liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
High Temperature Fatigue Crack Growth in a Ni-based Superalloy: Modelling Including the Interaction of Dwell Times
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Safe life of gas turbines is always of major concern for manufacturers in order to ensure passenger safety and stable continuous power output. An increasing amount of resources have been put into research and development to assure that all safety aspects are covered in the design of new turbines and to ensure that enough frequent service intervals are scheduled to avoid complications. Many of these issues require good knowledge of material properties and of how to use these in the design process. Some of these relate to fatigue which is of major concern in all parts of a development programme. However, while some fatigue problems have been extensively studied, some have not. One example is crack growth with influence of dwell times at elevated temperature in combination with cyclic loading. Such loading conditions have been shown to give a different cracking behaviour compared to rapid cyclic loading, increasing the growth rate significantly with respect to the number of load cycles. Improved models for predicting this behaviour is therefore of major interest for gas turbine manufacturers, and could substantially increase the reliability. As a result, more research is needed in order  solve these problems.

The work presented in this dissertation has focused on how to predict life under the above-mentioned circumstances. The materials used in high temperature gas turbine applications are often nickel-based superalloys, and in this work the most common one, Inconel 718, has been studied. Mechanical experiments have been performed under operation like conditions in order to receive material data for the subsequent modelling work. The modelling approach was chosen such that the underlying physics of the dwell time cracking have been incorporated on a phenomenological basis, creating a model which can be physically motivated as well as used for industrial applications. The main feature of the modelling work has been to track material damage which is received from dwell times, how this interacts with cyclic loading and how it affects the crack growth rate, thus creating a load history dependent model.

The outcome of this work has resulted in a model which is both easy to use and which has shown to give good correlation to available experimental data. Key components such as calibration for cheap and easy parameter determination, validation on complex engine spectra loadings, three dimensional crack growth, overload influences, material scatter, thermo-mechanical fatigue crack growth and the impact of high cycle fatigue loadings, are all covered in the presented work, both as experimental findings and as continuous development of the modelling concept.

The dissertation consists of two parts. In the first an introduction with the theory and background to crack growth with dwell times is given, while the second part consists of 10 papers.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. , 51 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1681
National Category
Mechanical Engineering Applied Mechanics Materials Engineering
Identifiers
URN: urn:nbn:se:liu:diva-121012DOI: 10.3384/diss.diva-121012ISBN: 978-91-7519-034-1 (print)OAI: oai:DiVA.org:liu-121012DiVA: diva2:850806
Public defence
2015-09-11, C3, Hus C, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved
List of papers
1. High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
Open this publication in new window or tab >>High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, 178-186 p.Article in journal (Refereed) Published
Abstract [en]

Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650°C. For such components, the main load cycle is typically defined by the start-up and shut-down of the engine. In this main loading cycle, hold times at high temperature are commonly present in critical components. These high temperature hold times may greatly increase the fatigue crack growth rate with respect to the number of cycles unless other beneficial factors such as for example initial overloads are present. The latter can be caused by abnormal service conditions but can also occur on a more regular basis and are then typically observed in components with strong thermal transients during engine start-up. In this paper, focus has been placed on the effect of overloads on the hold time fatigue crack growth behaviour and its subsequent description. More specifically, crack propagation in Inconel 718 has been studied at the temperatures 550°C and 650°C with and without an overload at the start of the cycle. The effect of initial overloads was found to be substantial. A simple model for describing the effect of these loading conditions has also been developed based on the concept of the damaged zone, present around the crack tip. Irregular crack fronts and unbroken ligaments left on the fracture surfaces seen in complementary microscopy studies seem to support this approach. Furthermore, the stress state in front of a crack tip in a 2D model was investigated both with and without an initial overload. The results were related to the observed crack growth retardation behaviour found in the material testing.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling, Finite Element modelling
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85931 (URN)10.1016/j.ijfatigue.2012.10.018 (DOI)000315617500020 ()
Available from: 2013-03-13 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
2. Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
Open this publication in new window or tab >>Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, 124-130 p.Article in journal (Refereed) Published
Abstract [en]

Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650 °C. The main load cycle for such components is typically defined by the start-up and shut-down of the engine. It generally includes hold times at high temperatures, which have been found to have a potential for greatly increasing the fatigue crack growth rate with respect to the number of load cycles. However, these effects may be totally or partly cancelled by other load features, such as overloads or blocks of continuous cyclic loading, and the actual crack propagation rate will therefore depend on the totality of features encompassed by the load cycle. It has previously been shown that the increased crack growth rate found in hold time experiments can be associated with a damage evolution, where the latter is not only responsible for the rapid intergranular crack propagation during the actual hold times, but also for the increased crack growth during the load reversals. In this paper, modelling of the hold time fatigue crack growth behaviour of Inconel 718 has been carried out, using the concept of a damaged zone as the basis for the treatment. With this conceptually simple and partly novel approach, it is shown that good agreement with experimental results can be found.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85933 (URN)10.1016/j.ijfatigue.2013.03.004 (DOI)000318831300013 ()
Available from: 2012-12-03 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
3. A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
Open this publication in new window or tab >>A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
2014 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 118, 17-30 p.Article in journal (Refereed) Published
Abstract [en]

Modelling of high temperature fatigue crack growth in Inconel 718 under the interaction of fast cyclic loading and hold times at maximum load has been conducted. A model, based on the concept of a damaged zone in front of the crack tip has been applied for three different temperatures, 550, 600 and 650 ◦C, with good agreement for both calibration and validation tests. A statistical evaluation of 22 tests in total was also conducted, which shows that the developed model gives a reasonable scatter factor at a probability of failure of 0.1 %.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling, Statistics
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-104809 (URN)10.1016/j.engfracmech.2014.02.005 (DOI)000334819600002 ()
Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2017-12-05Bibliographically approved
4. Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
Open this publication in new window or tab >>Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
2014 (English)In: Advanced Materials Research, ISSN 1662-8985, Vol. 891-892, 759-764 p.Article in journal (Refereed) Published
Abstract [en]

Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage near the crack tip, thus rapidly increasing the crack growth rate. Since the damaged zone will affect the crack propagation rate due to cyclic loadings as well, the complete load history of a component therefore has to be considered. The crack propagation model presented in this paper is based on the damaged zone concept, and considers the history effect in the form of damaged zone build up during hold times, and subsequent destruction as the crack propagates onwards by rapidly applied load reversals. By incorporating crack closure for handling different R-values, an aero engine component spectrum is evaluated for a surface crack at 550 C. The result shows a good correlation to model simulation, despite the complexity of the load spectrum.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
Keyword
Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-104812 (URN)10.4028/www.scientific.net/AMR.891-892.759 (DOI)000337767700118 ()
Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2016-05-18Bibliographically approved
5. Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop
Open this publication in new window or tab >>Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop
2015 (English)In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 55, no 3, 559-568 p.Article in journal (Refereed) Published
Abstract [en]

Crack length evaluations for cyclic loading and sustained loading at high temperature and a mix of both have been conducted on Inconel 718 surface crack specimens at 550 C-a similar to. The choice of method for evaluating the crack length is seen to have a non-negligible impact on the resulting crack propagation rate values. In this paper, some aspects regarding how to evaluate such testing when using the potential drop technique are presented, with the aim of giving a firm explanation on how to proceed for the best possible result.

Place, publisher, year, edition, pages
Society for Experimental Mechanics (SEM), 2015
Keyword
Fatigue crack propagation; Fatigue test evaluation; Sustained load; Dwell time effects; Crack length evaluation; Potential drop
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-117241 (URN)10.1007/s11340-014-9963-2 (DOI)000351444300007 ()
Note

Funding Agencies|Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through the Swedish research programme TURBO POWER

Available from: 2015-04-22 Created: 2015-04-21 Last updated: 2017-12-04
6. Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading
Open this publication in new window or tab >>Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading
2016 (English)In: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638Article in journal (Refereed) Published
Abstract [en]

High temperature materials subjected to elevated temperature have been shown to be sensitive to dwell times, giving an increased crack growth rate. The interaction between these dwell times and rapid cyclic loads have been shown to constitute a complex problem. Many models have been developed for 1D conditions, but the application to general 3D conditions has seldom been seen, although this is the most common case in most structures. In this paper a model for taking care of the interaction between these load modes in general 3D crack growth has been developed. The model uses 1D results for extension to general 3D, thus providing for local crack front evolution with a minimum of numerical simulations. The model has been implemented for usage with finite element calculations and several different tests are simulated and compared with experimental results for the nickel based superalloy Inconel 718 at 550◦C. The simulation results show crack shapes in agreement with experimental fracture surfaces and time to failure.

Keyword
Sustained load, Crack growth modelling, Crack tunnelling, Ni-based superalloy, High temperature
National Category
Applied Mechanics Materials Engineering
Identifiers
urn:nbn:se:liu:diva-121004 (URN)10.1016/j.tafmec.2015.11.008 (DOI)000369204600002 ()
Note

Funding agencies:  Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through the Swedish research programme TURBO POWER

Vid tiden för disputation förelåg publikationen som manuskript

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
7. Modeling of Crack Growth With Dwell Time for Aero-engine Spectra Loadings in a Ni-Based Superalloy
Open this publication in new window or tab >>Modeling of Crack Growth With Dwell Time for Aero-engine Spectra Loadings in a Ni-Based Superalloy
Show others...
2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, 012501-012501 p.Article in journal (Refereed) Published
Abstract [en]

Testing and simulation of aero-engine spectra with dwell times are reported in this paper. The modeling concept used is built on linear elastic fracture mechanics (LEFM) and provides a history-dependent evolution description of dwell damage and its interaction with cyclic load. The simulations have been carried out for three spectra: (1) cyclic loads, (2) combined sustained load and cyclic loads, and (3) slow load ramps and cyclic loads, all for surface cracks at 550 °C for Inconel 718. All simulations show reasonable good agreement with experimental results. Prediction of multiple tests of several batches is also provided to show statistical scatter.

Place, publisher, year, edition, pages
ASME Press, 2016
National Category
Applied Mechanics Mechanical Engineering Materials Engineering
Identifiers
urn:nbn:se:liu:diva-121005 (URN)10.1115/1.4031155 (DOI)000371127900012 ()
Note

Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish Research Programme TURBO POWER

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
8. Scatter in Dwell Time Cracking for a Ni-Based Superalloy in Combination With Overloads
Open this publication in new window or tab >>Scatter in Dwell Time Cracking for a Ni-Based Superalloy in Combination With Overloads
Show others...
2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, 012502-012502 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, scatter in crack growth for dwell time loadings in combination with overloads has been investigated. Multiple tests were performed for surface cracks at 550 °C in the commonly used high temperature material Inconel 718. The test specimens originate from two different batches which also provide for a discussion of how material properties affect the dwell time damage and overload impact. In combination with these tests, an investigation of the microstructure was also carried out, which shows how it influences the growth rate. The results from this study show that, in order to take overloads into consideration when analyzing spectrum loadings containing dwell times, one needs a substantial amount of material data available as the scatter seen from one batch to the other are of significant proportions.

Place, publisher, year, edition, pages
ASME Press, 2016
National Category
Mechanical Engineering Materials Engineering Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-121007 (URN)10.1115/1.4031157 (DOI)000371127900013 ()
Note

Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish research programme TURBO POWER

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
9. Thermomechanical Fatigue Crack Growth Modeling in a Ni-Based Superalloy Subjected to Sustained Load
Open this publication in new window or tab >>Thermomechanical Fatigue Crack Growth Modeling in a Ni-Based Superalloy Subjected to Sustained Load
2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, 012503-012503 p.Article in journal (Refereed) Published
Abstract [en]

Thermomechanical fatigue (TMF) crack growth modeling has been conducted on Inconel 718 with dwell time at maximum load. A history dependent damage model taking dwell damage into account, developed under isothermal conditions, has been extended for TMF conditions. Parameter determination for the model is carried out on isothermal load controlled tests at 550–650 °C for surface cracks, which later have been used to extrapolate parameters used for TMF crack growth. Further, validation of the developed model is conducted on a notched specimen subjected to strain control at 50–550 °C. Satisfying results are gained within reasonable scatter level compared for test and simulated number of cycles to failure.

Place, publisher, year, edition, pages
ASME Press, 2016
National Category
Mechanical Engineering Materials Engineering Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-121008 (URN)10.1115/1.4031158 (DOI)000371127900014 ()
Note

Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish research programme TURBO POWER

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
10. Impact of high cycle fatigue on dwell time crack growth in a Ni-based superalloy
Open this publication in new window or tab >>Impact of high cycle fatigue on dwell time crack growth in a Ni-based superalloy
Show others...
2015 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Sustained load have been shown to give rise to increased crack growth rate at elevated temperature. Such loads generate a history dependent fatigue problem due to weakening and cracking of grain boundaries during dwell times, later broken apart during subsequent load cycles. So far most studies have focused on sustained load and the interaction of load cycles, overloads, and temperature, but few studies have been carried out for vibrations and how these affect the dwell time crack growth. Vibrations of different kinds are frequently seen in engine components, and present in combination with sustained loads a more realistic loading situation than the latter itself. An investigation of how a vibrational load affects the dwell time cracking and how to incorporate it in a modelling context is therefore of importance. In this paper a study of the most frequently used gas turbine material, Inconel 718, has been carried out. Mechanical testing has been conducted at 550◦C for surface cracks with and without the interaction of engine vibrations on sustained load, here represented by a superimposed high cycle fatigue (HCF) load. Subsequent investigation of the fracture behaviour was performed by Scanning Electron Microscope (SEM) and the modelling work has been conducted by incorporating the HCF load description within a history dependent crack growth law. The obtained results show reasonable accuracy with respect to the mechanical tests.

Keyword
Hold time effects, Dwell times, Sustained load, Crack growth modelling, Inconel 718, High temperature
National Category
Mechanical Engineering Materials Engineering Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-121009 (URN)
Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved

Open Access in DiVA

fulltext(1715 kB)511 downloads
File information
File name FULLTEXT01.pdfFile size 1715 kBChecksum SHA-512
9d0744154f1810ea6df4dcf02eae7b63325f467fedc4a8688f2a8f7f2f40c5d2958a73940cfc55af04decc165afab08b623cd157962367a929ac025b7c2cd830
Type fulltextMimetype application/pdf
omslag(43 kB)17 downloads
File information
File name COVER01.pdfFile size 43 kBChecksum SHA-512
2c70d3557f1817fe1aed65480514dda99c211c7bc68a8c4a0a5b1010cd9b44854dc21c6d960c01b4500621c285f8acb4baa36a89458306bed17bebdf0f565827
Type coverMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Storgärds, Erik

Search in DiVA

By author/editor
Storgärds, Erik
By organisation
Solid MechanicsFaculty of Science & Engineering
Mechanical EngineeringApplied MechanicsMaterials Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 512 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 1183 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf