on-cooling with the nil strength temperature acting as the peak temperature. The nil strength temperature was 2273°F, nil ductility temperature was 2182°F, and the ductility recovery temperature was 1925°F.
Both the Varestraint and Gleeble results were compared with relevant literature to determine the weldability of the Inconel 718. Four criteria were used to determine the weldability of Inconel 718 and in three of the four tests; the Inconel 718 had equal to or greater weldability than the compared materials. In the fourth test, the Inconel 718 demonstrated lower weldability than the compared alloy systems, however, Inconel 718 operates in different conditions specifically, the high temperature and pressure conditions mentioned above.
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Tavakoli, Manshadi Salar. "Laser assisted machining of Inconel 718 superalloy". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40803.
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This research work assesses the effect of Laser Assisted Machining (LAM) on the machinability of Inconel 718 using a triple layer coated carbide and a sialon ceramic tool. This study was motivated by issues related to poor machinability of IN718 under conventional machining operations. In this work a focused Nd:YAG laser beam was used as a localized heat source to thermally soften the workpiece prior to material removal. Finishing operations were assumed throughout the experiments. Optimization screening tests were performed over a wide range of cutting speeds (ranging from 100 to 500 m/min) and feeds (ranging from 0.125 to 0.5 mm/rev). Results showed a significant drop in all three components of cutting force when thermal softening caused by the laser power was in effect. These tests yielded the optimum cutting speed and feed to be 200 m/min and 0.25 mm/rev for the coated carbide and 300 m/min and 0.4 mm/rev for the ceramic tool. Under these optimum conditions tool life tests were carried out. Drastic increase in terms of the material removal rate (MRR) was demonstrated under LAM conditions as compared to conventional machining. A nearly %300 increase in MRR was established for the coated carbide tool while slightly reducing tool life, mainly because the coatings offering thermal and wear protection could not withstand the high temperatures associated with LAM. Nearly %800 increase in MRR for the ceramic tool was achieved while improving tool life (about %50). In all cases, improvements in surface finish and surface integrity were observed. The dominant mode of tool failure was observed to be average flank wear for all tools tested. However, the coated carbide tool exhibited signs of chipping and flaking in the coatings. The morphology of the chips produced was analyzed and it was shown that temperature and increased chip thickness were the main causes of transition from steady state to shear localized chip structure. Shear localized or sawtooth chips tended toCette recherche évalue l'effet de l’usinage assisté par Laser (UAL) sur l’usinabilité d'Inconel 718 en utilisant deux outils : Le premier est enrobé d’une triple couche de carbure et le second est en céramique sialon. Cette étude a été motivée par la difficulté d’usiner IN718 conventionnellement. Dans ce travail, un rayon laser Nd:YAG a été utilisé comme une source de chaleur localisée pour adoucir thermiquement la pièce avant l'usinage. Les expériences représentaient les opérations de finitions. Une optimisation a été exécutée à travers une sélection unitaire pour une large gamme de vitesses de coupes (aux limites de 100 à 500 m/min) et de vitesses d’avance (aux limites de 0.125 à 0.5 mm/rév). Les résultats ont manifesté une réduction significative dans toutes les trois composantes de la force de coupe quand l'adoucissement thermique provoqué par le laser était mis en effet. D’après les tests, les valeurs optimales de vitesse de coupe et d’avance sont 200 m/min et 0.25 mm/rév pour l’outil avec la couche de carbure et 300 m/min et 0.4 mm/rév pour l’outil en céramique. Dans ces conditions optimales, des épreuves de tenue d’outils ont été réalisées. Une augmentation du taux d’enlèvement de matière a été démontrée lors de l’application de l’UAL en comparaison à l’usinage conventionnel. Une augmentation dans le taux d’enlèvement de matière de 300% a été établie pour l’outil enrobé de carbure avec une légère réduction en tenue d’outil. La raison de cette réduction est le fait que ces couches qui offrent une protection thermique et une résistance d’usure ne pouvaient pas résister aux températures élevées associées à l’UAL. Une augmentation de 800% dans le taux d’enlèvement de matière a été accomplie pour l’outil en céramique avec une amélioration de tenue d’outils d’environ 50%. Dans tous les cas, une amélioration de l’intégrité de la surface à ét
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Yang, Libin. "Modelling of the inertia welding of Inconel 718". Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/760/.
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In this study, the inertia welding process was studied by both an FEM model and three analytical models. The thermal analysis shows that there is a steep temperature gradient near the mating surface, which is the cause for the existence of a band of high hydrostatic stress near the weld line. The holding effect of this high static stress is the reason for the presence of the very soft material at the welding interface. The models were used to predict the displacement of the weld line (upset) with a lambda model to describe the constitutive relation of IN718 at high temperature. The results from the different models are in broad agreement. The shear stress induced by friction at the interface is found to enlarge the upset value; its effect must be taken into account if the upset is to be predicted accurately. The extrusion of the burr during the last second of the welding is a direct result of the quick stop of the rotating part due to the balance of the momentum, which is clearly explained by the analytical mechanical model put forward in this work.
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Chang, Min Carleton University Dissertation Engineering Mechanical. "Damage tolerance of Inconel 718 turbine disc material". Ottawa, 1991.
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Deng, Dunyong. "Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties". Licentiate thesis, Linköpings universitet, Konstruktionsmaterial, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-144491.
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Additive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome. Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases λ’/λ’’ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships. The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments. For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture. Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is “work-hardened” by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can minimize this difference. Results from this licentiate thesis provide the basis for the further research on the cyclic mechanical properties of EBM and SLM IN718, which would be the focus of following phase of the Ph.D. research.Information about opponent and seminar are missing.
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Cazic, Ivan. "Coaxial laser wire additive manufacturing of Inconel 718". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0113.
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L'utilisation de l'alliage Inconel 718 en fabrication additive a fait l'objet de nombreuses études au cours des dernières années. Il est rapidement apparu que le contrôle de la morphologie et la taille des grains se formant durant la solidification constitue un véritable défi. Notre travail s'attache à le relever dans le cas de la technologie laser-fil coaxial en apportant une meilleure compréhension de la formation des microstructures, notamment des conditions d'apparition de grains équiaxes fins observés en fond de bain de fusion. En premier lieu, la stabilité du procédé ainsi que les aspects thermiques ont été étudiés, en lien avec la solidification. Ainsi, grâce à l'imagerie rapide et l'imagerie thermique, nous avons pu estimer les conditions de solidification en fond de bain. Dans un second temps, nous avons analysé par EBSD les grains équiaxes et révélé qu'ils sont très souvent regroupés en amas multi-maclés présentant une symétrie icosaédrique. Nous proposons que cette organisation particulière est la signature d'un mécanisme «Icosahedral Short Range Order mediated nucleation» (ISRO), qui serait favorisé par les vitesses de refroidissement élevées imposées par le procédé d'une part, et par des enrichissements locaux du liquide en fond de bain lors de la fusion de la couche précédente d'autre part. Nous avons donc caractérisé finement les zones équiaxes par MEB et MET. Nous avons identifié la présence de carbures TiC au sein des amas multi-maclés et nous avons mis en évidence un fort enrichissement local en Nb autour des carbures par EDS. Nous avons pu identifier la phase Nb2Ni à la surface d'un TiC qui requiert une composition locale importante en Nb pour apparaître. À partir de ces observations nous proposons un scenario possible pour l'apparition des grains équiaxes fins dans l'Inconel 718 déposé par la technologie laser-fil coaxial. Les TiC y joueraient un rôle important en capturant les éléments minoritaires lors la refonte, et en promouvant l'apparition locale d'amas icosaédriques dans le liquide qui favoriseraient la germination de grains dont les orientations relatives reflèteraient cet ordre icosaédriqueThe use of Inconel 718 alloy in additive manufacturing has been the subject of numerous studies in recent years. It has appeared early that the control of the morphology and size of the grains forming during solidification is a formidable challenge. Our work aims to address this challenge in the case of coaxial laser wire technology by providing a better understanding of the formation of microstructures, including the conditions for the appearance of fine equiaxed grains observed at the bottom of the melt pools.First, the stability of the process as well as the thermal aspects have been investigated, in connection with solidification. Thanks to fast imaging and thermal imaging, we have been able to estimate the solidification conditions at the bottom of the bath.In a second step, we have analyzed by EBSD the equiaxed zones and we have observed that they are very often clustered with twin relations compliant with some icosahedral symmetry. It is proposed that this particular organization is the signature of an "Icosahedral Short Range Order mediated nucleation" (ISRO) mechanism, which would be favored by the high cooling rates imposed by the process on the one hand, and by local enrichments of the liquid at the bottom of the melt pool during the melting of the previous layer on the other hand.We have therefore characterized the equiaxed zones by SEM and TEM. We have identified TiC carbides in the grain clusters and we have highlighted a strong local enrichment in Nb around the carbides by EDS. We have been able to identify Nb2Ni at the surface of a TiC carbide which requires a high local Nb composition to appear.From these observations we propose a possible scenario for the appearance of fine equiaxed grains in Inconel 718 deposited by the coaxial laser wire technology. TiC would play an important role by capturing minority elements during remelting, and by promoting the local appearance of icosahedral clusters in the liquid that would favor the nucleation of grains whose relative orientations would reflect this icosahedral order
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Gustafsson, David. "High temperature fatigue crack propagation behaviour of Inconel 718". Doctoral thesis, Linköpings universitet, Hållfasthetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85934.
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The overall objective of this work has been to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the nickel-based superalloy Inconel 718. The fatigue crack propagation behaviour under high temperature hold times has been studied. Firstly, the main fatigue crack propagation phenomena have been investigated with the aim of setting up a basis for fatigue crack propagation modelling. Secondly, modelling of the observed behaviour has been performed. Finally, the constitutive behaviour of the material has been studied, where focus has been placed on trying to describe the mean stress relaxation and initial softening of the material under intermediate temperatures. This thesis is divided into two parts. The first part describes the general framework, including basic observed fatigue crack propagation behaviour of the material when subjected to hold times at high temperature as well as a background for the constitutive modelling of mean stress relaxation. This framework is then used in the second part, which consists of the seven included papers.
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Gustafsson, David. "Constitutive and fatigue crack propagation behaviour of Inconel 718". Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-72610.
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In this licentiate thesis the work done in the TURBO POWER project Influence of high temperature hold times on the fatigue life of nickel-based superalloys will be presented. The overall objective of this project is to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the nickel-based superalloy Inconel 718. Firstly, the constitutive behaviour of the material has been been studied, where focus has been placed on trying to describe the mean stress relaxation and initial softening of the material under intermediate temperatures. Secondly, the fatigue crack propagation behaviour under high temperature hold times has been studied. Focus has here been placed on investigating the main fatigue crack propagation phenomena with the aim of setting up a basis for fatigue crack propagation modelling. This thesis is divided into two parts. The first part describes the general framework, including basic constitutive and fatigue crack propagation behaviour as well as a theoretical background for the constitutive modelling of mean stress relaxation. This framework is then used in the second part, which consists of the four included papers.
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Bach, H. T., T. A. Saleh, S. A. Maloy, O. Anderoglu, T. J. Romero, M. A. Connors, C. T. Kelsey, E. R. Olivas i K. D. John. "Post irradiation evaluation of inconel alloy 718 beam window". Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166275.
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Introduction
Annealed Inconel 718 alloy was chosen for the beam window at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF) [1]. The window was replaced after 5 years of operation. Mechanical properties and microstructure changes were measured to assess its expected lifetime.
Material and Methods
A cutting plan was developed based on the IPF rasterred beam profile (FIG. 1). 3-mm OD samples were cut out from the window and thinned to 0.25-mm thick. Shear punch tests were per-formed at 25 °C on 21 samples to quantify shear yield, ultimate shear stress, and ductility. From 1-mm OD, 0.25-mm thick shear punched out disks, 4 TEM specimens of ~30×10×2 μm were obtained using standard FIB lift-out techniques. TEM was performed on an FEI Tecnai TF30-FEG operating at 300 kV.
Results and Conclusions
TABLE 1 shows MCNPX tally results of accumulated dpa, He and H content from both protons and neutrons fluences and ANSYS steady-state irradiation temperature for the 3-mm OD samples [2]. These peak values are at the peak density of Typically increases in shear yield and shear maximum stress occur with increasing dose. In this case, highest shear yield and ultimate stress was on the lowest dose samples at the outer edge (FIG. 2).
Optical microscopy images of the fracture surfaces on the shear punched out disks show no significant change in the fracture mode or reduction in ductility in the un-irradiated, high and low dose irradiated samples.
One un-irradiated and 4 irradiated samples (5, E, 16 and 19) were selected for TEM analysis. Figure 3 shows bright field TEM images of an un-irradiated, high and low dose irradiated samples.
Un-irradiated sample shows some dislocations and some large precipitates. The high dose sample #5 (~11 dpa, 122 oC) shows small loops and dislocations (left and center images) and no γ\' or γ\'\' precipitates in SAD from z = [011] (right image). Low dose sample #19 (~0.7 dpa, 40 oC) shows a high density of dislocation loops (left image), high density of H/He bubbles (center image) and presence of γ\'\' precipitates in SAD from z = [011] (right image).
Radiation induced-hardening is highest at the low dose region in the outer most edge. The hardening from γ\'\' precipitates is determined to be more pronounced than that from trapped bubbles. The lack of significant hardening in the highest dose region is attributed to a lower dis-location density and no γ” precipitates or bubbles [3]. Identification of H or He bubbles and the higher accumulation of these bubbles in the low dose region (no direct beam hitting) warrant further studies.
Despite the evidence of irradiation-induced hardening, this spent beam window appears to retain useful ductility after 5 years in service. At the conclusion of 2013 run cycle, the current in-service beam window had reached the same dpa as of the spent window. We plan to extend the service of the current in-service window until it reaches its intended design threshold limit of ~20 dpa (in the highest dose region). Additional measurements at higher dpa values will enable better decision-making in managing risks of the window failure.
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Tanner, David W. J. "Life assessment of welded INCONEL 718 at high temperature". Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10796/.
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The overall aim behind this work was to gain and apply an understanding of the mechanical effects of welding, in order to mitigate distortions that had previously hampered uniaxial testing of tungsten inert gas (TIG) butt-welded, thin-section, nickel-base superalloy INCONEL 718 (IN718). With this aim achieved, better test data could be obtained, leading to more reliable material data for IN718 welds, which can be used for more accurate life assessments for shell structures and components. ABAQUS finite element (FE) simulations of the arc welding process were used to understand the development of welding-induced distortions and reduce their prevalence. An efficient, distortion-mitigating welding procedure, devised using the numerical simulations, was used to manufacture TIG butt-welded specimens that were free of distortion. Uniaxial tensile, creep and high temperature (620°C) fatigue tests were performed on both welded and non-welded IN718 specimens. It was found that IN718 welds are significantly less ductile than the parent material, and although welded IN718 exhibits comparatively little loss of tensile strength, its creep and high temperature fatigue properties are severely compromised. The lower performance of the welded specimens was attributed to the microstructural differences when compared with the non-welded material. The mechanical properties of the IN718 weld material were calculated and verified using FE analyses, based on the test data obtained. A continuum damage mechanics approach was employed for creep modelling and the necessary material constants were determined. A Smith, Watson and Topper (SWT) strain range parameter was proposed for fatigue life assessment, based on validation obtained using the test data. Three-dimensional, quasi-static elastic-plastic and creep FE analyses were used for a life assessment case study of an IN718 generic spoke structure. The effect of including a weld in a critical region was investigated for both constant (creep) and cyclic loading conditions at 620°C.
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Sugahara, Tarcila. "Estudo do comportamento em fluência da superliga Inconel 718". Instituto Tecnológico de Aeronáutica, 2011. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2001.
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Esta proposta de trabalho de mestrado tem como objetivo estudar o comportamento em fluência da superliga Inconel 718. A liga foi submetida a ensaios de fluência na modalidade de carga constante, nas temperaturas de 650, 675 e 700C. A faixa de tensão utilizada foi determinada por ensaio de tração a quente e variou de 625 a 814 MPa. Deve ser ressaltado que estudos completos de ensaio de fluência da superliga Inconel 718 são escassos na literatura. O presente projeto é inovador, permitindo o conhecimento mais detalhado da superliga Inconel 718. Foram obtidos conjuntos de curvas e parâmetros experimentais relativos às regiões primária, secundária e terciária, em função das tensões e temperaturas aplicadas. Foram avaliados a ductilidade, a taxa de fluência estacionária e o tempo de vida. A caracterização microestrutural, com o emprego da técnica de microscopia eletrônica de varredura, foi uma ferramenta valiosa para a compreensão dos mecanismos de fluência. Foram realizados ensaios de tração a quente, a fim de se determinar as propriedades mecânicas da superliga nas temperaturas de ensaio de fluência e ensaios de oxidação, a fim de se analisar a influência da formação de óxidos nos resultados dos ensaios de fluência. As técnicas de caracterização utilizadas nesse trabalho foram: microscopia eletrônica de varredura (MEV), para análise fractográfica e microestrutural; microscopia eletrônica de transmissão (MET), para análise de precipitados; difração de raios X rasante, para análise de formação de óxidos; indentaçãop Vickers. A liga apresenta comportamento típico em fluência com a presença dos três estágios de fluência. O estágio secundário foi predominante durante o ensaio; a taxa mínima de fluência apresentou aumento significativo com o aumento da tensão aplicada. A análise do valor do expoente de tensão (n=36,48527) e da energia de ativação (Qc= 512,97), sugere que o mecanismo de fluência a 650 C é o mecanismo de escalagem de discordâncias. Dependendo da temperatura de trabalho do Inconel 718, podem ocorrer dois tipos de fratura: fratura dúctil a 650 e 700C e fratura do tipo intergranular a 675C.
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Marques, Armando. "Torneamento de Inconel 718 com aplicação de lubrificantes sólidos". Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/14776.
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Fundação de Amparo a Pesquisa do Estado de Minas GeraisThe nickel-based superalloys have a high mechanical strength which remains at elevated temperature, high creep and fatigue resistances and excellent oxidation resistance. This makes these alloys highly recommended for use in high temperature working environments such as mechanical components for the aerospace industry. However, these characteristics are major problems when machining them, as it promotes high heat generation in the flow zone, resulting in the development of high wear rates on the cutting tools. In order to reduce the problems caused by the high temperatures generated, the application of a cutting fluid, when possible, is essential to reduce friction at the chip-tool-workpiece interfaces and lower the temperatures in the cutting zone. Seeking to further increase in the efficiency of cutting fluids during machining of nickel alloys, this work presents a study of the influence of solid lubricants, graphite and molybdenum disulphide (MoS2) mixed to a vegetal based cutting fluid, applied by conventional method (flooding) and minimal quantity of fluid - MQF in turning of Inconel 718 with carbide and ceramic (mixed, whisker and SiAlON) tools. When turning with cemented carbide tools the addition of graphite to the cutting fluid provided the best results, while with ceramic tools MoS2 presented the best performance. The life of the carbide tool had an average increase above 200% in conventional flooding application of cutting fluid when compared to MQF, regardless the addition of solid lubricant. The addition of solid lubricants promoted an increase in the life of whisker and SiAlON tools. The flank wear was dominant for cemented carbide tools and SiAlON ceramics, while for whisker and mixed ceramics the notch wear was predominant. Attrition and diffusion wear mechanism were observed in all evaluated conditions. The addition of solid lubricant to the cutting fluid provided significant improvements in the surface roughness values for most of the evaluated conditions. However, there were no significant changes in the machining forces and cutting temperature. The residual stress was tensile and compression, depending on the fluid application method. Overall, the addition of solid lubricant showed no significant differences.
As superligas à base de níquel apresentam alta resistência mecânica que se mantém em elevadas temperaturas, altas resistência à fluência e à fadiga e excelente resistência a oxidação. Isso torna estas ligas altamente recomendadas para utilização em ambientes que trabalham a altas temperaturas, como por exemplo na fabricação de componentes mecânicos para a indústria aeroespacial. Entretanto, esta característica representa um grande problema quando elas são usinadas, pois promove elevada geração de calor na zona de fluxo, implicando no desenvolvimento de altas taxas de desgaste da ferramenta de corte. A fim de reduzir os problemas causados pelas altas temperaturas geradas, a aplicação de um fluido de corte, quando possível, é essencial, proporcionando redução do atrito na interface cavaco-ferramenta-peça e menores temperaturas na zona de corte. Na busca de aumentar ainda mais a eficiência dos fluidos de corte na complexa usinagem das ligas de níquel, este trabalho apresenta um estudo da influência dos lubrificantes sólidos grafite e bissulfeto de molibdênio (MoS2) misturado a um fluido de corte de base vegetal, aplicados pelo método convencional (jorro) e mínima quantidade de fluído MQF, no torneamento do Inconel 718, com ferramentas de metal duro e cerâmicas (mista, whisker e SiAlON). No torneamento com ferramentas de metal duro a adição de grafite ao fluido de corte proporcionou os melhores resultados, enquanto que no torneamento com ferramentas cerâmicas, foi o MoS2 que apresentou melhor desempenho. A vida da ferramenta de metal duro teve um incremento acima de 200% na usinagem convencional (jorro) quando comparado com a usinagem por MQF, sem considerar a adição do lubrificante sólido. A adição de lubrificantes sólidos promoveu um incremento na vida das ferramentas whisker e SiAlON. O desgaste de flanco foi predominante para as ferramentas de metal duro e cerâmica SiAlON, enquanto que nas cerâmicas whisker e mista o desgaste de entalhe foi predominante. Os mecanismo de desgaste de attrition e difusão foram observados em todas as condições avaliadas. A adição de lubrificante sólido ao fluido de corte proporcionou melhorias significativas nos valores da rugosidade para a maioria das condições avaliadas. No entanto, não se observou mudanças significativas nas forças e temperatura de usinagem. As tensões residuais foram de tração e compressão, dependendo do método de aplicação do fluido. No geral, a adição do lubrificante sólido não apresentou diferenças significativas.
Doutor em Engenharia Mecânica
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Ressa, Aaron. "Plastic Deformation and Ductile Fracture Behavior of Inconel 718". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449001835.
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Smith, Mathew MacMaster. "Characterization of linear friction welded in-service Inconel 718 superalloy". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61436.
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The focus of this thesis was to study the suitability of the linear friction welding (LFWing) process to manufacture or repair of Inconel® 718 superalloy (IN 718) aero engine BLISKs. This was achieved by simulating a LFW joint made of virgin (V) and in-service (IS) (from samples extracted from an actual turbine disk) IN 718 material.
An in-depth microstructural characterization of the V and IS material in the as-received, as-welded and post weld heat treated (PWHT) conditions was carried out. Quantitative analysis of the phase constituents, such as the δ phase, MC-type carbides, MN-type nitrides and the γ grain size of the as-welded and PWHT samples was performed using electron backscattered diffraction (EBSD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. Mechanical testing also revealed that variation in the γ grain size, as well as the distribution and the volume fraction of the precipitates had a significant impact on the alloy’s hardness and tensile properties. Defect analysis of the as-welded samples revealed that the weld interface was free of oxides, voids, contamination and liquation of secondary phases (e.g., carbides and Laves phases). Grain refinement of the γ grains was observed at the weld interface and was related to the occurrence of dynamic recrystallization during the LFWing process.
Quantitative analysis of the residual strains and stresses in the as-received, as-welded and PWHT samples was achieved using the neutron diffraction technique. The results revealed that careful selection of the beam gauge volume and stress-free lattice spacing were essential for accurate stress analysis. The results suggested the residual stress increased in magnitude from the base metal and reached a peak at the weld interface. The peak magnitudes of the residual stresses were below the yield strength of IN 718. The results of this work are of significant importance when developing manufacturing and repair processes for IN 718 material components.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Soo, Sein Leung. "3D modelling when high speed end milling inconel 718 superalloy". Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580322.
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Inconel 718 (a nickel based superalloy) is widely used in the aerospace industry for the manufacture of aeroengine components that are subjected to relatively high temperature and stresses during operation, such as turbine disks, shafts, compressor blades and combustion chamber casings. Aeroengine manufacturers have recently begun to evaluate alternative production methods for these parts as opposed to the conventional route, which can involve arduous and environmentally hazardous chemical milling processes. High speed machining (HSM) involving the use of end / ball end mills is one such technology that has been earmarked as a potential substitute after successful trials on titanium components yielded significantly improved productivity and component quality. Metal cutting research has traditionally been a laboratory-based activity requiring massive investment in equipment, manpower, time and workpiece materials. Over the course of the last two decades however, computer based techniques such as finite element (FE) modelling have been shown to provide an acceptable and cost effective tool for metal cutting process simulation. Unfortunately, up until recently, the majority of published FE work on metal cutting has been confined to 2D orthogonal turning. Following an extensive literature review on analytical modelling techniques and FEM in metal cutting together with HSM technology, details are given of the development of a Lagrangian based, 3D finite element model to simulate the high speed ball nose end milling of Inconel 718 using the commercial FE package ABAQUS Explicit. Preliminary 2D, plane strain analysis of orthogonal turning was carried out utilising ABAQUS Standard followed by 3D turning using ABAQUS Explicit as a precursor to full scale milling research. ABAQUS Standard was deemed to be inappropriate for segmented / discontinuous chip and 3D formulations due to the nature of its code, which was not suited to highly non-linear and large deformation type problems. Outputs from FE models were validated against corresponding experimental data. Chip morphology studies were performed using an explosive quick stop device for orthogonal turning. This was used to investigate the effect of cutting speed (20,50 and 80m/min) and tool rake angle on chip formation, but also to obtain input 'parameters such as shear angle & deformed chip thickness for analytical modelling of cutting temperatures as a comparison with predicted FE results. Force measurements were carried out using Kistler piezoelectric dynamometers while chip surface temperatures were measured using infrared techniques. Flow stress data ofInconel 718 at elevated strain rates (up to lOOS-I) and temperatures (up to 850°) were determined through uniaxial compression tests on a Gleeble 3500 thermomechanical simulator. Based on this Gleeble data, material property constants for the overstress power law constitutive model were calculated. This was then applied in the finite element models in order for flow behaviour at high strain rates and temperatures to be reasonably defined. The 3D turning model in general provided reasonable predictions of tangential cutting forces and chip surface temperatures, with a difference of approximately 14% and 5% respectively to experimental results. The model however failed to describe the segmented chip morphology that was expected when turning at 50 & 80m/min. This was due to the lack of a user subroutine containing a suitable fracture criterion to define the adiabatic shear localisation and failure within the chip.
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Pinheiro, Cleverson. "Avaliação da usinagem do inconel 718 via metodologia de Taguchi /". Guaratinguetá, 2018. http://hdl.handle.net/11449/154790.
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Orientador: Marcos Valério RibeiroResumo: Apesar de ser amplamente utilizado em componentes aeroespaciais, o Inconel 718 apresenta algumas características que dificultam a sua usinagem: dureza elevada, resistência em altas temperaturas, forte afinidade para reagir com materiais de ferramentas e baixa condutividade térmica. Além do mais, esta liga possui tendência para a formação da aresta postiça de corte, endurecimento por deformação, assim como efeito abrasivo de carbonetos e fases intermetálicas, que resultam em tensões mecânicas e térmicas elevadas na aresta de corte. A qualidade de acabamento exigido pela indústria, para este material, é de 1,6 µm de rugosidade média (Ra) e 6 µm de rugosidade total (Rt). Sabendo da importância do Inconel 718, assim como da necessidade de conciliar os desafios de usinagem com a qualidade exigida, o objetivo deste trabalho foi encontrar a condição experimental que resulte em melhores resultados de usinagem. Para encontrar a condição ótima, a liga foi usinada utilizando duas ferramentas: experimental de cerâmica – Al2O3 + MgO (perfil S) e comercial de metal duro revestido (perfil C). Com a metodologia de Taguchi foram planejadas duas matrizes experimentais. Para a ferramenta cerâmica, a usinagem ocorreu a seco e nas seguintes condições: avanços de 0,10–0,20–0,30 mm/rev; velocidades de corte de 300–400–500 m/min; profundidades de usinagem de 0,20–0,35–0,50 mm. A ferramenta de metal duro revestido foi utilizada em profundidade fixa de 0,5 mm, nas seguintes condições experimentais: av... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Despite being widely used in aerospace components, the Inconel 718 presents some characteristics that make difficult its machining: high hardness, resistance at high temperatures, strong affinity to react with tools materials and low thermal conductivity. Moreover, this alloy has a tendency to form the built up edge, hardening by deformation, as well as the abrasive effect of carbides and intermetallic phases, which result in high mechanical and thermal tensions in the cutting edge. The surface finishing quality required by the industry, for this material, is 1.6 μm of average roughness (Ra) and 6 μm of total roughness (Rt). Knowing the importance of Inconel 718, as well as the need to combine the machining challenges with the required quality, the objective of this work was to find the experimental condition that results in better machining results. To find the optimal condition, the alloy was machined using two tools: experimental ceramic – Al2O3 + MgO (profile S) and commercial coated tungsten carbide (profile C). With Taguchi methodology, two experimental matrices were planned. For the ceramic tool, the machining occurred in the dry and under the following conditions: feed rates of 0.10–0.20–0.30 mm/rev; cutting speeds of 300–400–500 m/min; machining depths of 0.20–0.35–0.50 mm. The coated carbide tool was employed at a fixed machining depth of 0.5 mm, under the following experimental conditions: feed rates of 0.10–0.15–0.20–0.25 mm/rev; cutting speeds of 55–70–85–100 m/m... (Complete abstract click electronic access below)
Doutor
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Washburn, Aaron. "Heat Treatment Optimization of Inconel 718 Cladded H13 Forging Dies". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1546599002026526.
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Ponnelle, Sylvain. "Propagation des fissures par fatigue a haute temperature dans l'Inconel 718 : effets de microstructure et de chargements complexes". Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1003.
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L'objectif de cette etude sur de la propagation des fissures par fatigue a haute temperature dans l'alliage 718 est d'une part de s'approcher des conditions reelles d'utilisation et d'autre part de contribuer a la comprehension de l'effet d'un temps de maintien pendant un cycle de fatigue. Le premier aspect est aborde par l'utilisation d'une piece industrielle reelle (disque de turbine) de la production de snecma moteurs. Des essais de propagation en fatigue-fluage a 650\c sur eprouvettes ct (fissures longues 2d) ainsi que sur eprouvettes kb 2. 5 (petites fissures semi-circulaires) montrent une forte interaction entre l'orientation du front de fissure et le fibrage induit par les operations de mise en forme. Lorsque le front de fissure est perpendiculaire au fibrage, le delaminage transverse des eprouvettes le long d'alignements de phases annule tout effet accelerateur du temps de maintien. Lorsque le front de fissure se propage entre les nappes de phase , l'effet de temps de maintien est tres marque. Sur defaut 3d, une forte anisotropie de la vitesse de propagation est observee, liee aux effets d'environnement car absente sous vide. Pour le second aspect, l'application de chargements mecaniques plus proches de la realite que le cycle de fatigue-fluage montre que la sensibilite au temps de maintien peut etre fortement reduite des qu'on decharge mecaniquement l'eprouvette avant l'application du palier (cycle avec pic de contrainte). Des 20% de decharge, l'effet d'un temps de maintien de 300s est annule. La simulation numerique de ce type de chargement montre que les effets d'environnement sont annihiles par une relaxation rapide des contraintes et une forte diminution de la vitesse de deformation, empechant le transport des especes fragilisantes dans le materiau. De plus, on montre que la variation de la temperature pendant le temps de maintien peut egalement mener a un fort ralentissement de la vitesse de propagation par rapport a des conditions isothermes.
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Lundström, Erik. "Overload effects on the fatigue crack propagation behaviour in Inconel 718". Thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77494.
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In this master thesis, work done in the TURBO POWER project High temperature fatigue crack propagation in nickel-based superalloys during spring 2012 will be presented. The overall objective of this project is to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the crack propagation in the nickel-based superalloy Inconel 718. Experiments have been performed to study the effect of initial overloads, and it has been shown that even for small initial overloads a significant reduction of the crack growth rate is received. Furthermore, FE simulations have been carried out in order to describe the local stress state in front of the crack tip since it is believed to control, at least partly the diffusion of oxygen into the crack tip and thus also the hold time crack growth behaviour of the material. Finally, an evaluation method for the stresses is presented, where the results are averaged over an identifiable process/damaged zone in front of the crack tip.
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Santos, Júlio César dos [UNESP]. "Estudo do uso de ferramentas cerâmicas na usinagem de inconel 718". Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/94416.
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A usinagem de superligas de níquel e ligas resistentes a altas temperaturas como o inconel 718 sempre representou uma tarefa difícil no chão-de-fábrica. Mas as aplicações industriais desses materiais passaram por rápida evolução nos últimos anos. Na indústria aeroespacial, o crescimento da popularidade destes materiais tem sido evidenciado na forma de palhetas de turbina, peças de compressor, suportes e elementos de conjuntos para aviação. Devido a suas propriedades e aos benefícios que trazem à indústria, o uso destes materiais se expandiu aos setores automotivo, médico, químico, indústria de miniaturas e outras indústrias. Para as superligas e ligas resistentes a altas temperaturas estima-se que a dificuldade na usinagem vai da combinação de forças de corte relativamente altas, combinadas com altas temperaturas que se desenvolvem durante o processo de usinagem. Estes níveis de calor podem causar a deterioração da aresta de corte, com quebras ou deformações. Os tipos comuns de desgaste de ferramenta para estes materiais são primeiramente reconhecidos como desgaste do flanco, entalhes e formação de arestas postiças. O presente trabalho consiste no torneamento cilíndrico externo da liga a base de níquel inconel 718, utilizando ferramenta cerâmica (Si3N4) visando à otimização da usinagem desta liga e buscando proporcionar aumentos reais de produtividade sem a necessidade de investimentos em novos meios de produção. Os ensaios de usinagem foram realizados em um corpo de prova da liga, considerando os parâmetros de usinagem: velocidade de corte, profundidade de usinagem e avanços próprios de acabamento. Os ensaios foram realizados em um torno CNC e ferramentas com pastilha de cerâmica à base de Nitreto de Silício Si3N4. Após cada etapa do torneamento foram realizadas as medidas do comprimento de corte, do desgaste das ferramentas e a rugosidade...
The nickel superalloys and resistant alloys machining to discharges temperatures as the inconel 718 always represented a difficult task in the job-shop. But the industrial applications of those materials went by fast evolution in the last years. In the aerospace industry, the growth of the popularity of these materials has been evidenced in the form of turbine blades, compressor parts, holders and elements of parts for aviation. Due to its properties and to the benefits that bring to the industry, the use of these materials expanded to the automotive sector, medical, chemical, in the industry of miniatures and other industries. For the superalloys and resistant alloys to high temperatures is considered that the difficulty in the machining is going relatively of the combination of high cutting forces, combined with high temperatures that grow during the machining process. These levels of heat can cause to deterioration of the cutting edge, with breaks or deformations. The types common of tool wear for these materials are recognized firstly as flank wear, incisions and formation of build up edge. The present work seeks to develop study of the machining for external cylindrical turning of the nickel base alloy inconel 718, using ceramic tool (Si3N4) seeking to the optimization of machining of this alloy and looking for to provide real increases of productivity without the need of investments in new production means. The machining tests were accomplished in a sample of the alloy, considering the machining parameters: cutting speed, cutting depth and own progresses of finish. The rehearsals were accomplished in a lathe CNC and tools with ceramic insert of Silicon Nitride. After each stage of the turning the measures of the cutting length were accomplished, of the tool wear and the roughness of the pieces (appraised in each phase of the process), with the aid of a portable roughness meter... (Complete abstract click electronic access below)
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Bhatt, Abhay. "Effect of cutting tool coating on the machinability of Inconel 718". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99403.
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This research is an assessment of the machinability of a nickel-based alloy Inconel 718 using a finish turning operation with carbide coated and uncoated tools having fine and medium grain size substrates, and the same tool geometry (a round tool shape geometry with a 0° rake angle and 7° clearance angle). In addition, orthogonal machining tests were carried out to generate experimental data for future identification of the constitutive laws of Inconel 718 (its behavior under high stress, strains, strain rates, and temperatures). The finish turning of this alloy was evaluated in terms of tool life, tool wear mechanisms, cutting forces, surface roughness, and chip formation process. The cutting speed range evaluated was from 50 to 100 m/min, and the feed range was from 0.075 to 0.125 mm/rev. Throughout the machining tests, the depth of cut was kept constant and equal to 0.25 mm. Tungsten carbide uncoated tool having fine grain size (<1 μm), strong and sharp cutting edges were found to be the most suitable tool material and tool geometry for the finish turning of Inconel 718 at a cutting speed of 50 m/min, and, moreover, yielded the best tool life of 53 minutes. When finish turning at a cutting speed of 75 m/min, a single layer PVD (TiAlN=3μm) carbide tool yielded the best tool life of 12 minutes. At a cutting speed of 100 m/min, triple layer CVD coated tools (TiCN/Al2O3/TiN=15 μm) produced the best performance, yielding an 8 minutes of tool life. During the machining tests, the common wear mechanisms of the three different tools were adhesion, abrasion, and diffusion. Flank wear was the dominant tool failure mode of all three tools. The analysis of chip morphology showed that no phase transformation existed even though the material was deformed. The increase of micro-hardness was confirmed by micro-hardness measurements on chips, as compared to the initial micro-hardness of the material (Inconel 718). Cutting forces for all the different tools were relatively low (< 300 N) when the cutting edge was new. For the finish turning operation, surface roughness of (<1 mum) was achieved in all the cutting tests.
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Chen, Zhe. "Surface Integrity of Broached Inconel 718 and Influence of Thermal Exposure". Licentiate thesis, Linköpings universitet, Konstruktionsmaterial, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111062.
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Inconel 718 is a nickel-based superalloy that is extensively used as a disc material in gas turbine engines. The service life of gas turbine discs is normally governed by the modes of material degradation and fatigue failure since they work mostly at high temperatures and are subjected to cyclic mechanical loadings. Fatigue failures often start with the initiation of cracks at the surface and the precise details of the failure process significantly depend on the surface conditions. In turbine disc production, one of the last manufacturing steps is to broach root fixings, commonly of fir-tree design, for blade mounting. It has always been a challenge when machining Inconel 718 due to its high strength retention at elevated temperatures, rapid work hardening, as well as low thermal conductivity. This usually leads to rapid tool wear, and consequently shorter tool life, and at the end to the deterioration of the surface integrity of the machined components. The aim of this licentiate thesis is to increase our knowledge about the surface integrity, especially microstructure and residual stresses, of broached Inconel 718 and its stability under thermal exposure. This knowledge can later be used for analyzing the initiation and propagation of fatigue cracks in broached Inconel 718, particularly in the case of high temperature fatigue, thereby giving a better understanding of the failure mechanism of gas turbine discs from a fatigue point of view. A broaching operation has been performed using similar cutting conditions as that used in turbo machinery industries for producing fir-tree root fixings. In addition, service damages were analyzed in a retired dis of Inconel 718. Surface defects, severe plastic deformation and generation of high tensile residual stresses have been found to be the main damages to the surface integrity caused by the broaching operation. The machining induced plastic deformation was found to accelerate the microstructural degradation beneath the broached surface when subjected to thermal exposure. The surface tensile residual stresses can be completely removed after short thermal exposure, the tensile layer in the sub-surface region, however, exhibited a high resistance to stress relief at high temperatures. The damage analysis on the retired disc indicated that presence of the highly deformed layer on the machined surface is negative for preventing the occurrence of fretting fatigue in turbine discs.
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Moiz, Muhammad. "The influence of grain size on mechanical properties of Inconel 718". Thesis, Linköpings universitet, Konstruktionsmaterial, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-113148.
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The thesis work discuss about how the materials mechanical properties are influenced by the microstructure. The most common way of altering the microstructure of the material is by heat treatment.The mechanical properties that are of interest are strength, toughness, ductility, creep and fatigue. The material under consideration iswidely used superalloy In718. Two different sets of specimens areheat treated at different temperatures and influence of heat treatmenton the grain size is analyzed. In order to get better understanding ofthe grain size on mechanical properties, microstructural investigation was done using SEM. Efforts are made to understand the influence of different elements on the overall characteristic of the material. The tensile, creep and stress relaxation tests were conducted and the results were discussed.Master Thesis
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Santos, Júlio César dos. "Estudo do uso de ferramentas cerâmicas na usinagem de inconel 718 /". Guaratinguetá : [s.n.], 2010. http://hdl.handle.net/11449/94416.
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Orientador: Marcos Valério RibeiroBanca: Humberto Lopes Rodrigues
Banca: Jose Vitor Candido de Souza
Resumo: A usinagem de superligas de níquel e ligas resistentes a altas temperaturas como o inconel 718 sempre representou uma tarefa difícil no chão-de-fábrica. Mas as aplicações industriais desses materiais passaram por rápida evolução nos últimos anos. Na indústria aeroespacial, o crescimento da popularidade destes materiais tem sido evidenciado na forma de palhetas de turbina, peças de compressor, suportes e elementos de conjuntos para aviação. Devido a suas propriedades e aos benefícios que trazem à indústria, o uso destes materiais se expandiu aos setores automotivo, médico, químico, indústria de miniaturas e outras indústrias. Para as superligas e ligas resistentes a altas temperaturas estima-se que a dificuldade na usinagem vai da combinação de forças de corte relativamente altas, combinadas com altas temperaturas que se desenvolvem durante o processo de usinagem. Estes níveis de calor podem causar a deterioração da aresta de corte, com quebras ou deformações. Os tipos comuns de desgaste de ferramenta para estes materiais são primeiramente reconhecidos como desgaste do flanco, entalhes e formação de arestas postiças. O presente trabalho consiste no torneamento cilíndrico externo da liga a base de níquel inconel 718, utilizando ferramenta cerâmica (Si3N4) visando à otimização da usinagem desta liga e buscando proporcionar aumentos reais de produtividade sem a necessidade de investimentos em novos meios de produção. Os ensaios de usinagem foram realizados em um corpo de prova da liga, considerando os parâmetros de usinagem: velocidade de corte, profundidade de usinagem e avanços próprios de acabamento. Os ensaios foram realizados em um torno CNC e ferramentas com pastilha de cerâmica à base de Nitreto de Silício Si3N4. Após cada etapa do torneamento foram realizadas as medidas do comprimento de corte, do desgaste das ferramentas e a rugosidade... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The nickel superalloys and resistant alloys machining to discharges temperatures as the inconel 718 always represented a difficult task in the job-shop. But the industrial applications of those materials went by fast evolution in the last years. In the aerospace industry, the growth of the popularity of these materials has been evidenced in the form of turbine blades, compressor parts, holders and elements of parts for aviation. Due to its properties and to the benefits that bring to the industry, the use of these materials expanded to the automotive sector, medical, chemical, in the industry of miniatures and other industries. For the superalloys and resistant alloys to high temperatures is considered that the difficulty in the machining is going relatively of the combination of high cutting forces, combined with high temperatures that grow during the machining process. These levels of heat can cause to deterioration of the cutting edge, with breaks or deformations. The types common of tool wear for these materials are recognized firstly as flank wear, incisions and formation of build up edge. The present work seeks to develop study of the machining for external cylindrical turning of the nickel base alloy inconel 718, using ceramic tool (Si3N4) seeking to the optimization of machining of this alloy and looking for to provide real increases of productivity without the need of investments in new production means. The machining tests were accomplished in a sample of the alloy, considering the machining parameters: cutting speed, cutting depth and own progresses of finish. The rehearsals were accomplished in a lathe CNC and tools with ceramic insert of Silicon Nitride. After each stage of the turning the measures of the cutting length were accomplished, of the tool wear and the roughness of the pieces (appraised in each phase of the process), with the aid of a portable roughness meter... (Complete abstract click electronic access below)
Mestre
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Lin, Yu-Pei. "Investigation of die wear by modelling the extrusion of Inconel 718". Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1310/.
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Die wear is always an important issue in hot forming processes, such as in forging and extrusion. Die life affects the economics of process to product and in order to optimise die life, the mechanism of wear should be approached scientifically. The aim of this work is to provide a systematic method for predicting and quantifying wear occurring in the extrusion of INCONEL 718 (IN718), nickel superalloy. To characterise wear, the process prediction which contributes to it must be identified and quantified. First, material characterisation was carried out using the Gleeble physical materials simulator. Then a set of unified viscoplastic constitutive equations was developed suitable for modelling microstructural evolution of IN718, i.e. evolution of average grain size, dislocation density and recrystallisation under hot forming conditions, which enabled resulting flow stress to be calculated and the microstructure of formed parts to be predicted. Second, heat transfer and friction during the forming process were investigated, by upsetting cylinders and performing ring tests on IN718. The heat transfer experimental work centres rounded the development of a reliable method for the measurement of the sub-surface temperatures in the bottom die during upsetting. The experimental values of sub-surface temperatures under various lubrication and forging conditions were analysed. A theoretical approach was proposed for the determination of the values of effective heat transfer coefficient and effective friction factor, and comparisons of experimental results and those from FE simulations were made and satisfactory matchings were obtained. Finally, integration of the material model and derived boundary conditions using subroutines for FEA are presented. Qualitative studies of abrasive die wear carrying out in a FE package, DEFORM, on the effect of various hot forming cases are shown. The numerical results are compared with the observations from mechanical measurements and metallurgical examinations for the studied die. Good correlations are found for most cases, which prove the presented methods can be used effectively in the prediction of die wear. Also, further work is suggested to enhance the modelling capabilities.
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Koort, Leyla, i Trollbäck Viktoria Sutorius. "Characterisation of additively manufactured Inconel 718 alloy by using electrolytic extraction". Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298413.
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The formation of non-metallic inclusions (NMIs) are common in all steel grades and it is not possible as of today to be able to remove all of them. The inclusions are categorised into endogenous (oxides, nitrides, sulfides, carbides, and phosphides), and exogenous (entrapment of nonmetals: slag, mold). Their morphology, size, number, chemical composition, and location are important parameters which need to be classified and controlled as they have a big impact on the final properties of steel grades. In this study, only endogenous NMIs for the superalloy Inconel 718 were investigated. An electrolytic extraction (EE) was performed to see if this was a suitable method to be used for the study of the NMIs in powder particles, and in a metal sample produced from metal powder. The results were compared with NMIs found in conventional Inconel 718. The powder particles and the NMIs were investigated on a scanning electron microscope (SEM) for mentioned parameters. When the NMIs were classified, it was found that four inclusions (Al2O3,TiNb-N, NbTi-C, NbTiCrMo-C) were found in the metal sample produced by the powder and three (TiNb-N, NbTi-C, NbTiCr-C) in the conventional sample. Two inclusion types were the same for both alloy 718 metal samples, but all inclusions differed in number, size, morphology, and location. Furthermore, the EE method did not work for the powder particles themselves, it was concluded that the EE method was suitable for the metal sample made out of metal powder, but not the powder particles. The EE method needs to be further developed and adapted for metal powder analysis.Icke-metalliska inneslutningar (NMI) förekommer i allt stål. Det är idag inte möjligt att eliminera dessa i tillverkning. NMI:er delas upp i endogena (oxider, nitrider, sulfider, karbider och fosfider) och exogena (infångning av icke-metaller: slagg, mögel). Deras morfologi, storlek, antal, kemiska sammansättning och placering är viktiga parametrar sommåste klassificeras och kontrolleras eftersom de har stor inverkan på stålets egenskaper. Denna studie undersökte endast endogena NMI:er för superlegeringen Inconel 718. Enelektrolytisk extraktion (EE) genomfördes för att utvärdera om EE är en lämplig metod för attstudera NMI:er i pulverpartiklar och i ett metallprov framställt av metallpulver. Resultaten jämfördes med NMI:er som finns i konventionellt producerad Inconel 718. Pulverpartiklarnaoch NMI:erna undersöktes i ett svepelektronmikroskop (SEM) för ovan nämnda parametrar. När NMI:erna klassificerades framkom det att fyra inneslutningar (Al2O3, TiNb-N, NbTi-C,NbTiCrMo-C) fanns i metallprovet producerat av pulvret och tre (TiNb-N, NbTi-C, NbTiCr-C) fanns i det konventionella provet. Två inneslutningstyper var desamma för båda legeringsprovbitar, medan NMI:erna skiljde sig åt i antal, storlek, morfologi och plats. Eftersom EE-metoden inte fungerade på pulverpartiklarna, drogs slutsatsen att EE-metoden lämpade sig för metallprovet tillverkat av metallpulver, men inte pulverpartiklarna i sig. EE-metoden måste vidareutvecklas och anpassas för analys av metallpulver.
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Booysen, Theo-Neal. "Microstructural effects on properties of additively manufactured Inconel 625 and 718". Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/3043.
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Thesis (MEng (Mechanical Engineering))--Cape Peninsula University of Technology, 2019Three Dimensional(3D) printing is known as additive manufacturing: it is a method of manufacturing parts or components form sheet, wire or powder in a manufacturing process. This method differs from traditional manufacturing techniques such as casting, moulding or subtracting materials which already exist. The type of material characterization is also very important in the development and improve or manufacturing of new materials for higher strength and various application. Selective Laser Melting(SLM) an additive manufacturing powder-based process has been adopted by automotive and aerospace industries. The reason for this is that it has many potential benefits, such as 3D designs of complex components in a shortened time frame, which offers financial savings. SLM process use metallic powders with different chemical composition to manufacture complex structures, which is an innovative material processing technology. In this research SLM, a typical additive manufacture process method, was used to manufacture additively manufactured Inconel 625 and 718. These sample specimens were investigated to determine their microstructural features and mechanical properties. The microstructural features were characterized using two different experimental surface microscopy methods: scanning electron microscope(SEM) and light optical microscope (LOM). The mechanical properties were determined by studying deformation and hardness characteristics using three-point bending and hardness tests. The relationship between processing, microstructure, grain sizes and mechanical properties was established. The understanding of SLM additive manufacturing of alloys is important as well for the adoption of the technology, and the possibility of replacing commercially produced cast and wrought alloys in the near future.
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Pautrat, Alexis. "Étude expérimentale quantitative de la solidification de l'inconel 718 en fonderie". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00998532.
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Cette étude financée par SNECMA et le CNES a pour objectif de mieux comprendre et caractériser le résultats de la solidification de l'inconel 718. Cet objectif est motivé par le besoin grandissant de fiabilité sur les pièces brutes de fonderies utilisées dans l'assemblage des moteurs de fusée. En effet, lors de la solidification, la ségrégation chimique provoque la formation de phase fragile. C'est notamment le cas des phases de Laves. Ainsi, un four de fonderie sous vide et un moule instrumenté ont été mise au point afin de couler au laboratoire des plaques de géométrie variable. Le but étant d'obtenir plusieurs échantillons obtenu sous différente conditions de solidifications. Une méthode d'analyse quantitative au MEB a par la suite été mise au point pour analyser les 4 coulées exploitables. Elle a permis de quantifier la quantité d'intermétalliques en fonction de la vitesse de refroidissement. Mais aussi leur répartition vis à vis des joints de grains d'une part et l'impact de la désorientation entre chaque grain d'autre part. La ségrégation chimique a aussi pu être quantifiée selon ces mêmes paramètres.De travaux numériques ont été entrepris en parallèles avec tout d'abord la simulation macroscopique des coulées avec le logiciel Thercast. Ces simulations ont permis de connaître les conditions de solidification de l'ensemble des échantillons coulés et ont fourni des données d'entré pour les autres aspects numériques. Par exemple, avec un modèle élément fini et automate cellulaire, la formation de la structure granulaire a pu être modélisée. Enfin, la simulation de la microségrégation a permis de valider notre compréhension des phénomènes prédominant lors de la solidification de l'inconel 718. Ces simulations numériques apportent à la fois un éclairage sur les résultats expérimentaux mais aussi démontrent leurs possibilités dans l'optique de mettre en place un modèle global de solidification recouvrant ces trois échelles pour des pièces industrielles
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Daneshi, Amir [Verfasser], i Claas [Akademischer Betreuer] Müller. "Micro chip formation mechanism in grinding of Nickel-base superalloy-Inconel 718". Freiburg : Universität, 2019. http://d-nb.info/1187133345/34.
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Lundström, Erik. "Modelling of fatigue crack propagation in Inconel 718 under hold time conditions". Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-104814.
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In this thesis an investigation and modelling of the fatigue crack propagation in the nickel based superalloy Inconel 718, with a special emphasis on the effect of hold times, is presented. The modelling work has been concentrated on describing the hold time fatigue crack propagation by using the concept of a damaged zone in front of the crack tip, which is believed to have a lowered resistance against crack propagation. The modelling framework is built on physically motivated parameters, which are all easy to calibrate through one specially designed test type. Later evaluation through many experimental tests has also shown that the model is capable, within reasonable scatter level to predict, the hold time fatigue crack propagation for many different temperatures and loading conditions. Further evaluation of a complex flight spectrum, with the incorporation of crack closure within the model, was also predicted with a satisfying result. This thesis is divided into two parts. First, a background and a somewhat deeper discussion of the modelling of fatigue crack growth under hold time conditions is presented. The second part consists of ve appended papers, which describe the work completed so far in the project.
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Agnoli, Andrea. "Origine de l’éclatement de grain sur des pièces forgées en Inconel 718". Thesis, Paris, ENMP, 2013. http://www.theses.fr/2013ENMP0098/document.
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L'Inconel 718 est un superalliage base nickel très utilisé pour produire les disques de turboréacteurs. Typiquement, une gamme de forgeage à chaud se compose de plusieurs étapes de déformation et de recuit. La présence des particules de seconde phase (particules de phase delta dans l'Inconel 718) permet en principe de limiter la croissance de grains pendant les étapes de recuit grâce au phénomène d'ancrage de Zener. Néanmoins, l'hétérogénéité microstructurale (distribution des particules, écrouissage, composition chimique) peut favoriser une croissance anormale des grains pendant le recuit. Ce phénomène est connu industriellement sous la terminologie d'"éclatement de grains". Les objectifs de la thèse étaient d'identifier les mécanismes responsables de l'éclatement des grains qui peut survenir durant les étapes de recuit sur les pièces forgées en Inconel 718, de les modéliser, et de simuler numériquement le phénomène. Les mécanismes physiques à l'origine du phénomène sont d'abord étudiés expérimentalement grâce à la caractérisation (par MEB et EBSD) des pièces forgées. L'influence des particules de seconde phase et de l'énergie stockée (estimée par des mesures de désorientations intragranulaires) est notamment étudiée. A partir des observations réalisées, une explication est proposée : le phénomène apparaît lorsque les forces motrices pour la migration des joints de grains dépassent la force de freinage de Zener ; ceci peut se produire lorsque la microstructure contient de l'énergie stockée, distribuée de manière hétérogène. Des essais de torsion à chaud sont mis en place pour reproduire, en laboratoire, le même phénomène, étudier la sensibilité aux paramètres thermomécaniques, et tester les hypothèses émises concernant les mécanismes. Les mécanismes ainsi identifiés comme responsables de l'éclatement de grains sont enfin simulés au moyen d'un modèle numérique en 2D. Le modèle numérique en champ complet est basé sur la méthode des éléments finis, et utilise le formalisme level-set pour décrire les joints de grains. La simulation de l'évolution microstructurale prend en compte à la fois les forces motrices des joints de grains liées à la capillarité et à l'énergie stockée, et l'interaction des joints de grains avec les particules de seconde phase. Ainsi, l'effet de la distribution de l'énergie stockée (estimée à partir de données expérimentales) a pu être étudié numériquement dans des microstructures avec particulesInconel 718 is a nickel base superalloy commonly used to manufacture the rotating disks of turbojet engines. Such disks are generally produced by hot forging, which involves a sequence of different deformation and annealing steps. The presence of second phase particles (delta phase in Inconel 718) is commonly exploited to limit grain growth during annealing via the Zener pinning phenomenon. Nonetheless, microstructure heterogeneity (with regards to second phase particles, hardening, texture and chemical composition) can lead to inhomogeneous grain growth during annealing. The objectives of this PhD work were to understand, model and simulate numerically the phenomenon of inhomogeneous grain growth that can occur in Inconel 718 turbine disks during the annealing steps of hot forging sequences. The physical mechanisms which may explain the occurrence of the phenomenon are investigated experimentally by performing SEM and EBSD analyses of Inconel 718 industrial pieces. The focus is placed on the influence of second phase particles and strain energy (estimated from intragranular misorientations) on the occurrence of the phenomenon. From those observations, it is inferred that the phenomenon occurs when the grain boundary driving forces overcome the Zener pinning forces; this is achieved when stored energy is present and heterogeneously distributed. Moreover, hot torsion tests are carried out to reproduce the phenomenon in laboratory, to evaluate its sensibility to thermomechanical parameters and to test the previously postulated mechanism. The validity of this mechanism is finally demonstrated by modelling numerically the phenomenon in 2D. The full field numerical model is based on a level set description of the grain boundaries in a finite element context. Microstructure evolution is simulated explicitly taking into account Zener pinning, capillarity and stored energy driven grain growth in a single framework. The effect of strain stored energy distributions (estimated from experimental data) in pinned microstructures is investigated focusing on the conditions leading to inhomogeneous grain growth
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Caliari, Felipe Rocha. "Avaliação do comportamento em fluência da superliga Inconel 718 após duplo envelhecimento". Instituto Tecnológico de Aeronáutica, 2012. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2118.
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Os oligossilsesquioxanos (OS) são estruturas oligoméricas de silsesquioxanos (fórmula unitária RSiO3/2) Materiais com comportamento adequado em temperaturas elevadas e ambientes agressivos tornaram-se uma necessidade científica e tecnológica nos dias de hoje. Estudos têm sido realizados, independentemente de objetivos comerciais, para o aprimoramento na obtenção de novas ligas e, em particular, para a reavaliação de ligas comerciais já existentes, por meio da aquisição de dados em condições de maior severidade. Superligas à base de níquel são conhecidas desde a década de 1930, e utilizadas principalmente em aplicações aeroespaciais. Estas aplicações requerem um material com elevada resistência mecânica, boa resistência à fadiga e à fluência, boa resistência à corrosão e capacidade de operar continuamente em elevadas temperaturas. Neste trabalho de mestrado estudou-se o comportamento em fluência da superliga Inconel 718 antes e após o duplo envelhecimento. Inicialmente foi realizado tratamento de solução sólida a 1095C por 1 hora, seguido de tratamento de duplo envelhecimento a 955C/1 h - 720C/6,5 h+720C/1,5 h + 620C/8 h. A liga foi submetida a ensaios de fluência na modalidade de carga constante, nas temperaturas de 650, 675 e 700C. A faixa de tensão utilizada foi determinada por ensaio de tração a quente. O tratamento térmico de duplo envelhecimento promoveu aumento do tamanho de grão (de 8,20 para 7,23 ASTM) e aumento da dureza em aproximadamente 98%. Os resultados dos ensaios de fluência indicaram que há aumento da resistência a fluência após o tratamento de duplo envelhecimento. Os mecanismos de fratura para a condição CR são do tipo dúctil por coalescência de microcavidades, e fratura do tipo mista. Já na condição DE as fraturas apresentaram aspecto do tipo frágil intergranular.
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Eriksson, Tobias. "Process Optimization and Characterization of Inconel 718 Manufactured by Metal Binder Jetting". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87168.
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The development of a process chain for Inconel 718 production utilizing Binder Jetting has been investigated. Different powder sources were compared by the effect they had on machine compatibility, powder bed packing, recyclability, green density, sintering parameters, final density, porosity, and mechanical properties. The three powder lots investigated originated from two different production sites. One of the three powder lots has a finer powder size distribution, due it being produced simultaneously with another powder lot with a coarser powder size distribution fraction. This synergy production results in a higher yield of the atomization process and thus is economically and environmentally beneficial. The compatibility between powder lots and Binder Jetting machine was investigated using new powder and recycled powder. By using recycled powder in the process an increase in green density by 5% could be achieved. Several temperature and hold time relations were tested to develop a sintering program with an acceptable final density above 94% of theoretical density. 1270◦C with a hold time of 4h generated the best results. Sintered samples did not reach acceptable strength properties. The elongation value was twice as high as required for one of the powder lots using recycled powder. Post heat treatment generated samples with an acceptable yield strength but highly reduced elongation properties.
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Eidt, Wesley Earl. "Defect Modeling and Vibration-Based Bending Fatigue of Additively Manufactured Inconel 718". Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1590502861855386.
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Huang, Dongfang. "Investigation of heterogeneity of FSW Inconel 718 coupled with welding thermal cycles /". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2750.pdf.
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Huang, Dong Fang. "Investigation of Heterogeneity of FSW Inconel 718 Coupled with Welding Thermal Cycle". BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1914.
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In order to develop a better understanding of the property, microstructure evolution and thermal history of FSW Inconel 718's, the strain, strain rate and thermal cycles need to be determined. In order to estimate the strain field of a deformed body, a displacement function needs to be determined. A 3D deformation model was developed to determine the displacement coefficients. A rectangular box created in this model deforms following a linear displacement function. Three orthogonal planes cut this deformed box, which leads to three deformed planes. The shape parameters (L, H, θ¹ and θ²) on the three orthogonal planes can be expressed as the functions of displacement coefficients. Although the displacement coefficients can not be expressed in the forms of the shape parameters symbolically, a numerical solution can be found using numerical optimization methods. The shape parameters were obtained by assuming the displacement coefficients (three cases). Then, the numerical optimization was carried out to determine the displacement coefficients. The solved displacement coefficients are the same as the assumed ones, which shows that this inverse problem can be solved, and this model is robust to determine the displacement function numerically. This model was used to estimate the strain and strain rate at the boundary of the nugget zone of Friction Stir Welding (FSW) Inconel 718. A numerical/experimental methodology was developed to estimate the thermal history in the stir zone of FSW Inconel 718.The thermocouple experiment was conducted to measure the thermal cycles in Heat Affected Zone (HAZ). Using the measured temperature in HAZ and a numerical model, the peak temperature (1039 ºC) and cooling rate (58.18 ºC/s) were determined. The microstructure in different regions was characterized and co-related with the thermal cycles. In order to understand the microstructure evolution in the stir zone, the strain rate (12.612 s-1) was estimated using the mathematical model as mentioned above. According to the estimated thermal history and strain rate, the assumption that the dynamic recrystallizaiton occurred during FSW was made. The grain size in the nugget zone affects the hardness. The relationship among the microstructure, mechanical properties, and thermal cycles was discussed.
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CALANDRI, MICHELE. "Inconel 718 superalloy produced through Selective Laser Melting for harsh environment applications". Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2739924.
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Guest, Robert Paul. "The dynamic and meta-dynamic recrystallisation of the Ni-base superalloy Inconel 718". Thesis, University of Cambridge, 2005. https://www.repository.cam.ac.uk/handle/1810/272127.
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Thompson, John Ryan. "RELATING MICROSTRUCTURE TO PROCESS VARIABLES IN BEAM-BASED ADDITIVE MANUFACTURING OF INCONEL 718". Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401699643.
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Andrews, Robert G. (Robert Garth) Carleton University Dissertation Engineering Mechanical. "High temperature fatigue crack initiation and propagation behaviour in Inconel 718 turbine discs". Ottawa, 1991.
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Taina, Fabio. "Optimisation of microstructure and fatigue properties of Inconel 718 for extrusion die applications". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0087/document.
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Ce travail est une contribution à une étude de recherche et développent, proposée par Hydro Aluminium, dans le domaine des mécanismes d'endommagement de filières d'extrusion et. L'originalité du travail de thèse est basée sur le développement d'un alliage Inconel 718 optimisé pour l'application spécifique de filière d’extrusion, ce qui représente un saut technologique dans l'emploi de ce superalliage dans le domaine des outils. L'impact des paramètres du procédé d'extrusion, appelés paramètres extrinsèques, - tels que la vitesse d'extrusion, la longueur de billette, le chargement thermo-mécanique - sur le comportement mécanique du matériau a été analysé. Les cycles traction-compression sont simulés à l'aide d’essais isothermes de fatigue oligocyclique (LCF) qui donnent des informations sur les différents mécanismes d'endommagement survenant dans la filière. Du point de vue scientifique, la sollicitation de fatigue oligocyclique isotherme (LCF) est considérée comme la plus représentative des conditions thermomécaniques agissant sur l'outil. Les résultats montrent que la vitesse de déformation et de temps de maintien ont un impact significatif sur la durés de vie en fatigue. Le développent du matériau, enfin, a été atteint en modifiant les paramètres intrinsèques au matériau - tels que la taille des grains et la morphologie des précipités intermétalliques. Des traitements thermiques alternatifs, permettant d'adapter le matériau aux conditions spécifiques imposées par le procédé d'extrusion, ont été formulés. Des essais de fatigue LCF supplémentaires, ont permit de comparer la réponse cyclique de ces nouvelles nuances à celle du traitement original. Un de ces traitement, élaboré au travers d’une approche pluridisciplinaire incluant les aspects métallurgie, chimie et mécanique, a été retenu comme la nouvelle procédure standard pour le traitement des matrices d'extrusion en Inconel 718This present work is a contribution to an extensive development study, promoted by Hydro Aluminium, in the field of the damage mechanisms of extrusion dies. The originality of the present work is based on the development of an optimized Inconel 718 alloy as bulk material for extrusion die., which corresponds to a new application of this alloy in the field of tools: The investigation of the impact of the so called “Material Extrinsic Parameters”, such as extrusion speed, billet length and thermo-mechanical loading on the mechanical behaviour of the material is proposed. The cyclic tensile and compressive stresses, acting on the die, are simulated by isothermal Low Cycle Fatigue (LCF) tests. Results show that strain rate and holding time have a significant impact on fatigue life. These considerations represent the “Input Data” for the design of an optimized Inconel 718 in order to adapt the material to the specific conditions imposed by the extrusion process. This objective is achieved by modifying the “Material Intrinsic Parameters” such as grain size or precipitates morphology through the formulation of alternative thermal treatments. Additional LCF tests, are carried out to compare the cyclic response of the alternative Inconel 718 grades. One of this treatment, elaborated by a multidisciplinary approach including metallurgical, chemical and mechanical experiments that has been implemented in the industrial production practice as the new standard procedure for the thermal treatment of the Inconel 718 extrusion dies
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Huang, Chih-Chung, i 黃志中. "Inconel 718 Turning Parameters Study". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/235gw3.
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碩士元智大學
機械工程學系
106
Inconel 718 nickel-based alloy maintains high strength at high temperatures and has excellent mechanical properties such as resistance to creep and fatigue, and is widely used in the aerospace industry. At the same time as the application and demand are getting larger and larger, the literature and experimental data of such alloy processing are insufficient. According to some literatures, although the tool fracture is improved, the machining accuracy of 0.02mm or less for lathe machining is still Unable to achieve, in order to break through this difficult point, this article began to study the best parameters of Inconel 718 nickel-based alloy turning.This paper uses the Taguchi method to analyze the optimal turning parameters, and uses the spindle speed, feed, and cutting depth to change the experiment. Then the error value after the experiment is used to calculate the small quality characteristic, and the SN ratio analysis result is obtained. Finally, the length difference value and The SN result table, length difference of each factor response table and the length difference of control factors were analyzed on the S / N ratio map to obtain the optimal conditions for turning parameters. The experimental results show that the Taguchi analysis of the length difference of turning length contribution is: spindle speed> depth of cut> feed sequence relationship. The optimal parameters for turning were spindle speed 1100 (rpm), depth of cut 0.1 (mm), feed 0.1 (mm/rev), and the error between the target turning length and the actual turning length after 50 cuttings was 0.007 mm. Keywords: Inconel 718, Taguchi method, Turning
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Tai, Chao-Chung, i 戴兆中. "Heat Treatment of Inconel 718 Superalloy". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/03933248346342431700.
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碩士義守大學
機械與自動化工程學系碩士班
96
This study conducted nine different kinds of heat treatment of Inconel 718 superalloy: HT1 (1095°C /1 hr ), HT2(1095°C /1hr +955°C /1 hr), HT3(1095°C /1hr +955°C /3.5 hr), HT4(1095°C /1hr + 720°C /8hr), HT5(1095°C /1hr+955°C /1 hr + 720°C /8hr ), HT6(1095°C /1hr+955°C /3.5 hr + 720°C /8hr ), HT7(1095°C /1hr +720°C/8hr + 620°C /8hr), HT8(1095°C /1hr +955°C /1hr +720°C /8hr + 620°C /8hr), and HT9(1095°C /1hr +955°C /3.5hr +720°C /8hr + 620°C /8hr). Hardness and grain size were measured after different heat treatment schemes. By the use of OM, SEM and TEM, the microstructure was observed. Analyzed by the EDX of SEM, most carbides are in composition of NbC. TEM diffraction pattern reveales that MC carbides are NbC and TiC types, and δ precipitations are Ni3Nb.
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Huang, Tsung-Lin, i 黃宗霖. "The Optimum Parameters for Milling Inconel 718". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/60734983138616989913.
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碩士國立高雄應用科技大學
機械與精密工程研究所
102
This study concentrates on optimal design of the parameters of Milling with the Inconel 718 Milling cutter which diameter is 6mm By Tachuchi Method. We used the Milling cutter to milling the standard samples by controlling the four parameters which including the spindle speeding ，feed rates ，cutting depth and the coating on the blade . After the experiment we measured the wearing and caught the pictures by optical microscopy. Finally we got the optimal parameters sets are the spindle speeding is 1600 rpm ，the feed rates is 100 mm/min， the cutting depth is 1mm and the coating materials are TiAlN.
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Kandula, Venkata Rama Sateesh. "Additive Manufacturing of Inconel 718 Cellular Structures". Thesis, 2020. https://etd.iisc.ac.in/handle/2005/5195.
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Additive Manufacturing (AM) is getting adopted in various industries like automobile, aerospace, medical, nuclear, defense, and space, amongst many others, in the last five to ten years due to the tremendous advantages of cost and flexibility. However, AM adoption rate in the aerospace industry is relatively lower than a few other sectors. The current work focuses on significant aspects of AM that impact the aerospace industry.
The thesis explores AM technology's historical development at the outset, focusing on various processes specific to metals. Among the multiple benefits of AM, the aspect of light-weighting the aerospace components using cellular structure stands out. Nickel superalloy Inconel 718 is one of the critical materials used to address the high-temperature, high-corrosion, high-strength, and high-toughness requirements of aerospace gas turbine engines, constituting more than 30% of the weight.
More than a thousand manufacturing process parameters impact the microstructure. The repeatability and reproducibility of mechanical properties of AM Inconel 718 components are widely studied topics. The thin sections of cellular structures add additional complexities, such as geometrical nonlinearities, which are not well explored in the literature.
The application of AM Inconel 718 cellular structures is the primary subject of this thesis. The details related to the proper process parameters are presented for the powder bed fusion AM process. Specimens are designed to evaluate the process capability to print planar, cylindrical, and spherical cellular structures.
The Inconel 718 AM printed planar cellular specimens are then evaluated through quasi-static tensile and compression tests. Thin-walled cellular structures along with disk and ring specimens are subjected to Split Hopkinson Bar (SHPB) impact loads to understand the high strain rate 'material' properties w.r.t to the cellular geometry.
Impact test on Inconel AM printed hemispherical cellular dome structure using a high-speed steel ball projectile is performed to understand the energy absorption characteristics.
Light-weighting structures using lattice geometries is still an art. The Topology Optimization technique to be used in conjunction with lattice structures is explored. Homogenization is a key enabler for computationally efficient and practically meaningful topology optimization. Thus, the Variational Asymptotic Method (VAM) is therefore proposed to render a simultaneously accurate and efficient homogenization of thin-walled lattice structures.
Finally, the thesis presents inferences from various design and experiments conducted as part of this work. It proposes a road map for the design and development of lightweight turbine disk containment rings for gas turbine engines. It suggests topics for potentially rewarding future research in this area.
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Chen, Weixing. "Grain boundary dependent creep behaviour of Inconel 718". 1995. http://hdl.handle.net/1993/18746.
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yao, Hsiao Shuo, i 蕭碩堯. "Inconel 718 Microstructure Analysis After Cyclic Heat Treatment". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/90569204199850962346.
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碩士國防大學中正理工學院
兵器系統工程研究所
94
The Inconel 718, a nickel-based superalloy with its high strength and high corrosion resistance at elevated temperature, becomes a popular superalloy for high high temperature application in the past decades. It has good castability, workability, and weldability enabling it being widely used to produce aero-parts and as structural material. This research is based on the mechanical properties of Inconel 718 after cyclic heat treatment. In accordance with the special changes of the testing pieces on its mechanical properties, the cyclic heat treatment has significantly affected the microstructure and the mechanical property. The results of M4 condition {twice heat treatment （980℃*1h/980℃*1h/ 720℃ *8h/620℃*10h）} show that the δ phase precipitate significantly on both grain boundary and within the grain with the needle shape. At M10 condition {4 times heat treatment（980℃*1h/980℃*1h/720℃*8h /620℃*10h）}. δ phase does not continuiously precipitate on grain boundary and the amount of δ phase are significantly decreased in the grain interior. It suggests that at M10 condition δ phase may reach the critical point of dissolution, which differs from M4 with lots of δ phase accumulated. In other words, once the critical point of dissolution is reached, further cyclic heat trement would not produce extra precipitated δ phase may also result in the precipitates dissolve into the matrix. At M13 condition {5 times heat treatment（980℃*1h/980℃*1h/720℃*8h /620℃*10h）} the dissolving temperature of δ phase is hogher than that operating temperature of solution treatment, δ phase may significantly precipitate, loading to its decreased of M13 to a value close to the M1 condition {1 time heat treatment（980℃*1h/980℃*1h/720℃ *8h /620℃*10h）}. Obviously, it had a similar trend of circulating. At M11 condition {4 times heat treatment（1065℃*1h/1065℃*1h/720℃*8h /620℃*10h）}, many NbC particles and a few NbC films are found. At M14 condition {5 times heat treatment（1065℃*1 h/1065℃*1h/720℃*8h/620℃*10 h）} , it appears significantly amount of NbC particles as well as NbC films present on the grain enhancing the resistance of grain boundary sliding , therefore its ductily and toughness. At M9 condition {3 times heat treatment（1065℃*1h/ 1065℃*1h /760℃*10h/650℃*10 h）},the NbC particles are more intensity presitipated at grain boundary than that M11 condition, althougth the presence of NbC particles may enhance the ductily of Inconel 718. However,similar problem as M11 and M14 may occur when welded. The significantly amount of NbC particles and NbC films at grain boundary may possibily produce microfissuring in HAZ, which is a possible reason for unexpected earlier fracture.
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Wang, Chao-An, i 王朝安. "Inconel 718 Nickel Base Melting and Modifying Research". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/19999578156788643622.
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碩士國防大學中正理工學院
兵器系統工程研究所
96
The material characteristics and mechanical properties, such as yield stress, tensile stress, elongation, and hardness, of cast Inconel 718 Nickel base superalloy were investigated in this thesis. The optimal heat treatment conditions for each mechanical property of Inconel 718 were obtained using analysis of Taguchi method. In addition, this thesis also investigated the effects of adding Hafnium (Hf) on the mechanical properties and microstructure of cast Inconel 718. We hope, by way of adding Hf, to improve the mechanical properties of cast Inconel 718 without conducting forging or hot isothermal pressing (HIP) process. At first, the heat treatment parameters including solid solution and aging treatment of remelted and cast Inconel 718 bought from Japan IHI corporation were investigated. The optimal condition for the process of solution and aging treatment was analyzed with Taguchi method. The appropriate heat treatment parameters, such as solid solution temperature, solid solution time, aging temperature and aging time, for each mechanical property like strength, elongation, or hardness were also analyzed using analysis of variance (ANOVA) and contribution analysis and then confirmed with experiments. Furthermore, using the IHI Inconel 718 as matrix, we investigated the variation of mechanical properties and microstructure of the specimens of cast Inconel 718, which were added with 1.0 wt%, 1.5 wt%, and 2.0 wt% Hf. The mechanical properties and microstructure between both the remelted and Hf-modified cast Inconel 718 that were heat treated with the aforementioned optimal parameters obtained from Taguchi analysis were also compared. Our results indicate that, using the appropriate parameters of heat treatment, the cast Inconel 718 can achieve good result for each mechanical property, such as yield stress, tensile stress, elongation or hardness. The best mechanical performance of the cast Inconel 718 for each mechanical property was list as follows, the best yield stress was at about 999 MPa which has improved 68.7% than that of the reference specimen (592 MPa), the best tensile stress was at about 1144 MPa which has improved 34.2% than the 852 MPa of the reference specimen, the best elongation was at about 27.8% which has improved 122%, and the highest hardness was at about HRC 39 with 95% improvement. Compared to the literatures, these optimal mechanical properties were all superior. Moreover, when the heat treatment condition was solid solution at 1140℃ for 2 hr, air cooling to room temperature, raising temperature to 780℃and holding for 10 hr for the first aging, and then furnace cooling to 600℃and holding for 12hr for the second aging, we can obtain a well-balanced cast Inconel 718 which has good quality at all mechanical properties. For the adding of Hf into cast Inconel 718, we have observed new phases precipitating in the Inconel 718 matrix. The phase identification of XRD and EPMA showed that these phases are Ni5Hf, and MC type carbides. When the adding amount of Hf was 1.5 wt% and the specimen was heat treated with the aforementioned optimal parameters obtained from Taguchi analysis, we found that the hardness of Hf-modified cast Inconel 718 has increased 20% to HRC 36. The yield stress and tensile stress has the highest value of 932 and 1108 MPa, which has improved 5% and 4.3%, respectively. Finally, all the data including the data of Taguchi experiments, confirming experiments and Hf-modified experiments of cast Inconel 718 have been integrated and analyzed to implement the multiple characteristics analysis of mechanical properties to obtain the optimal heat treatment parameters to achieve good results for well-balanced multiple mechanical properties.