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Andersson, C. & Lundbäck, A. (2023). Modeling the Evolution of Grain Texture during Solidification of Laser-Based Powder Bed Fusion Manufactured Alloy 625 Using a Cellular Automata Finite Element Model. Metals, 13(11), Article ID 1846.
Open this publication in new window or tab >>Modeling the Evolution of Grain Texture during Solidification of Laser-Based Powder Bed Fusion Manufactured Alloy 625 Using a Cellular Automata Finite Element Model
2023 (English)In: Metals, E-ISSN 2075-4701, Vol. 13, no 11, article id 1846Article in journal (Refereed) Published
Abstract [en]

The grain texture of the as-printed material evolves during the laser-based powder bed fusion (PBF-LB) process. The resulting mechanical properties are dependent on the obtained grain texture and the properties vary depending on the chosen process parameters such as scan velocity and laser power. A coupled 2D Cellular Automata and Finite Element model (2D CA-FE) is developed to predict the evolution of the grain texture during solidification of the nickel-based superalloy 625 produced by PBF-LB. The FE model predicts the temperature history of the build, and the CA model makes predictions of nucleation and grain growth based on the temperature history. The 2D CA-FE model captures the solidification behavior observed in PBF-LB such as competitive grain growth plus equiaxed and columnar grain growth. Three different nucleation densities for heterogeneous nucleation were studied, 1 × 1011, 3 × 1011, and 5 × 1011. It was found that the nucleation density 3 × 1011 gave the best result compared to existing EBSD data in the literature. With the selected nucleation density, the aspect ratio and grain size distribution of the simulated grain texture also agrees well with the observed textures from EBSD in the literature.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
additive manufacturing, SLM, microstructure, equiaxed, columnar, CET, numerical, simulation
National Category
Metallurgy and Metallic Materials Manufacturing, Surface and Joining Technology
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-102321 (URN)10.3390/met13111846 (DOI)001119965000001 ()2-s2.0-85177652651 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-11-06 (joosat);

Part of Special Issue: Multi-Scale Simulation of Metallic Materials (2nd Edition)

CC BY 4.0 License

Funder: EU Just Transition Fund and the Swedish Agency for Economic and Regional Growth (FINAST project, grant number 20358499)

Available from: 2023-11-06 Created: 2023-11-06 Last updated: 2024-03-11Bibliographically approved
Andersson, C. & Lundbäck, A. (2023). Modeling the Evolution of Grain Texture in Laser-Based Powder Bed Fusion Manufactured Alloy 625. In: : . Paper presented at 4th International Conference on Simulation for Additive Manufacturing - Sim-Am 2023, July 26-28, 2023, Munich, Germany.
Open this publication in new window or tab >>Modeling the Evolution of Grain Texture in Laser-Based Powder Bed Fusion Manufactured Alloy 625
2023 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-99540 (URN)
Conference
4th International Conference on Simulation for Additive Manufacturing - Sim-Am 2023, July 26-28, 2023, Munich, Germany
Available from: 2023-08-11 Created: 2023-08-11 Last updated: 2023-08-14Bibliographically approved
Hassila, C.-J., Malmelöv, A., Andersson, C., Hektor, J., Fisk, M., Wiklund, U. & Lundbäck, A. (2022). Influence of Scanning Strategy on Residual Stresses in Laser Powder Bed Fusion Manufactured Alloy 718: Modelling and Experiments. 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 >>Influence of Scanning Strategy on Residual Stresses in Laser Powder Bed Fusion Manufactured Alloy 718: Modelling and Experiments
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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 Manufacturing, Surface and Joining Technology
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-95130 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2023-01-03 Created: 2023-01-03 Last updated: 2023-01-03Bibliographically approved
Malmelöv, A., Hassila, C.-J., Fisk, M., Wiklund, U. & Lundbäck, A. (2022). Numerical modeling and synchrotron diffraction measurements of residual stresses in laser powder bed fusion manufactured alloy 625. Materials & design, 216, Article ID 110548.
Open this publication in new window or tab >>Numerical modeling and synchrotron diffraction measurements of residual stresses in laser powder bed fusion manufactured alloy 625
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2022 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 216, article id 110548Article in journal (Refereed) Published
Abstract [en]

Residual stresses in metal additive manufactured components are a well-known problem. It causes distortion of the samples when removing them from the build plate, as well as acting detrimental with regard to fatigue. The understanding of how residual stresses in a printed sample are affected by process parameters is crucial to allow manufacturers to tune their process parameters, or the design of their component, to limit the negative influence of residual stresses. In this paper, residual stresses in additive manufactured samples are simulated using a thermo-mechanical finite element model. The elasto-plastic behavior of the material is described by a mechanism-based material model that accounts for microstructural and relaxation effects. The heat source in the finite element model is calibrated by fitting the model to experimental data. The residual stress field from the finite element model is compared with experimental results attained from synchrotron X-ray diffraction measurements. The results from the model and measurement give the same trend in the residual stress field. In addition, it is shown that there is no significant difference in trend and magnitude of the resulting residual stresses for an alternation in laser power and scanning speed.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Residual stress, Material model, Alloy 625, Deformations, Finite Element Method, Synchrotron X-ray diffraction
National Category
Applied Mechanics Manufacturing, Surface and Joining Technology
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-89092 (URN)10.1016/j.matdes.2022.110548 (DOI)000793343200004 ()2-s2.0-85126860901 (Scopus ID)
Funder
Swedish Foundation for Strategic Research, GMT14-0048Swedish Research Council, 2016-05460Vinnova
Note

Validerad;2022;Nivå 2;2022-04-05 (hanlid);

This article has previously appeared as a manuscript in a thesis with the title: Residual stresses in laser-based powder bed fusion manufactured alloy 625: Modeling and experiments

Available from: 2022-02-02 Created: 2022-02-02 Last updated: 2022-05-30Bibliographically approved
Lindwall, J., Ericsson, A., Marattukalam, J. J., Hassila, C. J., Karlsson, D., Sahlberg, M., . . . Lundbäck, A. (2022). Simulation of phase evolution in a Zr-based glass forming alloy during multiple laser remelting. Journal of Materials Research and Technology, 16, 1165-1178
Open this publication in new window or tab >>Simulation of phase evolution in a Zr-based glass forming alloy during multiple laser remelting
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2022 (English)In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 16, p. 1165-1178Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing by laser-based powder bed fusion is a promising technique for bulk metallic glass production. But, reheating by deposition of subsequent layers may cause local crystallisation of the alloy. To investigate the crystalline phase evolution during laser scanning of a Zr-based metallic glass-forming alloy, a simulation strategy based on the finite element method and the classical nucleation theory has been developed and compared with experimental results from multiple laser remelting of a single-track. Multiple laser remelting of a single-track demonstrates the crystallisation behaviour by the influence of thermal history in the reheated material. Scanning electron microscopy and transmission electron microscopy reveals the crystalline phase evolution in the heat affected zone after each laser scan. A trend can be observed where repeated remelting results in an increased crystalline volume fraction with larger crystals in the heat affected zone, both in simulation and experiment. A gradient of cluster number density and mean radius can also be predicted by the model, with good correlation to the experiments. Prediction of crystallisation, as presented in this work, can be a useful tool to aid the development of process parameters during additive manufacturing for bulk metallic glass formation.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Additives, Glass, Heat affected zone, High resolution transmission electron microscopy, Laser heating, Laser theory, Metals, Nucleation, Scanning electron microscopy, Zircaloy, (metallic) glass, Classical nucleation theory, Growth theory, Laser-based, Multiple lasers, Nucleation and growth, Phase evolutions, Phase transformation modelling, Powder bed, Simulation of laser-based powder bed fusion, Metallic glass
National Category
Manufacturing, Surface and Joining Technology
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-88722 (URN)10.1016/j.jmrt.2021.12.056 (DOI)000782650200002 ()2-s2.0-85121898134 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , GMT14-0048
Note

Validerad;2022;Nivå 2;2022-01-13 (johcin)

Available from: 2022-01-13 Created: 2022-01-13 Last updated: 2022-05-09Bibliographically approved
Lindwall, J., Lundbäck, A., Marattukalam, J. J. & Ericsson, A. (2022). Virtual Development of Process Parameters for Bulk Metallic Glass Formation in Laser-Based Powder Bed Fusion. Materials, 15(2), Article ID 450.
Open this publication in new window or tab >>Virtual Development of Process Parameters for Bulk Metallic Glass Formation in Laser-Based Powder Bed Fusion
2022 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 2, article id 450Article in journal (Refereed) Published
Abstract [en]

The development of process parameters and scanning strategies for bulk metallic glass formation during additive manufacturing is time-consuming and costly. It typically involves trials with varying settings and destructive testing to evaluate the final phase structure of the experimental samples. In this study, we present an alternative method by modelling to predict the influence of the process parameters on the crystalline phase evolution during laser-based powder bed fusion (PBF-LB). The methodology is demonstrated by performing simulations, varying the following parameters: laser power, hatch spacing and hatch length. The results are compared in terms of crystalline volume fraction, crystal number density and mean crystal radius after scanning five consecutive layers. The result from the simulation shows an identical trend for the predicted crystalline phase fraction compared to the experimental estimates. It is shown that a low laser power, large hatch spacing and long hatch lengths are beneficial for glass formation during PBF-LB. The absolute values show an offset though, over-predicted by the numerical model. The method can indicate favourable parameter settings and be a complementary tool in the development of scanning strategies and processing parameters for additive manufacturing of bulk metallic glass.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
Additive manufacturing, Classical nucleation and growth theory, Crystallisation in metallic glass, Metallic glass, Simulation of laser-based powder bed fusion
National Category
Manufacturing, Surface and Joining Technology
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-88904 (URN)10.3390/ma15020450 (DOI)000757986100001 ()35057168 (PubMedID)2-s2.0-85122234396 (Scopus ID)
Funder
Swedish Foundation for Strategic Research, GMT14-0048
Note

Validerad;2022;Nivå 2;2022-01-24 (johcin)

Available from: 2022-01-24 Created: 2022-01-24 Last updated: 2022-07-05Bibliographically approved
Malmelöv, A., Lundbäck, A. & Lindgren, L.-E. (2020). History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing. Metals, 10(1), Article ID 58.
Open this publication in new window or tab >>History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing
2020 (English)In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 58Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing is the process by which material is added layer by layer. In most cases, many layers are added, and the passes are lengthy relative to their thicknesses and widths. This makes finite element simulations of the process computationally demanding owing to the short time steps and large number of elements. The classical lumping approach in computational welding mechanics, popular in the 80s, is therefore, of renewed interest and is evaluated in this work. The method of lumping means that welds are merged. This allows fewer time steps and a coarser mesh. It was found that the computation time can be reduced considerably, with retained accuracy for the resulting temperatures and deformations. The residual stresses become, to a certain degree, smaller. The simulations were validated against a directed energy deposition (DED) experiment with alloy 625.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
finite element, thermo-mechanical analysis, additive manufacturing, alloy 625
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-77958 (URN)10.3390/met10010058 (DOI)000516827800058 ()2-s2.0-85077642374 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , GMT14-0048
Note

Validerad;2020;Nivå 2;2020-04-01 (alebob)

Available from: 2020-03-04 Created: 2020-03-04 Last updated: 2022-02-02Bibliographically approved
Malmelöv, A., Fisk, M., Lundbäck, A. & Lindgren, L.-E. (2020). Mechanism based flow stress model for Alloy 625 and Alloy 718. Materials, 13(24), Article ID 5620.
Open this publication in new window or tab >>Mechanism based flow stress model for Alloy 625 and Alloy 718
2020 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 24, article id 5620Article in journal (Refereed) Published
Abstract [en]

To predict the final geometry in thermo-mechanical processes, the use of modeling tools is of great importance. One important part of the modeling process is to describe the response correctly. A previously published mechanism-based flow stress model has been further developed and adapted for the nickel-based superalloys, alloy 625, and alloy 718. The updates include the implementation of a solid solution strengthening model and a model for high temperature plasticity. This type of material model is appropriate in simulations of manufacturing processes where the material undergoes large variations in strain rates and temperatures. The model also inherently captures stress relaxation. The flow stress model has been calibrated using compression strain rate data ranging from 0.01 to 1 s−1 with a temperature span from room temperature up to near the melting temperature. Deformation mechanism maps are also constructed which shows when the different mechanisms are dominating. After the model has been calibrated, it is validated using stress relaxation tests. From the parameter optimization, it is seen that many of the parameters are very similar for alloy 625 and alloy 718, although it is two different materials. The modeled and measured stress relaxation are in good agreement.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
material model, flow stress model, dislocation density, Inconel, stress relaxation
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-78575 (URN)10.3390/ma13245620 (DOI)000602836700001 ()33317127 (PubMedID)2-s2.0-85097421068 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , GMT14-0048Vinnova, 2017-05200
Note

Validerad;2021;Nivå 2;2021-01-08 (alebob);

Artikeln har tidigare förekommit som manuskript i avhandling

Available from: 2020-04-20 Created: 2020-04-20 Last updated: 2022-02-02Bibliographically approved
Karlsson, D., Lindwall, G., Lundbäck, A., Amnebrink, M., Boström, M., Riekehr, L., . . . Jansson, U. (2019). Binder jetting of the AlCoCrFeNi alloy. Additive Manufacturing, 27, 72-79
Open this publication in new window or tab >>Binder jetting of the AlCoCrFeNi alloy
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2019 (English)In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 27, p. 72-79Article in journal (Refereed) Published
Abstract [en]

High density components of an AlCoCrFeNi alloy, often described as a high-entropy alloy, were manufactured by binder jetting followed by sintering. Thermodynamic calculations using the CALPHAD approach show that the high-entropy alloy is only stable as a single phase in a narrow temperature range below the melting point. At all other temperatures, the alloy will form a mixture of phases, including a sigma phase, which can strongly influence the mechanical properties. The phase stabilities in built AlCoCrFeNi components were investigated by comparing the as-sintered samples with the post-sintering annealed samples at temperatures between 900 °C and 1300 °C. The as-sintered material shows a dominant B2/bcc structure with additional fcc phase in the grain boundaries and sigma phase precipitating in the grain interior. Annealing experiments between 1000 °C and 1100 °C inhibit the sigma phase and only a B2/bcc phase with a fcc phase is observed. Increasing the temperature further suppresses the fcc phase in favor for the B2/bcc phases. The mechanical properties are, as expected, dependent on the annealing temperature, with the higher annealing temperature giving an increase in yield strength from 1203 MPa to 1461 MPa and fracture strength from 1996 MPa to 2272 MPa. This can be explained by a hierarchical microstructure with nano-sized precipitates at higher annealing temperatures. The results enlighten the importance of microstructure control, which can be utilized in order to tune the mechanical properties of these alloys. Furthermore, an excellent oxidation resistance was observed with oxide layers with a thickness of less than 5 μm after 20 h annealing at 1200 °C, which would be of great importance for industrial applications.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Additive manufacturing, Binder jetting, High-entropy alloy, HEA
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-73154 (URN)10.1016/j.addma.2019.02.010 (DOI)000466995800008 ()2-s2.0-85062234032 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-03-11 (inah)

Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2021-06-11Bibliographically approved
Lindwall, J., Hassila, C.-J., Marattukalam, J. J. & Lundbäck, A. (2019). Boundary conditions for simulation of powder bed fusion for metallic glass formation: Measurements and calibrations. In: F. Auricchio, E. Rank, P. Steinmann, S. Kollmannsberger and S. Morganti (Ed.), II International Conference on Simulation for Additive Manufacturing: Sim-AM 2019. Paper presented at II International Conference on Simulation for Additive Manufacturing (Sim-AM 2019), 11-13 September, 2019, Pavia, Italy (pp. 51-59).
Open this publication in new window or tab >>Boundary conditions for simulation of powder bed fusion for metallic glass formation: Measurements and calibrations
2019 (English)In: II International Conference on Simulation for Additive Manufacturing: Sim-AM 2019 / [ed] F. Auricchio, E. Rank, P. Steinmann, S. Kollmannsberger and S. Morganti, 2019, p. 51-59Conference paper, Published paper (Other academic)
Abstract [en]

A finite element model for prediction of the temperature field in the powder bed fusion process is presented and compared to measurements. Accurate temperature predictions at the base plate are essential to accurately predict the formation of crystals in a metallic glass forming material. The temperature measurements were performed by equipping the base plate with thermocouples during manufacturing of a cylinder with the glass forming alloy AMZ4. Boundary conditions for heat losses through the base plate/machine contact interfaces was calibrated to fit the measurements. Additional heat losses was used to account for radiation at the top surface and conduction through the powder bed. An interface boundary condition based on conservation of heat flux was examined to match the heat flow to the machine structure and the temperature predictions was satisfying. Still, temperature predictions with a constant heat transfer coefficient matched the measurements within 1.5oC during the entire building process of about 9 hours.

Keywords
Computational Methods, Additive Manufacturing, Thermal Simulation, Bulk Metallic Glass
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-77936 (URN)000563504100004 ()2-s2.0-85102060858 (Scopus ID)
Conference
II International Conference on Simulation for Additive Manufacturing (Sim-AM 2019), 11-13 September, 2019, Pavia, Italy
Funder
Swedish Foundation for Strategic Research, GMT14-0048
Note

ISBN för värdpublikation: 978-84-949194-8-0

Available from: 2020-03-03 Created: 2020-03-03 Last updated: 2022-06-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0053-5537

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