Thermo Mechanical Fatigue Crack Growth Modeling Of A Nickel Based Superalloy
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Thermo Mechanical Fatigue Crack Growth Modeling Of A Nickel Based Superalloy
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Author : Vincent Mark Barker
language : en
Publisher:
Release Date : 2011
Thermo Mechanical Fatigue Crack Growth Modeling Of A Nickel Based Superalloy written by Vincent Mark Barker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Heat resistant alloys categories.
A model was created to predict the thermo-mechanical fatigue crack growth rates under typical engine spectrum loading conditions. This model serves as both a crack growth analysis tool to determine residual lifetime of ageing turbine components and as a design tool to assess the effects of temperature and loading variables on crack propagation. The material used in the development of this model was a polycrystalline superalloy, Inconel 100 (IN-100). The first step in creating a reliable model was to define the first order effects that influence TMF crack growth in a typical engine spectrum. Load interaction effects were determined to be major contributors to lifetime estimates by influencing crack growth rates based upon previous load histories. A yield zone model was modified to include temperature dependent properties that controlled the effects of crack growth retardation and acceleration based upon overloads and underloads, respectively. Multiple overload effects were included in the model to create enhanced retardation compared to single overload tests. Temperature interaction effects were also considered very important due to the wide temperature ranges of turbine engine components. Oxidation and changing temperature effects were accounted for by accelerating crack growth in regions that had been affected by higher temperatures. Constant amplitude crack growth rates were used as a baseline, upon which load and temperature interaction effects were applied. Experimental data of isolated first order effects was used to calibrate and verify the model. Experimental data provided the means to verify that the model was a good fit to experimental results. The load interaction effects were described by a yield zone model, which included temperature dependent properties. These properties were determined experimentally and were essential in the model's development to include load and temperature contributions. Other interesting factors became apparent through testing. It was seen that specific combinations of strain rate and temperature would lead to serrated yielding, discovered to be the Portevin-Le Chatelier effect. This effect manifested itself as enhanced hardening, leading to unstable strain bursts in specimens that cyclically yielded while changing temperature.
Fatigue Life Prediction Under Thermal Mechanical Loading In A Nickel Base Superalloy
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Author : H. Bernard
language : en
Publisher:
Release Date : 1993
Fatigue Life Prediction Under Thermal Mechanical Loading In A Nickel Base Superalloy written by H. Bernard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Alloys categories.
Thermal-mechanical fatigue of IN-100, a cast nickel base superalloy, was previously shown to involve mainly early crack growth using either bare or aluminized specimens. This crack growth was found to be controlled by interdendritic oxidation. A model for engineering life to crack initiation is thus proposed to describe this microcrack growth phase using local stresses in a microstructural volume element at the crack tip. The identification of damage equations involves fatigue crack growth data on compact tension (CT) specimens, interdendritic oxidation kinetics measurements and fatigue crack growth on CT specimens that have been embrittled by previous oxidation at high temperature. The application of this model to life prediction is shown for low cycle fatigue and thermal-mechanical fatigue specimens of bare and coated specimens as well as for thermal shock experiments.
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.
Thermomechanical Fatigue Behavior Of Materials
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Author : Huseyin Sehitoglu
language : en
Publisher: ASTM International
Release Date : 1993
Thermomechanical Fatigue Behavior Of Materials written by Huseyin Sehitoglu and has been published by ASTM International this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with AIIoys categories.
Thermomechanical Fatigue Crack Propagation In An Anisotropic Directionally Solidified Nickel Base Superalloy
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Author : AE. Gemma
language : en
Publisher:
Release Date : 1976
Thermomechanical Fatigue Crack Propagation In An Anisotropic Directionally Solidified Nickel Base Superalloy written by AE. Gemma and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with Crack propagation categories.
Strain-controlled thermomechanical fatigue tests were performed on two nickel-base superalloys, directionally solidified (DS) Mar-M200 plus hafnium and conventionally cast B-1900 plus hafnium. The DS alloy was tested at various angles (?) to the direction of grain growth. It was found that crack growth rates were a minimum for the DS alloy tested parallel to the direction of grain growth (crack propagating normal to the direction of grain growth). The crack growth rate increased for other orientations in the sequence ? = 15, 30 or 90, and 45 deg until equivalence was reached with rates for the conventionally cast alloy, B-1900 plus hafnium. A linear elastic fracture mechanics approach was extended to strain-controlled crack growth as a function of ? for the DS alloy. Prediction of crack growth rates as a function of ? was achieved by normalizing with the elastic modulus. The sequencing of crack growth rates with ? and a smooth-to-rough fracture surface transition are explained on the basis of the orientation dependence of crack opening displacement for a given strain intensity range.
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.
Nasa Technical Memorandum
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Author :
language : en
Publisher:
Release Date : 1988
Nasa Technical Memorandum written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Aeronautics categories.
Thermomechanical Fatigue Crack Formation In Nickel Base Superalloys At Notches
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Author : Patxi Fernandez-Zelaia
language : en
Publisher:
Release Date : 2012
Thermomechanical Fatigue Crack Formation In Nickel Base Superalloys At Notches written by Patxi Fernandez-Zelaia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Alloys categories.
Hot sections of gas engine turbines require specialized materials to withstand extreme conditions present during engine operation. Nickel-base superalloys are typically used as blades and disks in the high pressure turbine section because they possess excellent fatigue strength, creep strength and corrosion resistance at elevated temperatures. Components undergo thermomechanical fatigue conditions as a result of transient engine operation. Sharp geometric features, such as cooling holes in blades or fir-tree connections in disks, act as local stress raisers. The material surrounding these features are potential sites of localized inelastic deformation and crack formation. To reduce customer costs associated with unnecessary overhauls or engine down-time, gas turbine manufacturers require accurate prediction methods to determine component endurances. The influence of stress concentration severity on thermomechanical fatigue crack formation is of particular importance as cracks often initiate in these hot spots. Circumferentially notched specimens were utilized to perform thermomechanical fatigue experiments on blade material CM247LC DS and disk material PM IN100. A parametric study on CM247LC DS was performed utilizing four notched specimens. Experimental results were coupled with finite element simulations utilizing continuum based constitutive models. The effects of applied boundary conditions on crack initiation life was studied in both alloys by performing experiments under remotely applied force and displacement boundary conditions. Finite element results were utilized to develop a life prediction method for notched components under thermomechanical fatigue conditions.
Thermo Mechanical Fatigue Crack Growth Of A Polycrystalline Superalloy
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Author : Benjamin Scott Adair
language : en
Publisher:
Release Date : 2011
Thermo Mechanical Fatigue Crack Growth Of A Polycrystalline Superalloy written by Benjamin Scott Adair and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Alloys categories.
A study was done to determine the temperature and load interaction effects on the fatigue crack growth rate of polycrystalline superalloy IN100. Temperature interaction testing was performed by cycling between 316°C and 649°C in blocks of 1, 10 and 100 cycles. Load interaction testing in the form of single overloads was performed at 316°C and 649°C. After compiling a database of constant temperature, constant amplitude FCGR data for IN100, fatigue crack growth predictions assuming no load or temperature interactions were made. Experimental fatigue crack propagation data was then compared and contrasted with these predictions. Through the aid of scanning electron microscopy the fracture mechanisms observed during interaction testing were compared with the mechanisms present during constant temperature, constant amplitude testing. One block alternating temperature interaction testing grew significantly faster than the non-interaction prediction, while ten block alternating temperature interaction testing also grew faster but not to the same extent. One hundred block alternating testing grew slower than non-interaction predictions. It was found that as the number of alternating temperature cycles increased, changes in the gamma prime morphology (and hence deformation mode) caused changes in the environmental interactions thus demonstrating the sensitivity of the environmental interaction on the details of the deformation mode. SEM fractography was used to show that at low alternating cycles, 316°C crack growth was accelerated due to crack tip embrittlement caused by 649°C cycling. At higher alternating cycles the 316°C cycling quickly grew through the embrittled crack tip but then grew slower than expected due to the possible formation of Kear-Wilsdorf locks at 649°C. Overload interaction testing led to full crack retardation at 2.0x overloads for both 316°C and 649°C testing. 1.6x overloading at both temperatures led to retarded crack growth whereas 1.3x overloads at 649°C created accelerated crack growth and at 316°C the crack growth was retarded.
Thermal Mechanical Fatigue Crack Propagation In Nickel And Cobalt Base Superalloys Under Various Strain Temperature Cycles
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Author : AE. Gemma
language : en
Publisher:
Release Date : 1973
Thermal Mechanical Fatigue Crack Propagation In Nickel And Cobalt Base Superalloys Under Various Strain Temperature Cycles written by AE. Gemma and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with Coatings categories.
Crack propagation rates under isothermal and thermal fatigue cycling have been determined for a conventionally-cast cobalt-base superalloy, and conventionally-cast and directionally-solidified nickel-base superalloys. Linear elastic fracture mechanics, where the crack growth rates under different strain ranges or for various crack lengths depend only on the strain intensity factor range, was found to be applicable over the range of crack growth rates of most practical importance. A comparison of crack growth rates is made for thermal fatigue under various strain-temperature cycles and isothermal low-cycle fatigue, and the influence of coatings and superimposed creep is discussed.