Download or read book Effect of Dwell times on Crack Propagation in Superalloys written by Jonas Saarimäki and published by Linköping University Electronic Press. This book was released on 2015-12-10 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. This thesis comprises two parts. The first giving an introduction to the field of superalloys and the acting microstructural mechanisms that influence fatigue during dwell times. The second part consists of two appended papers, which report the work completed so far in the project.
Download or read book Cracks in superalloys written by Jonas Saarimäki and published by Linköping University Electronic Press. This book was released on 2018-01-18 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 ?-phase boundaries with subsequent oxidation of the ?-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.
Download or read book Constitutive modelling of an additively manufactured alloy for fatigue lifing in high temperature applications written by Thomas Lindström and published by Linköping University Electronic Press. This book was released on 2020-04-28 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of the work presented in this Licentiate thesis is to investigate and model the cyclic behaviour of an additively manufactured ductile nickel-based superalloy, with special emphasis on modelling the stabilised material behaviour, which is of interest for fatigue life predictions. Cyclic fatigue tests at different temperatures have been performed to investigate the cyclic mechanical behaviour of the material, where specimens built in different orientations have been used to also study the anisotropic behaviour of the material. Based on the tests, a constitutive description has progressively been developed and implemented in a finite element context that incorporates the anisotropic behaviour under both elastic and inelastic deformations. In addition, the room temperature crack initiation behaviour has been studied and modelled. This thesis is divided into two parts. The first part gives an introduction and background to the research, while the second part consists of three included papers. Det huvudsakliga målet med arbetet som presenteras i denna avhandling har varit att studera och modellera det cykliska beteendet hos en additivt tillverkad duktil nickelbaserad superlegering, med fokus på att modellera det stabiliserade materialbeteendet, vilket är av intresse vid livslängdprediktering. Cykliska utmattningsprov vid olika temperaturer har utförts för att studera det cykliska beteendet hos materialet, där provstavar byggda i olika riktningar har använts för att studera materialets anisotropi. Baserat på proven har en konstitutiv beskrivning av material progressivt utvecklats och implementerats i ett finita element-verktyg, där modellen tar hänsyn till det anisotropa materialbeteendet för både elastiska och plastiska deformationer. En modell för prediktering av sprickinitiering vid rumstemperatur har också tagits fram. Denna avhandling består av två delar. Den första delen ger en introduktion samt bakgrund till forskningen, medan den andra delen består av tre inkluderade artiklar.
Download or read book Biaxial Multiaxial Fatigue and Fracture written by Andrea Carpinteri and published by Elsevier. This book was released on 2003-03-19 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt: The European Structural Integrity Society (ESIS) Technical Commitee on Fatigue of Engineering Materials and Structures (TC3) decided to compile a Special Technical Publication (ESIS STP) based on the 115 papers presented at the 6th International Conference on Biaxial/Multiaxial Fatigue and Fracture. The 25 papers included in the STP have been extended and revised by the authors. The conference was held in Lisbon, Portugal, on 25-28 June 2001, and was chaired by Manual De Freitas, Instituto Superior Tecnico, Lisbon. The meeting, organised by the Instituto Superior Tecnico and sponsored by the Portuguese Minesterio da Cienca e da Tecnologia and by the European Structural Integrity Society, was attended by 151 delegates from 20 countries. The papers in the present book deal with the theoretical, numerical and experimental aspects of the Multiaxial fatigue and fracture of engineering materials and structures. They are divided in to the following six sections; Multiaxial Fatigue of Welded Structures; High cycle Multiaxial fatigue; Non proportional and Variable-Amplitude loading; Defects, Notches, Crack Growth; Low Cycle Multiaxial Fatigue; Applications and Testing Methods. As is well-known, most engineering components and structures in the mechanical, aerospace, power generation, and other industries are subjected to multiaxial loading during their service life. One of the most difficult tasks in design against fatigue and fracture is to translate the information gathered from uniaxial fatigue and fracture tests on engineering materials into applications involving complex states of cyclic stress-strain conditions. This book is the result of co-operation between many researchers from different laboratories, universities and industries in a number of countries.
Download or read book Low Cycle Fatigue and Elasto Plastic Behaviour of Materials 3 written by K.T. Rie and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 911 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceeds of the Third International Conference on Low Cycle Fatigue and Elasto-plastic Behaviour of Materials, Berlin Congress Center, Berlin, Germany, 7-11 September 1992
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue of Materials written by Subra Suresh and published by Cambridge University Press. This book was released on 1998-10-29 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a leading researcher in the field, this revised and updated second edition of a highly successful book provides an authoritative, comprehensive and unified treatment of the mechanics and micromechanisms of fatigue in metals, non-metals and composites. The author discusses the principles of cyclic deformation, crack initiation and crack growth by fatigue, covering both microscopic and continuum aspects. The book begins with discussions of cyclic deformation and fatigue crack initiation in monocrystalline and polycrystalline ductile alloys as well as in brittle and semi-/non-crystalline solids. Total life and damage-tolerant approaches are then introduced in metals, non-metals and composites followed by more advanced topics. The book includes an extensive bibliography and a problem set for each chapter, together with worked-out example problems and case studies. This will be an important reference for anyone studying fracture and fatigue in materials science and engineering, mechanical, civil, nuclear and aerospace engineering, and biomechanics.
Download or read book Metals Abstracts written by and published by . This book was released on 1997 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biaxial and Multiaxial Fatigue EGF 3 written by M. W. Brown and published by . This book was released on 1989 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 36 paper spresented in this volume were presented at the second international conference on biaxial/multiaxial fatigue.
Download or read book Proceedings of the 8th International Symposium on Superalloy 718 and Derivatives written by The Minerals, Metals & Materials Society (TMS) and published by John Wiley & Sons. This book was released on 2014-12-02 with total page 951 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Microstructure of Superalloys written by Madeleine Durand-Charre and published by Routledge. This book was released on 2017-11-22 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents all the main aspects of the microstructure of nickel-base superalloys, and includes micrographs chosen from among a large range of commercial and academic alloys, from the as-cast product to in-situ components, worn from in-service use. Including more than 100 illustrations, the text explains all the transformation mechanisms involved in the origination (creation) of microstructures during solidification or heat treatments (crystallization paths, segregation, crystal orientation, precipitation, TCP, coarsening and rafting, etc.). It includes up-to-date information and data such as phase diagrams, crystallographic structures, and relationships with functional properties. Nearly 300 references provide a key to further investigation.
Download or read book Proceedings of Fatigue Durability and Fracture Mechanics written by S. Seetharamu and published by Springer. This book was released on 2017-11-01 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of Fatigue Durability India 2016, which was held on September 28–30 at J N Tata Auditorium, Indian Institute of Science, Bangalore. This 2nd International Conference & Exhibition brought international industrial experts and academics together on a single platform to facilitate the exchange of ideas and advances in the field of fatigue, durability and fracture mechanics and its applications. This book comprises articles on a broad spectrum of topics from design, engineering, testing and computational evaluation of components and systems for fatigue, durability, and fracture mechanics. The topics covered include interdisciplinary discussions on working aspects related to materials testing, evaluation of damage, nondestructive testing (NDT), failure analysis, finite element modeling (FEM) analysis, fatigue and fracture, processing, performance, and reliability. The contents of this book will appeal not only to academic researchers, but also to design engineers, failure analysts, maintenance engineers, certification personnel, and R&D professionals involved in a wide variety of industries.
Download or read book Frattura ed Integrit Strutturale Annals 2014 written by Luca Susmel and published by Gruppo Italiano Frattura. This book was released on 2014-09-12 with total page 1208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Methods for Plasticity written by Eduardo A. de Souza Neto and published by John Wiley & Sons. This book was released on 2011-09-21 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of computational plasticity encapsulates the numerical methods used for the finite element simulation of the behaviour of a wide range of engineering materials considered to be plastic – i.e. those that undergo a permanent change of shape in response to an applied force. Computational Methods for Plasticity: Theory and Applications describes the theory of the associated numerical methods for the simulation of a wide range of plastic engineering materials; from the simplest infinitesimal plasticity theory to more complex damage mechanics and finite strain crystal plasticity models. It is split into three parts - basic concepts, small strains and large strains. Beginning with elementary theory and progressing to advanced, complex theory and computer implementation, it is suitable for use at both introductory and advanced levels. The book: Offers a self-contained text that allows the reader to learn computational plasticity theory and its implementation from one volume. Includes many numerical examples that illustrate the application of the methodologies described. Provides introductory material on related disciplines and procedures such as tensor analysis, continuum mechanics and finite elements for non-linear solid mechanics. Is accompanied by purpose-developed finite element software that illustrates many of the techniques discussed in the text, downloadable from the book’s companion website. This comprehensive text will appeal to postgraduate and graduate students of civil, mechanical, aerospace and materials engineering as well as applied mathematics and courses with computational mechanics components. It will also be of interest to research engineers, scientists and software developers working in the field of computational solid mechanics.
Download or read book Mechanical Behaviour of Materials written by Dominique François and published by Springer Science & Business Media. This book was released on 2012-03-14 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in technology are demanding ever-increasing mastery over the materials being used: the challenge is to gain a better understanding of their behaviour, and more particularly of the relations between their microstructure and their macroscopic properties. This work, of which this is the first volume, aims to provide the means by which this challenge may be met. Starting from the mechanics of deformation, it develops the laws governing macroscopic behaviour – expressed as the constitutive equations – always taking account of the physical phenomena which underlie rheological behaviour. The most recent developments are presented, in particular those concerning heterogeneous materials such as metallic alloys, polymers and composites. Each chapter is devoted to one of the major classes of material behaviour. As the subtitles indicate, Volume 1 deals with micro- and macroscopic constitutive behaviour and Volume 2 with damage and fracture mechanics. A third volume will be devoted to exercises and their full solutions complementing the content of these two first volumes. Most of the chapters end with a set of exercises, to many of which either the full solution or hints on how to obtain this are given; each volume is profusely illustrated with explanatory diagrams and with electron-microscope photographs. This book, now in its second edition, has been rigorously re-written, updated and modernised for a new generation. The authors improved the existing material, in particular in modifying the organisation, and added new up-to-date content. Understanding the subject matter requires a good knowledge of solid mechanics and materials science; the main elements of these fields are given in a set of annexes at the end of the first volume. The authors also thought it interesting for the readers to give as footnotes some information about the many scientists whose names are attached to theories and formulae and whose memories must be celebrated. Whilst the present book, as well as Volume 2, is addressed primarily to graduate students, part of it can be used in undergraduate courses; and it is hoped that practising engineers and scientists will find the information it conveys useful. It is the authors’ hope also that English-speaking readers will want to learn about the aspects of French culture, and more particularly of the French school of micromechanics of materials, which this treatment undoubtedly displays.
Download or read book Stress Analysis for Creep written by J.T. Boyle and published by Elsevier. This book was released on 2013-10-22 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stress Analysis for Creep focuses on methods on creep analysis. The book first ponders on the occurrence of creep in mechanical engineering components, including background to stress analysis for creep and general-purpose computer programs for creep analysis. The text presents a phenomenological description of creep. The phenomenon of creep, physical mechanisms of creep, convenient uniaxial constitutive relationships, and creep rupture are described. The book also explains simple component behavior, creep under multiaxial states of stress, and stress analysis for steady creep. The text focuses on reference stress methods in steady creep. Reference stresses for combined loading with a power law; non-isothermal power-law creep; reference temperatures; and approximate reference stress methods are elaborated. The text also focuses on stress analysis for transient creep; approximate solution of transient creep problems; and creep buckling and rupture. The text highlights the design for creep, including material data requirements and constitutive modeling for design; verification and qualification of stress analysis; and design methodology. The book is a good source of data for readers wanting to study creep analysis.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1979 with total page 1520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
