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Moretti, M. A., Lindgren, L.-E. & Åkerström, P. (2023). Physics-based flow stress model for alloy 718. Paper presented at 4th European Symposium on Superalloys and their Applications (EuroSuperalloys 2022), Hybrid online and Bamberg, Germany, September 18-22, 2022. Metallurgical and Materials Transactions. A, 54(5), 1985-1997
Open this publication in new window or tab >>Physics-based flow stress model for alloy 718
2023 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 54, no 5, p. 1985-1997Article in journal (Refereed) Published
Abstract [en]

A dislocation density-based model for alloy 718 in the annealed state is proposed in order to accurately describe the deformation behavior of this alloy for a wide range of thermo-mechanical loadings. The model accounts for numerous microstructural mechanisms, including strain hardening, grain size effect, dynamic strain aging (DSA), solid solution strengthening, as well as phonon and electron drag which affects dislocation movements at high strain rates. Two types of recovery mechanisms are also included: recovery due to dislocation glide and recovery associated with cross-slip of screw dislocations. The model is calibrated using experimentally determined stress–strain curves for both low and high strain rates in the order of 10–3 to 103 s−1, and for temperatures in the range 20 °C to 800 °C. The stress–strain data computed with the model are in good agreement with the experimental data. The inclusion of DSA is found to be effective in the combination of temperatures and strain rates corresponding to experimental observations. The solid solution strengthening contribution increases with decreasing temperature and increasing strain rate. The drag effect in the model proves to be significant only for deformation at high strain rate (~ 103 s−1)

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
flow stress model, alloy 718, Nickel-based superalloys, dynamic strain aging, solid solution strengthening, high strain rates
National Category
Other Mechanical Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-83832 (URN)10.1007/s11661-022-06819-7 (DOI)000862215400001 ()2-s2.0-85139208802 (Scopus ID)
Conference
4th European Symposium on Superalloys and their Applications (EuroSuperalloys 2022), Hybrid online and Bamberg, Germany, September 18-22, 2022
Projects
European Network for Alloys Behaviour Laws Enhancement (ENABLE) project
Funder
EU, Horizon 2020, 764979VinnovaSwedish Research Council FormasSwedish Energy Agency
Note

Godkänd;2023;Nivå 0;2023-04-20 (hanlid);Konferensartikel i tidskrift;

Licens full text: Metallurgical and Materials Transactions A articles are published open access under a CC BY licence (Creative Commons Attribution 4.0 International licence). 

Available from: 2021-04-20 Created: 2021-04-20 Last updated: 2023-04-20Bibliographically approved
Dalai, B., Moretti, M. A., Åkerström, P., Arvieu, C., Jacquin, D. & Lindgren, L.-E. (2022). Corrigendum to “Mechanical behavior and microstructure evolution during deformation of AA7075-T651” [J. Mater. Sci. Eng. A 822 (2021) 141615]. Materials Science & Engineering: A, 845, Article ID 143210.
Open this publication in new window or tab >>Corrigendum to “Mechanical behavior and microstructure evolution during deformation of AA7075-T651” [J. Mater. Sci. Eng. A 822 (2021) 141615]
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2022 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 845, article id 143210Article in journal (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2022
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-90489 (URN)10.1016/j.msea.2022.143210 (DOI)000830300600001 ()2-s2.0-85129649854 (Scopus ID)
Note

Correction to: Dalai, B., Moretti, M. A., Åkerström, P. et al. Mechanical behavior and microstructure evolution during deformation of AA7075-T651. Materials Science & Engineering: A, 822, 141615 (2021). https://doi.org/10.1016/j.msea.2021.141615

Available from: 2022-05-02 Created: 2022-05-02 Last updated: 2022-08-11Bibliographically approved
Moretti, M. A., Dalai, B., Åkerström, P., Esin, V., Arvieu, C., Jacquin, D., . . . Lindgren, L.-E. (2022). Experimental study of high strain rate deformation of alloy 718. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Experimental study of high strain rate deformation of alloy 718
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2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå: Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2022
Keywords
alloy 718, high strain rate, Split-Hopkinson pressure bar, scanning electron microscopy, EBSD, recrystallization
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-91972 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Projects
H2020-MSCA-ITN-2017 - grant agreement 764979
Available from: 2022-06-28 Created: 2022-06-28 Last updated: 2022-09-21Bibliographically approved
Dalai, B., Moretti, M. A., Åkerström, P., Esin, V. A. & Lindgren, L.-E. (2022). High strain rate deformation behavior of AA7075-T651. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>High strain rate deformation behavior of AA7075-T651
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2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-92508 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-08-16 Created: 2022-08-16 Last updated: 2022-12-29Bibliographically approved
Dalai, B., Moretti, M. A., Åkerström, P., Esin, V. A. & Lindgren, L.-E. (2022). Mechanical behavior and microstructure evolution during high strain rate deformation of AA7075-T651. SN Applied Sciences, 4(10), Article ID 251.
Open this publication in new window or tab >>Mechanical behavior and microstructure evolution during high strain rate deformation of AA7075-T651
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2022 (English)In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 4, no 10, article id 251Article in journal (Refereed) Published
Abstract [en]

The current study presents the effects of strain and temperature on the mechanical response and microstructure evolution in AA7075-T651 at high strain rates. Compression tests have been performed at room temperature (RT), 200, 300 and 400 °C using a Split-Hopkinson pressure bar (SHPB) setup with strain rates ranging between 1400 and 5300 s−1. For deformation at RT, the flow stress increases with increase in strain rate. Whereas deformation at elevated temperatures show a non-monotonous behavior of the flow stress with respect to the strain rate. This trait is attributed to the pronounced effects from the adiabatic shear bands (ASBs); namely, distorted shear bands (DSBs) and transformed shear bands (TSBs); and cracks resulting from the plastic deformation instability during hot deformation. The sequence of microstructure evolution is: inhomogeneity in the initial microstructure – DSB – TSB – crack –fracture. The feasibility of formation and growth of ASBs and cracks increases with increase in strain and temperature, neglecting any significant effect from the strain rate. During the compression tests, temperature of the material rises due to adiabatic heating. Considering a certain strain developed in the material, this adiabatic temperature rise decreases as the deformation temperature is increased. Furthermore, during individual deformation processes, the temperature rise increases with increasing strain. The adiabatic temperature leading to the formation of TSB is approximated to be 0.7 times of the melting temperature of the alloy. These results from the current study are to be used in developing a physics-based material model for the alloy.

Place, publisher, year, edition, pages
Springer, 2022
Keywords
AA7075-T651, Split-Hopkinson pressure bar, High strain rate, Stress/strain measurements, Optical microscopy, Adiabatic shear bands
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-84323 (URN)10.1007/s42452-022-05141-6 (DOI)000849485700004 ()2-s2.0-85137553649 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-09-06 (johcin);

Funder: ENABLE project funded by the European Union’s Marie Skłodowska-Curie Actions (MSCA) Innovative Training Networks (ITN) H2020-MSCA-ITN-2017 under the Grant Agreement No 764979.;

This article has previously appeared as a manuscript in a thesis.

Available from: 2021-05-18 Created: 2021-05-18 Last updated: 2023-03-28Bibliographically approved
Lundholm, E., Akerström, P., Jonsén, P., Forouzan, F. & Sala, R. (2022). Numerical Modelling of the Mechanical Properties of Press Hardened Boron Steels. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>Numerical Modelling of the Mechanical Properties of Press Hardened Boron Steels
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2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Applied Mechanics
Research subject
Solid Mechanics; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-95111 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-12-30 Created: 2022-12-30 Last updated: 2023-09-05Bibliographically approved
Moretti, M. A., Dalai, B., Åkerström, P., Arvieu, C., Jacquin, D., Lacoste, E. & Lindgren, L.-E. (2021). High Strain Rate Deformation Behavior and Recrystallization of Alloy 718. Metallurgical and Materials Transactions. A, 52(12), 5243-5257
Open this publication in new window or tab >>High Strain Rate Deformation Behavior and Recrystallization of Alloy 718
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2021 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 52, no 12, p. 5243-5257Article in journal (Refereed) Published
Abstract [en]

To study the deformation behavior and recrystallization of alloy 718 in annealed and aged state, compression tests were performed using Split-Hopkinson pressure bar (SHPB) at high strain rates (1000 to 3000 s−1), for temperatures between 20 °C and 1100 °C (293 K to 1373 K). Optical microscope (OM) and electron back-scatter diffraction (EBSD) technique were employed to characterize the microstructural evolution of the alloy. The stress–strain curves show that the flow stress level decreases with increasing temperature and decreasing strain rate. In addition, up to 1000 °C, the aged material presents higher strength and is more resistant to deformation than the annealed one, with a yield strength around 200 MPa higher. For both states, dynamic and meta-dynamic recrystallization occurred when the material is deformed at 1000 °C and 1100 °C, leading to a refinement of the microstructure. As necklace structures were identified, discontinuous recrystallization is considered to be the main recrystallization mechanism. The recrystallization kinetics is faster for higher temperatures, as the fraction of recrystallized grains is higher and the average recrystallized grain size is larger after deformation at 1100 °C than after deformation at 1000 °C.

Place, publisher, year, edition, pages
Springer, 2021
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-83829 (URN)10.1007/s11661-021-06463-7 (DOI)000705165800001 ()2-s2.0-85116821888 (Scopus ID)
Projects
H2020 MSCA-ITN-2017 grant agreement Nº764979 - ENABLE project
Funder
EU, Horizon 2020, 764979
Note

Validerad;2021;Nivå 2;2021-11-18 (beamah);

For correction, see: Moretti, M. A., Dalai, B., Åkerström, P. et al. Correction to: High Strain Rate Deformation Behavior and Recrystallization of Alloy 718. Metallurgical and Materials Transactions A 53, 2796 (2022). https://doi.org/10.1007/s11661-022-06676-4

Available from: 2021-04-20 Created: 2021-04-20 Last updated: 2022-06-16Bibliographically approved
Dalai, B., Moretti, M. A., Åkerström, P., Arvieu, C., Jacquin, D. & Lindgren, L.-E. (2021). Mechanical behavior and microstructure evolution during deformation of AA7075-T651. Materials Science & Engineering: A, 822, Article ID 141615.
Open this publication in new window or tab >>Mechanical behavior and microstructure evolution during deformation of AA7075-T651
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2021 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 822, article id 141615Article in journal (Refereed) Published
Abstract [en]

In view of developing a physics-based constitutive material model for AA7075-T651, the mechanical behavior and microstructure evolution of the material has been studied through compression tests using Gleeble thermo-mechanical simulator. The tests were performed at wide range of temperatures (room temperature (RT), 100, 200, 300, 400 and 500 °C) with two constant strain rates (0.01 and 1 s-1). The true stress-strain curves depicted an increase in the flow stress with increase in the strain rate and decrease in the deformation temperature, with an exception at RT. The effects of softening mechanisms, such as adiabatic heating, dissolution of precipitates, dynamic recovery (DRV) and dynamic recrystallisation (DRX), on the flow stress level, strain rate sensitivity (SRS) and temperature sensitivity over the entire range of temperatures were analyzed. Pertaining to the microstructure analysis, the intermetallic particles present in the initial as-received (AR) material were identified as (Al,Cu)6(Fe,Cu) and SiO2 with the help of back-scattered electron (BSE) imaging and energy dispersive X-ray spectroscopy (EDS). The microstructure of the material after the deformation processes were analyzed and compared with that of the AR state using inverse pole figures (IPF), grain orientation spread (GOS) and grain boundary rotation maps generated from electron back-scattered diffraction (EBSD) scans. DRV was observed for deformation at 300 °C, whereas a combination of DRV and incomplete DRX took place for 400 and 500 °C depending on the strain rate. The fraction of recrystallized grains was higher in case of deformation at higher temperature and lower strain rate. Furthermore, the difference in microstructure evolution on different surfaces of the deformed samples as well as at different locations on individual surfaces was also investigated.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Aluminum alloys, Characterization, Stress/strain measurements, Electron back-scattered diffraction (EBSD), Dynamic recrystallisation (DRX)
National Category
Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-84320 (URN)10.1016/j.msea.2021.141615 (DOI)000708189600003 ()2-s2.0-85108870288 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-08-11 (alebob);

Forskningsfinansiärer: European Union's Marie Skłodowska-Curie Actions (MSCA) Innovative Training Networks (ITN) H2020-MSCA-ITN-2017 (764979);

For correction, see: Dalai, B., Moretti, M. A., Åkerström, P. et al. Corrigendum to “Mechanical behavior and microstructure evolution during deformation of AA7075-T651” [J. Mater. Sci. Eng. A 822 (2021) 141615]. Materials Science & Engineering: A, 845, 143210 (2022). https://doi.org/10.1016/j.msea.2022.143210

Available from: 2021-05-18 Created: 2021-05-18 Last updated: 2022-05-02Bibliographically approved
Draxler, J., Åkerström, P., Edberg, J., Lindgren, L.-E., Singh, S., Raza, T. & Andersson, J. (2020). A numerical model for simulating the effect of strain rate on eutectic band thickness. Welding in the World, 64(10), 1635-1658
Open this publication in new window or tab >>A numerical model for simulating the effect of strain rate on eutectic band thickness
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2020 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, no 10, p. 1635-1658Article in journal (Refereed) Published
Abstract [en]

Large tensile strains acting on the solidifying weld metal can cause the formation of eutectic bands along grain boundaries. These eutectic bands can lead to severe liquation in the partially melted zone of a subsequent overlapping weld. This can increase the risk of heat-affected zone liquation cracking. In this paper, we present a solidification model for modeling eutectic bands. The model is based on solute convection in grain boundary liquid films induced by tensile strains. The proposed model was used to study the influence of strain rate on the thickness of eutectic bands in Alloy 718. It was found that when the magnitude of the strain rate is 10 times larger than that of the solidification rate, the calculated eutectic band thickness is about 200 to 500% larger (depending on the solidification rate) as compared to when the strain rate is zero. In the paper, we also discuss how eutectic bands may form from hot cracks.

Place, publisher, year, edition, pages
Springer, 2020
Keywords
Macrosegregation, Solidification, Hot cracking, Alloy 718
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-76423 (URN)10.1007/s40194-020-00918-y (DOI)000540687300001 ()2-s2.0-85086930636 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-09-21 (johcin)

Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2023-09-05Bibliographically approved
Lindgren, L.-E., Edberg, J., Åkerström, P. & Zhang, Z. (2019). Modeling of thermal stresses in low alloy steels. Paper presented at The 12th International Congress on Thermal Stresses June 1–5, 2019, Zhejiang University, Hangzhou, China. Journal of thermal stresses, 42(6), 725-743
Open this publication in new window or tab >>Modeling of thermal stresses in low alloy steels
2019 (English)In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 42, no 6, p. 725-743Article in journal (Refereed) Published
Abstract [en]

Computing the evolution of thermal stresses accurately requires appropriate constitutive relations. This includes both the thermal and mechanical aspects, as temperature is the driver to thermal stresses. The paradigm of Integrated Computational Materials Engineering (ICME) aims at being able to quantitatively relate process-structure-property of a material. The article describes physics based models, denoted bridging elements, which are one step towards the vision of ICME. They couple material structure with heat capacity, heat conductivity, thermal and transformation strains and elastic properties for hypo-eutectoid steels. The models can account for the chemical composition of the steel and its processing, i.e. thermomechanical history, giving the evolution of the microstructure and the corresponding properties.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Elastic properties, heat capacity, heat conductivity, thermal expansion, thermal stresses
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-73488 (URN)10.1080/01495739.2019.1587329 (DOI)000468282400003 ()2-s2.0-85063905757 (Scopus ID)
Conference
The 12th International Congress on Thermal Stresses June 1–5, 2019, Zhejiang University, Hangzhou, China
Note

Konferensartikel i tidskrift

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2020-08-24Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3514-9441

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