Effective Utilization Of Strategic Materials Through Improvement Of Fatigue Crack Propagation Behavior Of Nickel Base Superalloys
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Effective Utilization Of Strategic Materials Through Improvement Of Fatigue Crack Propagation Behavior Of Nickel Base Superalloys
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Author : Stephen D. Antolovich
language : en
Publisher:
Release Date : 1985
Effective Utilization Of Strategic Materials Through Improvement Of Fatigue Crack Propagation Behavior Of Nickel Base Superalloys written by Stephen D. Antolovich and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Materials categories.
Modelling Of Crack Growth In Single Crystal Nickel Base Superalloys
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Author : Christian Busse
language : en
Publisher: Linköping University Electronic Press
Release Date : 2019-09-24
Modelling Of Crack Growth In Single Crystal Nickel Base Superalloys written by Christian Busse and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-09-24 with categories.
This dissertation was produced at the Division of Solid Mechanics at Linköping University and is part of a research project, which comprises modelling, microstructure investigations and material testing of cast nickel-base superalloys. The main objective of this work was to deepen the understanding of the fracture behaviour of single-crystal nickel-base superalloys and to develop a model to predict the fatigue crack growth behaviour. Frequently, crack growth in these materials has been observed to follow one of two distinct cracking modes; Mode I like cracking perpendicular to the loading direction or crystallographic crack growth on the octahedral {111}-planes, where the latter is associated with an increased fatigue crack growth rate. Thus, it is of major importance to account for this behaviour in component life prediction. Consequently, a model for the prediction of the transition of cracking modes and the correct active crystallographic plane, i.e. the crack path, and the crystallographic crack growth rate has been developed. This model is based on the evaluation of appropriate crack driving forces using three-dimensional finite-element simulations. A special focus was given towards the influence of the crystallographic orientation on the fracture behaviour. Further, a model to incorporate residual stresses in the crack growth modelling is presented. All modelling work is calibrated and validated by experiments on different specimen geometries with different crystallographic orientations. This dissertation consists of two parts, where Part I gives an introduction and background to the field of research, while Part II consists of six appended papers. Die vorliegende Dissertation wurde in der Abteilung für Festigkeitslehre an der Universität von Linköping erstellt und ist Teil eines Forschungsprojektes, welches Modellierung, Mikrostrukturuntersuchungen und Materialtests von gegossenen nickelbasierten Superlegierungen umfasst. Das Hauptziel dieser Arbeit war es, das Verständnis des Bruchverhaltens von einkristallinen Superlegierungen auf Nickelbasis zu vertiefen und ein Modell zur Vorhersage des Wachstumsverhaltens von Ermüdungsrissen zu entwickeln. Es wurde beobachtet, dass das Risswachstum in diesen Materialien einem von zwei unterschiedlichen Rissmodi folgt; Modus I Rissfortschritt senkrecht zur Belastungsrichtung oder kristallographisches Risswachstum auf den oktaedrischen f111g-Ebenen, wobei letzteres mit einer erhöhten Ermüdungsrisswachstumsrate verbunden ist. Somit ist es von grosser Bedeutung dieses Verhalten in der Lebensdauervorhersage einer Komponente zu berücksichtigen. Demzufolge wurde ein Modell für die Vorhersage des Übergangs zwischen den Rissmodi und der korrekten aktiven kristallographischen Ebene, d.h. des Risspfades, sowie der kristallographischen Risswachstumsrate erarbeitet. Dieses Modell basiert auf geeigneten Rissantriebskräften, welche mit Hilfe dreidimensionaler Finite-Elemente-Simulationen berechnet werden. Im Fokus stand insbesondere der Einuss der kristallographischen Orientierung auf das Bruchverhalten. Ausserdem wird ein Modell zur Berücksichtigung von Restspannungen in der Risswachstumsmodellierung präsentiert. Alle Modellierungsarbeiten wurden durch Experimente an verschiedenen Probengeometrien mit unterschiedlichen kristallographischen Orientierungen kalibriert und validiert. Diese Dissertation besteht aus zwei Teilen, wobei Teil I aus einer Einführung und einem Hintergrund in das Forschungsgebiet und Teil II aus sechs beigefügten Forschungsartikeln besteht.
Thermal Mechanical Fatigue Behavior Of Nickel Base Superalloys
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Author : Norman J. Marchand
language : en
Publisher:
Release Date : 19??
Thermal Mechanical Fatigue Behavior Of Nickel Base Superalloys written by Norman J. Marchand and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 19?? with categories.
This report presents the main achievements of a 36-month research program the main objective of which was to gain more insight into the problem of crack growth under thermal mechanical fatigue (TMF) conditions. The program was arranged into five technical tasks. Under Task I, the goal was to identify the crack propagation conditions in aircraft engines (hot section) and to assess the validity of conventional fracture mechanics parameters to address TMF crack growth. The second task defined the test facilities, test specimen and the testing conditions needed to establish the effectiveness of data correlation parameters identified in Task I. Under Task III, a computerized testing system to measure the TMF behavior (LCF and CG behaviors) of various alloy systems was built. A crack propagation test program was defined and conducted under Task IV. The test variables included strain range, strain rate (frequency) and temperature. Task V correlated and generalized the Task IV data for isothermal and variable temperature conditions so that several crack propagation parameters could be compared and evaluated.
Effect Of Dwell Times On Crack Propagation In Superalloys
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Author : Jonas Saarimäki
language : en
Publisher: Linköping University Electronic Press
Release Date : 2015-12-10
Effect Of Dwell Times On Crack Propagation In Superalloys written by Jonas Saarimäki and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-12-10 with categories.
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.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1993
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Aeronautics categories.
Crystallographic Fatigue Crack Propagation In Single Crystal Nickel Base Superalloy
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Author : Otis Yuchia Chen
language : en
Publisher:
Release Date : 1985
Crystallographic Fatigue Crack Propagation In Single Crystal Nickel Base Superalloy written by Otis Yuchia Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Metals categories.
Superalloys 2012
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Author : Eric S. Huron
language : en
Publisher: John Wiley & Sons
Release Date : 2012-10-02
Superalloys 2012 written by Eric S. Huron and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-10-02 with Technology & Engineering categories.
A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength at high temperatures. Superalloy development has been driven primarily by the aerospace and power industries. This compilation of papers from the Twelfth International Symposium on Superalloys, held from September 9-13, 2012, offers the most recent technical information on this class of materials.
Microstructural Conditions Contributing To Fatigue Variability In P M Nickel Base Superalloys Preprint
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Author :
language : en
Publisher:
Release Date : 2008
Microstructural Conditions Contributing To Fatigue Variability In P M Nickel Base Superalloys Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Variability in the fatigue behavior of two common nickel-base superalloys is discussed, with emphasis given to understanding the behavior of short fatigue cracks. Rene88DT and IN100 are the materials of interest. and serve important roles in many turbine engine systems. Multiple specimens of each material were tested under low cycle fatigue (LCF) conditions at elevated temperature. Two IN100 specimens that exhibited significant difference in cycles to failure and three Rene88DT specimens having dissimilar short fatigue crack growth rates were interrogated to determine the reasons for these variation. This paper will discuss the microstructure adjacent to the initiation sites in these specimens and its role in affecting the observed disparate crack growth behavior. Additionally, an image correlation technique, use to evaluate the development of strain concentrations in a Rene88DT tensile specimen at room temperature, is described. The utility of image correlation for identifying microstructural 'hot spots' (i.e., initiation sites) in concert with LCF testing is considered.
Effect Of Microstructure On The Fatigue Crack Propagation Behavior Of Ni Base Superalloys
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Author : Stephen D. Antolovich
language : en
Publisher:
Release Date : 1987
Effect Of Microstructure On The Fatigue Crack Propagation Behavior Of Ni Base Superalloys written by Stephen D. Antolovich and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with categories.
The objective of this study is to determine the effect of microstructural properties on the fatigue crack propagation (FCP) response of nickel-base superalloys. This report describes the results of four experimental alloys containing various amounts of Al, Ti, Cr, and Mo. Chemistry, precipitate size, and grain size were varied to produce systematically controlled microstructures. The four alloys were characterized for chemical composition, microstructure, tensile properties, low cycle fatigue (LCF), and FCP resistance. The FCP tests were performed under constant load (increasing K) conditions in air at a stress ratio (R) of 0.1 and 0.8. Closure loads were measured with a clip gage, back-face strain gage, and a laser extensometer. Keywords: Fatigue crack propagation, Ni-base superalloys, Microstructure, Closure, Mismatch, Anti-phase boundary, Aluminum, Titanium, Chromium, Molybdenum.
Identifying And Understanding Environment Induced Crack Propagation Behavior In Ni Based Superalloy Inconel 617
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Author :
language : en
Publisher:
Release Date : 2012
Identifying And Understanding Environment Induced Crack Propagation Behavior In Ni Based Superalloy Inconel 617 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or SAGBOE damage process under hold-time fatigue and sustained loading conditions.