TY - CONF A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Zocca, Andrea A1 - Günster, Jens T1 - Additive Manufacturing of Dense Ceramics with Laser Induced Slip Casting (LIS) N2 - The possibility to produce dense monolithic ceramic parts with additive manufacturing is at the moment restricted to small parts with low wall thickness. Up to now, the additive manufacturing of voluminous ceramic parts is realized by powder bed based processes which, however, generate parts with residual porosity. Via infiltration these parts can be processed to dense parts like for example SiC but this is not possible for all ceramics like for example Si3N4. There is a lack of methods for the additive manufacturing of dense voluminous parts for most ceramics. We have developed a new additive manufacturing technology, the Laser Induced Slip casting (LIS), based on the layerwise deposition of slurries and their local drying by laser radiation. Laser Induced Slip casting generates ceramic green bodies which can be sintered to dense ceramic components like traditional formed ceramic powder compacts. We will introduce the LIS technology, green bodies and sintered parts will be shown and their microstructure and mechanical properties will be discussed. T2 - 42nd International Conference and Expo on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 21.01.2018 KW - Additive Manufacturing KW - Ceramics PY - 2018 AN - OPUS4-44182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Farahbod, L. A1 - Thiede, Tobias A1 - Rule, D. A1 - Haberland, C. A1 - Piegert, S. A1 - Witt, G. T1 - Assessment of SLM-Manufactured Single Struts as Major Elements of Complex Lattice Structures N2 - Additive Manufacturing (AM) enables the unique capability of building highly complex parts with integrated functional design. One particular advantageous design feature is known as lattice structures, which provide opportunities for innovative applications in the high-temperature regime of gas turbines. Generally, manufacturing of these structures is already known to be achievable with AM, however proof of structural integrity and geometrical accuracy is not yet reliably established. In this investigation, a systematic design-follows-complexity approach is utilized to pursue a holistic assessment of Ni based high temperature lattice. As the major element of lattice structures, single struts of different build orientations are investigated at first. This approach includes the application of Computed Tomography (CT), which allows for a non destructive assessment of quality criteria such as porosity and inner geometries as well as the parts’ metrology at a micrometre scale. The applied laboratory CT benefits from high magnification factors around 100 and voxel sizes down to a thousandth of the specimens’ diameter. Preliminary results show a correlation between the inclination angle and the struts’ quality, which indicate a dependency of geometrical accuracy and structural properties to the AM process setup. Consequently, lattice structures require the development of reliable manufacturing to produce dependable characteristics. While there is large potential for use of lattice structures in gas turbine and high temperature applications, the results indicate the strong need for an increased understanding of manufacturing and design as well as of the validation methods for these complex lattice structures. T2 - DDMC CY - Berlin, Germany DA - 14.03.2018 KW - Lattice Structures KW - AM KW - SLM KW - Porosity PY - 2018 AN - OPUS4-44512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiede, Tobias A1 - Farahbod, L. A1 - Léonard, Fabien A1 - Bruno, Giovanni T1 - Computed Tomography of SLM Produced IN625 Parts: From Powder Grains to Lattice Structures N2 - The layer-by-layer Additive Manufacturing (AM) by means of Selective Laser Melting (SLM) offers many prospects regarding the design of a part used in aeroplane components and gas turbines. However, structural deviations from the nominal morphology are unavoidable. The cooling of the finished part leads to shrinkage and a high surface roughness is induced by attached powder particles affecting the part volume too. The integrity and load-bearing capacity of a SLM produced lattice structure has been investigated by means of in-situ X-ray computed tomography during compression. The lattice structure was compressed by 10 % in height with an applied maximum force of 5 kN. Additionally, a single strut has been investigated ex-situ as a component of the lattice structure. With the higher resolution achieved on the single strut, the pore distribution (size and location) as well as the surface roughness were assessed. The particle and pore size distribution of the raw powder have been investigated, too. One of the main results coming from the in-situ analysis was that the nodes were identified as the weakest points in the lattice structure. T2 - Inno Testing CY - Wildau, Germany DA - 22.02.2018 KW - Additive Manufacturing KW - Selective Laser Melting KW - Computed Tomography KW - Lattice Structures KW - Porosity PY - 2018 AN - OPUS4-44515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiede, Tobias A1 - Farahbod, L. A1 - Léonard, Fabien A1 - Bruno, Giovanni T1 - In-situ compression CT on additively manufactured IN 625 lattice structures N2 - The layer-by-layer Additive Manufacturing (AM) by means of Selective Laser Melting (SLM) offers many prospects regarding the design of a part used in aeroplane components and gas turbines. However, structural deviations from the nominal morphology are unavoidable. The cooling of the finished part leads to shrinkage and a high surface roughness is induced by attached powder particles affecting the part volume too. The integrity and load-bearing capacity of a SLM produced lattice structure (see Fig.1) has been investigated by means of in-situ X-ray computed tomography during compression. The lattice structure was compressed by 10 % in height with an applied maximum force of 5 kN. Additionally, a single strut has been investigated ex-situ as a component of the lattice structure. With the higher resolution achieved on the single strut, the pore distribution (size and location) as well as the surface roughness were assessed. One of the main results coming from the in-situ analysis was that the nodes were identified as the weakest points in the lattice structure. T2 - iCT 2018 CY - Wels, Austria DA - 06.02.2018 KW - Additive manufacturing KW - Selective laser melting KW - Computed tomography KW - Lattice structure KW - In-situ compression CT KW - IN 625 PY - 2018 AN - OPUS4-44516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Maierhofer, Christiane A1 - Wachtendorf, Volker A1 - Fischer, C. T1 - Additiv gefertigte Kunststoffteile: Untersuchung der Beständigkeit durch künstliche Bewitterung und zerstörungsfreie Charakterisierung N2 - Es wird ein Verfahren zur Charakterisierung der Beständigkeit und Langzeitstabilität von additiv gefertigten Kunststoff-Bauteilen vorgestellt. Dabei sollen die Prüfkörper über 2000 Stunden künstlich bewittert und währenddessen die Änderungen der Eigenschaften der Bauteile zerstörungsfrei untersucht werden. Die Erkenntnisse dienen für die Entwicklung einer Strategie für eine Qualitätskontrolle von additiv gefertigten Kunststoffteilen. T2 - 47. Jahrestagung der GUS CY - Stutensee-Blankenloch, Germany DA - 21.03.2018 KW - Additive Fertigung KW - Additive manufacturing KW - Beständigkeit von Kunststoffen KW - Zerstörungsfreie Prüfung KW - Künstliche Bewitterung PY - 2018 AN - OPUS4-44589 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Active thermography for quality assurance of 3D-printed polymer structures T2 - DGZfP-Proceedings BB 167 N2 - Additively manufactured test specimens made of polyamide 12 (PA 12) by Laser Sintering (LS) as well as of acrylnitril-butadien-styrol (ABS) by Fused Layer Modeling (FLM), were tested with active thermography. For this, two different excitation methods (flash and impulse excitation) were used and compared, regarding the suitability for the detection of constructed and imprinted defects. To increase the quality of the thermograms, data processing methods like thermal signal reconstruction (TSR) and Fourier-Transformation were applied. Furthermore, the long-term stability of the probes towards environmental stress, like UV-radiation, heat, water contact and frost is being investigated in the presented project with artificial weathering tests. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Active thermography KW - Artificial weathering PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-453919 SP - Tu.3.A.2, 1 EP - 9 AN - OPUS4-45391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiede, Tobias A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Nadammal, Naresh A1 - Kromm, Arne A1 - Bode, Johannes A1 - Haberland, C. A1 - Bruno, Giovanni T1 - An assessment of bulk residual stress in selective laser melted Inconel 718 T2 - Proceedings ECNDT2018 N2 - Additive Manufacturing (AM) of metals has become industrially viable for a large variety of applications, including aerospace, automotive and medicine. Powder bed techniques such as Selective Laser Melting (SLM) based on layer-by-layer deposition and laser melt enable numerous degrees of freedom for the geometrical design. Developing during the manufacturing process, residual stresses may limit the application of SLM parts by reducing the load bearing capacity as well as induce unwanted distortion depending on the boundary conditions specified in manufacturing. The residual stress distribution in the bulk of IN718 elongated prisms produced by SLM was studied non-destructively by means of neutron diffraction. The samples with different scanning strategies, i.e. hatching length, were measured in as-build condition (on a build plate) and after removal from the build plate. The absolute values of all stress components decreased after removal from the build plate. Together with surface scan utilizing a coordinate-measuring machine (CMM), it is possible to link the stress release to the sample distortion. Obtained results indicated different residual stress states for each of the transversal, longitudinal and normal component depending on the thermal gradient in the respective direction. T2 - ECNDT 2018 CY - Göteborg, Sweden DA - 11.06.2018 KW - Residual stress KW - Selective laser melting KW - Neutron diffraction KW - IN718 PY - 2018 UR - http://cdn.ecndt2018.com/wp-content/uploads/2018/05/ecndt-0315-2018-File001.pdf SP - 1 AN - OPUS4-45325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Cabeza, Sandra A1 - Artzt, Katia A1 - Bruno, Giovanni A1 - Haubrich, Jan A1 - Requena, Guillermo T1 - Subsurface Residual Stress Analysis in Ti-6Al-4V Additive Manufactured Parts by Synchrotron X-ray Diffraction N2 - Synchrotron X-ray diffraction is a powerful non-destructive technique for the analysis of the material stress-state. High cooling rates and heterogeneous temperature distributions during additive manufacturing lead to high residual stresses. These high residual stresses play a crucial role in the ability to achieve complex geometries with accuracy since they can promote distortion of parts during manufacturing. Furthermore, residual stresses are critical for the mechanical performance of parts in terms of durability and safety. In the present study, Ti-6Al-4V bridge-like specimens were manufactured additively by selective laser melting (SLM) under different laser scanning speed conditions in order to compare the effect of process energy density on the residual stress state. Subsurface residual stress analysis was conducted by means of synchrotron X-ray diffraction in energy dispersive mode for three conditions: as-built on base plate, released from base plate, and after heat treatment on the base plate. The quantitative residual stress characterization shows a correlation with the qualitative bridge curvature method. Computed tomography (CT) was carried out to ensure that no stress relief took place owing to the presence of porosity. CT allows obtaining spatial and size pores distribution which helps in optimization of the SLM process. High tensile residual stresses were found at the lateral surface for samples in the as-built conditions. We observed that higher laser energy density during fabrication leads to lower residual stresses. Samples in released condition showed redistribution of the stresses due to distortion. T2 - ECNDT 2018 CY - Göteborg, Sweden DA - 11.06.2018 KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Computed tomography KW - Ti-6Al-4V PY - 2018 AN - OPUS4-45202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano Munoz, Itziar A1 - Laquai, René A1 - Müller, Bernd R. A1 - Mishurova, Tatiana A1 - Thiede, Tobias A1 - Bruno, Giovanni T1 - Microstructural characterization of the influence of SLM scan parameters by means of X ray and neutrons sources N2 - An overview of the main Non-Destructive activities conducted at BAM for the microstructural characterization of Additive Manufacturing (AM) materials will be presented. Focus is made on the study of the influence of Selective Laser Melted (SLM) scan strategies on the defect population of a Ti-6Al-4V alloy using the Analyzer Based Imaging (ABI) technique available at the BAMline (BESSY II synchrotron facility). ABI technique takes advantage of X Ray refraction at interfaces to enable the determination of porosity features (orientation, homogeneity, etc.) within large volumes, otherwise not possible to image by means X ray micro Computed Tomography. Additionally, for a SLM IN718 material, Energy Dispersive X Ray Diffraction (subsurface measurements at 100 µm depth) and neutrons diffraction (internal measurements at 3 mm depth) are combined with distortion measurements to produce a 3D description of the Residual Stress distribution throughout the entire sample. T2 - TMS (The Minerals, Metals & Materials Society) CY - Gaithersburg, Maryland, USA DA - 18.06.2018 KW - X-Ray refraction KW - Selective laser melted materials KW - Energy dispersive X Ray diffraction KW - Neutrons diffraction PY - 2018 AN - OPUS4-45435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Laquai, René A1 - Müller, Bernd R. A1 - Kasperovich, G. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Unterscheidung verschiedener charakteristischer Defekte in mittels selektivem Laserschmelzen hergestelltem Ti-6Al-4V durch Röntgen-Refraktionsradiographie T2 - DGZfP-Jahrestagung 2018 N2 - Das selektive Laserschmelzen (SLM) ist eine pulverbasierte, additive Fertigungsmethode, welche die Herstellung von komplex und individuell geformten Bauteilen ermöglicht. Im Laufe der vergangenen Jahre haben verschiedene Branchen, unter anderem die Luft- und Raumfahrt Industrie, begonnen diese Technologie intensiv zu erforschen. Insbesondere die Titanlegierung Ti-6Al-V4, welche aufgrund ihrer Kombination von mechanischen Eigenschaften, geringer Dichte und Korrosionsbeständigkeit häufig in der Luft- und Raumfahrt eingesetzt wird, eignet sich für die Herstellung mittels SLM. Allerdings können durch nicht optimal gewählte Prozessparameter, welche für gewöhnlich in einer Energiedichte zusammengefasst werden, Defekte in den Bauteilen entstehen. In dieser Studie wurde untersucht, in wie weit Röntgen-Refraktionsradiographie geeignet ist diese Defekte zu detektieren und zu charakterisieren. Bei der Röntgen-Refraktionsradiographie wird die Röntgenstrahlung, nachdem sie die Probe transmittiert hat, über einen Analysatorkristall gemäß der Bragg-Bedingung in den 2D-Detektor reflektiert und dabei nach ihrer Ausbreitungsrichtung gefiltert. Dadurch wird neben der Schwächung auch die Ablenkung der Röntgenstrahlung durch Refraktion im inneren der Probe zur Bildgebung ausgenutzt. Aus den aufgenommen Refraktionsradiogrammen kann der Refraktionswert berechnet werden. Dieser ist ein Maß für die Menge an inneren Oberflächen in der Probe. Zum einen konnte gezeigt werden, dass die Röntgen-Refraktionsradiographie Defekte detektieren kann, die kleiner sind als die Ortsauflösung des verwendeten 2D-Detektors. Zum anderen können zwei verschiedene Typen von Defekten unterschieden werden. Bei dem ersten Typ handelt es sich um runde Poren mit geringer innerer Oberfläche. Diese, sogenannten „keyhole pores“ sind charakteristisch für eine zu hohe Energiedichte während des SLM Prozesses. Bei dem zweiten Typ handelt es sich um nicht komplett aufgeschmolzenes Pulver. Diese Defekte zeichnen sich durch eine hohe innere Oberfläche aus und sind charakteristisch für eine zu geringe Energiedichte. Vergleichende Messungen mit hochauflösender Synchrotron CT und optischer Mikroskopie bestätigen die charakteristischen Formen der verschiedenen Defekte. T2 - DGZfP-Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Röntgen-Refraktion KW - Additive Fertigung KW - Porosität PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449524 SN - 978-3-940283-92-4 VL - DGZfP BB166 SP - Mo.2.A.2., 1 EP - 7 AN - OPUS4-44952 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -