Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 36) Show all publications
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
Show others...
2019 (English)In: Additive Manufacturing, ISSN 2214-8604, 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: 2019-09-13Bibliographically approved
Lindgren, L.-E., Lundbäck, A., Fisk, M. & Draxler, J. (2019). Modelling additive manufacturing of superalloys. Paper presented at The 2nd International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2019, 8-10 March 2019, Sun City, South Africa. Procedia Manufacturing, 35, 252-258
Open this publication in new window or tab >>Modelling additive manufacturing of superalloys
2019 (English)In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 35, p. 252-258Article in journal (Refereed) Published
Abstract [en]

There exist several variants of Additive Manufacturing (AM) applicable for metals and alloys. The two main groups are Directed Energy Deposition (DED) and Powder Bed Fusion (PBF). AM has advantages and disadvantages when compared to more traditional manufacturing methods. The best candidate products are those with complex shape and small series and particularly individualized product. Repair welding is often individualized as defects may occur at various instances in a component. This method was used before it became categorized as AM and in most cases, it is a DED process. PBF processes are more useful for smaller items and can give a finer surface. Both DED and PBF products require subsequent surface finishing for high performance components and sometimes there is also a need for post heat treatment. Modelling of AM as well as eventual post-processes can be of use in order to improve product quality, reducing costs and material waste. The paper describes the use of the finite element method to simulate these processes with focus on superalloys.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Additive manufacturing, Simulation, Superalloys, Quality
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-75726 (URN)10.1016/j.promfg.2019.05.036 (DOI)
Conference
The 2nd International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2019, 8-10 March 2019, Sun City, South Africa
Note

Konferensartikel i tidskrift

Available from: 2019-08-28 Created: 2019-08-28 Last updated: 2019-08-28Bibliographically approved
Babu, B., Lundbäck, A. & Lindgren, L.-E. (2019). Simulation of Ti-6Al-4V Additive Manufacturing Using Coupled Physically Based Flow Stress and Metallurgical Model. Materials, 12(23), Article ID 3844.
Open this publication in new window or tab >>Simulation of Ti-6Al-4V Additive Manufacturing Using Coupled Physically Based Flow Stress and Metallurgical Model
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 23, article id 3844Article in journal (Refereed) Published
Abstract [en]

Simulating the additive manufacturing process of Ti-6Al-4V is very complex due to the microstructural changes and allotropic transformation occurring during its thermomechanical processing. The α -phase with a hexagonal close pack structure is present in three different forms—Widmanstatten, grain boundary and Martensite. A metallurgical model that computes the formation and dissolution of each of these phases was used here. Furthermore, a physically based flow-stress model coupled with the metallurgical model was applied in the simulation of an additive manufacturing case using the directed energy-deposition method. The result from the metallurgical model explicitly affects the mechanical properties in the flow-stress model. Validation of the thermal and mechanical model was performed by comparing the simulation results with measurements available in the literature, which showed good agreement

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
dislocation density, vacancy concentration, Ti-6Al-4V, additive manufacturing, directed energy deposition
National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-77109 (URN)10.3390/ma12233844 (DOI)31766563 (PubMedID)
Note

Validerad;2019;Nivå 2;2019-12-09 (johcin)

Available from: 2019-12-09 Created: 2019-12-09 Last updated: 2019-12-09Bibliographically approved
Murgau, C. C., Lundbäck, A., Åkerfeldt, P. & Pederson, R. (2019). Temperature and Microstructure Evolution in Gas Tungsten Arc Welding Wire Feed Additive Manufacturing of Ti-6Al-4V. Materials, 12(21), Article ID 3534.
Open this publication in new window or tab >>Temperature and Microstructure Evolution in Gas Tungsten Arc Welding Wire Feed Additive Manufacturing of Ti-6Al-4V
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 21, article id 3534Article in journal (Refereed) Published
Abstract [en]

In the present study, the gas tungsten arc welding wire feed additive manufacturing process is simulated and its final microstructure predicted by microstructural modelling, which is validated by microstructural characterization. The Finite Element Method is used to solve the temperature field and microstructural evolution during a gas tungsten arc welding wire feed additive manufacturing process. The microstructure of titanium alloy Ti-6Al-4V is computed based on the temperature evolution in a density-based approach and coupled to a model that predicts the thickness of the α lath morphology. The work presented herein includes the first coupling of the process simulation and microstructural modelling, which have been studied separately in previous work by the authors. In addition, the results from simulations are presented and validated with qualitative and quantitative microstructural analyses. The coupling of the process simulation and microstructural modeling indicate promising results, since the microstructural analysis shows good agreement with the predicted alpha lath size.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
additive manufacturing, titanium, Ti-6Al-4V, microstructural modeling, metal deposition, finite element method
National Category
Other Materials Engineering
Research subject
Material Mechanics; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-76788 (URN)10.3390/ma12213534 (DOI)31661882 (PubMedID)2-s2.0-85074651225 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-11-20 (johcin)

Available from: 2019-11-20 Created: 2019-11-20 Last updated: 2019-11-20Bibliographically approved
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
Show others...
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)000466995800034 ()
Note

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

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-06-24Bibliographically 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)000485804300034 ()
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: 2019-10-08Bibliographically 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
Lundbäck, A. & Lindgren, L.-E. (2016). Finite Element Simulation to Support Sustainable Production by Additive Manufacturing. Paper presented at International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2017, 23-25 January 2017, Kruger. Procedia Manufacturing, 7, 127-130
Open this publication in new window or tab >>Finite Element Simulation to Support Sustainable Production by Additive Manufacturing
2016 (English)In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 7, p. 127-130Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing (AM) has been identified as a disruptive manufacturing process having the potential to provide a number of sustainability advantages. Functional products with high added value and a high degree of customization can be produced. AM is particularly suited for industries in which mass customization, light weighting of parts and shortening of the supply chain are valuable. Its applications can typically be found in fields such as the medical, dental, and aerospace industries. One of the advantages with AM is that little or no scrap is generated during the process. The additive nature of the process is less wasteful than traditional subtractive methods of production. The capability to optimize the geometry to create lightweight components can reduce the material use in manufacturing. One of the challenges is for designers to start using the power of AM. To support the designers and manufacturing, there is a need for computational models to predicting the final shape, deformations and residual stresses. This paper summarizes the advantages of AM in a sustainability perspective. Some examples of application of simulation models for AM are also given.

National Category
Other Materials Engineering
Research subject
Material Mechanics
Identifiers
urn:nbn:se:ltu:diva-61268 (URN)10.1016/j.promfg.2016.12.033 (DOI)000398151100021 ()2-s2.0-85010369736 (Scopus ID)
Conference
International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2017, 23-25 January 2017, Kruger
Note

2016-12-27 (andbra);Konferensartikel i tidskrift

Available from: 2016-12-27 Created: 2016-12-27 Last updated: 2018-08-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0053-5537

Search in DiVA

Show all publications