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Lindgren, L.-E. & Gyhlesten Back, J. (2019). Elastic properties of ferrite and austenite in low alloy steels versus temperature and alloying. Materialia, 5, Article ID 100193.
Open this publication in new window or tab >>Elastic properties of ferrite and austenite in low alloy steels versus temperature and alloying
2019 (English)In: Materialia, ISSN 2589-1529, Vol. 5, article id 100193Article in journal (Refereed) Published
Abstract [en]

Models for elastic properties, as a function of temperature, are required when simulating various thermo-mechanical processes. A model for hypoeutectoid steels is proposed that accounts for this temperature dependency as well as the influence of alloying. The model consists of separate parts for the ferrite and austenite phases. The latter also includes a specific contribution due to ferromagnetism. The model is calibrated versus iron and evaluated against various steels.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Elastic properties, Steels, Temperature, Alloying
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-72815 (URN)10.1016/j.mtla.2018.100193 (DOI)2-s2.0-85061033793 (Scopus ID)
Available from: 2019-02-07 Created: 2019-02-07 Last updated: 2019-02-27Bibliographically approved
Olaogun, O., Edberg, J., Lindgren, L.-E., Oluwole, O. O. & Akinlabi, E. (2019). Heat transfer in cold rolling process of AA8015 alloy: a case study of 2-D FE simulation of coupled thermo-mechanical modeling. The International Journal of Advanced Manufacturing Technology, 100(9-12), 2617-2627
Open this publication in new window or tab >>Heat transfer in cold rolling process of AA8015 alloy: a case study of 2-D FE simulation of coupled thermo-mechanical modeling
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2019 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 100, no 9-12, p. 2617-2627Article in journal (Refereed) Published
Abstract [en]

The finite element method (FEM) is one of the most applicable mathematical analytic methods of rolling processes and is also an efficient method for analyzing coupled heat transfer. Thermal analysis of cold rolling process is not frequently used due to the widespread assumption of insignificant impact during rolling process. This research focuses on the development of coupled thermo-mechanical 2-D FE model analysis approach to study the thermal influence and varying coefficient of friction during the industrial cold rolling process of AA8015 aluminum alloy. Both deformable-rigid and deformable-deformable rigid contact algorithms were examined in the 2-D FE model. Findings revealed that temperature distribution in the roll bite rises steadily in a stepwise manner. The deformable-deformable contact algorithm is the best investigations of thermal behavior of the rolled metal and work rolls necessary for typical application in work roll design. The predicted roll separating force is validated with industrial measurements.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
2-D FE model, Contact algorithm, Coupled thermo-mechanical, Heat transfer
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-71692 (URN)10.1007/s00170-018-2811-2 (DOI)000458310400033 ()2-s2.0-85055479036 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-03-08 (johcin)

Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2019-03-08Bibliographically approved
Lindgren, L.-E., Edberg, J., Åkerström, P. & Zhang, Z. (2019). Modeling of thermal stresses in low alloy steels. Journal of thermal stresses
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 1521-074XArticle in journal (Refereed) Epub ahead of print
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)
Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-04-08
Lindwall, J., Pacheco, V., Sahlberg, M., Lundbäck, A. & Lindgren, L.-E. (2019). Thermal simulation and phase modeling of bulk metallic glass in the powder bed fusion process. Additive Manufacturing, 27, 345-352
Open this publication in new window or tab >>Thermal simulation and phase modeling of bulk metallic glass in the powder bed fusion process
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2019 (English)In: Additive Manufacturing, ISSN 2214-8604, Vol. 27, p. 345-352Article in journal (Refereed) Published
Abstract [en]

One of the major challenges with the powder bed fusion process (PBF) and formation of bulk metallic glass (BMG) is the development of process parameters for a stable process and a defect-free component. The focus of this study is to predict formation of a crystalline phase in the glass forming alloy AMZ4 during PBF. The approach combines a thermal finite element model for prediction of the temperature field and a phase model for prediction of crystallization and devitrification. The challenge to simulate the complexity of the heat source has been addressed by utilizing temporal reduction in a layer-by-layer fashion by a simplified heat source model. The heat source model considers the laser power, penetration depth and hatch spacing and is represented by a volumetric heat density equation in one dimension. The phase model is developed and calibrated to DSC measurements at varying heating rates. It can predict the formation of crystalline phase during the non-isothermal process. Results indicate that a critical location for devitrification is located a few layers beneath the top surface. The peak is four layers down where the crystalline volume fraction reaches 4.8% when 50 layers are built.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Additive manufacturing simulation, BMG, Heat input modeling, PBF, Phase evolution
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-73489 (URN)10.1016/j.addma.2019.03.011 (DOI)
Note

Validerad;2019;Nivå 2;2019-04-08 (svasva)

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-04-08Bibliographically approved
Lindgren, L.-E., Lundbäck, A. & Malmelöv, A. (2019). Thermal stresses and computational welding mechanics. Journal of thermal stresses, 42(1), 107-121
Open this publication in new window or tab >>Thermal stresses and computational welding mechanics
2019 (English)In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 42, no 1, p. 107-121Article in journal (Refereed) Published
Abstract [en]

Computational welding mechanics (CWM) have a strong connection to thermal stresses, as they are one of the main issues causing problems in welding. The other issue is the related welding deformations together with existing microstructure. The paper summarizes the important models related to prediction of thermal stresses and the evolution of CWM models in order to manage the large amount of ‘welds’ in additive manufacturing.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Additive manufacturing, flow stress, thermal expansion, thermal stresses welding
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-73063 (URN)10.1080/01495739.2018.1530965 (DOI)000459732500008 ()2-s2.0-85062086622 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-28 (johcin)

Available from: 2019-02-28 Created: 2019-02-28 Last updated: 2019-04-12Bibliographically approved
Lindgren, L.-E. & Lundbäck, A. (2018). Additive manufacturing and high performance applications. In: Chua C.K.,Yeong W.Y.,Liu E.,Tan M.J.,Tor S.B. (Ed.), Proceedings Of The 3rd International Conference On Progress In Additive Manufacturing (PRO-AM 2018): . Paper presented at 3rd International Conference on Progress in Additive Manufacturing, Pro-AM 2018; Nanyang Technological University; Singapore; 14-17 May 2018. (pp. 214-219). Pro-AM
Open this publication in new window or tab >>Additive manufacturing and high performance applications
2018 (English)In: Proceedings Of The 3rd International Conference On Progress In Additive Manufacturing (PRO-AM 2018) / [ed] Chua C.K.,Yeong W.Y.,Liu E.,Tan M.J.,Tor S.B., Pro-AM , 2018, p. 214-219Conference paper, Published paper (Refereed)
Abstract [en]

The requirement on life and robustness for aero-engine components poses obstacles to additive manufacturing. It is expected that increasing knowledge about the process and thereby its development together with adaption of existing alloys may improve this state. Simulations can contribute to understanding as well as be used in the design of process and components in order to reduce residual deformations and stresses as well as defects. Models for the latter are still not well established. The paper describes various existing approaches and also on-going developments at Luleå University of Technology that enable better descriptions in the near weld region for crack initiation.

Place, publisher, year, edition, pages
Pro-AM, 2018
Series
Proceedings of the International Conference on Progress in Additive Manufacturing, ISSN 2424-8967
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-72443 (URN)10.25341/D4JC76 (DOI)
Conference
3rd International Conference on Progress in Additive Manufacturing, Pro-AM 2018; Nanyang Technological University; Singapore; 14-17 May 2018.
Available from: 2019-01-04 Created: 2019-01-04 Last updated: 2019-01-04Bibliographically approved
Lindgren, L.-E. & Lundbäck, A. (2018). Approaches in computational welding mechanics applied to additive manufacturing: Review and outlook. Comptes rendus. Mecanique, 346(11), 1033-1042
Open this publication in new window or tab >>Approaches in computational welding mechanics applied to additive manufacturing: Review and outlook
2018 (English)In: Comptes rendus. Mecanique, ISSN 1631-0721, E-ISSN 1873-7234, Vol. 346, no 11, p. 1033-1042Article in journal (Refereed) Published
Abstract [en]

The development of computational welding mechanics (CWM) began more than four decades ago. The approach focuses on the region outside the molten pool and is used to simulate the thermo-metallurgical-mechanical behaviour of welded components. It was applied to additive manufacturing (AM) processes when they were known as weld repair and metal deposition. The interest in the CWM approach applied to AM has increased considerably, and there are new challenges in this context regarding welding. The current state and need for developments from the perspective of the authors are summarised in this study.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-70648 (URN)10.1016/j.crme.2018.08.004 (DOI)000446667900004 ()2-s2.0-85051826867 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-05 (inah)

Available from: 2018-08-29 Created: 2018-08-29 Last updated: 2018-12-05Bibliographically approved
Lindwall, J., Malmelöv, A., Lundbäck, A. & Lindgren, L.-E. (2018). Efficiency and Accuracy in Thermal Simulation of Powder Bed Fusion of Bulk Metallic Glass. JOM: The Member Journal of TMS, 70(8), 1598-1603
Open this publication in new window or tab >>Efficiency and Accuracy in Thermal Simulation of Powder Bed Fusion of Bulk Metallic Glass
2018 (English)In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 70, no 8, p. 1598-1603Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing by powder bed fusion processes can be utilized to create bulk metallic glass as the process yields considerably high cooling rates. However, there is a risk that reheated material set in layers may become devitrified, i.e., crystallize. Therefore, it is advantageous to simulate the process to fully comprehend it and design it to avoid the aforementioned risk. However, a detailed simulation is computationally demanding. It is necessary to increase the computational speed while maintaining accuracy of the computed temperature field in critical regions. The current study evaluates a few approaches based on temporal reduction to achieve this. It is found that the evaluated approaches save a lot of time and accurately predict the temperature history.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-68768 (URN)10.1007/s11837-018-2919-8 (DOI)000440845900039 ()
Note

Validerad;2018;Nivå 2;2018-08-07 (rokbeg)

Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2019-01-29Bibliographically approved
Fisk, M., Lindgren, L.-E., Datchary, W. & Deshmukh, V. (2018). Modelling of induction hardening in low alloy steels. Finite elements in analysis and design (Print), 144, 61-75
Open this publication in new window or tab >>Modelling of induction hardening in low alloy steels
2018 (English)In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 144, p. 61-75Article in journal (Refereed) Published
Abstract [en]

Induction hardening is a useful method for improving resistance to surface indentation, fatigue and wear that is favoured in comparison with through hardening, which may lack necessary toughness. The process itself involves fast heating by induction with subsequent quenching, creating a martensitic layer at the surface of the workpiece. In the present work, we demonstrate how to simulate the process of induction hardening using a commercial finite element software package with focuses on validation of the electromagnetic and thermal parts, together with evolution of the microstructure. Experiments have been carried out using fifteen workpieces that have been heated using three different heating rates and five different peak temperatures resulting in different microstructures. It is found that the microstructure and hardening depth is affected by the heating rate and peak temperature. The agreement between the experimental and simulated results is good. Also, it is demonstrated that the critical equilibrium temperatures for phase transformation is important for good agreement between the simulated and experimental hardening depth. The developed simulation technique predicts the hardness and microstructure sufficiently well for design and the development of induction hardening processes.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-67999 (URN)10.1016/j.finel.2018.03.002 (DOI)000431206900006 ()2-s2.0-85044131610 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-19 (andbra)

Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2018-07-18Bibliographically approved
Babu, B., Charles, C. & Lindgren, L.-E. (2018). Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase Composition. International journal of plasticity
Open this publication in new window or tab >>Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase Composition
2018 (English)In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154Article in journal (Refereed) Submitted
Abstract [en]

The principal challenge in producing aerospace components using Ti-6Al-4V alloy is to employ the optimum process window of deformation rate and temperature to achieve desired material properties. Qualitatively understanding the microstructure-property relationship is not enough to accomplish this goal. Developing advanced material models to be used in manufacturing process simulation is the key to compute and optimize the process iteratively. The focus in this work is on physically based flow stress models coupled with microstructure evolution models. Such a model can be used to simulate processes involving complex and cyclic thermo-mechanical loading.

Keywords
Finite Element Method, Dislocation density, Vacancy concentration, Ti-6Al-4V, Alpha, Beta
National Category
Applied Mechanics
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-70904 (URN)
Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-11-23
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2544-9168

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