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  • 1.
    Chen, Zhe
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Zhou, Jinming
    Division of Production and Materials Engineering,Lunds University, Sweden.
    Peng, Ru Lin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    M'Saoubi, R
    Seco Tools AB, Fagersta, Sweden.
    Gustafsson, David
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Palmert, Frans
    Siemens Industrial Turbomachinery AB, Finspång.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Plastic Deformation and Residual Stress in High Speed Turning of AD730™ Nickel-based Superalloy with PCBN and WC Tools2018Inngår i: Procedia CIRP 71 (2018) pp 440-445, Elsevier, 2018, Vol. 71, s. 440-445Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A higher gas turbine efficiency can be achieved by increasing the operating temperature in hot sections. AD730™ is a recently-developed wrought/cast nickel-based superalloy which can maintain excellent mechanical properties above 700 ℃. However, machining of AD730™ could be a difficult task like other nickel-based superalloys. Therefore, studies are needed with respect to the machinability of this new alloy.

    In this paper, high-speed turning was performed on AD730™ using polycrystalline cubic boron nitride (PCBN) tools and coated tungsten carbide (WC) tools at varied cutting speeds. The surface integrity was assessed in two important aspects, i.e., surface and sub-surface plastic deformation and residual stresses. The PCBN tools generally showed better performance compared with the WC tools since it led to reduced machining time without largely compromising the surface integrity achieved. The optimal cutting speed was identified in the range of 200-250 m/min when using the PCBN tools, which gives rise to a good combination of machining efficiency and surface integrity. The further increase of the cutting speed to 300 m/min resulted in severe and deep plastic deformation. Meanwhile, a continuous white layer was formed at the machined surface. When turning with the WC tools, the increased cutting speed from 80 m/min to 100 m/min showed very little effect with respect to the plastic deformation on the machined surface. It was found that tensile residual stresses were developed on all machined surfaces no matter when the PCBN or WC tools were used, and the surface tension was generally increased with increasing cutting speed. The tensile layer might need to be modified by e.g., post-machining surface treatments such as shot peening, if taking good fatigue performance into consideration.

  • 2. Bestill onlineKjøp publikasjonen >>
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Constitutive and fatigue crack propagation behaviour of Inconel 7182010Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this licentiate thesis the work done in the TURBO POWER project Influence of high temperature hold times on the fatigue life of nickel-based superalloys will be presented. The overall objective of this project is to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the nickel-based superalloy Inconel 718. Firstly, the constitutive behaviour of the material has been been studied, where focus has been placed on trying to describe the mean stress relaxation and initial softening of the material under intermediate temperatures. Secondly, the fatigue crack propagation behaviour under high temperature hold times has been studied. Focus has here been placed on investigating the main fatigue crack propagation phenomena with the aim of setting up a basis for fatigue crack propagation modelling.

    This thesis is divided into two parts. The first part describes the general framework, including basic constitutive and fatigue crack propagation behaviour as well as a theoretical background for the constitutive modelling of mean stress relaxation. This framework is then used in the second part, which consists of the four included papers.

    Delarbeid
    1. Fatigue crack growth behaviour of Inconel 718 with high temperature hold times
    Åpne denne publikasjonen i ny fane eller vindu >>Fatigue crack growth behaviour of Inconel 718 with high temperature hold times
    Vise andre…
    2010 (engelsk)Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 2, nr 1, s. 1095-1104Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this work, fatigue crack growth measurements have been made on center-cracked tension specimens of Inconel 718, where the focus has been to observe the effect of high temperature hold times on the fatigue crack growth behaviour of the material. The material testing has been done at three different temperatures, namely 450 degrees C, 550 degrees C and 650 degrees C. All testing were done in an isothermal LCF context with a standard test method for measuring the fatigue crack growth rates.

    sted, utgiver, år, opplag, sider
    ELSEVIER SCIENCE BV, 2010
    Emneord
    nickel-base superalloys; fatigue crack propagation; Inconel 718
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-58352 (URN)10.1016/j.proeng.2010.03.118 (DOI)000278762900116 ()
    Tilgjengelig fra: 2010-08-13 Laget: 2010-08-11 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    2. Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures
    Åpne denne publikasjonen i ny fane eller vindu >>Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures
    2011 (engelsk)Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 133, s. 094501-1-094501-4Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Turbine disks are of large importance to turbine designers as theyare exposed to hot environment and subjected to high loads. Inorder to analyze such components with respect to fatigue crackinitiation, the work generally starts with a rigorous analysis of thefirst few cycles, during which an important stress redistributionwill always take place in an inelastic structure. In this work, thenonlinear kinematic hardening law by Ohno and Wang (1998,“Constitutive Modeling of Cyclic Plasticity With Emphasis onRatchetting,” Int. J. Mech. Sci., 40, pp. 251–261) has been used incombination with an isotropic softening law for describing theinitial stress-strain distribution for strain controlled uniaxial testsof the material Inconel 718. Focus has been placed on finding asimple model with few material parameters and to describe theinitial softening and the comparatively small mean stress relaxationobserved during the material testing. The simulation resultsobtained by using the model fit the experimental resultswell.

    sted, utgiver, år, opplag, sider
    ASME, 2011
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-68035 (URN)10.1115/1.4002913 (DOI)000290494800020 ()
    Tilgjengelig fra: 2011-05-06 Laget: 2011-05-06 Sist oppdatert: 2017-12-11
    3. Influence of high temperature hold times on the fatigue crack propagation in Inconel 718
    Åpne denne publikasjonen i ny fane eller vindu >>Influence of high temperature hold times on the fatigue crack propagation in Inconel 718
    Vise andre…
    2011 (engelsk)Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 33, nr 11, s. 1461-1469Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    High temperature fatigue crack growth in Inconel 718 has been studied at the temperatures 450 degrees C, 500 degrees C, 550 degrees C and 650 degrees C. The tests were conducted both without hold times and with hold times of different lengths and with a mix of both. Focus has been on quantifying the effect the hold time has upon the crack growth rate and how much it damages the material. Furthermore, it has been investigated how this damage influences the actual cracking behavior, i.e. where in the loading cycle the damage contributes most to the crack growth. This damage is related to the concept of a damaged zone in front of the crack tip. The size of the damaged zone has been derived from the tests and a microscopy study to confirm the findings has also been carried out. It is found that the concept of a damaged zone can be a successful explanatory model for the observed crack growth behavior under high temperature hold time.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    Nickel-base superalloys, Fatigue crack propagation, Inconel 718, Hold times, Grain boundary embrittlement
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-70317 (URN)10.1016/j.ijfatigue.2011.05.011 (DOI)000293991000006 ()
    Merknad
    Funding Agencies|Swedish Energy Agency||Siemens Industrial Turbomachinery AB||Volvo Aero Corporation||Royal Institute of Technology||Tilgjengelig fra: 2011-09-02 Laget: 2011-09-02 Sist oppdatert: 2017-12-08
    4. Hold-time effect on the thermo-mechanical fatigue crack growth behaviour of Inconel 718
    Åpne denne publikasjonen i ny fane eller vindu >>Hold-time effect on the thermo-mechanical fatigue crack growth behaviour of Inconel 718
    2011 (engelsk)Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 528, nr 29-30, s. 8660-8670Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In-phase TMF crack growth testing with different lengths of the hold time at the maximum temperature of 550 °C has been conducted on Inconel 718 specimens. Focus has been on establishing a method for TMF crack growth testing and investigating the effect of high temperature hold times on the TMF crack growth of the material. The tests are compared to isothermal crack propagation tests and show good correlation. It is concluded that the controlling effect of the crack growth is an embrittlement of the material. This embrittlement is related to the concept of a damaged zone active in front of the crack tip. The size of this damaged zone will control the crack propagation rate and therefore it does not matter if the load is cycled under isothermal or TMF conditions.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    TMF, crack growth
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-71304 (URN)10.1016/j.msea.2011.08.027 (DOI)000296676800046 ()
    Merknad
    Funding agencies|Swedish Energy Agency||Siemens Industrial Turbomachinery AB||Volvo Aero Corporation||Royal Institute of Technology||Tilgjengelig fra: 2011-10-11 Laget: 2011-10-11 Sist oppdatert: 2017-12-08
  • 3. Bestill onlineKjøp publikasjonen >>
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    High temperature fatigue crack propagation behaviour of Inconel 7182013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The overall objective of this work has been to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the nickel-based superalloy Inconel 718. The fatigue crack propagation behaviour under high temperature hold times has been studied. Firstly, the main fatigue crack propagation phenomena have been investigated with the aim of setting up a basis for fatigue crack propagation modelling. Secondly, modelling of the observed behaviour has been performed. Finally, the constitutive behaviour of the material has been studied, where focus has been placed on trying to describe the mean stress relaxation and initial softening of the material under intermediate temperatures.

    This thesis is divided into two parts. The first part describes the general framework, including basic observed fatigue crack propagation behaviour of the material when subjected to hold times at high temperature as well as a background for the constitutive modelling of mean stress relaxation. This framework is then used in the second part, which consists of the seven included papers.

    Delarbeid
    1. Fatigue crack growth behaviour of Inconel 718 with high temperature hold times
    Åpne denne publikasjonen i ny fane eller vindu >>Fatigue crack growth behaviour of Inconel 718 with high temperature hold times
    Vise andre…
    2010 (engelsk)Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 2, nr 1, s. 1095-1104Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this work, fatigue crack growth measurements have been made on center-cracked tension specimens of Inconel 718, where the focus has been to observe the effect of high temperature hold times on the fatigue crack growth behaviour of the material. The material testing has been done at three different temperatures, namely 450 degrees C, 550 degrees C and 650 degrees C. All testing were done in an isothermal LCF context with a standard test method for measuring the fatigue crack growth rates.

    sted, utgiver, år, opplag, sider
    ELSEVIER SCIENCE BV, 2010
    Emneord
    nickel-base superalloys; fatigue crack propagation; Inconel 718
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-58352 (URN)10.1016/j.proeng.2010.03.118 (DOI)000278762900116 ()
    Tilgjengelig fra: 2010-08-13 Laget: 2010-08-11 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    2. Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures
    Åpne denne publikasjonen i ny fane eller vindu >>Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures
    2011 (engelsk)Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 133, s. 094501-1-094501-4Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Turbine disks are of large importance to turbine designers as theyare exposed to hot environment and subjected to high loads. Inorder to analyze such components with respect to fatigue crackinitiation, the work generally starts with a rigorous analysis of thefirst few cycles, during which an important stress redistributionwill always take place in an inelastic structure. In this work, thenonlinear kinematic hardening law by Ohno and Wang (1998,“Constitutive Modeling of Cyclic Plasticity With Emphasis onRatchetting,” Int. J. Mech. Sci., 40, pp. 251–261) has been used incombination with an isotropic softening law for describing theinitial stress-strain distribution for strain controlled uniaxial testsof the material Inconel 718. Focus has been placed on finding asimple model with few material parameters and to describe theinitial softening and the comparatively small mean stress relaxationobserved during the material testing. The simulation resultsobtained by using the model fit the experimental resultswell.

    sted, utgiver, år, opplag, sider
    ASME, 2011
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-68035 (URN)10.1115/1.4002913 (DOI)000290494800020 ()
    Tilgjengelig fra: 2011-05-06 Laget: 2011-05-06 Sist oppdatert: 2017-12-11
    3. Influence of high temperature hold times on the fatigue crack propagation in Inconel 718
    Åpne denne publikasjonen i ny fane eller vindu >>Influence of high temperature hold times on the fatigue crack propagation in Inconel 718
    Vise andre…
    2011 (engelsk)Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 33, nr 11, s. 1461-1469Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    High temperature fatigue crack growth in Inconel 718 has been studied at the temperatures 450 degrees C, 500 degrees C, 550 degrees C and 650 degrees C. The tests were conducted both without hold times and with hold times of different lengths and with a mix of both. Focus has been on quantifying the effect the hold time has upon the crack growth rate and how much it damages the material. Furthermore, it has been investigated how this damage influences the actual cracking behavior, i.e. where in the loading cycle the damage contributes most to the crack growth. This damage is related to the concept of a damaged zone in front of the crack tip. The size of the damaged zone has been derived from the tests and a microscopy study to confirm the findings has also been carried out. It is found that the concept of a damaged zone can be a successful explanatory model for the observed crack growth behavior under high temperature hold time.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    Nickel-base superalloys, Fatigue crack propagation, Inconel 718, Hold times, Grain boundary embrittlement
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-70317 (URN)10.1016/j.ijfatigue.2011.05.011 (DOI)000293991000006 ()
    Merknad
    Funding Agencies|Swedish Energy Agency||Siemens Industrial Turbomachinery AB||Volvo Aero Corporation||Royal Institute of Technology||Tilgjengelig fra: 2011-09-02 Laget: 2011-09-02 Sist oppdatert: 2017-12-08
    4. Hold-time effect on the thermo-mechanical fatigue crack growth behaviour of Inconel 718
    Åpne denne publikasjonen i ny fane eller vindu >>Hold-time effect on the thermo-mechanical fatigue crack growth behaviour of Inconel 718
    2011 (engelsk)Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 528, nr 29-30, s. 8660-8670Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In-phase TMF crack growth testing with different lengths of the hold time at the maximum temperature of 550 °C has been conducted on Inconel 718 specimens. Focus has been on establishing a method for TMF crack growth testing and investigating the effect of high temperature hold times on the TMF crack growth of the material. The tests are compared to isothermal crack propagation tests and show good correlation. It is concluded that the controlling effect of the crack growth is an embrittlement of the material. This embrittlement is related to the concept of a damaged zone active in front of the crack tip. The size of this damaged zone will control the crack propagation rate and therefore it does not matter if the load is cycled under isothermal or TMF conditions.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    TMF, crack growth
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-71304 (URN)10.1016/j.msea.2011.08.027 (DOI)000296676800046 ()
    Merknad
    Funding agencies|Swedish Energy Agency||Siemens Industrial Turbomachinery AB||Volvo Aero Corporation||Royal Institute of Technology||Tilgjengelig fra: 2011-10-11 Laget: 2011-10-11 Sist oppdatert: 2017-12-08
    5. Fatigue Crack Growth behaviour of Inconel 718 - the Concept of a Damaged Zone Caused by High Temperature Hold Times
    Åpne denne publikasjonen i ny fane eller vindu >>Fatigue Crack Growth behaviour of Inconel 718 - the Concept of a Damaged Zone Caused by High Temperature Hold Times
    Vise andre…
    2011 (engelsk)Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 10, s. 2821-2826Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Fatigue crack growth testing of Inconel 718 has been carried out at the temperatures 550 °C and 650 °C. The tests were conducted using a mix of hold times and pure cyclic loading, referred to as block tests. From the test results, the existence of an embrittled volume or damaged zone in the vicinity of the crack tip has been revealed. It has been found that the evolution of this damaged zone can be sufficiently well described using a power law function with an exponent n = 0.25.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    nickel base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-70552 (URN)10.1016/j.proeng.2011.04.469 (DOI)
    Tilgjengelig fra: 2011-09-12 Laget: 2011-09-12 Sist oppdatert: 2017-12-08
    6. High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    Åpne denne publikasjonen i ny fane eller vindu >>High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    2013 (engelsk)Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, s. 178-186Artikkel i tidsskrift (Fagfellevurdert) 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.

    sted, utgiver, år, opplag, sider
    Elsevier, 2013
    Emneord
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling, Finite Element modelling
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-85931 (URN)10.1016/j.ijfatigue.2012.10.018 (DOI)000315617500020 ()
    Tilgjengelig fra: 2013-03-13 Laget: 2012-12-03 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    7. Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    Åpne denne publikasjonen i ny fane eller vindu >>Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    2013 (engelsk)Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, s. 124-130Artikkel i tidsskrift (Fagfellevurdert) 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.

    sted, utgiver, år, opplag, sider
    Elsevier, 2013
    Emneord
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-85933 (URN)10.1016/j.ijfatigue.2013.03.004 (DOI)000318831300013 ()
    Tilgjengelig fra: 2012-12-03 Laget: 2012-12-03 Sist oppdatert: 2017-12-07bibliografisk kontrollert
  • 4.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Lundström, Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Correction: Corrigendum to High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions [Int. J. Fatigue 48 (2013) 178–186]2013Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, s. 157-157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    n/a

  • 5.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Lundström, Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions2013Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, s. 178-186Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 6.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Lundström, Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions2013Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, s. 124-130Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Johansson, Sten
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Hornqvist, Magnus
    Volvo Aero Corporation.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Sjöström, Sören
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Sharifimajd, Babak
    Siemens Industrial Turbomachinery AB.
    Fatigue crack growth behaviour of Inconel 718 with high temperature hold times2010Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 2, nr 1, s. 1095-1104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, fatigue crack growth measurements have been made on center-cracked tension specimens of Inconel 718, where the focus has been to observe the effect of high temperature hold times on the fatigue crack growth behaviour of the material. The material testing has been done at three different temperatures, namely 450 degrees C, 550 degrees C and 650 degrees C. All testing were done in an isothermal LCF context with a standard test method for measuring the fatigue crack growth rates.

  • 8.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Johansson, Sten
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Hornqvist, M
    Volvo Aero Corp.
    Mansson, T
    Volvo Aero Corp.
    Sjöström, Sören
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Influence of high temperature hold times on the fatigue crack propagation in Inconel 7182011Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 33, nr 11, s. 1461-1469Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High temperature fatigue crack growth in Inconel 718 has been studied at the temperatures 450 degrees C, 500 degrees C, 550 degrees C and 650 degrees C. The tests were conducted both without hold times and with hold times of different lengths and with a mix of both. Focus has been on quantifying the effect the hold time has upon the crack growth rate and how much it damages the material. Furthermore, it has been investigated how this damage influences the actual cracking behavior, i.e. where in the loading cycle the damage contributes most to the crack growth. This damage is related to the concept of a damaged zone in front of the crack tip. The size of the damaged zone has been derived from the tests and a microscopy study to confirm the findings has also been carried out. It is found that the concept of a damaged zone can be a successful explanatory model for the observed crack growth behavior under high temperature hold time.

  • 9.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära.
    Johansson, Sten
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Hörnqvist, Magnus
    Volvo Aero Corporation, Trollhättan.
    Månsson, Tomas
    Volvo Aero Corporation, Trollhättan.
    Sjöström, Sören
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära.
    Fatigue Crack Growth behaviour of Inconel 718 - the Concept of a Damaged Zone Caused by High Temperature Hold Times2011Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 10, s. 2821-2826Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fatigue crack growth testing of Inconel 718 has been carried out at the temperatures 550 °C and 650 °C. The tests were conducted using a mix of hold times and pure cyclic loading, referred to as block tests. From the test results, the existence of an embrittled volume or damaged zone in the vicinity of the crack tip has been revealed. It has been found that the evolution of this damaged zone can be sufficiently well described using a power law function with an exponent n = 0.25.

  • 10.
    Gustafsson, David
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Sjöström, Sören
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures2011Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 133, s. 094501-1-094501-4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Turbine disks are of large importance to turbine designers as theyare exposed to hot environment and subjected to high loads. Inorder to analyze such components with respect to fatigue crackinitiation, the work generally starts with a rigorous analysis of thefirst few cycles, during which an important stress redistributionwill always take place in an inelastic structure. In this work, thenonlinear kinematic hardening law by Ohno and Wang (1998,“Constitutive Modeling of Cyclic Plasticity With Emphasis onRatchetting,” Int. J. Mech. Sci., 40, pp. 251–261) has been used incombination with an isotropic softening law for describing theinitial stress-strain distribution for strain controlled uniaxial testsof the material Inconel 718. Focus has been placed on finding asimple model with few material parameters and to describe theinitial softening and the comparatively small mean stress relaxationobserved during the material testing. The simulation resultsobtained by using the model fit the experimental resultswell.

  • 11.
    Hörnqvist, Magnus
    et al.
    Volvo Aero Corporation, Trollhättan, Sweden.
    Månsson, Tomas
    Volvo Aero Corporation, Trollhättan, Sweden.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    High temperature fatigue crack growth in Alloy 718 - Effect of tensile hold times2011Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 10, s. 147-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present investigation aims to clarify the mechanisms behind hold-time fatigue crack growth in Alloy 718 by using well designed tests where the crack length is carefully monitored. The results indicate that there is a significant embrittlement in a zone ahead of the crack tip during the hold-time, which is cracked open on the next load reversal. This leads to a very large cyclic contribution to the total crack length increment during a cycle, orders of magnitude larger than expected from purely cyclic tests at higher frequencies. During the hold-time follows the growth determined from pure sustained load tests, with the exception of an initial transient after the opening of the embrittled zone. An attempt to model the crack growth rate was made using a superposition model where the crack growth increments from high frequency da/dN testing and sustained load tests were added. The predictions of the total crack growth rate are generally adequate, but when the predictions of the individual contributions are scrutinized, it is obvious that the simple model does not correlate with the physical reality. Therefore both inter- and extrapolations from such a model are uncertain. Further, the test results show a decreased sustained load crack growth immediately after unloading/reloading of the crack. This transient behavior can potentially explain the reduction in crack growth rates previously explained by overload effects.

  • 12.
    Leidermark, Daniel
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Aspenberg, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    The effect of random grain distributions on fatigue crack initiation in a notched coarse grained superalloy specimen2012Inngår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 51, nr 1, s. 273-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coarse grained superalloys are of large interest in high temperature applications, and can be found in e.g.gas turbine components, where great care must be given with respect to high temperature fatigue. Due tothe large grain size, the material behaviour at e.g. sharp notches cannot be considered homogeneous. As aconsequence, the fatigue behaviour is likely to expose a large variation. In order to numerically investigatethis variation, a Monte Carlo analysis has been carried out by 100 FE-simulations of notched specimens,where placements and orientations of the grains were randomised. Furthermore, each grain wasmodelled as a unique single-crystal, displaying both anisotropic elastic and plastic behaviour and tension/compression asymmetry. The effect of randomness was investigated by the obtained dispersion infatigue crack initiation life. It was concluded that the fatigue life behaviour of coarse grained nickel-basesuperalloys may show a considerable variation, which cannot be captured by one single deterministicanalysis based on data for a homogenised material. Furthermore, the dispersion is of such a magnitudethat it needs to be taken into account in industrial applications where highly stressed coarse grainedmaterials are used.

  • 13.
    Lundström, Erik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Månsson, T.
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions2014Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 118, s. 17-30Artikkel i tidsskrift (Fagfellevurdert)
    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 %.

  • 14.
    Lundström, Erik
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Simonsson, Kjell
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum2014Inngår i: Advanced Materials Research, ISSN 1662-8985, Vol. 891-892, s. 759-764Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 15.
    Moverare, Johan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska högskolan.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Hållfasthetslära. Linköpings universitet, Tekniska högskolan.
    Hold-time effect on the thermo-mechanical fatigue crack growth behaviour of Inconel 7182011Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 528, nr 29-30, s. 8660-8670Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In-phase TMF crack growth testing with different lengths of the hold time at the maximum temperature of 550 °C has been conducted on Inconel 718 specimens. Focus has been on establishing a method for TMF crack growth testing and investigating the effect of high temperature hold times on the TMF crack growth of the material. The tests are compared to isothermal crack propagation tests and show good correlation. It is concluded that the controlling effect of the crack growth is an embrittlement of the material. This embrittlement is related to the concept of a damaged zone active in front of the crack tip. The size of this damaged zone will control the crack propagation rate and therefore it does not matter if the load is cycled under isothermal or TMF conditions.

  • 16.
    Palmert, Frans
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, David
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Thermomechanical fatigue crack growth in a single crystal nickel base superalloy2019Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 122, s. 184-198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermomechanical fatigue crack growth in a single crystal nickel base superalloy was studied. Tests were performed on single edge notched specimens, using in phase and out of phase thermomechanical fatigue cycling with temperature ranges of 100-750°C and 100-850°C and hold times at maximum temperature ranging from 10s to 6h. Isothermal testing at 100°C, 750°C and 850°C was also performed using the same test setup. A compliance-based method is proposed to experimentally evaluate the crack opening stress and thereby estimate the effective stress intensity factor range ΔKeff for both isothermal and nonisothermal conditions. For in phase thermomechanical fatigue, the crack growth rate is increased if a hold time is applied at the maximum temperature. By using the compliance-based crack opening evaluation, this increase in crack growth rate was explained by an increase in the effective stress intensity factor range which accelerated the cycle dependent crack growth. No significant difference in crack growth rate vs ΔKeff was observed between in phase thermomechanical fatigue tests and isothermal tests at the maximum temperature. For out of phase thermomechanical fatigue, the crack growth rate was insensitive to the maximum temperature and also to the length of hold time at maximum temperature. The crack growth rate vs ΔKeff during out of phase thermomechanical fatigue was significantly higher than during isothermal fatigue at the minimum temperature, even though the advancement of the crack presumably occurs at the same temperature. Dissolution of γ′ precipitates and recrystallization at the crack tip during out of phase thermomechanical fatigue is suggested as a likely explanation for this difference in crack growth rate.

    Fulltekst tilgjengelig fra 2021-01-25 17:11
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