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Romanov, P., Jahedi, M., Petersson, A., Moshfegh, B. & Calmunger, M. (2023). Quenching of Carbon Steel Plates with Water Impinging Jets: Differential Properties and Fractography. Procedia Structural Integrity, 43, 154-159
Open this publication in new window or tab >>Quenching of Carbon Steel Plates with Water Impinging Jets: Differential Properties and Fractography
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2023 (English)In: Procedia Structural Integrity, ISSN 2452-3216, Vol. 43, p. 154-159Article in journal (Refereed) Published
Abstract [en]

The demand for steel components with tailored properties is constantly growing. To obtain a specific variation of microstructures and mechanical properties along the component it must undergo a controllable cooling. One way to control the cooling rates along the component is by using different simultaneous water jet impingements on a hot austenitized surface. This can be done by a newly developed test rig for water Impinging Jet Quenching Technique (IJQT). This work discusses the effect of IJQT on mechanical properties and fracture behavior of 15 mm steel plates containing 0.27 and 0.38 mass-% carbon. The samples were cooled in a specifically designed setup of the technique to obtain simultaneous water and air cooling resulting in diverse microstructures. The mechanical property gradients of both steels were analyzed through hardness measurements and tensile tests. The fracture surfaces and the near fracture regions were observed using scanning electron microscope and light optical microscope respectively. The results from tensile tests showed that the larger part of the sample with higher carbon content was fully hardened, however smoothly transitioning to a more ductile region. The sample with lower carbon content combined various degrees of hardening and transitioned from higher to lower ultimate tensile strength values. Fracture behavior of higher carbon steel was predominantly brittle transitioning to a ductile, while the lower carbon steel had a small region showing brittle fracture transitioning to a larger region of predominant ductile fracture behavior.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Martensite, Brittle fracture, Ductile fracture, Impinging Jet Quenching, Boron steel
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:liu:diva-191833 (URN)10.1016/j.prostr.2022.12.251 (DOI)
Available from: 2023-02-20 Created: 2023-02-20 Last updated: 2023-02-20
Calmunger, M., Wärner, H., Chai, G. & Segersäll, M. (2023). Thermomechanical Fatigue of Heat Resistant Austenitic Alloys. Procedia Structural Integrity, 43, 130-135
Open this publication in new window or tab >>Thermomechanical Fatigue of Heat Resistant Austenitic Alloys
2023 (English)In: Procedia Structural Integrity, ISSN 2452-3216, Vol. 43, p. 130-135Article in journal (Refereed) Published
Abstract [en]

Rising global energy consumption and the increase in emissions of greenhouse gases (e.g. CO2) causing global warming, make need for more sustainable power generation. This could be accomplished by increasing the efficiency of the biomass-fired power plants, which is achieved by increasing the temperature and pressure. In addition, flexible generation of power is critical if only renewable power generation is to be achieved and this will increase the number of start-and stop cycles. Cyclic condition in a long-term high temperature environment is an operation process that such materials must withstand, in order to satisfy the needs for future power generation.

Commonly austenitic stainless steel are used for critical components of power plants. Because of future change in operating conditions, further investigations are needed to verify that the demands on safety for cyclic long-term usage is fulfilled. This work includes investigation of two commercial austenitic steels: Esshete 1250 and Sanicro 25. The materials were exposed to thermomechanical fatigue (TMF) in strain control under In-Phase and Out-of-Phase conditions and main testing temperature ranges of 100-650°C and 100-800°C respectively. Some of the specimens were pre-aged to simulate prolonged service condition. Mechanical test data were obtained and analysed in order to define the TMF performance of the investigated alloys. The differences in performance were discussed in relation to mechanical and microstructural characterization.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:liu:diva-200462 (URN)10.1016/j.prostr.2022.12.247 (DOI)2-s2.0-85159831221 (Scopus ID)
Available from: 2024-01-27 Created: 2024-01-27 Last updated: 2024-02-01Bibliographically approved
Wärner, H., Chai, G., Moverare, J. & Calmunger, M. (2022). High Temperature Fatigue of Aged Heavy Section Austenitic Stainless Steels. Materials, 15(1), Article ID 84.
Open this publication in new window or tab >>High Temperature Fatigue of Aged Heavy Section Austenitic Stainless Steels
2022 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 1, article id 84Article in journal (Refereed) Published
Abstract [en]

This work investigates two austenitic stainless steels, Sanicro 25 which is a candidate for high temperature heavy section components of future power plants and Esshete 1250 which is used as a reference material. The alloys were subjected to out-of-phase (OP) thermomechanical fatigue (TMF) testing under strain-control in the temperature range of 100 ∘C to 650 ∘C. Both unaged and aged (650 ∘C, 3000 h) TMF specimens were tested to simulate service degradation resulting from long-term usage. 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 Sanicro 25 results show that the aged specimens suffered increased plastic straining and shorter TMF-life compared to the unaged specimens. The difference in TMF-life of the two test conditions was attributed to an accelerated microstructural evolution that provided decreased the effectiveness for impeding dislocation motion. Ageing did not affect the OP-TMF life of the reference material, Esshete 1250. However, the structural stability and its resistance for cyclic deformation was greatly reduced due to coarsening and cracking of the strengthening niobium carbide precipitates. Sanicro 25 showed the higher structural stability during OP-TMF testing compare with the reference material.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2022
Keywords
high temperature austenitic stainless steels, out-of-phase thermomechanical fatigue, crack propagation analysis, electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDS)
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-182258 (URN)10.3390/ma15010084 (DOI)000751248900001 ()35009228 (PubMedID)2-s2.0-85121749412 (Scopus ID)
Note

Funding: AB Sandvik Materials Technology in Sweden; Swedish Energy Agency through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-801]

Available from: 2022-01-11 Created: 2022-01-11 Last updated: 2022-02-18Bibliographically approved
Norman, V. & Calmunger, M. (2021). An Accelerated Creep Assessment Method Based on Inelastic Strain Partitioning and Slow Strain Rate Testing. Materials & design, 205, Article ID 109697.
Open this publication in new window or tab >>An Accelerated Creep Assessment Method Based on Inelastic Strain Partitioning and Slow Strain Rate Testing
2021 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Materials & Design, Vol. 205, article id 109697Article in journal (Refereed) Published
Abstract [en]

A new accelerated creep assessment method to evaluate the creep performance of metals and alloys from high-temperature tensile tests, i.e. slow-strain-rate testing (SSRT), is proposed and evaluated. The method consists of decomposing the inelastic strain into a plastic and creep component by adopting general assumptions on the inelastic strain behaviour of materials, formulated using a state variable formalism and verified by tensile tests with intermediate dwell times at constant stress. Either, the plastic and creep strain components are considered non-interacting and additive, as observed in the stainless steel AISI 316L at 600 °C. Or, as in the case of the ductile cast iron EN-GJS-SiMo5-1 at 500 °C and the nickel-base superalloy Hastelloy X at 800 °C, the components are considered unified, meaning that the effect of inelastic straining is the same irrespective of whether it is caused through creep at constant stress or by plastic deformation due to an instantaneous stress increase. Based on these assumptions, the proposed method is used to assess the creep strain from SSRT in good agreement with conventional creep test results.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Creep, Slow-strain-rate testing, Stress relaxation, Constitutive behaviour, Metallic material
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-175764 (URN)10.1016/j.matdes.2021.109697 (DOI)000663557800008 ()2-s2.0-85104641343 (Scopus ID)
Note

Funding: Swedish Governmental Agency for Innovation SystemsVinnova [2018-04302]; Sandvik Materials Technology

Available from: 2021-05-19 Created: 2021-05-19 Last updated: 2021-07-05Bibliographically approved
Wärner, H., Xu, J., Chai, G., Moverare, J. & Calmunger, M. (2021). Microstructural Evolution During High Temperature Dwell-fatigue of Austenitic Stainless Steels. International Journal of Fatigue, 143, Article ID 105990.
Open this publication in new window or tab >>Microstructural Evolution During High Temperature Dwell-fatigue of Austenitic Stainless Steels
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2021 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 143, article id 105990Article in journal (Refereed) Published
Abstract [en]

Microstructural evolution related to the mechanical response from isothermal dwell-fatigue testing at 700 °C of two austenitic steels, Esshete 1250 and Sanicro 25, is reported. Coherent Cu-precipitates and incoherent Nb-carbides were found to impede dislocation motion, increase hardening and improving the high temperature properties of Sanicro 25. Sparsely placed intergranular Cr- and Nb-carbides made Esshete 1250 susceptible to creep damage and intergranular crack propagation, mainly from interaction of the carbides and fatigue induced slip bands. Dynamic recrystallization of the plastic zone at the crack tip appeared to affect crack propagation of Sanicro 25 by providing an energetically privileged path.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
creep-fatiuge interaction, high temperature austenitic alloys, high-resolution microscopy, dynamic recrystallization of crack tip plastic zone
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-171872 (URN)10.1016/j.ijfatigue.2020.105990 (DOI)000597143700003 ()2-s2.0-85095446912 (Scopus ID)
Note

Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish Energy Agency through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]

Available from: 2020-12-10 Created: 2020-12-10 Last updated: 2021-05-21Bibliographically approved
Romanov, P., Jahedi, M., Moshfegh, B. & Calmunger, M. (2021). Water Impinging Jet Quenching of Boron Steels by Different Simultaneous Cooling Rates. In: : . Paper presented at EUROMAT 2021, Virtual, 13-17 September 2021.
Open this publication in new window or tab >>Water Impinging Jet Quenching of Boron Steels by Different Simultaneous Cooling Rates
2021 (English)Conference paper, Poster (with or without abstract) (Refereed)
Keywords
impinging jet cooling, boron steel, martensite-bainite
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-182969 (URN)
Conference
EUROMAT 2021, Virtual, 13-17 September 2021
Available from: 2022-02-15 Created: 2022-02-15 Last updated: 2022-03-18
Yu, C.-H., Peng, R. L., Calmunger, M., Luzin, V., Brodin, H. & Moverare, J. (2020). Anisotropic Deformation and Fracture Mechanisms of an Additively Manufactured Ni-Based Superalloy. In: Tin, Sammy; Hardy, Mark; Clews, Justin; Cormier, Jonathan; Feng, Qiang; Marcin, John; O'Brien, Chris; Suzuki, Akane (Ed.), Superalloys 2020: . Paper presented at Cham (pp. 1003-1013). Springer International Publishing
Open this publication in new window or tab >>Anisotropic Deformation and Fracture Mechanisms of an Additively Manufactured Ni-Based Superalloy
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2020 (English)In: Superalloys 2020 / [ed] Tin, Sammy; Hardy, Mark; Clews, Justin; Cormier, Jonathan; Feng, Qiang; Marcin, John; O'Brien, Chris; Suzuki, Akane, Springer International Publishing , 2020, p. 1003-1013Conference paper, Published paper (Refereed)
Abstract [en]

This study investigates the anisotropic mechanical and microstructural behavior of the laser powder bed fusionLaser powder bed fusion (LPBF) manufactured Ni-based superalloy Hastelloy X (HX) by using slow strain rate (10−5 and 10−6s−1) tensile testing (SSRT) at 700 °C. LPBF HX typically exhibits an elongated grain structure along the building direction (BD) and the texture analysis from the combination of neutron diffractionNeutron diffraction and EBSD discloses a major texture component <011> and a minor texture component <001> along BD, and a texture component <001> in the other two sample directions perpendicular to BD. Two types of tests have been performed, the horizontal tests where the loading direction (LD) is applied perpendicular to BD, and the vertical tests where LD is applied parallel to BD. The vertical tests exhibit lower strength but better ductility, which is explained by the texture effect and the elongated grain structure. A comparison of the mechanical behavior to the wrought HX shows that LPBF HX has better yield strength due to the high dislocation density as proved by TEM images. Creep voids are observed at grain boundaries in SSRT for both directions and are responsible for the poor ductility of the horizontal tests. The vertical ductility in SSRT maintains the same level as the reference tensile test at the strain rate of 10−3s−1, due to the extra deformation capacity contributed by the discovered deformation twinningDeformation twinning and lattice rotation. The deformation twinningDeformation twinning, which is only observed in the vertical tests and has not been found in the conventionally manufactured HX, is beneficial to maintain the ductility but does not strengthen the material.

Place, publisher, year, edition, pages
Springer International Publishing, 2020
Keywords
Laser powder bed fusion, Slow strain rate tensile testing, Deformation twinning, Texture evolution, Neutron diffraction
National Category
Geotechnical Engineering
Identifiers
urn:nbn:se:liu:diva-169053 (URN)10.1007/978-3-030-51834-9_98 (DOI)
Conference
Cham
Available from: 2020-09-07 Created: 2020-09-07 Last updated: 2022-05-06Bibliographically approved
Lindström, T., Calmunger, M., Eriksson, R. & Leidermark, D. (2020). Fatigue Behaviour of an Additively Manufactured Ductile Gas Turbine Superalloy. Theoretical and applied fracture mechanics (Print) (108), Article ID 102604.
Open this publication in new window or tab >>Fatigue Behaviour of an Additively Manufactured Ductile Gas Turbine Superalloy
2020 (English)In: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638, no 108, article id 102604Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing (AM) offers new possibilities in gas turbine technology by allowing for more complex geometries. However, the fatigue performance, including crack initiation and crack propagation of AM gas turbine material, is not fully known. In addition, AM materials shows anisotropic properties due to the columnar grain growth in the building direction during the AM process, which needs to be accounted for. Also, an AM component often solidifies with a cellular dendritic structure during the manufacturing process. In the present study, the bulk material of an AM adopted nickel-based superalloy based on Hastelloy X was subjected to low-cycle fatigue (LCF) loading at room temperature. The LCF tests were conducted in strain control on additively manufactured smooth bars,with two different build orientations (with an angle of 0° and 90° relative to the building platform). The LCF results showed that the major part of the fatigue life is spent in the crack initiation phase, namely 78% to 99% of the total fatigue life. Based on the experiments, a model to predict the crack initiation life was developed that takes the anisotropic material behaviour into account. The last part of the fatigue life, the crack propagation phase, was studied on a microstructural level, where initial fractography of the ruptured LCF specimens revealed that the dendritic structure was visible on the fracture surface. It was noted that the dendritic structure could easily be mistaken for regular striations although they represent a different fracture mechanism. The fracture surfaces were therefore cross sectioned and possible correlations between fracture surface characteristics and underlying microstructure were studied using electron backscatter diffraction and electron channelling contrast imaging. The outcome showed that the dendritic structure had some effect on the LCF crack propagation behaviour by interdendritic tearing, which was discussed.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Additive manufacturing, fatigue, fractography, EBSD, crack initiation model
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-166081 (URN)10.1016/j.tafmec.2020.102604 (DOI)000552039000037 ()
Note

Funding agencies:  Swedish Energy AgencySwedish Energy Agency; Siemens Industrial Turbomachinery AB through "Turbines for Future Energy Systems" [44112-1]

Available from: 2020-06-08 Created: 2020-06-08 Last updated: 2022-09-09Bibliographically approved
Azeez, A., Eriksson, R., Leidermark, D. & Calmunger, M. (2020). Low cycle fatigue life modelling using finite element strain range partitioning for a steam turbine rotor steel. Theoretical and applied fracture mechanics (Print), 107, Article ID 102510.
Open this publication in new window or tab >>Low cycle fatigue life modelling using finite element strain range partitioning for a steam turbine rotor steel
2020 (English)In: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638, Vol. 107, article id 102510Article in journal (Refereed) Published
Abstract [en]

Materials made for modern steam power plants are required to withstand high temperatures and flexible operational schedule. Mainly to achieve high efficiency and longer components life. Nevertheless, materials under such conditions experience crack initiations and propagations. Thus, life prediction must be made using accurate fatigue models to allow flexible operation. In this study, fully reversed isothermal low cycle fatigue tests were performed on a turbine rotor steel called FB2. The tests were done under strain control with different total strain ranges and temperatures (20 °C to 625 °C). Some tests included dwell time to calibrate the short-time creep behaviour of the material. Different fatigue life models were evaluated based on total life approach. The stress-based fatigue life model was found unusable at 600 °C, while the strain-based models in terms of total strain or inelastic strain amplitudes displayed inconsistent behaviour at 500 °C. To construct better life prediction, the inelastic strain amplitudes were separated into plastic and creep components by modelling the deformation behaviour of the material, including creep. Based on strain range partitioning approach, the fatigue life depends on different damage mechanisms at different strain ranges at 500 °C. This allows for the formulation of life curves based on either plasticity-dominated damage or creep-dominated damage. At 600 °C, creep dominated while at 500 °C creep only dominates for higher strain ranges. The deformation mechanisms at different temperatures and total strain ranges were characterised by scanning electron microscopy and by quantifying the amount of low angle grain boundaries. The quantification of low angle grain boundaries was done by electron backscatter diffraction. Microscopy revealed that specimens subjected to 600 °C showed signs of creep damage in the form of voids close to the fracture surface. In addition, the amount of low angle grain boundaries seems to decrease with the increase in temperature even though the inelastic strain amplitude was increased. The study indicates that a significant amount of the inelastic strain comes from creep strain as opposed of being all plastic strain, which need to be taken into consideration when constructing a life prediction model.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Creep-fatigue interaction, Creep-resistant steel, EBSD, Low cycle fatigue, Steam turbine steel, Strain range partitioning
National Category
Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-164610 (URN)10.1016/j.tafmec.2020.102510 (DOI)000528008200019 ()2-s2.0-85079627150 (Scopus ID)
Note

Funding agencies: European UnionEuropean Union (EU) [764545]

Available from: 2020-03-26 Created: 2020-03-26 Last updated: 2023-09-29Bibliographically approved
Yu, C.-H., Peng, R. L., Luzin, V., Sprengel, M., Calmunger, M., Lundgren, J.-E., . . . Moverare, J. (2020). Thin-wall Effects and Anisotropic Deformation Mechanisms of an Additively Manufactured Ni-based Superalloy. Additive Manufacturing, 36, Article ID 101672.
Open this publication in new window or tab >>Thin-wall Effects and Anisotropic Deformation Mechanisms of an Additively Manufactured Ni-based Superalloy
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2020 (English)In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 36, article id 101672Article in journal (Refereed) Published
Abstract [en]

Laser powder bed fusion (LPBF) of Ni-based superalloys shows great potential for high temperature applications, for example, as a burner repair application for gas turbines where the thin-walled structure is important. It motivates this work to investigate the evolution of microstructure and the anisotropic mechanical behavior when plate-like specimens are built with a thickness from 4 mm down to 1 mm. By performing texture analysis using neutron diffraction, a clear transition in fiber texture from <011> to <001> is indicated when the specimen becomes thinner. The residual stress shows no thickness dependence, and at the subsurface the residual stress reaches the same level as the yield strength. Due to the rough as-built surface, a roughness compensation method for mechanical properties of thin-walled structures is outlined and demonstrated. Tensile tests from room temperature up to 700 °C have been carried out. Anisotropic mechanical behavior is found at all temperatures, which is strongly related to the anisotropic texture evolution. Stronger texture evolution and grain rotations are discovered when the tensile loading is applied along the building direction. The mechanical behavior has been compared to a wrought material, where the high dislocation density and the subgrain structure of the LPBF material result in a higher yield strength. Combining the statistical texture analysis by neutron diffraction with mechanical testing, EBSD grain orientation mapping and the investigation of dislocation structures using transmission electron microscopy, this work illustrates the significance of texture for the thin-wall effect and anisotropic mechanical behavior of LPBF materials.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Hastelloy X; Hot tensile test; Crystallographic texture, roughness; Residual stress; Dislocation density
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-171983 (URN)10.1016/j.addma.2020.101672 (DOI)000600807800193 ()2-s2.0-85095614801 (Scopus ID)
Note

Funding agencies: Swedish Governmental Agency for Innovation Systems (Vinnova)Vinnova [2016-05175]; Center for Additive Manufacturing-metal (CAM2); AFM at Linkoping University; faculty grant SFO-MATLiU [2009-00971]

Available from: 2020-12-16 Created: 2020-12-16 Last updated: 2023-09-08Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8306-3987

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