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  • 1.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandvik Materials Technology, Sandviken, Sweden.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan J.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Characterization of austenitic stainless steels deformed at elevated temperature2017In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 10, p. 4525-4538Article in journal (Refereed)
    Abstract [en]

    Highly alloyed austenitic stainless steels are promising candidates to replace more expansive nickel-based alloys within the energy-producing industry. The present study investigates the deformation mechanisms by microstructural characterisation, mechanical properties and stress-strain response of three commercial austenitic stainless steels and two commercial nickel-based alloys using uniaxial tensile tests at elevated temperatures from 400 C up to 700 C. The materials showed different influence of temperature on ductility, where the ductility at elevated temperatures increased with increasing nickel and solid solution hardening element content. The investigated materials showed planar dislocation driven deformation at elevated temperature. Scanning electron microscopy showed that deformation twins were an active deformation mechanism in austenitic stainless steels during tensile deformation at elevated temperatures up to 700 C.

  • 2.
    Cao, Haiping
    et al.
    Department of Mechanical Engineering/Component Technology, Jönköping University, Sweden.
    Wessén, Magnus
    Department of Mechanical Engineering/Component Technology, Jönköping University, Sweden.
    Effect of microstructure on mechanical properties of as-cast Mg-Al alloys2004In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 35, no 1, p. 309-319Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of Mg-Al alloys are mainly determined by the microstructure, i.e., the amount and morphology of the phases, but also by the presence of defects arising from the melt handling and casting process. In order to obtain information about the isolated effect of the microstructure, it is, therefore, necessary to minimize the amounts of defects. In this study, this has been achieved by remelting and solidifying the alloys in a gradient furnace. The drawing rate was varied from 0.3 to 6 mm/s, which yielded a wide variety of microstructures. Three samples were produced for each parameter set, in order to have a statistical basis for the evaluation. The results showed that homogeneous and reproducible samples could be produced, and that the tensile properties obtained showed a very small scatter. The effects of microstructural parameters such as grain size, secondary dendrite arm spacing (SDAS), eutectic fraction, and eutectic morphology on the yield strength, ultimate tensile strength (UTS), fracture elongation, and hardness has been investigated.

  • 3.
    Chen, Zhe
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru Lin
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Avdovic, Pajazit
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Zhou, Jinming
    Division of Production and Materials Engineering, Lund university.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures2016In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47A, no 7, p. 3664-3676Article in journal (Refereed)
    Abstract [en]

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 A degrees C, 550 A degrees C, and 650 A degrees C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and alpha-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

  • 4.
    Cong, D Y
    et al.
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Wang, Yandong
    Key Lab for Anisotropy & Texture of Mater., Northeastern Univ., Shenyang, China.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials . Linköping University, The Institute of Technology.
    Zetterström, P
    The Studsvik Neutron Research Laboratory, Uppsala University.
    Zhao, X
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Liaw, P K
    Dept of Materials Science and Eng, The University of Tennessee, Knoxville, USA.
    Zuo, L
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Crystal structures and textures in the hot-forged Ni-Mn-Ga shape memory alloys2006In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 37A, no 5, p. 1397-1403Article in journal (Refereed)
    Abstract [en]

    Three ferromagnetic shape-memory alloys with the chemical compositions of Ni53Mn25Ga22, Ni48Mn30Ga22, and Ni48Mn25Ga22Co5 were prepared by the induction-melting and hot-forging process. The crystal structures were investigated by the neutron powder diffraction technique, showing that Ni53Mn25Ga22 and Ni48Mn25Ga22Co5 have a tetragonal, I4/mmm martensitic structure at room temperature, while Ni48Mn30Ga22 has a cubic, L2(1) austenitic structure at room temperature. The development of textures in the hot-forged samples shows the in-plane plastic flow anisotropy from the measured pole figures by means of the neutron diffraction technique. Significant texture changes were observed for the Ni48Mn25Ga22Co5 alloy after room temperature deformation, which is due to the deformation-induced rearrangements of martensitic variants. An excellent shape-memory effect (SME) with a recovery ratio of 74 pct was reported in this Ni48Mn25Ga22Co5 polycrystalline alloy after annealing above the martensitic transformation temperature, and the "shape-memory" influence also occurs in the distributions of grain orientations.

  • 5.
    Cong, D Y
    et al.
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Wang, Yandong
    Key Lab for Anisotropy & Texture of Mater., Northeastern Univ., Shenyang, China.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials . Linköping University, The Institute of Technology.
    Zetterström, P
    The Studsvik Neutron Research Laboratory, Uppsala University.
    Zhao, X
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Liaw, P K
    Dept of Materials Science and Eng, The University of Tennessee, Knoxville, USA.
    Zuo, L
    School of Materials and Metallurgy, Northeastern University, Shenyang, China.
    Crystal Structures and Textures in the Hot-Froged Ni-Mn-Ga Shape Memory Alloys2006In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 37A, no 5, p. 1397-1403Article in journal (Refereed)
  • 6.
    Johansson (Moverare), Johan
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Load sharing between austenite and ferrite in a duplex stainless steel during cyclic loading2000In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 31, no 6, p. 1557-1570Article in journal (Refereed)
    Abstract [en]

    The load sharing between phases and the evolution of micro- and macrostresses during cyclic loading has been investigated in a 1.5-mm cold-rolled sheet of the duplex stainless steel SAF 2304. X-ray diffraction (XRD) stress analysis and transmission electron microscopy (TEM) show that even if the hardness and yield strength are higher in the austenitic phase, more plastic deformation will occur in this phase due to the residual microstresses present in the material. The origin of the microstresses is the difference in coefficients of thermal expansion between the two phases, which leads to tensile microstresses in the austenite and compressive microstresses in the ferrite. The microstresses were also found to increase from 50 to 140 MPa in the austenite during the first 100 cycles when cycled in tension fatigue with a maximum load of 500 MPa. The cyclic loading response of the material was, thus, mainly controlled by the plastic properties of the austenitic phase. It was also found that initial compressive macrostresses on the surface increased from −40 to 50 MPa during the first 103 cycles. After the initial increase of microstresses and macrostresses, no fading of residual stresses was found to occur for the following cycles. A good correlation was found between the internal stress state and the microstructure evolution. The change in texture during cyclic fatigue showed a sharpening of the deformation texture in the ferritic phase, while no significant changes were found in the austenitic phase.

  • 7.
    Kahl, Sören
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sapa Heat Transfer Technology, Finspång, Sweden .
    Ekström, Hans-Erik
    Sapa Technology, Finspång, Sweden .
    Mendoza, Jesus
    Sapa Technology, Finspång, Sweden .
    Tensile, Fatigue and Creep Properties of Aluminum Heat Exhanger Tube Alloys for Temperatures from 293 K to 573 K (20°C to 300°C)2014In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, ISSN 1073-5623, Vol. 45A, no 2, p. 663-681Article in journal (Refereed)
    Abstract [en]

    Since automotive heat exchangers are operated at varying temperatures and under varying pressures, both static and dynamic mechanical properties should be known at different temperatures. Tubes are the most critical part of the most heat exchangers made from aluminum brazing sheet. We present tensile test, stress amplitude-fatigue life, and creep–rupture data of six AA3XXX series tube alloys after simulated brazing for temperatures ranging from 293 K to 573 K (20 °C to 300 °C). While correlations between several mechanical properties are strong, ranking of alloys according to one property cannot be safely deduced from the known ranking according to another property. The relative reduction in creep strength with increasing temperature is very similar for all six alloys, but the general trends are also strong with respect to tensile and fatigue properties; an exception is one alloy that exhibits strong Mg-Si precipitation activity during fatigue testing at elevated temperatures. Interrupted fatigue tests indicated that the crack growth time is negligible compared to the crack initiation time. Fatigue lifetimes are reduced by creep processes for temperatures above approximately 423 K (150 °C). When mechanical properties were measured at several temperatures, interpolation to other temperatures within the same temperature range was possible in most cases, using simple and well-established equations.

  • 8.
    Kontis, Paraskevas
    et al.
    Max Planck Inst Eisenforsch GmbH, Germany.
    Li, Zhuangming
    Max Planck Inst Eisenforsch GmbH, Germany.
    Segersäll, Mikael
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Reed, Roger C.
    Univ Oxford, England.
    Raabe, Dierk
    Max Planck Inst Eisenforsch GmbH, Germany.
    Gault, Baptiste
    Max Planck Inst Eisenforsch GmbH, Germany.
    The Role of Oxidized Carbides on Thermal-Mechanical Performance of Polycrystalline Superalloys2018In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, no 9, p. 4236-4245Article in journal (Refereed)
    Abstract [en]

    Oxidized MC carbides which act as main crack initiation sites in a polycrystalline superalloy under thermal-mechanical fatigue (TMF) conditions at 850 degrees C were studied. Microstructural observations in the TMF tested specimens were compared to findings from bulk samples exposed isothermally in air at 850 degrees C for 30 hours in the absence of any external applied load. Carbides were found to oxidize rapidly after exposure at 850 degrees C for 30 hours resulting in surface eruptions corresponding to oxidation products, from where micro-cracks initiated. Plastic deformation due to volume expansion of the often porous oxidized carbides led to high dislocation densities in the adjacent matrix as revealed by controlled electron channeling contrast imaging. The high dislocation density facilitated the dissolution kinetics of gamma precipitates by segregation and diffusion of chromium and cobalt along the dislocations via pipe diffusion, resulting in the formation of soft recrystallized grains. Atom probe tomography revealed substantial compositional differences between the recrystallized grains and the adjacent undeformed gamma matrix. Similar observations were made for the TMF tested alloy. Our observations provide new insights into the true detrimental role of oxidized MC carbides on the crack initiation performance of polycrystalline superalloys under TMF.

  • 9.
    Kumara, Chamara
    et al.
    Univ West, Sweden.
    Deng, Dunyong
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Hanning, Fabian
    Chalmers Univ Technol, Sweden.
    Raanes, Morten
    NTNU, Norway.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Univ West, Sweden.
    Nylen, Per
    Univ West, Sweden.
    Predicting the Microstructural Evolution of Electron Beam Melting of Alloy 718 with Phase-Field Modeling2019In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50A, no 5, p. 2527-2537Article in journal (Refereed)
    Abstract [en]

    Electron beam melting (EBM) is a powder bed additive manufacturing process where a powder material is melted selectively in a layer-by-layer approach using an electron beam. EBM has some unique features during the manufacture of components with high-performance superalloys that are commonly used in gas turbines such as Alloy 718. EBM has a high deposition rate due to its high beam energy and speed, comparatively low residual stresses, and limited problems with oxidation. However, due to the layer-by-layer melting approach and high powder bed temperature, the as-built EBM Alloy 718 exhibits a microstructural gradient starting from the top of the sample. In this study, we conducted modeling to obtain a deeper understanding of microstructural development during EBM and the homogenization that occurs during manufacturing with Alloy 718. A multicomponent phase-field modeling approach was combined with transformation kinetic modeling to predict the microstructural gradient and the results were compared with experimental observations. In particular, we investigated the segregation of elements during solidification and the subsequent in situ homogenization heat treatment at the elevated powder bed temperature. The predicted elemental composition was then used for thermodynamic modeling to predict the changes in the continuous cooling transformation and time-temperature transformation diagrams for Alloy 718, which helped to explain the observed phase evolution within the microstructure. The results indicate that the proposed approach can be employed as a valuable tool for understanding processes and for process development, including post-heat treatments. (C) The Author(s) 2019

  • 10.
    Li, J. H.
    et al.
    Institute of Casting Research, Leoben, Austria.
    Barrirero, Jenifer
    Department of Materials Science, Saarland University, Saarbrücken, Germany.
    Engstler, M.
    Department of Materials Science, Saarland University, Saarbrücken, Germany.
    Aboulfadl, H.
    Department of Materials Science, Saarland University, Saarbrücken, Germany.
    Mücklich, F.
    Department of Materials Science, Saarland University, Saarbrücken, Germany.
    Schumacher, P.
    Institute of Casting Research, Leoben, Austria; Austrian Foundry Research Institute, Leoben, Austria.
    Nucleation and Growth of Eutectic Si in Al-Si Alloys with Na Addition2015In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 46, no 3, p. 1300-1311Article in journal (Refereed)
    Abstract [en]

    Al-5 wt pct Si-based alloys with Na additions (19 and 160 ppm) have been produced by controlled sand casting and melt spinning. Entrained droplet technique and differential scanning calorimetry were employed to investigate the nucleation behavior of eutectic Si. High-resolution transmission electron microscopy and atom probe tomography were used to investigate the distribution of Na atoms within eutectic Si and at the interfaces between eutectic Si and eutectic Al. It was found that (i) only 19 ppm Na addition results into a high undercooling (49 K (49 °C)) of the entrained eutectic droplet. However, further increasing Na addition up to 160 ppm exerts no positive effect on the nucleation of eutectic Si, instead a decreased undercooling (29 K (29 °C)) was observed. (ii) Na addition suppresses the growth of eutectic Si due to the Na segregation at the interface between eutectic Si and eutectic Al, and (iii) Na addition promotes significant multiple Si twins, which can be attributed to the proposed adsorption of Na atoms at the intersection of Si twins and along the 〈112〉Si growth direction of Si. The present investigation demonstrates, for the first time, a direct observation on the distribution of Na atoms within eutectic Si and thereby provides strong experimental supports to the well-accepted impurity-induced twinning growth mechanism and poisoning of the twin plane re-entrant edge growth mechanism.

  • 11.
    Liu, X. P.
    et al.
    Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education).
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Hofmann, M
    FRM-II, TU München, Garching, Germany .
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Wang, Y D
    Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, People’s Republic of China and School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, People’s Republic of China.
    In-Situ Neutron Diffraction Studies of Micromechanical Behavior in a Friction Stir Welded AA7475-T7612011In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 42A, no 1, p. 89-94Article in journal (Refereed)
    Abstract [en]

    An in-situ neutron diffraction technique was used to investigate the lattice strain distributions and micromechanical behavior in a friction stir welded (FSW) sheet of AA7475-T761. The neutron diffraction experiments were performed on the spectrometer for material research, STRESS-SPEC, at FRM II (Garching, Germany). The lattice strain profiles around the weld center were measured as a function of the applied strain during the tensile loading and unloading. The anisotropic elastic and plastic properties of the FSW aluminum alloy were simulated by elasto-plastic self-consistent (EPSC) model to predict the anisotropic deformation behaviors involving the grain-to-grain interactions. Material parameters used for describing the constitutive laws of each test position were determined from the measured lattice strain distributions for different diffraction hkl planes as well as the macroscopic stress-strain curve of the FSW aluminum alloy. A good agreement between experimental results and numerical simulations was obtained. The present investigations provided a reliable prediction of the anisotropic micromechanical behavior of the FSW aluminum alloy during tensile deformation.

  • 12.
    Moverare, Johan
    et al.
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Influence of elastic and plastic anisotropy on the flow behavior in a duplex stainless steel2002In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 33, no 1, p. 57-71Article in journal (Refereed)
    Abstract [en]

    The load partitioning between two phases in a cold-rolled duplex stainless steel has been experimentally studied in situ by X-ray diffraction, for different loading directions. It was found that the load partitioning between the two phases is dependent on the loading direction. For loading in the rolling direction, both phases deform plastically to the same degree, while more plastic deformation occurs in the austenitic phase during loading in the transverse direction. For loading in the 45-deg direction, more plastic deformation occurs in the ferritic phase. The strong crystallographic texture in the ferritic phase makes the material anisotropic, with a higher stiffness and yield strength in the transverse direction compared to the rolling direction. The measured texture was used as input to theoretical predictions of both elastic and plastic anisotropy. The plastic anisotropy was predicted by assuming intragranular slip as the main deformation mechanism. The predicted anisotropic material properties were then used in finite-element simulations to study the flow behavior of the material in different directions. The predicted flow behavior was found to be in good agreement with the experimentally observed load partitioning between the phases for loading in the rolling and transverse directions. However, the yield strength of the ferritic phase during loading in the 45-deg direction was found to be lower than what was predicted. The reason for this is the difference in slip characteristics in different sample directions, because of the morphological texture.

  • 13.
    Sato, Atsushi
    et al.
    University of Birmingham, United Kingdom.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Hasselqvist, Magnus
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Reed, Roger C.
    University of Birmingham, United Kingdom.
    On the Mechanical Behavior of a New Single-Crystal Superalloy for Industrial Gas Turbine Applications2012In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 43A, no 7, p. 2302-2315Article in journal (Refereed)
    Abstract [en]

    The mechanical behavior of a new single-crystal nickel-based superalloy for industrial gas turbine (IGT) applications is studied under creep and out-of-phase (OP) thermomechanical fatigue (TMF) conditions. Neutron diffraction methods and thermodynamic modeling are used to quantify the variation of the gamma prime (γ′) strengthening phase around the γ′ solvus temperature; these aid the design of primary aging heat treatments to develop either uniform or bimodal microstructures of the γ′ phase. Under creep conditions in the temperature range 1023 K to 1123 K (750 °C to 850 °C), with stresses between 235 to 520 MPa, the creep performance is best with a finer and uniform γ′ microstructure. On the other hand, the OP TMF performance improves when the γ′ precipitate size is larger. Thus, the micromechanical degradation mechanisms occurring during creep and TMF are distinct. During TMF, localized shear banding occurs with the γ′ phase penetrated by dislocations; however, during creep, the dislocation activity is restricted to the matrix phase. The factors controlling TMF resistance are rationalized.

  • 14.
    Segersäll, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Moverare, Johan J.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Leidermark, Daniel
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Creep and Stress Relaxation Anisotropy of a Single-Crystal Superalloy2014In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 45, no 5, p. 2532-2544Article in journal (Refereed)
    Abstract [en]

    In this study, the TMF stress relaxation and creep behavior at 1023 K and 1223 K (750 °C and 950 °C) have been investigated for a Ni-based single-crystal superalloy. Specimens with three different crystal orientations along their axes were tested; 〈001〉, 〈011〉, and 〈111〉, respectively. A highly anisotropic behavior during TMF stress relaxation was found where the 〈111〉 direction significantly shows the worst properties of all directions. The TMF stress relaxation tests were performed in both tension and compression and the results indicate a clear tension/compression asymmetry for all directions where the greatest asymmetry was observed for the 〈001〉 direction at 1023 K (750 °C); here the creep rate was ten times higher in compression than tension. This study also shows that TMF cycling seems to influence the creep rate during stress relaxation temporarily, but after some time it decreases again and adapts to the pre-unloading creep rate. Creep rates from the TMF stress relaxation tests are also compared to conventional constant load creep rates and a good agreement is found.

  • 15.
    Stekovic, Svjetlana
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials . Linköping University, The Institute of Technology.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials . Linköping University, The Institute of Technology.
    Ericsson, Torsten
    Linköping University, Department of Management and Engineering, Engineering Materials . Linköping University, The Institute of Technology.
    Low Cycle Fatigue, Thermo-Mechanical Fatigue and Failure of an Uncoated and Coated Polycrystalline Nickel-Base Superalloy IN7922007In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940Article in journal (Refereed)
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