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  • 1.
    Azeez, Ahmed
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Arts and Sciences. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Characterisation of Deformation and Damage in a Steam Turbine Steel Subjected to Low Cycle Fatigue2019In: Structural Integrity Procedia / [ed] Elsevier, 2019Conference paper (Refereed)
  • 2.
    Azeez, Ahmed
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Arts and Sciences. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Lindström, Stefan B
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Low Cycle Fatigue Modelling of Steam Turbine Rotor Steel2019In: Structural Integrity Procedia / [ed] Elsevier, Elsevier, 2019Conference paper (Refereed)
  • 3.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    High-Temperature Behaviour of Austenitic Alloys: Influence of Temperature and Strain Rate on Mechanical Properties and Microstructural Development2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global increase in energy consumption and the global warming from greenhouse gas emission creates the need for more environmental friendly energy production processes. Biomass power plants with higher efficiency could generate more energy but also reduce the emission of greenhouse gases, e.g. CO2. Biomass is the largest global contributor to renewable energy and offers no net contribution of CO2 to the atmosphere. One way to increase the efficiency of the power plants is to increase temperature and pressure in the boiler parts of the power plant.

    The materials used for the future biomass power plants, with higher temperature and pressure, require improved properties, such as higher yield strength, creep strength and high-temperature corrosion resistance. Austenitic stainless steels and nickel-base alloys have shown good mechanical and chemical properties at the operation temperatures of today’s biomass power plants. However, the performance of austenitic stainless steels at the future elevated temperatures is not fully understood.

    The aim of this licentiate thesis is to increase our knowledge about the mechanical performance of austenitic stainless steels at the demanding conditions of the new generation power plants. This is done by using slow strain rate tensile deformation at elevated temperature and long term hightemperature ageing together with impact toughness testing. Microscopy is used to investigate deformation, damage and fracture behaviours during slow deformation and the long term influence of temperature on toughness in the microstructure of these austenitic alloys. Results show that the main deformation mechanisms are planar dislocation deformations, such as planar slip and slip bands. Intergranular fracture may occur due to precipitation in grain boundaries both in tensile deformed and impact toughness tested alloys. The shape and amount of σ-phase precipitates have been found to strongly influence the fracture behaviour of some of the austenitic stainless steels. In addition, ductility is affected differently by temperature depending on alloy tested and dynamic strain ageing may not always lead to a lower ductility.

    List of papers
    1. Deformation and damage behaviours of austenitic alloys in the dynamic strain ageing regime
    Open this publication in new window or tab >>Deformation and damage behaviours of austenitic alloys in the dynamic strain ageing regime
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Deformation and damage behaviours influenced by dynamic strain ageing (DSA) in three austenitic stainless steels and two nickel-base alloys have been investigated using tensile tests at elevated temperatures. The deformation and damage behaviours have been analysed using electron channeling contrast imaging and electron backscatter diffraction. The results from this study show that DSA not always reduce ductility, in fact for some materials the ductility can increase in the DSA regime. This is attributed to the formation of nano twins by DSA stimulated twinning induced plasticity. Damage mechanisms due to DSA were also investigated and discussed.

    Keywords
    Dynamic strain ageing, austenitic stainless steel, nickel-base alloy, TWIP, damage
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-98239 (URN)
    Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2013-10-04Bibliographically approved
    2. Influence of deformation rate on mechanical response of an AISI 316L austenitic stainless steel
    Open this publication in new window or tab >>Influence of deformation rate on mechanical response of an AISI 316L austenitic stainless steel
    2014 (English)In: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 922, p. 49-54Article in journal (Refereed) Published
    Abstract [en]

    Austenitic stainless steels are often used for components in demanding environment. These materials can withstand elevated temperatures and corrosive atmosphere like in energy producing power plants. They can be plastically deformed at slow strain rates and high alternating or constant tensile loads such as fatigue and creep at elevated temperatures. This study investigates how deformation rates influence mechanical properties of an austenitic stainless steel. The investigation includes tensile testing using strain rates of 2*10-3/ and 10-6/s at elevated temperatures up to 700°C. The material used in this study is AISI 316L. When the temperature is increasing the strength decreases. At a slow strain rate and elevated temperature the stress level decreases gradually with increasing plastic deformation probably due to dynamic recovery and dynamic recrystallization. However, with increasing strain rate elongation to failure is decreasing. AISI 316L show larger elongation to failure when using a strain rate of 10-6/s compared with 2*10-3/s at each temperature. Electron channelling contrast imaging is used to characterize the microstructure and discuss features in the microstructure related to changes in mechanical properties. Dynamic recrystallization has been observed and is related to damage and cavity initiation and propagation.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Keywords
    Austenitic stainless steel, elevated temperature, ageing, dynamic recrystallization
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-98240 (URN)10.4028/www.scientific.net/AMR.922.49 (DOI)
    Conference
    THERMEC '2013, International Conference on Processing & Manufacturing of Advanced Materials. Processeing, Fabrication, Properties, Applications. December 2-6, Las Vegas, USA
    Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2017-12-06Bibliographically approved
    3. Mechanical Behaviours of Alloy 617 with Varied Strain Rate at High Temperatures
    Open this publication in new window or tab >>Mechanical Behaviours of Alloy 617 with Varied Strain Rate at High Temperatures
    2014 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 783-786, p. 1182-1187Article in journal (Refereed) Published
    Abstract [en]

    Nickel-base alloys due to their high performances have been widely used in biomass and coal fired power plants. They can undertake plastic deformation with different strain rates such as those typically seen during creep and fatigue at elevated temperatures. In this study, the mechanical behaviours of Alloy 617 with strain rates from 10-2/s down to 10-6/s at temperatures of 650°C and 700°C have been studied using tensile tests. Furthermore, the microstructures have been investigated using electron backscatter detection and electron channeling contrast imaging. At relatively high strain rate, the alloy shows higher fracture strains at these temperatures. The microstructure investigation shows that it is caused by twinning induced plasticity due to DSA. The fracture strain reaches the highest value at a strain rate of 10-4/s and then it decreases  dramatically. At strain rate of 10-6/s, the fracture strain at high temperature is now smaller than that at room temperature, and the strength also decreases with further decreasing strain rate. Dynamic recrystallization can also be observed usually combined with crack initiation and propagation. This is a new type of observation and the mechanisms involved are discussed.

    Keywords
    Nickel-base superalloy, twinning, Dynamic strain ageing, elevated temperature
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-98241 (URN)10.4028/www.scientific.net/MSF.783-786.1182 (DOI)
    Conference
    THERMEC '2013, International Conference on Processing & Manufacturing of Advanced Materials. Processing, Fabrication, Properties, Applications. December 2-6, Las Vegas, USA
    Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2017-12-06Bibliographically approved
    4. Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing
    Open this publication in new window or tab >>Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing
    2014 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Biomass power plants with high efficiency are desired as a renewable energy resource. High efficiency can be obtained by increasing temperature and pressure. An upgrade of the material performance to high temperature material is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. In this study, the material’s high-temperature behaviours of AISI 304 and Alloy617 under slow deformation rate are evaluated using high-temperature long-term aged specimens subjected to slow strain rate tensile testing (SSRT) with strain rates down to 10-6/s at 700°C. Both materials show decreasing stress levels and elongation to fracture when tensile deformed using low strain rate and elevated temperature. At high-temperature and low strain rates cracking in grain boundaries due to larger precipitates formed during deformation is the most common fracture mechanism.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Series
    Key Engineering Materials, ISSN 1662-9795
    Keywords
    High-temperature, ageing, slow strain rate, biomass power plant, austenitic stainless steel, nickel base alloy and dynamic strain ageing
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-96028 (URN)10.4028/www.scientific.net/KEM.592-593.590 (DOI)000336694400133 ()
    Conference
    MSMF7 Materials Structure & Micromechanics of Fracture , July 13, Brno, Czech Republic
    Available from: 2013-08-13 Created: 2013-08-13 Last updated: 2015-11-30Bibliographically approved
    5. Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In-Situ Tensile Testing in SEM
    Open this publication in new window or tab >>Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In-Situ Tensile Testing in SEM
    Show others...
    2014 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    In this study an advanced method for investigation of the microstructure such as electron backscatter diffraction (EBSD) together with in-situ tensile test in a scanning electron microscope (SEM) has been used at room temperature and 300°C. EBSD analyses provide information about crystallographic orientation in the microstructure and dislocation structures caused by deformation. The in-situ tensile tests enabled the same area to be investigated at different strain levels. For the same macroscopic strain values a lower average misorientation in individual grains at elevated temperature indicates that less residual strain at grain level are developed compared to room temperature. For both temperatures, while large scatters in grain average misorientation are observed for grains of similar size, there seems to be a tendency showing that larger grains may accumulate somewhat more strains.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Series
    Key Engineering Materials, ISSN 1662-9795
    Keywords
    Austenitic stainless steel, electron backscatter diffraction, in-situ tensile test, Schmid factor, grain wsize and slip system
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-97015 (URN)10.4028/www.scientific.net/KEM.592-593.497 (DOI)000336694400111 ()
    Conference
    MSMF7 Materials Structure & Micromechanics of Fracture, July 1-3, Brno, Czech Republic
    Available from: 2013-09-03 Created: 2013-09-03 Last updated: 2015-11-30Bibliographically approved
    6. Influence of High Temperature Ageing on the Toughness of Advanced Heat Resistant Materials
    Open this publication in new window or tab >>Influence of High Temperature Ageing on the Toughness of Advanced Heat Resistant Materials
    2013 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Advanced biomass, biomass co-firing in coal-fired and future advanced USC coal-fired power plants with high efficiency require the materials to be used at even higher temperature under higher pressure. The reliability and integrity of the material used are therefore of concern. In this study, the influence of ageing at temperatures up to 700°C for up to 3 000 hours on the toughness of two advanced heat resistant austenitic steels and one nickel alloy are investigated. The influence on toughness due to differences in the chemical composition as well as the combined effect of precipitation and growth of the precipitates has been analysed by using SEM techniques. The fracture mechanisms that are active for the different ageing treatments are identified as a function of temperature and time. Local approach methods are used to discuss the influence of the precipitation and growth of precipitates on the toughness or fracture in  the different aged materials.

    Keywords
    high-temperature, ageing, toughness, austnitic stainless steel, incke base alloy
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-95440 (URN)
    Conference
    13th International Conference on Fracture (ICF13), June 16-21, Beijing, China
    Available from: 2013-07-03 Created: 2013-07-03 Last updated: 2013-12-13Bibliographically approved
  • 4.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    On High-Temperature Behaviours of Heat Resistant Austenitic Alloys2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Advanced heat resistant materials are important to achieve the transition to long term sustainable power generation. The global increase in energy consumption and the global warming from greenhouse gas emissions create the need for more sustainable power generation processes. Biomass-fired power plants with higher efficiency could generate more power but also reduce the emission of greenhouse gases, e.g. CO2. Biomass offers no net contribution of CO2 to the atmosphere. To obtain greater efficiency of power plants, one option is to increase the temperature and the pressure in the boiler section of the power plant. This requires improved material properties, such as higher yield strength, creep strength and high-temperature corrosion resistance, as well as structural integrity and safety.

    Today, some austenitic stainless steels are design to withstand temperatures up to 650 °C in tough environments. Nickel-based alloys are designed to withstand even higher temperatures. Austenitic stainless steels are more cost effective than nickel-based alloys due to a lower amount of expensive alloying elements. However, the performance of austenitic stainless steels at the elevated temperatures of future operation conditions in biomass-red power plants is not yet fully understood.

    This thesis presents research on the influence of long term high-temperature ageing on mechanical properties, the influence of very slow deformation rates at high-temperature on deformation, damage and fracture, and the influence of high-temperature environment and cyclic operation conditions on the material behaviour. Mechanical and thermal testing have been performed followed by subsequent studies of the microstructure, using scanning electron microscopy, to investigate the material behaviours.

    Results shows that long term ageing at high temperatures leads to the precipitation of intermetallic phases. These intermetallic phases are brittle at room temperature and become detrimental for the impact toughness of some of the austenitic stainless steels. During slow strain rate tensile deformation at elevated temperature time dependent deformation and recovery mechanisms are pronounced. The creep-fatigue interaction behaviour of an austenitic stainless steel show that dwell time gives shorter life at a lower strain range, but has none or small effect on the life at a higher strain range.

    Finally, this research results in an increased knowledge of the structural, mechanical and chemical behaviour as well as a deeper understanding of the deformation, damage and fracture mechanisms that occur in heat resistant austenitic alloys at high-temperature environments. It is believed that in the long term, this can contribute to material development achieving the transition to more sustainable power generation in biomass-red power plants.

    List of papers
    1. Long Term High-Temperature Environmental Effect on Impact Toughness in Austenitic Alloys
    Open this publication in new window or tab >>Long Term High-Temperature Environmental Effect on Impact Toughness in Austenitic Alloys
    2015 (English)In: / [ed] Key Engineering Materials Vol 627 (2015),pp 205-208., 2015, p. 205-308Conference paper, Published paper (Refereed)
    Series
    KEY ENGINEERING MATERIALS, ISSN 1662-9795 ; 627
    Keywords
    high-temperature environment, precipitation, impact toughness, austenitic stainless steel, nickel-base alloy
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-109512 (URN)10.4028/www.scientific.net/KEM.627.205 (DOI)
    Conference
    13th International Conference on Fracture and Damage Mechanics, Azorerna, 23-25 September 2014
    Available from: 2014-08-21 Created: 2014-08-21 Last updated: 2018-03-09
    2. Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing
    Open this publication in new window or tab >>Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing
    2014 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Biomass power plants with high efficiency are desired as a renewable energy resource. High efficiency can be obtained by increasing temperature and pressure. An upgrade of the material performance to high temperature material is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. In this study, the material’s high-temperature behaviours of AISI 304 and Alloy617 under slow deformation rate are evaluated using high-temperature long-term aged specimens subjected to slow strain rate tensile testing (SSRT) with strain rates down to 10-6/s at 700°C. Both materials show decreasing stress levels and elongation to fracture when tensile deformed using low strain rate and elevated temperature. At high-temperature and low strain rates cracking in grain boundaries due to larger precipitates formed during deformation is the most common fracture mechanism.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Series
    Key Engineering Materials, ISSN 1662-9795
    Keywords
    High-temperature, ageing, slow strain rate, biomass power plant, austenitic stainless steel, nickel base alloy and dynamic strain ageing
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-96028 (URN)10.4028/www.scientific.net/KEM.592-593.590 (DOI)000336694400133 ()
    Conference
    MSMF7 Materials Structure & Micromechanics of Fracture , July 13, Brno, Czech Republic
    Available from: 2013-08-13 Created: 2013-08-13 Last updated: 2015-11-30Bibliographically approved
    3. Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In-Situ Tensile Testing in SEM
    Open this publication in new window or tab >>Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In-Situ Tensile Testing in SEM
    Show others...
    2014 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    In this study an advanced method for investigation of the microstructure such as electron backscatter diffraction (EBSD) together with in-situ tensile test in a scanning electron microscope (SEM) has been used at room temperature and 300°C. EBSD analyses provide information about crystallographic orientation in the microstructure and dislocation structures caused by deformation. The in-situ tensile tests enabled the same area to be investigated at different strain levels. For the same macroscopic strain values a lower average misorientation in individual grains at elevated temperature indicates that less residual strain at grain level are developed compared to room temperature. For both temperatures, while large scatters in grain average misorientation are observed for grains of similar size, there seems to be a tendency showing that larger grains may accumulate somewhat more strains.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Series
    Key Engineering Materials, ISSN 1662-9795
    Keywords
    Austenitic stainless steel, electron backscatter diffraction, in-situ tensile test, Schmid factor, grain wsize and slip system
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-97015 (URN)10.4028/www.scientific.net/KEM.592-593.497 (DOI)000336694400111 ()
    Conference
    MSMF7 Materials Structure & Micromechanics of Fracture, July 1-3, Brno, Czech Republic
    Available from: 2013-09-03 Created: 2013-09-03 Last updated: 2015-11-30Bibliographically approved
    4. Mechanical Behaviours of Alloy 617 with Varied Strain Rate at High Temperatures
    Open this publication in new window or tab >>Mechanical Behaviours of Alloy 617 with Varied Strain Rate at High Temperatures
    2014 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 783-786, p. 1182-1187Article in journal (Refereed) Published
    Abstract [en]

    Nickel-base alloys due to their high performances have been widely used in biomass and coal fired power plants. They can undertake plastic deformation with different strain rates such as those typically seen during creep and fatigue at elevated temperatures. In this study, the mechanical behaviours of Alloy 617 with strain rates from 10-2/s down to 10-6/s at temperatures of 650°C and 700°C have been studied using tensile tests. Furthermore, the microstructures have been investigated using electron backscatter detection and electron channeling contrast imaging. At relatively high strain rate, the alloy shows higher fracture strains at these temperatures. The microstructure investigation shows that it is caused by twinning induced plasticity due to DSA. The fracture strain reaches the highest value at a strain rate of 10-4/s and then it decreases  dramatically. At strain rate of 10-6/s, the fracture strain at high temperature is now smaller than that at room temperature, and the strength also decreases with further decreasing strain rate. Dynamic recrystallization can also be observed usually combined with crack initiation and propagation. This is a new type of observation and the mechanisms involved are discussed.

    Keywords
    Nickel-base superalloy, twinning, Dynamic strain ageing, elevated temperature
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-98241 (URN)10.4028/www.scientific.net/MSF.783-786.1182 (DOI)
    Conference
    THERMEC '2013, International Conference on Processing & Manufacturing of Advanced Materials. Processing, Fabrication, Properties, Applications. December 2-6, Las Vegas, USA
    Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2017-12-06Bibliographically approved
    5. Deformation behaviour in advanced heat resistant materials during slow strain rate testing at elevated temperature
    Open this publication in new window or tab >>Deformation behaviour in advanced heat resistant materials during slow strain rate testing at elevated temperature
    2014 (English)In: Theoretical and Applied Mechanics Letters, ISSN 2095-0349, Vol. 4, no 041004Article in journal (Refereed) Published
    Abstract [en]

    In this study, slow strain rate tensile testing at elevated temperature is used to evaluate the influence of temperature and strain rate on deformation behaviour in two different austenitic alloys. One austenitic stainless steel (AISI 316L) and one nickel-base alloy (Alloy 617) have been investigated. Scanning electron microscopy related techniques as electron channelling contrast imaging and electron backscattering diffraction have been used to study the damage and fracture micromechanisms. For both alloys the dominante damage micromechanisms are slip bands and planar slip interacting with grain bounderies or precipitates causing strain concentrations. The dominante fracture micromechanism when using a slow strain rate at elevated temperature, is microcracks at grain bounderies due to grain boundery embrittlement caused by precipitates. The decrease in strain rate seems to have a small influence on dynamic strain ageing at 650°C.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2014
    Keywords
    dynamic strain ageing, slow strain rate tensile testing, fracture, damage
    National Category
    Materials Engineering Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-109511 (URN)10.1063/2.1404104 (DOI)
    Available from: 2014-08-21 Created: 2014-08-21 Last updated: 2017-12-05Bibliographically approved
    6. Characterization of austenitic stainless steels deformed at elevated temperature
    Open this publication in new window or tab >>Characterization of austenitic stainless steels deformed at elevated temperature
    Show others...
    2017 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 10, p. 4525-4538Article in journal (Refereed) Published
    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.

    Place, publisher, year, edition, pages
    Springer-Verlag New York, 2017
    Keywords
    Austenitic stainless steel, Nickel-based alloy, Microstructural characterization, Deformation twinning, Stress-strain response
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-122942 (URN)10.1007/s11661-017-4212-9 (DOI)000408884300012 ()
    Note

    Previous status of this publication was manuscript

    Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish National Energy Administration through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]; AFM Strategic Faculty Grant SFO-MAT-LiU at Linkoping University [2009-00971]

    Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2017-09-22Bibliographically approved
    7. Characterisation of creep deformation during slow strain rate tensile testing
    Open this publication in new window or tab >>Characterisation of creep deformation during slow strain rate tensile testing
    2015 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The strain-rate dependent deformation of the superalloy Haynes 282 during slow strain-rate tensile testing (SSRT) at 700 C has been investigated. The stress-strain response is remarkably well described by a simple constitutive model over a wide range of different strain-rates. The microstructure development is characterised and related to the influence of both strainrate dependent and independent deformation. Damage and cracking similar to what has been observed previously during conventional creep testing of Haynes 282 was found and explained. The model and the microstructure investigations show that the deformation and damage mechanisms during SSRT are essentially the same as under creep.

    Keywords
    Slow strain-rate tensile testing, Creep, Norton equation, Constitutive modelling, Cavity
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-122943 (URN)
    Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2015-11-30Bibliographically approved
    8. Creep and Fatigue Interaction Behavior in Sanicro 25 Heat Resistant Austenitic Stainless Steel
    Open this publication in new window or tab >>Creep and Fatigue Interaction Behavior in Sanicro 25 Heat Resistant Austenitic Stainless Steel
    2016 (English)In: Transactions of the Indian Institute of Metals, ISSN 0972-2815, E-ISSN 0975-1645, Vol. 69, no 2, p. 337-342Article in journal (Refereed) Published
    Abstract [en]

    Sanicro 25 is a newly developed advanced high strength heat resistant austenitic stainless steel. The material shows good resistance to steam oxidation and flue gas corrosion, and has higher creep rupture strength than other austenitic stainless steels available today. It is thus an excellent candidate for superheaters and reheaters for advanced ultra-super critical power plants with efficiency higher than 50 %. This paper provides a study on the creep–fatigue interaction behavior of Sanicro 25 at 700 °C. Two strain ranges, 1 and 2 %, and two dwell times, 10 and 30 min, were used. The influences of dwell time on the cyclic deformation behavior and life has been evaluated. Due to stress relaxation the dwell time causes a larger plastic strain range compared to the tests without dwell time. The results also show that the dwell time leads to a shorter fatigue life for the lower strain range, but has no or small effect on the life for the higher strain range. Fracture investigations show that dwell times result in more intergranular cracking. With the use of the electron channeling contrast imaging technique, the influences of dwell time on the cyclic plastic deformation, precipitation behavior, recovery phenomena and local plasticity exhaustion have also been studied.

    Place, publisher, year, edition, pages
    Springer, 2016
    Keywords
    Sanicro 25, advanced ultra-super critical power plant, creep, low cycle fatigue, cyclic plastic deformation
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-123646 (URN)10.1007/s12666-015-0806-3 (DOI)000368032700027 ()
    Conference
    7th International Conference on Creep, 19-22 January 2016, IGCAR, Kalpakkam, India
    Note

    At the time for thesis presentation publication was in status: Manuscript

    Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish National Energy Administration through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]; AFM Strategic Faculty Grant SFO-MAT-LiU at Linkoping University [2009-00971]

    Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2017-12-01
    9. Surface Phase Transformation in Austenitic Stainless Steel Induced by Cyclic Oxidation in Humidified Air
    Open this publication in new window or tab >>Surface Phase Transformation in Austenitic Stainless Steel Induced by Cyclic Oxidation in Humidified Air
    Show others...
    2015 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 100, p. 524-534Article in journal (Refereed) Published
    Abstract [en]

    The formation of α’ martensite at the surface of an AISI 304 stainless steel subjected to cyclic heating in humidified air is reported. The α’ martensite formed during the cooling part of the cyclic tests due to local depletion of Cr and Mn and transformed back to austenite when the temperature again rose to 650 °C. The size of the α’ martensite region increased with increasing number of cycles. Thermodynamical simulations were used as basis for discussing the formation of α’ martensite. The effect of the α’ martensite on corrosion is also discussed.

    Place, publisher, year, edition, pages
    Pergamon Press, 2015
    Keywords
    Stainless steel, thermal cycling, SEM, oxidation, high temperature corrosion
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-122008 (URN)10.1016/j.corsci.2015.08.030 (DOI)000363070100049 ()
    Note

    Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish National Energy Administration through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]; Agora Materiae and AFM Strategic Faculty Grant SFO-MAT-LiU at Linkoping Unive

    Available from: 2015-10-15 Created: 2015-10-15 Last updated: 2017-12-01
  • 5.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Temperaturpåverkan på egenskaperna hos högtemperaturtåliga austenitiska rostfria stål KME 7012018Report (Refereed)
    Abstract [sv]

    Den globala ökningen av energianvändning och sammanhängande ökning i CO2-utsläpp vid förbränning har skärpt kraven på energileverantörer att i större utsträckning använda hållbara biobränslen samt att höja verkningsgraden på energiomvandlingsprocesserna. Detta kan uppnås genom att höja tryck och temperatur i biomasseldade förbränningspannor. Sådana omställningar leder oftast till nya utmaningar kopplade till materialegenskaper.

    I framtiden kommer behovet av reglerkraft att öka för att kompensera för väderbaserade energianläggningar, såsom sol- och vindkraft. Detta leder till att anläggningarna måste stoppas och startas betydlig oftare än nu. Det skapar ett behov av provningsmetoder som tar hänsyn till cykliska mekaniska och temperaturbaserade laster. Tillsammans med att framtidens material måste tåla högre temperaturer och tuffare miljöer, relaterat till bränsleflexibiliteten, innebär detta att befintliga austenitiska rostfria stål måste förbättras. Inte bara genom en ökning av andelen nickel och andra verksamma legeringselement utan även genom att generera ny kunskap om hur de mekaniska egenskaperna påverkas av den tuffare högtemperatursmiljön.

    Syftet med detta projekt var att utvärdera mekaniska beteenden relaterade till kombinerad cyklisk och statisk belastning, långtidsåldring samt cyklisk mekanisk och temperaturbelastning vid höga temperaturer. Detta uppnåddes genom att:

    1. Utvärdera kryp-utmattningsinteraktion beteendet hos pannmaterial.
    2. Utvärdera den strukturella stabiliteten hos de austenitiska rostfria stålen efter långtidsåldring vid hög temperatur.
    3. Utvärdera termomekaniska utmattningsegenskaper hos pannmaterial.
    4. Utvärdera spänningsrelaxation sprickningsbeteenden hos pannmaterial.

    Mekanisk provning enligt ovan har utförts och analyserats vid Linköpings universitet samt Sandvik Materials Technology för att få en ökad förståelse för hur mekaniska egenskaper påverkas av den tuffare högtemperatursmiljön som framtidens biomasseldade pannor utgör. Detta kan användas i materialutveckling samt vidare för att förbättra konstruktionen av framtidens biomasseldade pannor.

    Resultaten visade att:

    1. De undersökta pannmaterialen uppvisar kryp-utmattningsinteraktion skador och längre cykliskt liv är relaterat till högt krypmotstånd.
    2. Austenitiska rostfria stål uppvisar försprödning på grund av intermetalliska utskiljningar efter långtidsåldring vid höga temperaturer.
    3. De austenitiska rostfria stålen med högst högtemperaturshållfasthet uppvisade bäst termomekaniska utmattningsegenskaper.
    4. Mer metodutveckling och undersökning krävs för att utvärdera spänningsrelaxation sprickningsbeteendet hos pannmaterialen.
  • 6.
    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.

  • 7.
    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.
    Johansson, Sten
    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.
    Creep and Fatigue Interaction Behavior in Sanicro 25 Heat Resistant Austenitic Stainless Steel2016In: Transactions of the Indian Institute of Metals, ISSN 0972-2815, E-ISSN 0975-1645, Vol. 69, no 2, p. 337-342Article in journal (Refereed)
    Abstract [en]

    Sanicro 25 is a newly developed advanced high strength heat resistant austenitic stainless steel. The material shows good resistance to steam oxidation and flue gas corrosion, and has higher creep rupture strength than other austenitic stainless steels available today. It is thus an excellent candidate for superheaters and reheaters for advanced ultra-super critical power plants with efficiency higher than 50 %. This paper provides a study on the creep–fatigue interaction behavior of Sanicro 25 at 700 °C. Two strain ranges, 1 and 2 %, and two dwell times, 10 and 30 min, were used. The influences of dwell time on the cyclic deformation behavior and life has been evaluated. Due to stress relaxation the dwell time causes a larger plastic strain range compared to the tests without dwell time. The results also show that the dwell time leads to a shorter fatigue life for the lower strain range, but has no or small effect on the life for the higher strain range. Fracture investigations show that dwell times result in more intergranular cracking. With the use of the electron channeling contrast imaging technique, the influences of dwell time on the cyclic plastic deformation, precipitation behavior, recovery phenomena and local plasticity exhaustion have also been studied.

  • 8.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    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.
    Damage and Fracture Behaviours in Advanced Heat Resistant Materials During Slow Strain Rate Test at High Temperature2013Conference paper (Other academic)
    Abstract [en]

    As a renewable energy resource, biomass or biomass co-firing in coal-fired power plants with high efficiency are desired which corresponding to elevated temperature and high pressure. An upgrade of the material performance to austenitic stainless steels is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. These materials suffer from creep and fatigue damage during the service. In this study, these behaviours are evaluated using slow strain rate testing (SSRT) with strain rate down to 1*10-6/s at temperature up to 700°C. The influence of temperature and strain rate on strength and ductility in one austenitic stainless steel and one nickel base alloys are investigated. The damage and fracture due to the interaction between moving dislocations and precipitates are studied using electron channelling contrast imaging (ECCI) and electron backscattering diffraction (EBSD). The deformation and damage mechanisms active during SSRT are essentially the same as under creep. The influence of dynamic strain ageing (DSA) phenomena that appears in the tested temperature and strain rate regime is also discussed, DSA is intensified by increased temperature and decreased strain rate.

  • 9.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    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.
    Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing2014Conference paper (Refereed)
    Abstract [en]

    Biomass power plants with high efficiency are desired as a renewable energy resource. High efficiency can be obtained by increasing temperature and pressure. An upgrade of the material performance to high temperature material is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. In this study, the material’s high-temperature behaviours of AISI 304 and Alloy617 under slow deformation rate are evaluated using high-temperature long-term aged specimens subjected to slow strain rate tensile testing (SSRT) with strain rates down to 10-6/s at 700°C. Both materials show decreasing stress levels and elongation to fracture when tensile deformed using low strain rate and elevated temperature. At high-temperature and low strain rates cracking in grain boundaries due to larger precipitates formed during deformation is the most common fracture mechanism.

  • 10.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    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.
    Deformation and damage behaviours of austenitic alloys in the dynamic strain ageing regimeManuscript (preprint) (Other academic)
    Abstract [en]

    Deformation and damage behaviours influenced by dynamic strain ageing (DSA) in three austenitic stainless steels and two nickel-base alloys have been investigated using tensile tests at elevated temperatures. The deformation and damage behaviours have been analysed using electron channeling contrast imaging and electron backscatter diffraction. The results from this study show that DSA not always reduce ductility, in fact for some materials the ductility can increase in the DSA regime. This is attributed to the formation of nano twins by DSA stimulated twinning induced plasticity. Damage mechanisms due to DSA were also investigated and discussed.

  • 11.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    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.
    Deformation behaviour in advanced heat resistant materials during slow strain rate testing at elevated temperature2014In: Theoretical and Applied Mechanics Letters, ISSN 2095-0349, Vol. 4, no 041004Article in journal (Refereed)
    Abstract [en]

    In this study, slow strain rate tensile testing at elevated temperature is used to evaluate the influence of temperature and strain rate on deformation behaviour in two different austenitic alloys. One austenitic stainless steel (AISI 316L) and one nickel-base alloy (Alloy 617) have been investigated. Scanning electron microscopy related techniques as electron channelling contrast imaging and electron backscattering diffraction have been used to study the damage and fracture micromechanisms. For both alloys the dominante damage micromechanisms are slip bands and planar slip interacting with grain bounderies or precipitates causing strain concentrations. The dominante fracture micromechanism when using a slow strain rate at elevated temperature, is microcracks at grain bounderies due to grain boundery embrittlement caused by precipitates. The decrease in strain rate seems to have a small influence on dynamic strain ageing at 650°C.

  • 12.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    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.
    Influence of deformation rate on mechanical response of an AISI 316L austenitic stainless steel2014In: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 922, p. 49-54Article in journal (Refereed)
    Abstract [en]

    Austenitic stainless steels are often used for components in demanding environment. These materials can withstand elevated temperatures and corrosive atmosphere like in energy producing power plants. They can be plastically deformed at slow strain rates and high alternating or constant tensile loads such as fatigue and creep at elevated temperatures. This study investigates how deformation rates influence mechanical properties of an austenitic stainless steel. The investigation includes tensile testing using strain rates of 2*10-3/ and 10-6/s at elevated temperatures up to 700°C. The material used in this study is AISI 316L. When the temperature is increasing the strength decreases. At a slow strain rate and elevated temperature the stress level decreases gradually with increasing plastic deformation probably due to dynamic recovery and dynamic recrystallization. However, with increasing strain rate elongation to failure is decreasing. AISI 316L show larger elongation to failure when using a strain rate of 10-6/s compared with 2*10-3/s at each temperature. Electron channelling contrast imaging is used to characterize the microstructure and discuss features in the microstructure related to changes in mechanical properties. Dynamic recrystallization has been observed and is related to damage and cavity initiation and propagation.

  • 13.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    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.
    Influence of Dynamic Strain Ageing on Damage in Austenitic Stainless Steels2012Conference paper (Other academic)
  • 14.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, sweden.
    Johansson, Sten
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Influence of High Temperature Ageing on the Toughness of Advanced Heat Resistant Materials2013Conference paper (Refereed)
    Abstract [en]

    Advanced biomass, biomass co-firing in coal-fired and future advanced USC coal-fired power plants with high efficiency require the materials to be used at even higher temperature under higher pressure. The reliability and integrity of the material used are therefore of concern. In this study, the influence of ageing at temperatures up to 700°C for up to 3 000 hours on the toughness of two advanced heat resistant austenitic steels and one nickel alloy are investigated. The influence on toughness due to differences in the chemical composition as well as the combined effect of precipitation and growth of the precipitates has been analysed by using SEM techniques. The fracture mechanisms that are active for the different ageing treatments are identified as a function of temperature and time. Local approach methods are used to discuss the influence of the precipitation and growth of precipitates on the toughness or fracture in  the different aged materials.

  • 15.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    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.
    Long Term High-Temperature Environmental Effect on Impact Toughness in Austenitic Alloys2015In: / [ed] Key Engineering Materials Vol 627 (2015),pp 205-208., 2015, p. 205-308Conference paper (Refereed)
  • 16.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Strategy research, SE-81181 Sandviken, Sweden.
    Johansson, Sten
    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.
    Mechanical behaviors of alloy 617 with varied strain rates at high temperatures2014In: THERMEC 2013, Trans Tech Publications Ltd , 2014, Vol. 783-786, p. 1182-1187Conference paper (Refereed)
    Abstract [en]

    Nickel base alloys due to their high performances have been widely used in biomass and coal fired power plants. They can undertake plastic deformation with different strain rates such as those typically seen during creep and fatigue at elevated temperatures. In this study, the mechanical behaviors of Alloy 617 with strain rates from 10-2/s down to 10-6/s at temperatures of 650C and 700C have been studied using tensile tests. Furthermore, the microstructures have been investigated using electron backscatter detection and electron channeling contrast imaging. At relatively high strain rate, the alloy shows higher fracture strains at these temperatures. The microstructure investigation shows that it is caused by twinning induced plasticity due to DSA. The fracture strain reaches the highest value at a strain rate of 10-4/s and then it decreases dramatically. At strain rate of 10-6/s, the fracture strain at high temperature is now smaller than that at room temperature, and the strength also decreases with further decreasing strain rate. Dynamic recrystallization can also be observed usually combined with crack initiation and propagation. This is a new type of observation and the mechanisms involved are discussed. © (2014) Trans Tech Publications, Switzerland.

  • 17.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    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.
    Mechanical Behaviours of Alloy 617 with Varied Strain Rate at High Temperatures2014In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 783-786, p. 1182-1187Article in journal (Refereed)
    Abstract [en]

    Nickel-base alloys due to their high performances have been widely used in biomass and coal fired power plants. They can undertake plastic deformation with different strain rates such as those typically seen during creep and fatigue at elevated temperatures. In this study, the mechanical behaviours of Alloy 617 with strain rates from 10-2/s down to 10-6/s at temperatures of 650°C and 700°C have been studied using tensile tests. Furthermore, the microstructures have been investigated using electron backscatter detection and electron channeling contrast imaging. At relatively high strain rate, the alloy shows higher fracture strains at these temperatures. The microstructure investigation shows that it is caused by twinning induced plasticity due to DSA. The fracture strain reaches the highest value at a strain rate of 10-4/s and then it decreases  dramatically. At strain rate of 10-6/s, the fracture strain at high temperature is now smaller than that at room temperature, and the strength also decreases with further decreasing strain rate. Dynamic recrystallization can also be observed usually combined with crack initiation and propagation. This is a new type of observation and the mechanisms involved are discussed.

  • 18.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Siemens Industrial Turbomachinery AB, Berlin.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Högberg, Jan
    AB Sandvik Materials Technology R&D Center Sandviken.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Local Surface Phase Stability During Cyclic Oxidation Process2017In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 879, p. 855-860Article in journal (Refereed)
  • 19.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. 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
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Influence of Cyclic Oxidation in Moist Air on Surface Oxidation-Affected Zones2017Conference paper (Refereed)
  • 20.
    Calmunger, Mattias
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Management and Engineering, Engineering Materials.
    Eriksson, Robert
    Siemens AG, Huttenstr. 12, 10553 Berlin, Germany.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandviken, Sweden.
    Johansson, Sten
    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.
    Surface Phase Transformation in Austenitic Stainless Steel Induced by Cyclic Oxidation in Humidified Air2015In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 100, p. 524-534Article in journal (Refereed)
    Abstract [en]

    The formation of α’ martensite at the surface of an AISI 304 stainless steel subjected to cyclic heating in humidified air is reported. The α’ martensite formed during the cooling part of the cyclic tests due to local depletion of Cr and Mn and transformed back to austenite when the temperature again rose to 650 °C. The size of the α’ martensite region increased with increasing number of cycles. Thermodynamical simulations were used as basis for discussing the formation of α’ martensite. The effect of the α’ martensite on corrosion is also discussed.

  • 21.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Arts and Sciences. Linköping University, Faculty of Science & Engineering.
    Lindström, Thomas
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Leidermark, Daniel
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Effect of Additive Manufacturing on Fatigue Crack Propagation of a Gas Turbine Superalloy2019In: Structural Integrity Procedia, Elsevier, 2019Conference paper (Refereed)
  • 22.
    Calmunger, Mattias
    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.
    Evaluation of Creep Properties Using Slow Strain Rate Tensile Testing2015Conference paper (Other academic)
  • 23.
    Calmunger, Mattias
    et al.
    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.
    Johansson, Sten
    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.
    Characterisation of creep deformation during slow strain rate tensile testing2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The strain-rate dependent deformation of the superalloy Haynes 282 during slow strain-rate tensile testing (SSRT) at 700 C has been investigated. The stress-strain response is remarkably well described by a simple constitutive model over a wide range of different strain-rates. The microstructure development is characterised and related to the influence of both strainrate dependent and independent deformation. Damage and cracking similar to what has been observed previously during conventional creep testing of Haynes 282 was found and explained. The model and the microstructure investigations show that the deformation and damage mechanisms during SSRT are essentially the same as under creep.

  • 24.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    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.
    Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In-Situ Tensile Testing in SEM2014Conference paper (Refereed)
    Abstract [en]

    In this study an advanced method for investigation of the microstructure such as electron backscatter diffraction (EBSD) together with in-situ tensile test in a scanning electron microscope (SEM) has been used at room temperature and 300°C. EBSD analyses provide information about crystallographic orientation in the microstructure and dislocation structures caused by deformation. The in-situ tensile tests enabled the same area to be investigated at different strain levels. For the same macroscopic strain values a lower average misorientation in individual grains at elevated temperature indicates that less residual strain at grain level are developed compared to room temperature. For both temperatures, while large scatters in grain average misorientation are observed for grains of similar size, there seems to be a tendency showing that larger grains may accumulate somewhat more strains.

  • 25.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Segersäll, Mikael
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Using the Student Diversity as a Strength in a Material Selection Course2014Conference paper (Other (popular science, discussion, etc.))
  • 26.
    Chai, Guocai
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. 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
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Toughening Behavior in Alloy 617 with Long Term Ageing2017In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 258, p. 302-305Article in journal (Refereed)
  • 27.
    Chai, Guocai
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandvik Materials Technology, Strategy research, Sandviken, Sweden.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. 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
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Odqvist, Joakim
    Sandvik Materials Technology, Strategy research, Sandviken, Sweden.
    Influence of Dynamic Strain Ageing and Long Term Ageing on Deformation and Fracture Behaviors of Alloy 6172016In: THERMEC 2016 / [ed] C. Sommitsch, M. Ionescu, B. Mishra, E. Kozeschnik and T. Chandra, Trans Tech Publications, 2016, Vol. 879, p. 306-311Conference paper (Refereed)
    Abstract [en]

    Influences of dynamic strain ageing and long term ageing on deformation, damage and fracture behaviors of Alloy 617 material have been studied. Dynamic strain ageing can occur in this alloy at temperature from 400 to 700°C, which leads to a strain hardening and also an increase in fracture strain due to plastic deformation caused by twinning. Long term ageing at 700°C for up to 20 000 hours can cause different precipitation such as γ ́, M6C (Mo-rich) and M23C6 (Cr-rich) carbides. These carbides are both inter-and intra-granular particles. The long term ageing reduces the fracture toughness of the material, but the alloy can still have rather high impact toughness and fracture toughness even with an ageing at 700°C for 20 000 hour. The mechanisms have been studied using electron backscatter detection and electron channeling contrast imaging. It shows that besides dislocation slip, twinning is another main deformation mechanism in these aged Alloy 617 materials. At the crack front, plenty of micro or nanotwins can be observed. The formation of these twins leads to a high ductility and toughness which is a new observation or a new concept for this type of material.

  • 28.
    Kahl, Sören
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Gränges Technology, Gränges AB, Finspång, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Olsson, Björn
    Sapa Technology, Sapa AB, Finspång, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    In Situ EBSD During Tensile Test of Aluminum AA3003 Sheet2014In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, ISSN 0968-4328, Vol. 58, p. 15-24Article in journal (Refereed)
    Abstract [en]

    Miniature tensile-test specimens of soft-annealed, weakly textured AA3003 aluminum sheet in 0.9 mm thickness were deformed until fracture inside a scanning electron microscope. Tensile strength measured by the miniature tensile test stage agreed well with the tensile strength by regular tensile testing. Strain over the microscope field of view was determined from changes in positions of constituent particles. Slip lines were visible in secondary electron images already at 0.3% strain; activity from secondary slip systems became apparent at 2% strain. Orientation rotation behavior of the tensile load axis with respect to the crystallographic axes agreed well with previously reported trends for other aluminum alloys. Start of the fracture and tensile crack propagation were documented in secondary electron images. The region of fracture nucleation included and was surrounded by many grains that possessed high Schmid factors at zero strain. Crystal lattice rotation angles in the grains surrounding the initial fracture zone were higher than average while rotations inside the initial fracture zone were lower than average for strains from zero to 31%. The orientation rotation behavior of the tensile load axes of the grains around the fracture zone deviated from the average behavior in this material.

  • 29.
    Lundberg, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    In-situ SEM/EBSD Study of Deformation adn Fracture Behaviour of Flake Cast Iron2013Conference paper (Refereed)
    Abstract [en]

    Cast irons’ position as an important engineering material is un-disputed. They are widely used in many important industrial applications such as the automotives and workshop machinery. Nevertheless, fracture mechanisms in cast irons are not fully understood. In this study the fracture path and non-linear elastic behaviour of a fully pearlitic flake cast iron under uniaxial tensile loading have been investigated in a Scanning Electron Microscope (SEM) equipped with an Electron Backscattering Diffraction (EBSD) detector. The tensile load was applied via a specially made sample stage. Under uniaxial tensile loading the graphite flakes act as notches or cracks and therefore the fracture process starts at one or many graphite tips. The crack can propagate in many different ways, at the graphite and matrix interface, through the graphite, at the interface between cementite and ferrite or through the pearlitic grains. At the point where the stress strain curve deviates from its linear path plastic deformation at graphite tips can be noticed. Interface cracking between graphite and the matrix also starts at this point.

  • 30.
    Lundberg, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Saarimäki, Jonas
    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.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Surface Integrity and Fatigue Behaviour of Electric Discharged Machined and Milled Austenitic Stainless Steel2017In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 124, p. 215-222Article in journal (Refereed)
    Abstract [en]

    Machining of austenitic stainless steels can result in different surface integrities and different machining process parameters will have a great impact on the component fatigue life. Understanding how machining processes affect the cyclic behaviour and microstructure are of outmost importance in order to improve existing and new life estimation models. Milling and electrical discharge machining (EDM) have been used to manufacture rectangular four-point bend fatigue test samples; subjected to high cycle fatigue. Before fatigue testing, surface integrity characterisation of the two surface conditions was conducted using scanning electron microscopy, surface roughness, residual stress profiles, and hardness profiles. Differences in cyclic behaviour were observed between the two surface conditions by the fatigue testing. The milled samples exhibited a fatigue limit. EDM samples did not show the same behaviour due to ratcheting. Recrystallized nano sized grains were identified at the severely plastically deformed surface of the milled samples. Large amounts of bent mechanical twins were observed ~ 5 μm below the surface. Grain shearing and subsequent grain rotation from milling bent the mechanical twins. EDM samples showed much less plastic deformation at the surface. Surface tensile residual stresses of ~ 500 MPa and ~ 200 MPa for the milled and EDM samples respectively were measured.

  • 31.
    Nordström, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Siriki, Raveendra
    Calmunger, Mattias
    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.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    TWIP and Fracture Behaviour in the Superalloy 625 at Room and Cryogenic Temperatures2019In: Structural Integrity Procedia / [ed] Elsevier, Elsevier, 2019Conference paper (Refereed)
  • 32.
    Norman, Viktor
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    On the micro- and macroscopic elastoplastic deformation behaviour of cast iron when subjected to cyclic loading2019In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 115, p. 200-215Article in journal (Refereed)
    Abstract [en]

    The complicated constitutive behaviour of cast iron, involving a non-linear elastic regime, tension-compression stress asymmetry, varying elastic modulus and an inflection in the tension-to-compression hardening curve, is investigated using a micromechanical modelling approach. In this way, it is demonstrated that the abnormalities observed in the constitutive behaviour are qualitatively and quantitatively explained by the interaction behaviour between the matrix and graphite constituents. In initial tension, the absence of linearity is rationalised by the successive loss in load-carrying capacity of the graphite phase due to debonding, which in subsequent cycling, results in the opening and re-contact of the matrix-graphite interface. This effect is demonstrated to result in tension-compression asymmetry in stress and elastic modulus, as well as the inflection in tension-to-compression loading. The given model of explanation is validated by comparison to the experimentally acquired microscopic strain field in EN-GJV-400 at locations where stress concentrations are generated due to the matrix-graphite debonding, using high-resolution digital image correlation of scanning electron images.

  • 33.
    Segersäll, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Norman, Viktor
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Fredriksson, Claes
    Student Reactions to CES EduPack in an Undergraduate Materials Selection Course2015Conference paper (Refereed)
  • 34.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    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.
    Johansson, Sten
    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.
    Thermomechanical Fatigue Behavior of Aged Heat Resistant Austenitic Alloys2017Conference paper (Refereed)
  • 35.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    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.
    Johansson, Sten
    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.
    Thermomechanical Fatigue Behaviour of Aged Heat Resistant Austenitic Alloys2019In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, no 127, p. 509-521Article in journal (Refereed)
    Abstract [en]

    The increasing demands for efficiency and flexibility result in more severe operating conditions for the materials used in critical components of biomass power plants. These operating conditions involve higher temperature ranges, more pronounced environmental effects and cyclic operations. Austenitic stainless steels have shown to possess promising high temperature properties which makes them suitable as candidates for critical components in biomass power plant. However, their behaviour under such conditions is not yet fully understood. This work investigates three commercial austenitic alloys: Esshete 1250, Sanicro 25 and Sanicro 31HT. The alloys were subjected to in-phase (IP) thermomechanical fatigue (TMF) testing under strain-control in the temperature range of 100–800 °C. Both virgin and pre-aged TMF specimens were tested in order to simulate service degradation resulting from long-term usage. The results show that the pre-aged specimens suffered shorter TMF-life compared to the virgin specimens. The scanning electron microscopy methods electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) were used to analyse and discuss active failure and deformation mechanisms. The difference in TMF-life produced by the two testing conditions was attributed to an embrittling effect by precipitation, reduced creep properties and oxidation assisted cracking.

    The full text will be freely available from 2021-06-18 08:00
  • 36.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    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.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Creep-Fatigue Interaction in Heat Resistant Austenitic Alloys2018In: MATEC Web of Conferences 165 , 05001 (2018) / [ed] EDP Sciences, EDP Sciences, 2018, Vol. 165Conference paper (Refereed)
  • 37.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    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. AB Sandvik Mat Technol, Sweden.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Creep-fatigue interaction in heat resistant austenitic alloys2018In: 12TH INTERNATIONAL FATIGUE CONGRESS (FATIGUE 2018), E D P SCIENCES , 2018, Vol. 165, article id 05001Conference paper (Refereed)
    Abstract [en]

    This work includes an investigation of two commercial austenitic steels: UNS S21500 (Esshete 1250) and UNS S31035 (Sandvik Sanicro (TM) 25). The materials were exposed to isothermal strain controlled fatigue with load controlled dwell time at maximum strain. The testing temperature used was 700 degrees C and the test cycles were performed in tension. Mechanical test data were obtained and analysed in order to define creep-fatigue damage diagrams at failure for the investigated austenitic alloys. During the given conditions, Sanicro 25 showed superior creep-fatigue life, suffered less amount of creep elongation for the same amount of strain amplitude and dwell times compared to Esshete 1250. Both alloys showed creep-fatigue interaction damage for specific test configurations.

  • 38.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    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 Mat Technol, Sweden.
    Polak, Jaroslav
    Acad Sci Czech Republ, Czech Republic.
    Petras, Roman
    Acad Sci Czech Republ, Czech Republic.
    Heczko, Milan
    Acad Sci Czech Republ, Czech Republic.
    Kruml, Tomas
    Acad Sci Czech Republ, Czech Republic.
    Johansson, Sten
    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.
    Fracture and Damage Behavior in an Advanced Heat Resistant Austenitic Stainless Steel During LCF, TMF and CF2018In: ECF22 - LOADING AND ENVIRONMENTAL EFFECTS ON STRUCTURAL INTEGRITY, ELSEVIER SCIENCE BV , 2018, Vol. 13, p. 843-848Conference paper (Refereed)
    Abstract [en]

    Future advanced ultra-supercritical power plant will be run at higher temperature and pressure. New materials will be used to meet the requirements. However, the structure integrity of these materials needs to be evaluated. Sanicro 25 is a newly developed advanced austenitic heat resistant stainless steel with the aim to be used in future 700 degrees C or 650 degrees C power plants to replace part of Ni based alloys. This paper provides an overview on the fracture and damage behavior in this material during LCF, TMF and CF. The cyclic hardening and fatigue life during LCF, TMF and CF will be discussed. The influence of prolonged service degradation has been analyzed by the use of pre-aged material for TMF and CF loading conditions. (C) 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers.

  • 39.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Arts and Sciences. Linköping University, Faculty of Science & Engineering.
    Chai, Guocai
    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.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Influence of Ageing on Thermomechaical Fatigue of Austenitic Stainless Steels2019In: Structural Integrity Procedia / [ed] Elsevier, Elsevier, 2019Conference paper (Refereed)
1 - 39 of 39
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