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Additive Manufacturing has brought about substantial benefits to the manufacturing industry due to the numerous advantages it provides, at the same time there are factors that can be improved upon. Temperature control is an important parameter during the build process as it affects build quality. The main objective of this thesis project was to investigate what sensors could be used for monitoring the temperature during the additive manufacturing processand to compare and evaluate their performance. This involved implementing two 2-color pyrometers and a short-wave infrared camera to monitor the temperature of the area behind the melt pool and then visualizing the respective data. Initial issues arose during test runs in the form of noise in the pyrometer data, this was solved by implementing a smoothing filter to the signal. Multiple runs were conducted to capture the required data as images produced by the camera were overexposed and out of focus during initial runs. This was solved by changing the camera position and exposure settings. Reading the temperature values from the images involved interpreting the Average Dark Units (ADU) values of the region of interest and then comparing those values to a reference chart. The data gathered with the help of LabVIEW software and the proprietary imaging software of the camera showed that the selected sensors were in fact suitable for the intended task and could be used in conjunction with each other. This data could then be used to create a closed-loop system in the future (not in the scope of this thesis work) and thus enable the increase in the level of automation for Robotized Laser Wire Additive Manufacturing.

Inconel 718 has widespread use in critical industries like aerospace, marine, and power generation. However, its challenging machinability, characterized by tool chipping/failure, and poor surface quality, remains a significant concern. Despite numerous efforts to enhance tool performance in machining hard-to-machine materials, the issue of sudden tool failure and chipping persists. This study presents an innovative in-situ tool treatment method, complemented by an optimized recoating strategy, aimed at tackling these challenges. The approach involves the application of a lubricating soft metallic Al-Si alloy coating to the tool’s faces, which can be recoated when needed. During subsequent Inconel machining, the Al-Si layer deposited on the tool melts due to high temperatures. The molten material fills microcracks on the tool surface, preventing their propagation. Moreover, the tool can slide on the beneficial tribo-films Al-Si layer which reduces friction, sticking, seizure, and built-up edge formation, resulting in decreased tool wear and chipping. The newly developed pre-machined recoating method has yielded promising outcomes, reducing cutting force and significantly improving tool lifespan compared to the PVD benchmark and uncoated tools. Additionally, this novel method enhances surface quality and minimizes undesirable microstructural alterations induced by machining. / Thesis / Master of Applied Science (MASc) / Chipping and excessive tool wear pose significant challenges in machining high-strength alloys like Inconel 718, limiting their applicability across various industries. According to research, conventional strategies used to deal with the machining challenges posed by Inconel 718 have not produced the best results. The goal of this research is to overcome the machining issues associated with such a difficult-to-cut material innovatively by depositing soft metallic coatings as a solid lubricant to enhance the machining performance. In this study, a cost-effective novel in-situ deposition technique with recoating capability as an alternative to conventional coatings is presented to achieve this goal. This innovative approach aims to improve tool performance during Inconel 718 machining significantly. This study also provides a thorough insight into the application of solid lubricants in machining, discussing their mechanisms, effectiveness, constraints, and potential to boost productivity and environmental sustainability. Furthermore, comprehensive investigations have been conducted to gain deeper insights into the prevalent wear mechanisms and surface treatments that can lead to improved machining performance for Inconel 718.

No / Nickel alloys including Inconel 718 are considered as challenging materials for machining. Laser beam machining could be a promising choice to deal with such materials for simple to complex machining features. The machining accuracy is mainly dependent on the rate of material removal per laser scan. Because of the involvement of many laser parameters and complexity of the machining mechanism it is not always simple to achieve machining with desired accuracy. Actual machining depth extremely varies from very low to aggressively high values with reference to the designed depth. Thus, a research is needed to be carried out to control the process parameters to get actual material removal rate (MRRact) equals to the theoretical material removal rate (MRRth) with minimum surface roughness (SR) of the machined surfaces. In this study, five important laser parameters have been used to investigate their effects on MRR and SR. Statistical analysis are performed to identify the significant parameters with their strength of effects. Mathematical models have been developed and validated to predict the machining responses. Optimal set of laser parameters have also been proposed and confirmed to achieve the actual MRR close to the designed MRR (MRR% = 100.1%) with minimum surface roughness (Ra = 2.67 µm). / The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through research group number RG-1440-026.

In recent years, additive manufacturing (AM) has been one of the essential production techniques in the engineering community. Rapid integration of this technique drew a bead on the reliability of the microstructural and mechanical properties of engineering components. However, due to the nature of the layer-by-layer approach of AM, complex thermal gradients can cause inhomogeneous microstructure and significant residual stresses (RS). These, expectedly, can lead to a dramatic reduction in material performance. Therefore, especially for alloys like Ni-based Inconel 718 (IN718) used in critical applications, the characterization and later optimization of the DED process on material properties become essential. Nevertheless, empirical and conventional approaches are needed to improve, or new techniques should be introduced. In this regard, this study aims to understand better the evolution of the mechanical and microstructural properties of IN718 during and post-DED processes. For this purpose, an in-situ 2D neutron diffraction strain monitoring was carried out during the DED of IN718. The strain contributions originated from microstructural, thermal, and stress-based events during deposition and cooling periods at different positions concerning melt pool were investigated. Stabilization of different positions and processing regions on the sample as a function of the temperature profile, build height, and microstructural events are examined. Laboratory-scale microstructural studies were performed on wire-DED parts to observe the process parameter dependency of precipitation, composition, and morphology of microstructural constituents. Moreover, these findings were benchmarked with neutron powder diffraction measurements to relate the crystallographic behavior with macroscopic ones. Solidification under different cooling rates and heat treatments was carried out using the neutron powder diffraction technique to comprehend the precipitation dynamics and explain the microstructural events during and after the DED process. Laboratory scale and neutron diffraction tensile characterization tests were performed to observe and relate the mechanical response of wire- DED IN718 at different temperatures and microstructural conditions.:Keywords i Abstract iii Table of Contents v List of Figures ix List of Tables xvii List of Abbreviations xix Acknowledgments xxi Chapter 1: Introduction 1 1.1 Residual Stress in Polycrystalline Materials 1 1.1.1 Residual Stress Determination 3 1.2 Neutron Scattering 5 1.2.1 Neutron-Matter Interaction 6 1.2.2 Strain Measurement by Neutron Diffraction 7 1.2.3 SALSA Neutron Strain Diffractometer 14 1.2.4 Neutron Powder Diffraction 16 1.2.5 D20 Neutron Powder Diffractometer 17 1.2.6 Peak Analysis in Diffraction Measurements 18 1.3 Nickel Superalloys 22 1.3.1 Physical Metallurgy of IN718 23 1.4 Metal Additive Manufacturing 33 1.4.1 Direct Energy Deposition (DED) 34 1.4.2 Process Monitoring in Metal AM 36 1.5 Context and Aim of the Study 40 Chapter 2: Materials and Experimental Methods 43 2.1 IN718 Feedstock Material 43 2.2 Fabrication Process by wire-DED Method 43 2.2.1 Post Processing of IN718 via Solution Treatment and Aging 47 2.2.2 Preparation of Tensile Specimens 48 2.3 Microstructural Characterization 49 2.3.1 Electron Microscopy Studies 49 2.3.2 Differential Scanning Calorimetry Analysis 50 2.3.3 Lattice Parameter Evolution of IN718 with Temperature 52 2.3.3.1 Data Reduction for Phase Analysis 54 2.4 Mechanical Characterization 57 2.4.1 Neutron Diffraction 2D Strain Monitoring during IN718 wire-DED 57 2.4.1.1 Temperature Data Treatment and Processing Regions 61 2.4.1.2 Neutron Data Acquisition and Analysis 64 2.4.2 Residual Stress Mapping of Samples for Mechanical Characterization 69 2.4.3 Macro-scale Tensile Characterization at Room and High Temperatures 71 2.4.4 Neutron Diffraction Tensile Characterization Testing 72 2.4.4.1 Neutron Data Processing Procedure 77 Chapter 3: Results and Discussion 79 3.1 Microstructural Characterization of Feedstock Wire 79 3.1.1 Metallography of IN718 Feedstock Wire 79 3.1.2 Simulation of Phase Precipitations in IN718 80 3.1.3 Thermal Stability of IN718 Feedstock Wire 82 3.1.3.1 Differential Scanning Calorimetry 82 3.1.3.2 Lattice Parameter Evolution during Melting & Solidification 83 3.1.4 Discussion 91 3.2 Microstructure of IN718 wire-DED Parts 94 3.2.1 IN718-DED Cylindrical Walls 94 3.2.2 IN718 -DED Prisms 103 3.2.3 Discussion 108 3.3 Heat Treatments of IN718 Wire-DED Parts 112 3.3.1 Time and Temperature Impact into Laves Phase Dissolution 112 3.3.2 Lattice Parameter Evolution of IN718 during Solution and Aging Treatments 115 3.3.3 Discussion 118 3.4 Mechanical Characterization of IN718 wire-DED 122 3.4.1 Neutron Diffraction 2D Strain Monitoring during IN718 wire-DED 122 3.4.1.1 Bragg Angle Evolution 122 3.4.1.2 Evolution of Bragg Angle Position in MP Processing Region 123 3.4.1.3 Evolution of Bragg Angle Position in the NMP Processing Region 126 3.4.1.4 Evolution of Bragg Angle Position in FF Processing Region 129 3.4.2 Discussion 131 3.4.2.1 Comparison of Equilibrium State of IN718 through In-situ and Ex-situ Investigations 135 3.4.3 Reference (d0) Approaches for Strain Calculations 136 3.4.3.1 Stable processing regime reference 136 3.4.3.2 Neutron powder diffraction reference 137 3.4.4 Evolution of Strain Contributions during IN718 wire-DED by Using Stable Reference (d0) Approach 140 3.4.4.1 Strain Evolution in MP Processing Region 141 3.4.4.2 Strain Evolution in NMP Processing Region 143 3.4.4.3 Strain Evolution in FF Processing Region 145 3.4.5 Evolution of Strain Contributions during IN718 wire-DED by Using Neutron Powder Diffraction Reference d0 Approach 148 3.4.6 Discussion 151 3.4.7 Tensile Characterization 153 3.4.7.1 Macro-scale Tensile Behavior 153 3.4.7.2 Residual Stress State in In-situ Tensile Test Specimens 155 3.4.7.3 Lattice-scale Tensile Behavior 158 3.4.8 Discussion 169 3.4.8.1 Residual Stress State prior to Tensile Test Characterization 169 3.4.8.2 Macro-scale Tensile Behavior of IN718 at Room and High Temperatures 169 3.4.8.3 Lattice-dependent Behavior As-built and Direct-aged Condition as a function of Applied Stresses 175 Chapter 4: Summary Discussion 182 4.1 Microstructural Considerations 182 4.1.1 Comparison of Materials and Extrapolation of Properties 182 4.2 Thermal Stability of IN718 Feedstock Wire and DED Parts 183 4.2.1 Matrix, Phase Precipitation, and CTE Evolution as a Function of Temperature 183 4.2.2 Heat Treatments of IN718 DED materials 184 4.3 Fabrication and Neutron Strain Monitoring Considerations 185 4.3.1 Temperature Gradients and Regions of Interest 185 4.3.2 In-situ Neutron Monitoring of Bragg Angle Evolution of γ-matrix 185 4.3.3 2D Strain Evolution 186 4.4 Tensile Mechanical Behaviour at Room and High-Temperature Considerations 189 4.4.1 Macro-scale Characterization 189 4.4.2 Lattice-scale Neutron Diffraction Characterization 189 Chapter 5: Conclusions 191 Bibliography 196 / In den letzten Jahren hat sich die additive Fertigung (AM) zu einer der wichtigsten Produktionstechniken in der Ingenieurwelt entwickelt. Die schnelle Integration dieser Technik hat die Zuverlässigkeit der mikrostrukturellen und mechanischen Eigenschaften von technischen Komponenten deutlich verbessert. Aufgrund des schichtweisen Ansatzes der AM können jedoch komplexe thermische Gradienten eine inhomogene Mikrostruktur und erhebliche Eigenspannungen (RS) verursachen. Diese können erwartungsgemäß zu einer dramatischen Verringerung der Materialleistung führen. Daher sind insbesondere bei Legierungen wie Inconel 718 (IN718) auf Ni-Basis, die in kritischen Anwendungen eingesetzt werden, die Charakterisierung und spätere Optimierung des DED-Prozesses auf die Materialeigenschaften von entscheidender Bedeutung. Dennoch müssen empirische und konventionelle Ansätze verbessert werden, oder es sollten neue Techniken eingeführt werden. In diesem Zusammenhang zielt diese Studie darauf ab, die Entwicklung der mechanischen und mikrostrukturellen Eigenschaften von IN718 während und nach dem DED-Prozess besser zu verstehen. Zu diesem Zweck wurde während des DED-Prozesses von IN718 eine in-situ 2D-Neutronenbeugungsmessung der Dehnung durchgeführt. Die Dehnungsbeiträge, die von mikrostrukturellen, thermischen und spannungsbasierten Ereignissen während der Abscheidungs- und Abkühlungsperioden an verschiedenen Positionen des Schmelzbades herrühren, wurden untersucht. Die Stabilisierung verschiedener Positionen und Verarbeitungsbereiche auf der Probe als Funktion des Temperaturprofils, der Aufschmelzhöhe und der mikrostrukturellen Ereignisse wurde untersucht. Im Labormaßstab wurden mikrostrukturelle Studien an Draht-DED-Teilen durchgeführt, um die Abhängigkeit der Prozessparameter von der Ausscheidung, Zusammensetzung und Morphologie der mikrostrukturellen Bestandteile zu beobachten. Darüber hinaus wurden diese Ergebnisse mit Neutronenpulverbeugungsmessungen verglichen, um das kristallographische Verhalten mit dem makroskopischen Verhalten in Beziehung zu setzen. Die Erstarrung unter verschiedenen Abkühlungsraten und Wärmebehandlungen wurde mit Hilfe der Neutronenpulverbeugungstechnik durchgeführt, um die Ausscheidungsdynamik zu verstehen und die mikrostrukturellen Ereignisse während und nach dem DED-Prozess zu erklären. Es wurden Zugversuche im Labormaßstab und mit Neutronenbeugung durchgeführt, um die mechanische Reaktion von IN718 bei verschiedenen Temperaturen und Mikrostrukturbedingungen zu beobachten und in Beziehung zu setzen.:Keywords i Abstract iii Table of Contents v List of Figures ix List of Tables xvii List of Abbreviations xix Acknowledgments xxi Chapter 1: Introduction 1 1.1 Residual Stress in Polycrystalline Materials 1 1.1.1 Residual Stress Determination 3 1.2 Neutron Scattering 5 1.2.1 Neutron-Matter Interaction 6 1.2.2 Strain Measurement by Neutron Diffraction 7 1.2.3 SALSA Neutron Strain Diffractometer 14 1.2.4 Neutron Powder Diffraction 16 1.2.5 D20 Neutron Powder Diffractometer 17 1.2.6 Peak Analysis in Diffraction Measurements 18 1.3 Nickel Superalloys 22 1.3.1 Physical Metallurgy of IN718 23 1.4 Metal Additive Manufacturing 33 1.4.1 Direct Energy Deposition (DED) 34 1.4.2 Process Monitoring in Metal AM 36 1.5 Context and Aim of the Study 40 Chapter 2: Materials and Experimental Methods 43 2.1 IN718 Feedstock Material 43 2.2 Fabrication Process by wire-DED Method 43 2.2.1 Post Processing of IN718 via Solution Treatment and Aging 47 2.2.2 Preparation of Tensile Specimens 48 2.3 Microstructural Characterization 49 2.3.1 Electron Microscopy Studies 49 2.3.2 Differential Scanning Calorimetry Analysis 50 2.3.3 Lattice Parameter Evolution of IN718 with Temperature 52 2.3.3.1 Data Reduction for Phase Analysis 54 2.4 Mechanical Characterization 57 2.4.1 Neutron Diffraction 2D Strain Monitoring during IN718 wire-DED 57 2.4.1.1 Temperature Data Treatment and Processing Regions 61 2.4.1.2 Neutron Data Acquisition and Analysis 64 2.4.2 Residual Stress Mapping of Samples for Mechanical Characterization 69 2.4.3 Macro-scale Tensile Characterization at Room and High Temperatures 71 2.4.4 Neutron Diffraction Tensile Characterization Testing 72 2.4.4.1 Neutron Data Processing Procedure 77 Chapter 3: Results and Discussion 79 3.1 Microstructural Characterization of Feedstock Wire 79 3.1.1 Metallography of IN718 Feedstock Wire 79 3.1.2 Simulation of Phase Precipitations in IN718 80 3.1.3 Thermal Stability of IN718 Feedstock Wire 82 3.1.3.1 Differential Scanning Calorimetry 82 3.1.3.2 Lattice Parameter Evolution during Melting & Solidification 83 3.1.4 Discussion 91 3.2 Microstructure of IN718 wire-DED Parts 94 3.2.1 IN718-DED Cylindrical Walls 94 3.2.2 IN718 -DED Prisms 103 3.2.3 Discussion 108 3.3 Heat Treatments of IN718 Wire-DED Parts 112 3.3.1 Time and Temperature Impact into Laves Phase Dissolution 112 3.3.2 Lattice Parameter Evolution of IN718 during Solution and Aging Treatments 115 3.3.3 Discussion 118 3.4 Mechanical Characterization of IN718 wire-DED 122 3.4.1 Neutron Diffraction 2D Strain Monitoring during IN718 wire-DED 122 3.4.1.1 Bragg Angle Evolution 122 3.4.1.2 Evolution of Bragg Angle Position in MP Processing Region 123 3.4.1.3 Evolution of Bragg Angle Position in the NMP Processing Region 126 3.4.1.4 Evolution of Bragg Angle Position in FF Processing Region 129 3.4.2 Discussion 131 3.4.2.1 Comparison of Equilibrium State of IN718 through In-situ and Ex-situ Investigations 135 3.4.3 Reference (d0) Approaches for Strain Calculations 136 3.4.3.1 Stable processing regime reference 136 3.4.3.2 Neutron powder diffraction reference 137 3.4.4 Evolution of Strain Contributions during IN718 wire-DED by Using Stable Reference (d0) Approach 140 3.4.4.1 Strain Evolution in MP Processing Region 141 3.4.4.2 Strain Evolution in NMP Processing Region 143 3.4.4.3 Strain Evolution in FF Processing Region 145 3.4.5 Evolution of Strain Contributions during IN718 wire-DED by Using Neutron Powder Diffraction Reference d0 Approach 148 3.4.6 Discussion 151 3.4.7 Tensile Characterization 153 3.4.7.1 Macro-scale Tensile Behavior 153 3.4.7.2 Residual Stress State in In-situ Tensile Test Specimens 155 3.4.7.3 Lattice-scale Tensile Behavior 158 3.4.8 Discussion 169 3.4.8.1 Residual Stress State prior to Tensile Test Characterization 169 3.4.8.2 Macro-scale Tensile Behavior of IN718 at Room and High Temperatures 169 3.4.8.3 Lattice-dependent Behavior As-built and Direct-aged Condition as a function of Applied Stresses 175 Chapter 4: Summary Discussion 182 4.1 Microstructural Considerations 182 4.1.1 Comparison of Materials and Extrapolation of Properties 182 4.2 Thermal Stability of IN718 Feedstock Wire and DED Parts 183 4.2.1 Matrix, Phase Precipitation, and CTE Evolution as a Function of Temperature 183 4.2.2 Heat Treatments of IN718 DED materials 184 4.3 Fabrication and Neutron Strain Monitoring Considerations 185 4.3.1 Temperature Gradients and Regions of Interest 185 4.3.2 In-situ Neutron Monitoring of Bragg Angle Evolution of γ-matrix 185 4.3.3 2D Strain Evolution 186 4.4 Tensile Mechanical Behaviour at Room and High-Temperature Considerations 189 4.4.1 Macro-scale Characterization 189 4.4.2 Lattice-scale Neutron Diffraction Characterization 189 Chapter 5: Conclusions 191 Bibliography 196

Afin d'améliorer la qualité des dépôts réalisés par projection thermique, diverses techniques connexes aux procédés de projection ont été développées. Parmi celles-ci, on peut noter les procédés laser qui peuvent présenter l'avantage de dispenser un traitement localisé en surface, simultané à la projection. Comparés aux techniques de préparation couramment employées, ces procédés sont également plus respectueux de l'environnement. Le sujet de thèse repose donc sur la compréhension et la maîtrise des prétraitements laser (préchauffage, ablation) afin d'améliorer les propriétés finales des revêtements réalisés et en particulier l'adhérence des dépôts sur le substrat.

Das Ziel der Arbeit war die Weiterführung der Substrukturanalyse von plastisch verformten metallischen Werkstoffen mit kubischer Struktur auf der Basis des Disklinationskonzeptes unter Berücksichtigung unterschiedlicher homologer Temperaturen und Stapelfehlerenergien. Die Untersuchungen wurden an Stauchproben von Wolfram, Aluminium und der Legierung Inconel 718 mit Hilfe der TEM, der REM (EBSD) und der röntgenografischen Profilanalyse durchgeführt. Bei allen drei Werkstoffen konnten im Temperatur- und Umformbereich T/Ts<=0,3, Deformation>=0,3 auf der Basis von lokalen TEM-Desorientierungsmessungen Partialdisklinationen identifiziert und ihre Frankvektoren bzw. Defektstärken bestimmt werden. Die Ergebnisse der EBSD-Untersuchungen und der Röntgendiffraktometrie sind mit den TEM-Beobachtungen kompatibel und zeigen, dass die Kombination der drei Methoden für die systematische Substrukturanalyse an stark verformten Werkstoffen gut geeignet ist.

Ces dernières années les développements des traitements thermomécaniques ont conduit à l'utilisation de l'alliage 718 à l'état DA (Direct Aged). Cette optimisation de l'alliage conduit de façon générale à une augmentation de la durée de vie en fatigue mais aussi de sa dispersion. L'objectif de cette étude est d'une part la compréhension des mécanismes d'amorçage en fatigue et d'autre part la modélisation de la durée de vie et de sa dispersion. Dans un premier temps une étude expérimentale des sites d'amorçage de fissures de fatigue a permis d'identifier les particules comme principale source d'amorçage pour l'alliage à grains fins. Des essais de traction interrompus ont par ailleurs montré que leur fissuration se produit lors du premier quart de cycle en fatigue. Des essais de comportement en fatigue ont ensuite été réalisés pour différentes tailles de grain. Enfin, des mesures directes de propagation de petites fissures en fatigue oligocyclique amorcées sur des micro-défauts d'électroérosion ont été réalisées à l'aide d'un microscope à grande distance focale. Cette technique a permis d'observer l'interaction de microfissures. Un modèle de durée de vie en fatigue est proposé. Il est basé sur la compétition entre trois mécanismes d'amorçage: l'amorçage sur particules surfaciques, internes et en stade I. L'amorçage sur particules est considéré instantané au passage d'une contrainte seuil. Le nombre de cycles à l'amorçage en stade I est déterminé à l'aide du modèle de Tanaka et Mura. Le modèle de propagation utilisé est celui de Tomkins, identifié à partir des mesures expérimentales de propagation de petites fissures. Le modèle proposé comporte trois niveaux: déterministe, probabiliste et probabiliste avec prise en compte des phénomènes de coalescence de petites fissures.

Factors such as environmental requirements and fuel efficiency have pushed aerospace industry to develop reduced-weight engine designs and thereby light-weight and thin-walled components. As component wall thickness gets thinner and the mechanical structures weaker, the structure becomes more sensitive for vibrations during milling operations. Demands on cost efficiency increase and new ways of improving milling operations must follow. Historically, there have been two “schools” explaining vibrations in milling. One states that the entry angle in which the cutting insert hits the work piece is of greater importance than the exit angle. The other states that the way the cutter leaves the work piece is of greater importance than the cutter entry. In an effort to shed some light over this issue, a substantial amount of experiments were conducted. Evaluations were carried out using different tools, different tool-to-workpiece offset positions, and varying workpiece wall overhang. The resultant force, the force components, and system vibrations have been analyzed. The first part of this work shows the differences in force behavior for three tool-to-workpiece geometries while varying the wall overhang of the workpiece. The second part studies the force behavior during the exit phase for five different tool-to-workpiece offset positions while the overhang is held constant. The workpiece alloy throughout this work is Inconel 718. As a result of the project a spread sheet milling stability prediction model is developed and presented. It is based on available research in chatter theory and predicts the stability for a given set of variable input parameters. / <p>QC 20121206</p>

Orientador: Marcos Valério Ribeiro / Resumo: 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