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Subasic, N., Alfredsson, B., Dahlberg, C. F. O., Öberg, M. & Efsing, P. (2023). Mechanical Characterization of Fatigue and Cyclic Plasticity of 304L Stainless Steel at Elevated Temperature. Experimental mechanics, 63(8), 1391-1407
Open this publication in new window or tab >>Mechanical Characterization of Fatigue and Cyclic Plasticity of 304L Stainless Steel at Elevated Temperature
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2023 (English)In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 63, no 8, p. 1391-1407Article in journal (Refereed) Published
Abstract [en]

Background: The mechanical characterization of the cyclic elastoplastic response of structural materials at elevated temperatures is crucial for understanding and predicting the fatigue life of components in nuclear reactors. Objective: In this study, a comprehensive mechanical characterization of 304L stainless steel has been performed including metallography, tensile tests, fatigue tests, fatigue crack growth tests and cyclic stress-strain tests. Methods: Isothermal tests were conducted at both room temperature and 300 °C for both the rolling direction and the transverse direction of the hot rolled steel. Mechanical properties were extracted from the uniaxial experiments by fitting relevant material models to the data. The cyclic plasticity behavior has been modelled with a radial return-mapping algorithm that utilizes the Voce nonlinear isotropic hardening model in combination with the Armstrong-Frederick nonlinear kinematic hardening model. The plasticity models are available in commercial FE software and accurately capture the stabilized hysteresis loops, including a substantial Bauschinger effect. Results: The material exhibits near isotropic properties, but its mechanical performance is generally reduced at high temperatures. Specifically, in the rolling direction, the Young’s modulus is reduced by 16 % at 300 °C, the yield strength at 0.2 % plastic strain is lower by 23 %, and the ultimate tensile strength is lower by 30 % compared to room temperature. Fatigue life is also decreased, leading to an accelerated fatigue crack growth rate compared to room temperature. A von Mises radial return mapping algorithm proves to be effective in accurately modelling the cyclic plasticity of the material. The algorithm has also been used to establish a clear correlation between energy dissipation per cycle and cycles to failure, leading to the proposal of an energy-based fatigue life prediction model. Conclusions: The material exhibits reduced mechanical performance at elevated temperatures, with decreased monotonic strength, compared to room temperature. Fatigue life is also compromised, resulting in accelerated fatigue crack growth. The material’s hardening behavior differs at room temperature and elevated temperature, with lower peak stress values observed at higher temperatures. The radial return mapping algorithm can be used to determine the dissipated energy per cycle which together with fatigue testing has been used to propose a low cycle fatigue life prediction model at both temperatures.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Cyclic properties, Fatigue strength, Plasticity, Return mapping algorithm, Stainless steel
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-349870 (URN)10.1007/s11340-023-00992-5 (DOI)001065130000002 ()2-s2.0-85170541942 (Scopus ID)
Note

QC 20240704

Available from: 2024-07-04 Created: 2024-07-04 Last updated: 2024-07-04Bibliographically approved
Sedlak Mosesson, M., Alfredsson, B. & Efsing, P. (2021). A duplex oxide cohesive zone model to simulate intergranular stress corrosion cracking. International Journal of Mechanical Sciences, 197, Article ID 106260.
Open this publication in new window or tab >>A duplex oxide cohesive zone model to simulate intergranular stress corrosion cracking
2021 (English)In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 197, article id 106260Article in journal (Refereed) Published
Abstract [en]

A finite element model with slip-oxidation is proposed for solving intergranular stress corrosion cracking (IGSCC) with duplex oxides replicating the cyclic physics of the slip oxidation. The purpose is to investigate the crack growth effect due to different rate, compositions and kinetics of the duplex oxide. The finite element model is based on a coupling between cohesive zone formulation, slip-oxidation model and a diffusion model. The cohesive zone formulation includes a degradation formulation which is linked to the slip-oxidation formulation. The environmental properties in the slip-oxidation were obtained from the diffusion modeled with Fick?s second law in one-dimension. This was then coupled to the structural model by a segregated solution scheme. The mesh of the cohesive zone adapts to the oxide thickness of the duplex oxide during the crack growth. The duplex oxide has the mathematical form of a power law or a logarithmic form. The model showed matching results for all duplex oxide combinations in varying stress, but the inner logarithmical oxide gave higher crack growth rates than the power law. The power law with the thicker inner oxide showed good results for the change of stress intensity factor and gave the best results when the yield stress was varied. Grain misorientation effect was higher for the duplex oxides with thicker outer oxides.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Cohesive zone model, Fracture mechanics, Diffusion, Duplex oxide, Multi-physics, Finite Element Model
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-295348 (URN)10.1016/j.ijmecsci.2020.106260 (DOI)000640902900003 ()2-s2.0-85100274674 (Scopus ID)
Note

QC 20210525

Available from: 2021-05-25 Created: 2021-05-25 Last updated: 2022-06-25Bibliographically approved
Everitt, C.-M., Alfredsson, B. & Öberg, M. (2021). An imprint method to produce surface asperities for EHL and RCF experiments. MethodsX, 8, Article ID 101178.
Open this publication in new window or tab >>An imprint method to produce surface asperities for EHL and RCF experiments
2021 (English)In: MethodsX, ISSN 1258-780X, E-ISSN 2215-0161, Vol. 8, article id 101178Article in journal (Refereed) Published
Abstract [en]

A method was developed for creating single well-defined surface asperities using an imprint technique. The proposed method enables: • Creation of well-defined micrometre high asperities • Creation of asperities which survived more than 35 million EHL contact cycles • Damage tracing thanks to the possibility to control the damage initiation sites.The technique is based on rolling a hard disc with indents against a soft disc for creating single surface asperities. The contact pressure causes plastic deformation forcing material into the indents to create the asperities. The height of the asperities can be controlled by adjusting the applied force. After initial reshaping during the run-in process, the asperities were strong enough to survive more than 35 million elastohydrodynamic lubrication cycles, which should be of great interest for the researchers who investigate rolling contact fatigue experimentally. The method could also aid the research on the run-in process by enabling tracing the development of specific surface defects. Since the method can produce high and strong asperities it might also prove useful for investigations how asperities deform under sever contact conditions.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Asperities, Asperity Imprint Method, Contact mechanics, Elastohydrodynamic lubrication, Imprint, Rough surface, Article, force, heat treatment, lubrication, pressure, priority journal, surface property
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-290272 (URN)10.1016/j.mex.2020.101178 (DOI)000707188500023 ()33365259 (PubMedID)2-s2.0-85097778771 (Scopus ID)
Note

Not a duplicate with DiVA 1396147

QC 20211105

Available from: 2021-03-11 Created: 2021-03-11 Last updated: 2022-09-23Bibliographically approved
Alfredsson, B., Hazar, S. & Lai, J. (2021). Loading rate and temperature effects on the fracture toughness of a high strength bearing steel. Engineering Fracture Mechanics, 245, Article ID 107600.
Open this publication in new window or tab >>Loading rate and temperature effects on the fracture toughness of a high strength bearing steel
2021 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 245, article id 107600Article in journal (Refereed) Published
Abstract [en]

Fracture of martensitic AISI 52100 steel with 12% retained austenite was experimentally studied at temperatures below the tempering temperature by K-Ic tests and at extremely low loading rates. Depending on temperature, K-Ic and J

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Fracture toughness, Phase transformation, Low temperature creep, High strength steel, Retained austenite, Martensite
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-292981 (URN)10.1016/j.engfracmech.2021.107600 (DOI)000633033000002 ()2-s2.0-85101322798 (Scopus ID)
Note

QC 20210419

Available from: 2021-04-19 Created: 2021-04-19 Last updated: 2022-06-25Bibliographically approved
Sedlak Mosesson, M., Alfredsson, B. & Efsing, P. (2021). Simulation of Slip-Oxidation Process by Mesh Adaptivity in a Cohesive Zone Framework. Materials, 14(13), Article ID 3509.
Open this publication in new window or tab >>Simulation of Slip-Oxidation Process by Mesh Adaptivity in a Cohesive Zone Framework
2021 (English)In: Materials, E-ISSN 1996-1944, Vol. 14, no 13, article id 3509Article in journal (Refereed) Published
Abstract [en]

Adaptive oxide thickness was developed in a cohesive element based multi-physics model including a slip-oxidation and diffusion model. The model simulates the intergranular stress corrosion cracking (IGSCC) in boiling water reactors (BWR). The oxide thickness was derived from the slip-oxidation and updated in every structural iteration to fully couple the fracture properties of the cohesive element. The cyclic physics of the slip oxidation model was replicated. In the model, the thickness of the oxide was taken into consideration as the physical length of the cohesive element. The cyclic process was modelled with oxide film growth, oxide rupture, and re-passivation. The model results agreed with experiments in the literature for changes in stress intensity factor, yield stress representing cold work, and environmental factors such as conductivity and corrosion potential.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
cohesive zone model, fracture mechanics, diffusion, oxide film, slip oxidation
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-298955 (URN)10.3390/ma14133509 (DOI)000671209400001 ()34201857 (PubMedID)2-s2.0-85109211058 (Scopus ID)
Note

QC 20210726

Available from: 2021-07-26 Created: 2021-07-26 Last updated: 2024-07-04Bibliographically approved
Everitt, C.-M., Alfredsson, B. & Öberg, M. (2020). An imprint method to produce surface asperities for EHL and RCF experiments.
Open this publication in new window or tab >>An imprint method to produce surface asperities for EHL and RCF experiments
2020 (English)Report (Other academic)
Abstract [en]

A method was developed for creating single well defined surface asperities using an imprint technique. The proposed method can be used to create asperities of different heights and widths in the micrometre range. The technique for creating single surface asperities is based on rolling a hard disc with indents against a soft disc. The contact pressure will cause plastic deformation forcing material into the indents to create the asperities. The height of the asperities can be controlled by adjusting the applied force. After initial reshaping during the run-in process, the asperities were strong enough to survive more than 35 million EHL contact cycles. The method should thus be of great interest for the researchers investigating rolling contact fatigue experimentally. The method could also aid the research of the run in process by enabling tracing the development of specific surface defects. Since the method can produce high and strong asperities it might also prove useful for investigations of exactly how asperities deform under sever contacts conditions.  

Publisher
p. 18
Keywords
Asperities; Contact Mechanics; Elastohydrodynamic lubrication; Rough Surface; Imprint.
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-268912 (URN)978-91-7873-464-1 (ISBN)
Funder
Swedish Research Council, 621-2012-5922
Note

QC 20200226

Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2024-03-15Bibliographically approved
Everitt, C.-M., Vrček, A. & Alfredsson, B. (2020). Experimental and numerical investigation of asperities and indents with respect to rolling contact fatigue. Tribology International, 151, Article ID 106494.
Open this publication in new window or tab >>Experimental and numerical investigation of asperities and indents with respect to rolling contact fatigue
2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 151, article id 106494Article in journal (Refereed) Published
Abstract [en]

Rolling contact experiments with slip were performed on artificial asperities and indents with pile-up. Micro-pits arose at the leading edge of the asperities and classic rolling contact fatigue (RCF) cracks initiated behind the trailing edge of the indents. The elastic-plastic run-in process and the thermal elastohydrodynamic lubrication (TEHL) load cycles were studied numerically. The run-in process caused high tensile residual stresses at the leading edge of the asperities while the TEHL load cycle caused high tensile stresses at the trailing edge of both the asperities and the indents. The conclusion was thus drawn that the classic RCF cracks behind the indents were caused by the TEHL load cycle while the micro-pits at these artificial asperities were caused by the tensile residual stresses from plastic deformation.

Place, publisher, year, edition, pages
Elsevier BV, 2020
Keywords
Contact mechanics, Rolling contact fatigue, Rough surface, Thermal elastohydrodynamic lubrication, Cracks, Elastoplasticity, Friction, Piles, Residual stresses, Elastic-Plastic, Numerical investigations, Rolling contact fatigue cracks, Rolling contacts, Tensile residual stress, Trailing edges, Fatigue of materials
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-287981 (URN)10.1016/j.triboint.2020.106494 (DOI)000580595400068 ()2-s2.0-85088959369 (Scopus ID)
Note

Not duplicate with DiVA 1396151 which is a report and part of a thesis

QC 20201230

Available from: 2020-12-30 Created: 2020-12-30 Last updated: 2022-06-25Bibliographically approved
Everitt, C.-M., Alfredsson, B. & Vrček, A. (2020). Experimental and numerical investigation of asperities and indents with respect to rolling contact fatigue.
Open this publication in new window or tab >>Experimental and numerical investigation of asperities and indents with respect to rolling contact fatigue
2020 (English)Report (Other academic)
Abstract [en]

Rolling contact experiments with slip were performed of artificial asperities and indents with pile-up. Micro-pits arose on the leading edge of the asperities and classic rolling contact fatigue (RCF) cracks initiated behind the trailing edge of the indents. The elastic-plastic run-in process and the thermal elastohydrodynamic lubrication (TEHL) load cycles were studied numerically. The run-in process caused high tensile residual stresses on the leading edges of the asperities while the TEHL load cycle caused high tensile stresses on the trailing edges of both the asperities and the indents. The conclusion was thus drawn that the classic RCF cracks behind the indents were caused by the THEL load cycle while the micro-pits on the asperities were caused by the residual stresses.

Publisher
p. 32
Keywords
Contact Mechanics; Rolling Contact Fatigue; Rough Surface; Thermal Elastohydrodynamic Lubrication.
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-268913 (URN)978-91-7873-463-4 (ISBN)
Funder
Swedish Research Council, 621-2012-5922
Note

QC 20200226

Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2024-03-15Bibliographically approved
Everitt, C.-M. & Alfredsson, B. (2020). The influence of gear surface roughness on rolling contact fatigue under TEHL conditions with slip.
Open this publication in new window or tab >>The influence of gear surface roughness on rolling contact fatigue under TEHL conditions with slip
2020 (English)Report (Other academic)
Abstract [en]

Measured shot peened, ground and worn surfaces were included in thermal elastohydrodynamic lubrication and fatigue simulations. Considering transient temperature fields, shear limit and metal to metal contact, moderate negative slip was found to be more detrimental than positive. The location of pitting in gears was thus explained by the surface roughness and the slide to roll ratio. The λ -ratio correlated with fatigue risk within each surface structure. As a supplement to the λ -ratio the surface skewness qualitatively ranked the fatigue risk between the surface structures. 

Publisher
p. 33
Keywords
Contact mechanics; Tribology; Rolling contact fatigue; Surface roughness; Thermal elastohydrodynamic lubrication.
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-268910 (URN)978-91-7873-462-7 (ISBN)
Funder
Swedish Research Council, 621-2012-5922
Note

QC 20200226

Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2024-03-15Bibliographically approved
Everitt, C.-M. & Alfredsson, B. (2020). The influence of gear surface roughness on rolling contact fatigue under thermal elastohydrodynamic lubrication with slip. Tribology International, 151, Article ID 106394.
Open this publication in new window or tab >>The influence of gear surface roughness on rolling contact fatigue under thermal elastohydrodynamic lubrication with slip
2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 151, article id 106394Article in journal (Refereed) Published
Abstract [en]

Measured shot peened, ground and worn surfaces were included in thermal elastohydrodynamic lubrication and fatigue simulations. Considering transient temperature fields, shear limit and metal to metal contact, moderate negative slip was found to be more detrimental than positive. The location of pitting in gears was thus explained by the surface roughness and the slide to roll ratio. The λ-ratio correlated with fatigue risk within each surface structure. As a supplement to the λ-ratio the surface skewness qualitatively ranked the fatigue risk between the surface structures.

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Contact mechanics, Rolling contact fatigue, Surface roughness, Thermal elastohydrodynamic lubrication, Tribology, Shot peening, Lambda ratio, Metal-to-metal contact, Shear limits, Slide-to-roll ratio, Transient temperature fields, Worn surface, Elastohydrodynamic lubrication
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-282673 (URN)10.1016/j.triboint.2020.106394 (DOI)000580595400008 ()2-s2.0-85086092694 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20201202

Available from: 2020-09-30 Created: 2020-09-30 Last updated: 2022-06-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6896-1834

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