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Brückner, Frank
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Publications (10 of 22) Show all publications
Näsström, J., Brueckner, F. & Kaplan, A. (2020). A near-vertical approach to Laser Narrow Gap Multi-Layer Welding. Optics and Laser Technology, 121, Article ID 105798.
Open this publication in new window or tab >>A near-vertical approach to Laser Narrow Gap Multi-Layer Welding
2020 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 121, article id 105798Article in journal (Refereed) Published
Abstract [en]

A novel, near-vertical approach to the usually horizontal laser Narrow Gap Multi-Layer Welding process is introduced. The process is applied to join X100 pipeline steel and studied through High Speed Imaging. The produced welded joints are compared to their horizontally welded counterparts using 3D scanning, longitudinal & perpendicular cross sections and Computed Tomography analysis. The near-vertical approach is found to be robust and produce welded joints with a uniform appearance. The top surface exhibits certain reoccurring morphological features, and variations in internal track melting boundaries are observed. Any observed cavities appear similar to those produced using the horizontal process, with the difference of their orientation. A combination of the horizontal and the near-vertical process could be beneficial; the near-vertical approach offers potential for shorter inter-layer time and the horizontal method for better surface finish than that of its counterpart. Potential benefits of, and improvements to, the near-vertical process are discussed.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Laser welding, Narrow Gap, Vertical Welding, Multi-Layer, Filler wire
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-74541 (URN)10.1016/j.optlastec.2019.105798 (DOI)000491217800032 ()2-s2.0-85072045298 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-09-20 (johcin)

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-11-06Bibliographically approved
Haack, M., Kuczyk, M., Seidel, A., López, E., Brueckner, F. & Leyens, C. (2020). Comprehensive study on the formation of grain boundary serrations in additively manufactured Haynes 230 alloy. Materials Characterization, 160, Article ID 110092.
Open this publication in new window or tab >>Comprehensive study on the formation of grain boundary serrations in additively manufactured Haynes 230 alloy
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2020 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 160, article id 110092Article in journal (Refereed) Published
Abstract [en]

Recently, grain boundary serrations have been introduced in conventionally processed Haynes 230 through a slow-cooling heat treatment. The aim of this work was to utilize these heat treatments to introduce serrations in additively manufactured (Laser Metal Deposition) Haynes 230. Contrary to expectations, serrations already formed during the fast-cooling of the Laser Metal Deposition process. Electron Backscatter Diffraction was used to elucidate the underlying phenomenon for the emergence of serrations during fast-cooling. As a result, a hypothesis regarding a new mechanism responsible for the formation of grain boundary serrations was formulated. Additionally, specific characteristics of the Laser Metal Deposition process have been identified. This includes a columnar-to-equiaxed transition (CET) for slower feed rates, leading to smaller grains despite lower cooling rates; the observation of an abrupt increase in grain growth for a raised solution annealing temperature; the fact that serrations hinder uncontrolled grain growth and finally that the LMD-process leads to a finer carbide morphology compared to conventional manufacturing methods, potentially leading to an increased precipitation strengthening effect.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Additive manufacturing, Laser metal deposition, Grain boundary serration, Superalloy, Haynes 230, EBSD
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-77902 (URN)10.1016/j.matchar.2019.110092 (DOI)000519655300028 ()2-s2.0-85077398171 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-03 (alebob)

Available from: 2020-02-28 Created: 2020-02-28 Last updated: 2020-04-03Bibliographically approved
Näsström, J., Brueckner, F. & Kaplan, A. F. .. (2020). Imperfections in narrow gap multi-layer welding: Potential causes and countermeasures. Optics and lasers in engineering, 129, Article ID 106011.
Open this publication in new window or tab >>Imperfections in narrow gap multi-layer welding: Potential causes and countermeasures
2020 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 129, article id 106011Article in journal (Refereed) Published
Abstract [en]

Narrow Gap Multi-Layer Welding (NGMLW) using a laser as the main heat source and metal wire for material addition has been a growing topic of interest in the last decade. This is in part due to its potential for joining much thicker sheets of steel than what is usually considered possible when using autogenous laser welding. The process has shown great potential but improvements can still be made, e.g. through increased process control to decrease welding imperfections. Using closed-loop control, where the process is continuously monitored and regulated automatically, can help to account for variations during manufacturing. However, achieving functional closed loop control can be challenging due to limitations in data gathering and processing speeds. Important initial steps include identifying what data can be useful and how frequently this data has to be recorded. Too much data takes too long to process while too little causes risks of missing important details. In this study, 20 mm thick X80 pipeline steel sheets are joined together using this multi-layer approach; the samples are examined using 3D scanning and Computed Tomography (CT) analysis and the process is observed using High-Speed Imaging (HSI). The quality of the welded joint and welding imperfections are discussed and potential points of formation are identified. Suggestions on how to mitigate imperfections to improve the quality of the welded joint are presented, including the potential to use camera imaging for closed-loop process control and additional industrial uses of the HSI footage.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Narrow gap multi-layer welding (NGMLW), Laser welding, Narrow gap, High-speed imaging, Porosity, Cavities
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-74542 (URN)10.1016/j.optlaseng.2020.106011 (DOI)
Note

Validerad;2020;Nivå 2;2020-02-25 (alebob)

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2020-03-18Bibliographically approved
Prasad, H. S., Brueckner, F., Volpp, J. & Kaplan, A. F. H. (2020). Laser metal deposition of copper on diverse metals using green laser sources. The International Journal of Advanced Manufacturing Technology
Open this publication in new window or tab >>Laser metal deposition of copper on diverse metals using green laser sources
2020 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015Article in journal (Refereed) Epub ahead of print
Abstract [en]

Green laser sources are advantageous in the processing of copper due to the increase of absorptivity compared with more commonly available infrared lasers. Laser metal deposition of copper with a green laser onto various substrate metals namely copper, aluminium, steel and titanium alloy was carried out and observed through high-speed imaging. The effects of process parameters such as laser power, cladding speed and powder feed rate, and material attributes such as absorptivity, surface conditions and thermal conductivity are tied together to explain the size and geometry of the melt pool as well as the fraction of the power used for melting material. The copper substrate has the smallest melt pool with a high angle, followed by aluminium, steel and titanium alloy. The incorporation times for powder grains in the melt pools vary based on the substrate materials. Its dependency on material properties, including surface tension forces, melting temperatures and material density, is discussed. Oxide skins present on melt pools can affect powder incorporation, most significantly on the aluminium substrate. The lower limits of the fraction of power irradiated on the surface used purely for melting were calculated to be 0.73%, 2.94%, 5.95% and 9.78% for the copper, aluminium, steel and titanium alloy substrates, respectively, showing a strong dependence on thermal conductivity of the substrate material. For a copper wall built, the fraction was 2.66%, much higher than a single clad on a copper substrate, due to reduced workpiece heating. The results of this paper can be transferred to other metals with low absorptivity such as gold.

Place, publisher, year, edition, pages
Springer, 2020
Keywords
Copper, Laser Metal Deposition, Additive Manufacturing, High Speed Imaging, Multi-material, Green 515 nm laser, Directed Energy Deposition, Absorptivity, Powder grain incorporation, LMD, DED
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73753 (URN)10.1007/s00170-020-05117-z (DOI)2-s2.0-85081542493 (Scopus ID)
Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2020-03-26
Tkachov, R., Stepien, L., Greifzu, M., Kiriy, A., Kiriy, N., Schüler, T., . . . Leyens, C. (2019). A Printable Paste Based on a Stable n-Type Poly[Ni-tto] Semiconducting Polymer. Coatings, 9(11), Article ID 764.
Open this publication in new window or tab >>A Printable Paste Based on a Stable n-Type Poly[Ni-tto] Semiconducting Polymer
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2019 (English)In: Coatings, ISSN 2079-6412, Vol. 9, no 11, article id 764Article in journal (Refereed) Published
Abstract [en]

Polynickeltetrathiooxalate (poly[Ni-tto]) is an n-type semiconducting polymer having outstanding thermoelectric characteristics and exhibiting high stability under ambient conditions. However, its insolubility limits its use in organic electronics. This work is devoted to the production of a printable paste based on a poly[Ni-tto]/PVDF composite by thoroughly grinding the powder in a ball mill. The resulting paste has high homogeneity and is characterized by rheological properties that are well suited to the printing process. High-precision dispenser printing allows one to apply both narrow lines and films of poly[Ni-tto]-composite with a high degree of smoothness. The resulting films have slightly better thermoelectric properties compared to the original polymer powder. A flexible, fully organic double-leg thermoelectric generator with six thermocouples was printed by dispense printing using the poly[Ni-tto]-composite paste as n-type material and a commercial PEDOT-PSS paste as p-type material. A temperature gradient of 100 K produces a power output of about 20 nW

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
semiconducting n-type polymer poly[Ni-tto], printable paste, surface roughness, dispenser printing, thermoelectric
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-77852 (URN)10.3390/coatings9110764 (DOI)000502298300074 ()
Note

Validerad;2020;Nivå 2;2020-02-25 (johcin)

Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2020-02-25Bibliographically approved
Schneider, J., Seidel, A., Gumpinger, J., Riede, M., Lopéz, E., Brückner, F. & Leyens, C. (2019). Advanced manufacturing approach via the combination of selective laser melting and laser metal deposition. Paper presented at Proceedings of the International Congress of Applications of Lasers & Electro-Optics (ICALEO 2018). Journal of laser applications, 31(2), Article ID 022317.
Open this publication in new window or tab >>Advanced manufacturing approach via the combination of selective laser melting and laser metal deposition
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2019 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, no 2, article id 022317Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing processes are frequently discussed in a competitive manner instead of being considered synergetically. This is particularly unfavorable since advanced machining processes in combination with additive manufacturing can be brought to the point that the results could not be achieved with the individual constituent processes in isolation [K. Gupta, R. F. Laubscher, and N. K. Jain, Hybrid Machining Processes—Perspectives on Machining and Finishing (Springer, New York, 2016), p. 68]. On that basis, boundary conditions from selective laser melting (SLM) and laser metal deposition (LMD) are considered in mutual contemplation [A. Seidel et al., in Proceedings of 36th International Congress on Applications of Laser & Electro-Optics, Atlanta, GA, 22–26 October 2017(Fraunhofer IWS, Dresden, 2017), pp. 6–8]. The present approach interlinks the enormous geometrical freedom of powder-bed processing with the scalability of the LMD process. To demonstrate the potential of this approach, two different strategies are pursued. Firstly, a hollow structure demonstrator is manufactured layer wise via LMD with powder and subsequently joined with geometrically complex elements produced via SLM. Afterward, possibilities for a microstructural tailoring within the joining zone via the modification of process parameters are theoretically and practically discussed. Therefore, hybrid sample materials have been manufactured and interface areas are subjected to microstructural analysis and hardness tests. The feasibility of the introduced approach has been demonstrated by both fields of observation. The process combination illustrates a comprehensive way of transferring the high geometric freedom of powder-bed processing to the LMD process. The adjustment of process parameters between both techniques seems to be one promising way for an alignment on a microstructural and mechanical scale.

Place, publisher, year, edition, pages
Laser Institute of America, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-74917 (URN)10.2351/1.5096123 (DOI)000484435200047 ()2-s2.0-85065202471 (Scopus ID)
Conference
Proceedings of the International Congress of Applications of Lasers & Electro-Optics (ICALEO 2018)
Note

Konferensartikel i tidskrift

Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-10-01Bibliographically approved
Kledwig, C., Perfahl, H., Reisacher, M., Brueckner, F., Bliedtner, J. & Leyens, C. (2019). Analysis of Melt Pool Characteristics and Process Parameters Using a Coaxial Monitoring System during Directed Energy Deposition in Additive Manufacturing. Materials, 12(2), Article ID 308.
Open this publication in new window or tab >>Analysis of Melt Pool Characteristics and Process Parameters Using a Coaxial Monitoring System during Directed Energy Deposition in Additive Manufacturing
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2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 2, article id 308Article in journal (Refereed) Published
Abstract [en]

The growing number of commercially available machines for laser deposition welding show the growing acceptance and importance of this technology for industrial applications. Their increasing usage in research and production requires process stability and user-friendly handling. A commercially available DMG MORI LT 65 3D hybrid machine used in combination with a CCD-based coaxial temperature measurement system was utilized in this work to investigate what information relating to the intensity distribution of melt pool surfaces could be appropriate to draw conclusions about process conditions. In this study it is shown how the minimal required specific energy for a stable process can be determined, and it is indicated that the evolution of a plasma plume depends on thermal energy within the base material. An estimated melt pool area—calculated by the number of pixels (NOP) with intensities larger than a fixed, predefined threshold—builds the main measure in analysing images from the process camera. The melt pool area and its temporal variance can also serve as an indicator for an increased working distance

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
directed energy deposition, laser metal deposition, laser cladding, process parameters, melt pool, coaxial monitoring, process monitoring
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73065 (URN)10.3390/ma12020308 (DOI)000459719000112 ()30669432 (PubMedID)2-s2.0-85060179711 (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
Moritz, J., Seidel, A., Braun, B., Brandao, A., Pambaguian, L., Köhler, B., . . . Leyens, C. (2019). Functional integration approaches via laser powder bed processing. Paper presented at Proceedings of the International Congress of Applications of Lasers & Electro-Optics (ICALEO® 2018).. Journal of laser applications, 31(2), Article ID 022319.
Open this publication in new window or tab >>Functional integration approaches via laser powder bed processing
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2019 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, no 2, article id 022319Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing design rules are different from those of conventional fabrication techniques. These allow geometries that would not be possible to achieve otherwise. One example of application is the integration of functional parts as part of the manufacturing process. Conceivable applications range from mechanical functions like integration of moving parts or thermodynamic functions, for example, cooling channels or incorporation of electric circuits for electrical functionalization [J. Glasschroeder, E. Prager, and M. F. Zaeh, Rapid Prototyping J. 21, 207–215 (2015)]. Nevertheless, the potential of functional integration using powder-bed processes is far from being exhausted. The present approach addresses the generation of inner cavities and internal structures of titanium-based parts or components by the use of selective laser melting. This paper focusses on the investigation of voids and cavities regarding their capabilities to add new functions to the material. To this end, comprehensive characterization is performed using destructive as well as nondestructive testing methods. These include 3D scanning, computed tomography, and surface roughness measurements as well as microscopic analysis. Voids and cavities were filled with different thermoplastic materials, followed by the qualitative assessment of the mold filling and resulting material properties. Finally, applications are derived and evaluated with respect to the field of lightweight design or damping structures.

Place, publisher, year, edition, pages
Laser Institute of America, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-74950 (URN)10.2351/1.5096097 (DOI)000484435200049 ()2-s2.0-85065253511 (Scopus ID)
Conference
Proceedings of the International Congress of Applications of Lasers & Electro-Optics (ICALEO® 2018).
Note

Konferensartikel i tidskrift

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-10-01Bibliographically approved
Frostevarg, J., Volpp, J., Thompson, C., Prasad, H. S., Fedina, T. & Brückner, F. (2019). Influence of the vapour channel on processing in laser powder bed fusion. Paper presented at 17th Nordic Laser Materials Processing Conference (NOLAMP17), 27-29 August, 2019, Trondheim, Norway. Procedia Manufacturing, 36, 80-87
Open this publication in new window or tab >>Influence of the vapour channel on processing in laser powder bed fusion
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2019 (English)In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 36, p. 80-87Article in journal (Refereed) Published
Abstract [en]

Additive Manufacturing provides many opportunities to design and manufacture parts that are difficult or not possible to produce with conventional methods. In Selective Laser Melting (SLM) in powder bed fusion (PBF), melt pool dynamics and stability is dependent on a large number of factors, e.g. laser power output, power density, travel speed, reflectivity of powder bed, rapid heating and vaporization. Since travel speeds are often very fast and the laser interaction zone is small, the physical events become difficult to predict but also to observe. This work aims to describe the formation and geometrical characteristics of the vaporization zone during processing. Using a combination of theoretical descriptions, resulting material structures and a comprehensive analysis of high-speed images of the processing zone for different heat inputs and travel speeds, explanations for the dynamic melt pool behaviour are derived. The melting and pressures from processing involved moves powder particles next to it, changing the conditions for neighbouring tracks due to lack of material. These findings can provide a basis for creating more efficient and stable SLM processing, with fewer imperfections.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
High speed imaging, SLMPowder movement, Pressure
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-75755 (URN)10.1016/j.promfg.2019.08.012 (DOI)
Conference
17th Nordic Laser Materials Processing Conference (NOLAMP17), 27-29 August, 2019, Trondheim, Norway
Note

Konferensartikel i tidskrift

Available from: 2019-08-29 Created: 2019-08-29 Last updated: 2019-08-29Bibliographically approved
Seidel, A., Saha, S., Maiwald, T., Moritz, J., Polenz, S., Marquardt, A., . . . Leyens, C. (2019). Intrinsic Heat Treatment Within Additive Manufacturing of Gamma Titanium Aluminide Space Hardware. JOM: The Member Journal of TMS, 71(4), 1513-1519
Open this publication in new window or tab >>Intrinsic Heat Treatment Within Additive Manufacturing of Gamma Titanium Aluminide Space Hardware
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2019 (English)In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 71, no 4, p. 1513-1519Article in journal (Refereed) Published
Abstract [en]

A major part of laser additive manufacturing focuses on the fabrication of metallic parts for applications in the space and aerospace sectors. Especially, the processing of the very brittle titanium aluminides can be particularly challenging because of their distinct tendency to lamellar interface cracking. In the present paper, a gamma titanium aluminide (γ-TiAl) nozzle, manufactured via electron beam melting, is extended and adapted via hybrid laser metal deposition. The presented example considers a new field of application for this class of materials and approaches the process-specific manipulation of the composition and/or microstructure via the adjustment of processing temperatures, temperature gradients and solidification conditions. Furthermore, intrinsic heat treatment is investigated for electron beam melting and laser metal deposition with powder, and the resulting influence is releated to conventional processing.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73182 (URN)10.1007/s11837-019-03382-2 (DOI)000462009900041 ()2-s2.0-85062338558 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-04-05 (johcin)

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-04-11Bibliographically approved
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