Author: Roger C. Reed
Publisher: Cambridge University Press
Release Date: 2008-07-31
Genre: Technology & Engineering
Superalloys are unique high-temperature materials used in gas turbine engines, which display excellent resistance to mechanical and chemical degradation. This book presents the underlying metallurgical principles which have guided their development and practical aspects of component design and fabrication from an engineering standpoint. The topics of alloy design, process development, component engineering, lifetime estimation and materials behaviour are described, with emphasis on critical components such as turbine blading and discs. The first introductory text on this class of materials, it will provide a strong grounding for those studying physical metallurgy at the advanced level, as well as practising engineers. Included at the end of each chapter are exercises designed to test the reader's understanding of the underlying principles presented. Solutions for instructors and additional resources are available at www.cambridge.org/9780521859042.
Author: Jonas Saarimäki
Publisher: Linköping University Electronic Press
Release Date: 2018-01-18
Genre: Electronic books
Gas turbines are widely used in industry for power generation and as a power source at hard to reach locations where other possibilities for electrical power supplies are insufficient. New ways of producing greener energy is needed to reduce emission levels. This can be achieved by increasing the combustion temperature of gas turbines. High combustion temperatures can be detrimental and degrade critical components. This raises the demands on the high temperature performance of the superalloys used in gas turbine components. These components are frequently subjected to different cyclic loads combined with for example dwell-times and overloads at elevated temperatures, which can influence the crack growth. Dwell-times have been shown to accelerate crack growth and change cracking behaviour in both Inconel 718, Haynes 282 and Hastelloy X. On the other hand, overloads at the beginning of a dwell-time cycle have been shown to retard the dwell-time effect on crack growth in Inconel 718. More experiments and microstructural investigations are needed to better understand these effects. The work presented in this thesis was conducted under the umbrella of the research program Turbo Power; "High temperature fatigue crack propagation in nickel-based superalloys", where I have mainly looked at fatigue crack growth mechanisms in superalloys subjected to dwell-fatigue, which can have a devastating effect on crack propagation behaviour. Mechanical testing was performed under operation-like cycles in order to achieve representative microstructures and material data for the subsequent microstructural work. Microstructures were investigated using light optical microscopy and scanning electron microscopy (SEM) techniques such as electron channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD). The outcome of this work has shown that there is a significant increase in crack growth rate when dwell-times are introduced at maximum load (0 % overload) in the fatigue cycle. With the introduction of a dwell-time there is also a shift from transgranular to intergranular crack growth for both Inconel 718 and Haynes 282. The crack growth rate decreases with increasing overload levels in Inconel 718 when an overload is applied prior to the dwell-time. At high temperature, intergranular crack growth was observed in Inconel 718 as a result of oxidation and the creation of nanometric voids. Another observed growth mechanism was crack advance along δ-phase boundaries with subsequent oxidation of the δ-phase. This thesis comprises two parts. Part I gives an introduction to the field of superalloys and the acting microstructural mechanisms related to fatigue and crack propagation. Part II consists of five appended papers, which report the work completed as part of the project.
Author: Jonas Saarimäki
Publisher: Linköping University Electronic Press
Release Date: 2015-12-10
Gas turbines are widely used in industry for power generation and as a power source at "hard to reach" locations where other possibilities for electrical supply are insufficient. There is a strong need for greener energy, considering the effect that pollution has had on global warming, and we need to come up with ways of producing cleaner electricity. A way to achieve this is by increasing the combustion temperature in gas turbines. This increases the demand on the high temperature performance of the materials used e.g. superalloys in the turbine. These high combustion temperatures can lead to detrimental degradation of critical components. These components are commonly subjected to cyclic loading of different types e.g. combined with dwell-times and overloads at elevated temperatures, which influence the crack growth. Dwell-times have shown to accelerate crack growth and change the cracking behaviour in both Inconel 718 and Haynes 282. Overloads at the beginning of the dwell-time cycle have shown to retard the dwell time effect on crack growth in Inconel 718. To understand these effects more microstructural investigations are needed. The work presented in this licentiate thesis was conducted under the umbrella of the research program Turbo Power; "High temperature fatigue crack propagation in nickel-based superalloys", concentrating on fatigue crack growth mechanisms in superalloys during dwell-times, which have shown to have a devastating effect on the crack propagation behaviour. Mechanical testing was performed under operation-like conditions in order to achieve representative microstructures and material data for the subsequent microstructural work. The microstructures were microscopically investigated in a scanning electron microscope (SEM) using electron channeling contrast imaging (ECCI) as well as using light optical microscopy. The outcome of this work has shown that there is a significant increase in crack growth rate when dwell-times are introduced at the maximum load (0% overload) in the fatigue cycle. With the introduction of a dwell-time there is also a shift from transgranular to intergranular crack growth for both Inconel 718 and Haynes 282. When an overload is applied prior to the dwell-time, the crack growth rate decreases with increasing overload levels in Inconel 718. At high temperature crack growth in Inconel 718 took place as intergranular crack growth along grain boundaries due to oxidation and the creation of nanometric voids. Another observed growth mechanism was crack advance along phase boundaries with subsequent severe oxidation of the phase.
Author: Michael C. Gao
Release Date: 2016-04-27
Genre: Technology & Engineering
This book provides a systematic and comprehensive description of high-entropy alloys (HEAs). The authors summarize key properties of HEAs from the perspective of both fundamental understanding and applications, which are supported by in-depth analyses. The book also contains computational modeling in tackling HEAs, which help elucidate the formation mechanisms and properties of HEAs from various length and time scales.
Die vorliegende Arbeit beschreibt die Entwicklung und den Aufbau eines Miniaturproben-Prüfsystems, mit dem sowohl einachsige Zugversuche als auch niederzyklische Ermüdungsversuche unter Zug/Druck-Wechselbeanspruchung im Hochtemperatur-Bereich bis 1000 Grad Celsius durchgeführt werden können. Ausgehend von einer detaillierten Beschreibung des Versuchsaufbaus wird dessen Qualifizierung und Validierung anhand von drei Versuchswerkstoffen - dem austenitischen Edelstahl AISI 316L, der Nickelbasis-Superlegierungen Waspaloy und IN738LC - gezeigt. Im Vergleich zu Standardproben-Versuchen derselben Materialcharge und Literaturdaten konnte bei den feinkörnigen Versuchswerkstoffen AISI 316L und Waspaloy eine sehr gute Übereinstimmung zwischen den Versuchsdaten festgestellt werden. Dagegen wurde in Versuchen mit Miniaturproben aus der grobkörnigen Nickelbasis-Superlegierung IN738LC ein Probengrößen-Effekt festgestellt. Des Weiteren wird die Anwendbarkeit der Prüfmethodik für die Restlebensdauerbewertung betriebsbeanspruchter Gasturbinen-Laufschaufeln (Werkstoff: IN738LC) einer stationären Gasturbinenanlage gezeigt. Im Ergebnis von Zugversuchen und niederzyklischen Ermüdungsversuchen bei 850 Grad Celsius konnte ein signifikanter Lebensdauerverbrauch nachgewiesen werden, der auf betriebsbedingte Mikrostrukturveränderungen zurückzuführen ist.
Vol 2A: Basic Technologies Handbook of Crystal Growth, 2nd Edition Volume IIA (Basic Technologies) presents basic growth technologies and modern crystal cutting methods. Particularly, the methodical fundamentals and development of technology in the field of bulk crystallization on both industrial and research scales are explored. After an introductory chapter on the formation of minerals, ruling historically the basic crystal formation parameters, advanced basic technologies from melt, solution, and vapour being applied for research and production of the today most important materials, like silicon, semiconductor compounds and oxides are presented in detail. The interdisciplinary and general importance of crystal growth for human live are illustrated. Vol 2B: Growth Mechanisms and Dynamics Handbook of Crystal Growth, 2nd Edition Volume IIB (Growth Mechanisms and Dynamics) deals with characteristic mechanisms and dynamics accompanying each bulk crystal growth method discussed in Volume IIA. Before the atoms or molecules pass over from a position in the fluid medium (gas, melt or solution) to their place in the crystalline face they must be transported in the fluid over macroscopic distances by diffusion, buoyancy-driven convection, surface-tension-driven convection, and forced convection (rotation, acceleration, vibration, magnetic mixing). Further, the heat of fusion and the part carried by the species on their way to the crystal by conductive and convective transport must be dissipated in the solid phase by well-organized thermal conduction and radiation to maintain a stable propagating interface. Additionally, segregation and capillary phenomena play a decisional role for chemical composition and crystal shaping, respectively. Today, the increase of high-quality crystal yield, its size enlargement and reproducibility are imperative conditions to match the strong economy. Volume 2A Presents the status and future of Czochralski and float zone growth of dislocation-free silicon Examines directional solidification of silicon ingots for photovoltaics, vertical gradient freeze of GaAs, CdTe for HF electronics and IR imaging as well as antiferromagnetic compounds and super alloys for turbine blades Focuses on growth of dielectric and conducting oxide crystals for lasers and non-linear optics Topics on hydrothermal, flux and vapour phase growth of III-nitrides, silicon carbide and diamond are explored Volume 2B Explores capillarity control of the crystal shape at the growth from the melt Highlights modeling of heat and mass transport dynamics Discusses control of convective melt processes by magnetic fields and vibration measures Includes imperative information on the segregation phenomenon and validation of compositional homogeneity Examines crystal defect generation mechanisms and their controllability Illustrates proper automation modes for ensuring constant crystal growth process Exhibits fundamentals of solution growth, gel growth of protein crystals, growth of superconductor materials and mass crystallization for food and pharmaceutical industries
Author: Christoph Leyens
Publisher: John Wiley & Sons
Release Date: 2006-03-06
Genre: Technology & Engineering
This handbook is an excellent reference for materials scientists and engineers needing to gain more knowledge about these engineering materials. Following introductory chapters on the fundamental materials properties of titanium, readers will find comprehensive descriptions of the development, processing and properties of modern titanium alloys. There then follows detailed discussion of the applications of titanium and its alloys in aerospace, medicine, energy and automotive technology.
These proceedings focus on the application of fundamental creep research to the design and development of high-temperature materials for engineering applications. The book deals with all aspects of creep deformation and high-temperature materials development, specifically the influence of microstructures on various aspects of creep and the application of this information in the design of highly creep-resistant materials. Emphasis will be placed on advanced ceramic and metal-matrix composites and advanced intermetallics. This volume brings together researchers working on fundamental issues relating to the development and characterization of high-temperature materials and design engineers involved in high-temperature applications.
Author: Werner Buckel
Publisher: John Wiley & Sons
Release Date: 2013-01-02
Grundlegende Konzepte und Eigenschaften von Supraleitern, die Herstellung und Entwicklung von neuen supraleitenden Materialien sowie moderne Anwendungsbereiche sind die Schwerpunktthemen des Buches. Das größte Potential zur Nutzung der Supraleitung liegt in der Energietechnik. Fast unbemerkt trägt die Einführung von Kabeln, Magneten, Transformatoren oder Lagern aus supraleitenden Materialien bei zur Effizienzsteigerung bei der Stromübertragung oder in Motoren. Durch seiner klare Sprache und zahlreiche erläuternde Abbildungen eignet sich der Band hervorragend als einführendes Lehrbuch. Der Schwierigkeitsgrad wird von Kapitel zu Kapitel gesteigert. So können auch Einsteiger ohne einschlägige Vorkenntnisse dem Stoff folgen. Dank der über 350 Literaturhinweise bekommt der Leser außerdem einen Überblick über die wichtigsten Publikationen zum Thema. Ein unverzichtbares Lehrbuch also für Physik-Studenten und Studierende der Ingenieurwissenschaften. Fachleuten in Forschung und Praxis leistet das Buch auch als Nachschlagewerk gute Dienste.
Editors Altan (Ohio State University), Ngaile (North Carolina University), and Shen (Ladish Company, Inc.) offer this extensive overview of the latest developments in the design of forging operations and dies. Basic technological principles are briefly reviewed in the first two chapters.
Summary: "The book covers a wide area ranging from the basic principles familiar in materials science and engineering to practical applications and is expected to serve as a first course text for graduate students, researchers, and engineers engaged in this field. Some chapters are added on the novel materials processing operations and recent topics attracting deep interest of researchers and engineers in the iron and steel industry. Chapter 1 provides information on the stability and time evolution of microstructure in metals and the related principles in statistical thermodynamics. Chapter 2 presents the structure and properties of anodic films on aluminum and micro- and nano-technologies based on anodizing. Chapter 3 is devoted to explain the hydrogen behavior in BCC metals. Chapter 4 describes some features of high-temperature oxidation and corrosion of metals and alloys used in, for example, engines and turbines working at very high temperatures. Chapter 5 is concerned with advanced high-temperature energy materials such as heat resistant ferritic steel and ODS ferritic steel. In Chapter 6 we introduce the basic principles in corrosion engineering. We describe the development of microstructure and its design in Chapter 7 focusing on the solidification of molten metal, peritectic reaction under supercooling condition and grain growth. Chapter 8 treats transport phenomena occurring in the conventional steelmaking reactors such as the converter and ladle. In Chapter 9 we describe environment-friendly titanium with special emphasis on its characteristics, resources, industrial production process currently used, and new production processes. Chapter 10 discusses how to recuperate material and energy for an ecological network."--Publisher description.
Dieses amerikanische Standardwerk wurde vom Übersetzer angepaßt auf die deutschen Verhältnisse. Es bietet wertvolle Informationen für Installation, Betrieb und Wartung, technische Details der Auslegung, Kennzahlen und vieles mehr.