TY - JOUR
A1 - Dudziak, Mateusz
A1 - Topolniak, Ievgeniia
A1 - Silbernagl, Dorothee
A1 - Altmann, Korinna
A1 - Sturm, Heinz
T1 - Long-time behavior of surface properties of microstructures fabricated by multiphoton lithography
N2 - The multiphoton lithography (MPL) technique represents the future of 3D microprinting, enabling the production of complex microscale objects with high precision. Although the MPL fabrication parameters are widely evaluated and discussed, not much attention has been given to the microscopic properties of 3D objects with respect to their surface properties and time-dependent stability. These properties are of crucial importance when it comes to the safe and durable use of these structures in biomedical applications. In this work, we investigate the surface properties of the MPL-produced SZ2080 polymeric microstructures with regard to the physical aging processes during the post-production stage. The influence of aging on the polymeric microstructures was investigated by means of Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). As a result, a time-dependent change in Young’s Modulus, plastic deformation, and adhesion and their correlation to the development in chemical composition of the surface of MPL-microstructures are evaluated. The results presented here are valuable for the application of MPL-fabricated 3D objects in general, but especially in medical technology as they give detailed information of the physical and chemical time-dependent dynamic behavior of MPL-printed surfaces and thus their suitability and performance in biological systems.
KW - Multiphoton lithography
KW - Additive manufacturing
KW - Microfabrication
KW - SZ2080 negative photo-resist
KW - Young´s modulus
KW - Aging
KW - Surface properties
KW - X-ray photoelectron spectroscopy
KW - Atomic force microscopy
KW - Force-distance-curve
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542166
DO - https://doi.org/10.3390/nano11123285
SN - 2079-4991
VL - 11
IS - 12
SP - 1
EP - 12
PB - MDPI
CY - Basel
AN - OPUS4-54216
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hejazi, Bardia
T1 - X-ray Computed Tomography Image Compression and Denoising with AI
N2 - The ever-growing volume of data in imaging sciences stemming from advancements in imaging technology, necessitates efficient and reliable storage solutions for such large datasets. In this study, we investigated the compression of industrial X-ray computed tomography (XCT) data using deep learning and examined how these compression algorithms affect the quality of the recovered data. To determine best strategies, we investigated two different network architectures with different compression rates. The XCT data used was from a sandstone sample with a complex internal pore network. The quality of the recovered images obtained from the two different deep learning architectures with different compression rates were quantified and compared to the original input data. We showed that the most suitable architecture and compression rate can change, depending on what specific characteristics we would need to preserve for later analysis. The findings presented here can aid scientists in determining the best approaches and strategies for their data storage and analysis requirements.
T2 - BAM AI & ML Symposium
CY - Berlin, Germany
DA - 06.11.2025
KW - X-ray computed tomography
KW - Compression
KW - Deep Learning
PY - 2025
AN - OPUS4-65610
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ponader, Marco
A1 - Röder, Bettina
A1 - Paul, Martin
A1 - Weller, Michael G.
T1 - Sintered glass monoliths as supports for affinity columns
N2 - A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 min. Due to the glass material’s excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nano-filtration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run.
KW - Affinity Chromatography
KW - Affinity Extraction
KW - Affinity Separation
KW - Protein Purification
KW - Down Stream Processing
KW - Antibody Purification
KW - Diagnostic Antibodies
KW - Therapeutic Antibodies
KW - Automated Purification
KW - HPLC
KW - FPLC
KW - IgG determination
KW - Concentration step
KW - Monoclonal Antibodies
KW - Polyclonal Antibodies
KW - Human Plasma
KW - Glass Support
KW - Borosilicate Glass
KW - Monolith
KW - Sintered Material
KW - Additive Manufacturing
KW - Column holder
KW - Construction
KW - Open Science
KW - Citizen Science
KW - Protein A
KW - Regeneration
KW - High-Speed Separations
KW - Robustness
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527581
DO - https://doi.org/10.3390/separations8050056
SN - 2297-8739
N1 - Geburtsname von Ponader, Marco: Wilke, M. - Birth name of Ponader, Marco: Wilke, M.
VL - 8
IS - 5
SP - 1
EP - 16
PB - MDPI
CY - Basel
AN - OPUS4-52758
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - INPR
A1 - Ponader, Marco
A1 - Röder, Bettina
A1 - Paul, Martin
A1 - Weller, Michael G.
T1 - Sintered glass monoliths as new supports for affinity columns
N2 - A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 minute. Due to the glass material's excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nanofiltration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run.
KW - Affinity Chromatography
KW - Glass
KW - Purification
KW - Antibodies
KW - Solid support
KW - HPLC
KW - FPLC
KW - Separation
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529117
DO - https://doi.org/10.20944/preprints202103.0298.v1
SN - 2310-287X
N1 - Geburtsname von Ponader, Marco: Wilke, M. - Birth name of Ponader, Marco: Wilke, M.
SP - 1
EP - 17
PB - MDPI
CY - Basel
AN - OPUS4-52911
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Heinekamp, Christian
T1 - An Amorphous Lewis-acidic Zirconium Chlorofluoride as HF Shuttle: C-F Bond Activation and Formation
N2 - In recent years, fluorine chemistry has gained increasing political attention. Owing to a growing shortage of fluorspar, a raw material used for producing fluorinated base chemicals, fluorospar has been named among the 30 critical raw materials in the EU.2 As such, it becomes increasingly important to recycle existing fluorinated compounds and make them available as sources of fluorine for reactions. Significant progress has been made in the field of C-F bond activation using heterogeneous catalysts such as aluminum chlorofluoride (ACF).3–5 However, the transfer of fluorine atoms from one molecule to another using heterogeneous catalysts has not yet been reported. In this study, we successfully synthesized amorphous zirconium chlorofluoride (ZCF), and we were able to establish a catalytic behavior of ZCF in C-F bond activation reactions. We present a heterogeneous catalyst that performs dehydrofluorination of a fluoroalkane and consecutive hydrofluorination of an alkyne at room temperature.
T2 - 2nd South African Fluorine Symposium
CY - Sun City, South Africa
DA - 09.02.2024
KW - ZCF
KW - Heterogeneous catalysis
KW - C-F bond activation
KW - HF-shuttle
PY - 2024
AN - OPUS4-59618
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hilberg, Alec
T1 - Untersuchung und Kompensation des Size-of-Source Effektes der Thermografie zur Prozessüberwachung in der metallischen additiven Fertigung
N2 - Der Einsatz der Thermografie zur Prozessüberwachung in der additiven Fertigung von Metallen ist aktueller Schwerpunkt diverser Forschungsprojekte. Prozessbedingt können im Bauteil Risse, innere Spannungen und sonstige interne Fehlerstellen auftreten, deren Entstehung durch wichtige thermische Größen wie Phasenumwandlungstemperaturen, Abkühlgeschwindigkeiten und thermische Gradienten beeinflusst wird. Um diese Einflüsse zu untersuchen, ist eine möglichst genaue Messung dieser Parameter notwendig.
Neben den häufig betrachteten Einflüssen des Emissionsgrades, der Umgebungstemperatur und der atmosphärischen Absorption besteht ein weiterer Einfluss, hervorgerufen durch das optische System. Der Kameraaufbau, das verwendete Objektiv und Teilchen im Strahlengang können zur Beugung, Streuung, Reflektion und Aberration der elektromagnetischen Strahlung führen, wodurch die thermografische Messung verfälscht wird. Dies ist ein in der Pyrometrie intensiv erforschter Effekt und wird, aufgrund der Abhängigkeit zur betrachteten Objektgröße, als Size-of-Source Effekt bezeichnet und in dieser Arbeit untersucht.
Im Laser-Pulver-Auftragsschweißen (LPA) wird mittels eines Lasers auf einer Substratplatte ein Schmelzbad erzeugt und durch Einblasen von Metallpulver die lagenweise Fertigung von komplexen Bauteilen ermöglicht. Dabei können, je nach geometrischer Auflösung der Kamera, Größen des Schmelzbades im Bereich weniger Prozente der gesamten Bildfläche auftreten. Aus durchgeführten Referenzmessungen an Schwarzkörperstrahlern kann in der gleichen Größenordnung eine Abweichung der Strahlungswerte im zweistelligen Prozentbereich festgestellt werden. Daher ist in diesem Anwendungsfall der dadurch verursachte Fehler nicht zu vernachlässigen, weshalb auf Basis der Referenzmessungen eine Methode entwickelt wurde, um in Abhängigkeit der Größe des Objektes einen Faktor zur Kompensation des Size-of-Source Effektes zu berechnen.
In diesem Beitrag werden erste Ergebnisse dieser im Rahmen des DFG Projektes QT-LPA (Nr. 516965606) durchgeführten Arbeiten präsentiert.
T2 - DGZfP Jahrestagung 2025
CY - Berlin, Germany
DA - 26.05.2025
KW - SSE
KW - Thermografie
KW - Size of source Effect
PY - 2025
AN - OPUS4-65651
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hilberg, Alec
T1 - Multispektrale Thermografie zur quantitativen Temperaturbestimmung im DED-LB/M Prozess
N2 - Additive Fertigungsverfahren bieten konstruktive Freiheiten, die mit konventionellen Herstellungsverfahren nur schwer zu realisieren sind. Durch die Möglichkeit hochkomplexe Bauteile aus Metall fertigen zu können, stellt die additive Fertigung in vielen Industriezweigen eine vielversprechende Fertigungsalternative da. Allerdings treten prozessbedingt hohe Temperaturgradienten und schnelle Phasenumwandlungen auf, die maßgeblich entscheidend für die Mikrostruktur und die Bildung von internen Spannungen, Rissen und weiteren Defekten sind. Diese Effekte wirken sich direkt auf die mechanischen Eigenschaften der gefertigten Bauteile aus und verdeutlichen die Notwendigkeit einer zuverlässigen Bauteilprüfung. Dabei sind nachgelagerte Verfahren in der Regel zeit- und kostenaufwändig, weshalb die Anwendung von in-situ Verfahren zur Qualitätssicherung im Fokus diverser Forschungsprojekte steht.
Die Thermografie erlaubt die orts- und zeitaufgelöste Messung der im Prozess auftretenden Temperaturfelder. Allerdings müssen die tatsächlich gemessenen digitalen Sensorwerte mittels geeigneter radiometrischer Modelle in Temperaturen umgewandelt werden. Da diese Modelle in der Regel auf Basis von Messungen an Schwarzkörperstrahlern kalibriert werden, kann dieses Vorgehen nur zufriedenstellende Werte liefern, sofern der Emissionsgrad des zu messenden Objektes bekannt ist. Während in statischen Anwendungen häufig ein konstanter Materialreferenzwert hinreichend befriedigende Ergebnisse liefert, ist man in der additiven Fertigung mit dem Problem konfrontiert, dass der Emissionsgrad lokal in kürzester Zeit starke Änderungen durchläuft. Beeinflusst wird dieser Effekt unter anderem durch Temperatur, Phasenzustand und Oberflächenzustand.
Das hier vorgestellte Verfahren nutzt Referenzmessungen des Emissionsgrades in Abhängigkeit von Temperatur, Winkel und Phasenzustand, um in einem DED-LB/M-Prozess (auch Laser-Pulver-Auftragschweißen, LPA) sowohl den Emissionsgrad als auch die tatsächliche Temperatur orts- und zeitaufgelöst zu bestimmen. Grundlage hierfür sind multispektrale thermografische Messungen, bei denen (quasi-) synchron in acht unterschiedlichen Wellenlängenbereichen gemessen wird.
In diesem Beitrag werden Ergebnisse der im Rahmen des DFG-Projektes QT-LPA (Nr. 516965606) durchgeführten Arbeiten präsentiert.
T2 - Thermo25
CY - Garching bei München, Germany
DA - 11.11.2025
KW - Thermografie
KW - TES
KW - Multispektral
KW - DED-LB/M
KW - Laserpulverauftragschweißen
PY - 2025
AN - OPUS4-65652
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Jesus, Vinicius D.
A1 - Merizio, Leonnam G.
A1 - Galleani, Gustavo
A1 - Raffy, Guillaume
A1 - Carpentier, Mathis
A1 - Petit, Yannick
A1 - Cardinal, Thierry
A1 - de Camargo, Andrea S. S.
T1 - Energy transfer from Ag species to Nd 3+ in Ga–fluoride–phosphate glasses: near-infrared emission enhancement via controlled heat treatment and femtosecond laser inscription
N2 - Gallium fluoride–phosphate glasses are promising materials with wide optical transmission window, high volumetric density, and the ability to accommodate high concentrations of rare earth dopant ions within a tailored fluoride-rich coordination environment, resulting in high emission cross sections. In this work, the compositional system 25Ga(PO3)3–20ZnF2–30BaF2–(25–x–y)SrF2–xAgNO3–yNdF3 (x = 0–10 mol%, y = 0 or 1 mol%) was studied to understand how silver species affect the near-infrared (NIR) emission of Nd3+ ions, when the glasses are subjected to controlled heat treatment and to femtosecond direct laser writing (DLW). The glasses were obtained via the melt-quenching technique and characterized by DSC, XRD, UV-Vis-NIR absorption, and PL spectroscopy. The as-prepared glasses show broad UV-Vis excitation and emission bands arising from the coexistence of Ag+ ions and ionic Ag pairs. In samples with 10 mol% Ag+, brownish coloration and modified emission profiles indicated Ag nanoparticle formation at the surface. Heat treatment promoted the conversion of isolated Ag+ into ionic pairs, producing broadband emissions tunable by excitation wavelength and Ag+ concentration. In co-doped samples, Nd3+ introduced absorption dips in the Ag-related UV-Vis bands, consistent with energy transfer, which was further confirmed by shortened Ag excited-state lifetimes and increased Nd3+ NIR emission under UVVis excitation. In order to control the spatial distribution and size of Ag aggregates (nanoclusters, NCs) and to increase the energy transfer efficiency to Nd3+, femtosecond direct laser writing (DLW) was employed to co-doped glasses with 3 and 5 mol% Ag+. This approach enabled three-dimensional localized growth of Ag NCs with sub-micron spatial control. In the laser processed regions, the NIR emissions of Nd3+ at 900 and 1060 nm were significantly enhanced, clearly evidencing enhanced energy transfer from the localized laserinduced Ag-NCs to the Nd3+ ions. These findings suggest the possibility of tailoring high optical contrast near-IR emissions in glasses, enabling progress in advanced photonic applications.
KW - Neodymium
KW - Silver
KW - Fluoride phosphate glasses
KW - Direct laser writing
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656888
DO - https://doi.org/10.1039/d5ma01430a
SN - 2633-5409
SP - 1
EP - 14
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-65688
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Scharf-Wildenhain, R.
A1 - Engelking, Lorenz
A1 - Hälsig, A.
A1 - Schröpfer, Dirk
A1 - Kannengießer, Thomas
A1 - Hensel, J.
T1 - Influence of build‑up height on residual stresses in additive repair and modification using DED‑Arc with high‑strength filler metals
N2 - Directed energy deposition (DED)-Arc is suitable for the hybrid additive manufacturing, modification and repair of large metal components with high deposition rates. Residual stresses and distortion are of central importance when characterizing the manufactured components and the sensitive transition area between additive manufactured (AM) component and semifinished product. Residual stresses caused by the thermal cycles during the manufacturing process can impair the mechanical properties of the manufactured parts and can lead to component failure, especially for high-strength steels. Therefore, understanding and controlling residual stresses, when combining different base and feedstock materials, is critical to improve the quality and efficiency of the hybrid DED-Arc process. This article deals with the influence of the build-up height on the residual stress distribution of additively manufactured components with a selected base and feedstock material from commercial high-strength steels. Using a robot-assisted DED-system and a controlled short arc, AM welding experiments were carried out with close to the application parameters at working temperature (200 °C) and heat input (650 kJ/m). Five hybrid AM specimens (AM wall on upright structural steel plate) were produced using a one bead per layer strategy and selected AM-wall heights between 15 and 300 mm. The influence of the AM build height on the longitudinal residual stress in the whole hybrid AM specimen (in welding direction) was analyzed and discussed. All experiments exhibit comparable stress distributions in the area of the substrate plate up to the heat-affected zone (HAZ) and the transition zone, regardless of the building height. The height significantly influences the residual stress distribution of the deposited AM-component. Tensile residual stresses with a maximum range between 300and 400 MPa were always found in the last approx. 18 component layers (upper 40 mm). This is due to restraint of the shrinking of the top layers by the layers below. The lower layers show homogeneous residual stress distributions characterized by low compressive stresses due to the process-related tempering during the deposition of each layer on top of each other. As a result, the significant difference between the various AM build-up heights of the hybrid AM specimens is the extent (or height) of this tempered zone with low compressive stresses. These correlations contribute to the understanding of residual stress development with increasing structure height or ratio of component heights of substrate semi-finished product and AM component in hybrid additive manufacturing.
T2 - 78th IIW Annual Assembly and International Conference
CY - Genoa, Italy
DA - 22.06.2025
KW - DED-Arc
KW - Residual stress
KW - Heat control
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656793
DO - https://doi.org/10.1007/s40194-026-02417-y
SN - 1878-6669
SP - 1
EP - 12
PB - Spriner
AN - OPUS4-65679
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Suarez Ocano, Patricia
T1 - Influence of heat-treatment-induced microstructural evolution on the Low Cycle Fatigue behavior of 316L stainless steel fabricated by Laser Powder Bed Fusion
N2 - Additive manufacturing, particularly the laser powder bed fusion (PBF-LB/M) process, has gained significant attention in recent years due to its ability to produce complex geometries with enhanced mechanical properties. Among the various materials used, 316L stainless steel is highly favored for cyclically loaded components due to its exceptional mechanical strength, high-temperature performance, and corrosion resistance, making it widely applicable across various industries. 316L SS fabricated by PBF-LB/M (PBF-LB/M/316L) exhibits a unique hierarchical microstructure, with high density of low-angle grain boundaries (LAGBs), nano-dispersed silicates, chemical micro-segregations, and solidification-induced cellular structures. Particularly, the submicron-sized cellular features enriched with chromium (Cr) and molybdenum (Mo), along with high dislocation densities, contribute to a superior strength-ductility balance compared to conventionally manufactured 316L SS. The dispersed silicate particles act also as a strengthening phase, impeding dislocation movement and enhancing plastic deformation resistance.
This study explores the effect of heat treatments on the low-cycle fatigue (LCF) behavior of PBF-LB/M/316L at room temperature (RT) and 600 °C. First, three heat treatment conditions were applied to the as-built material: 450 °C for 4 hours (HT450/4), 800 °C for 3 hours (HT800/3), and 900 °C for 1 hour (HT900/1) to investigate their influence on microstructural evolution. Microstructural analysis revealed that the HT450/4 condition preserved the cellular structure with high dislocation density, while the HT800/3 condition showed partial dissolution of cells together with reduction in segregated elements along the cell walls and a reduced dislocation density. The HT900/1 condition resulted in complete segregation and cellular structure dissolution with comparable dislocation density to HT800/3 while maintaining the crystallographic texture and grain morphology. Intermetallic χ phase was mostly observed at the grain boundaries in HT800/3, but not in HT900/1. Fully reversed LCF tests were conducted under strain-controlled conditions with a strain amplitude of 0.8 %. Tests were interrupted at specific intervals to analyze the interaction between hierarchical microstructural features and deformation mechanisms in the three heat-treated conditions. Due to the pronounced dislocation cell structures and elemental segregation, the microstructure of the HT450/4 condition significantly impact deformation and damage mechanisms during cyclic loading, which in turn, differ from the conventional produced counterparts. The results provide insights into the relationship between microstructural features and fatigue performance, highlighting key deformation and failure mechanisms under cyclic loading.
T2 - FEMS 2025 EUROMAT 18th European Congress and Exhibition on Advanced Materials and Processes
CY - Granada, Spain
DA - 14.09.2025
KW - Additive manufacturing
KW - 316L stainless steel
KW - Heat treatments
KW - Low Cycle Fatigue
KW - Microstructure
PY - 2025
AN - OPUS4-64238
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Agudo Jácome, Leonardo
T1 - Low-Cycle Fatigue Behavior of Laser Powder Bed Fused Inconel 718 at Room and High Temperature
N2 - The nickel-base superalloy Inconel 718 (IN718) is one of the most commonly used Ni-based superalloys for high temperature structural applications for its remarkable strength, as well as creep, fatigue, and corrosion resistance up to 650 °C. While IN718 has traditionally been employed as cast or wrought material, it is difficult to machine because of its high strength and toughness. The additive manufacturing of IN718 components made by metal AM has thus gained extensive attention to produce expensive near-net shaped components of high-temperature alloys such as IN718, for it saves material and costs in processing and machining steps. Among all metal additive manufacturing (AM) technologies, laser powder bed fusion (PBF-LB/M) is the most widespread, IN718 being one of the most common alloys produced with it. However, high cooling rates associated to the PBF-LB/M process, hinders the primary strengthening phases γ’’ and γ’ to form, as these cooling rates induce a dislocation cellular substructure, at which walls primary Laves phases bind segregating Nb, Ti and Mo. Many of the therefore needed heat-treatment strategies can then promote Laves-phase transformation into the stable δ phase along the cell and grain boundaries. Laves and δ phases, as well as grain-boundary primary carbides may have adverse effects on mechanical properties. The mostly needle-shaped δ phase was namely found to have a detrimental effect on creep rupture life while no direct effect on LCF fatigue life was evident. In this work room- and high-temperature (650 °C) low-cycle fatigue behavior of PBF-LB/M IN718 is investigated in the four-step heat-treated state and compared to wrought IN718. The microstructure of both materials is characterized across length scales via microscopy methods. The fatigue life at room temperature of the PBF-LB/M IN718 material is slightly lower than that for the wrought material, which is reversed at 650 °C. The cyclic stress response for both materials is marked by cyclic softening that is more pronounced at higher test temperatures. Multiple secondary cracks form at high strain amplitudes, at both room and high temperatures. High testing temperatures enhance specially crack formation at the transitions of regions between elongated grains and columns of stacked grains with ripple patterns in the PBF-LB/M material. Additional to this behavior, pronounced crack branching and deflection indicate that the cracks are controlled by sharp micromechanical gradients.
T2 - EUROMAT 2025
CY - Granada, Spain
DA - 14.09.2025
KW - Additive manufacturing
KW - Low-cycle fatigue
KW - Microstructural characterization
KW - Ni-base superalloy
PY - 2025
AN - OPUS4-64354
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Witte, Julien
A1 - Treutler, Kai
A1 - Schroepfer, Dirk
A1 - Kannengiesser, Thomas
A1 - Wesling, Volker
T1 - Influence of microstructure on the machinability and surface integrity of additively manufactured iron aluminides
N2 - The increasing global focus on energy and resource efficiency has stimulated a growing interest in additive manufacturing. AM offers economic advantages and enables an efficient use of materials. However, AM components often require subsequent mechanical post-processing, such as machining (e.g., milling), to achieve the final contours or surfaces. This is a particular challenge due to the heterogeneous and anisotropic nature of AM structures, which affect machining and the resulting component properties. High-performance materials such as iron aluminide represent a promising alternative to conventional high-temperature materials with a significant economic advantage. However, the strength and hardness properties, which are advantageous for applications in highly stressed lightweight components, pose a challenge for economical machining in addition to the AM microstructure properties. The difficult-to-cut material causes accelerated tool wear and insufficient surface quality. This study shows that crack-free additive manufacturing of the three-component system of iron-nickel-aluminum is possible, and advantages in terms of machinability compared to FeAl-AM components are achieved. The more homogeneous microstructure leads to a reduction in cutting forces, with positive effects on the machinability and optimized surface integrity. Ultrasonic assisted milling (USAM) offers great potential to address the major challenges posed by difficult-to-cut materials and additively manufactured weld structures. Therefore, this study focuses on assessing the transferability of previous positive results by USAM to the selected iron aluminide alloys. The machinability of the aluminides is analyzed by varying significant influencing variables in finish milling experiments and evaluated in terms of the loads on the tool and the resulting surface integrity.
KW - Iron aluminide
KW - Additive manufacturing
KW - Machinability
KW - Surface integrity
KW - Ultrasonic-assisted milling process
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656993
DO - https://doi.org/10.1007/s40194-026-02382-6
SN - 0043-2288
SP - 1
EP - 13
PB - Springer Science and Business Media LLC
AN - OPUS4-65699
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mohr, Gunther
T1 - R&D insights into sustainable additive manufacturing for high-temperature applications (HTA)
N2 - Im Rahmen des AM Forums Berlin 2026 wird durch diesen Vortrag ein Einblick in FuE-Aktivitäten der BAM auf dem Gebiet der additiven Fertigung für Hochtemperaturanwendungen gegeben. Es werden dabei insbesondere Aspekte der nachhaltigen Verwendung von Pulverausgangswerkstoff und der Einfluss von Sauerstoff im Pulverwerkstoff auf die Degradation resultierender mechanischer Eigenschaften von Probekörpern beleuchtet. Die präsentierten Arbeiten sind im Rahmen des Pro FIT Projektes HTA2.0 entstanden.
T2 - 10. AM Forum 2026
CY - Berlin, Germany
DA - 10.03.2026
KW - Additive Manufacturing
KW - Sustainability
KW - Powder recycling
KW - Powder degradation
PY - 2026
AN - OPUS4-65725
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Suarez Ocano, Patricia
T1 - Effect of the powder composition on the microstructure and mechanical properties of 316L stainless steel fabricated by laser powder bed fusion
N2 - Additive manufacturing (AM) has seen rapid growth in recent decades, with Laser Powder Bed Fusion (PBF-LB/M) emerging as the leading technique for producing high-density, geometrically complex metal parts. Austenitic stainless steel 316L is one of the most studied alloys for PBF-LB/M due to its excellent strength, ductility, and corrosion resistance [1]. The microstructure formed during PBF-LB/M processing can improve certain mechanical properties compared to conventionally manufactured 316L [2].
However, the current 316L standards allow broad ranges for key alloying elements, particularly Cr and Ni. While such variations have little effect on conventionally produced alloys, emerging evidence shows that they can markedly alter the microstructure and mechanical properties in PBF-LB/316L—even within specification limits [3]. This study investigates through microstructural and thermodynamical assessment, how two powders of nominally standard 316L composition (Alloys A and B) respond to identical PBF-LB/M processing parameters. Despite identical printing conditions, Alloy A exhibited
twice the grain size and five times higher low-angle grain boundary (LAGB) density compared to Alloy B . Conversely, Alloy B showed a significantly higher density of Σ3 twin boundaries, nearly absent in Alloy A. These microstructural differences are attributed primarily to variations in Cr and Ni content in the liquid, which may influence icosahedral short-range ordering (ISRO) mechanism [4]. ISRO potentially facilitates twin boundary formation, ultimately refining grain structure [5]. This work highlights the critical impact of compositional control on final part microstructures and consequent mechanical properties and emphasizes the need to reassess compositional tolerances for AM-specific applications.
T2 - 5th Symposium on Materials and Additive Manufacturing (Additive 2026)
CY - Kassel, Germany
DA - 24.03.2026
KW - Additive manufacturing
KW - 316L stainless steel
KW - Chemical composition
KW - Lcosahedral short-range ordering mechanism
KW - Grain size
PY - 2026
AN - OPUS4-65738
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Raute, J.
A1 - Schmidt, J.
A1 - Bhadeliya, A.
A1 - Rehmer, B.
A1 - Olbricht, J.
A1 - Jokisch, T.
A1 - Biegler, M.
A1 - Rethmeier, M.
T1 - Investigation on seam quality and fatigue crack propagation in electron beam welded additive manufactured Inconel 939
N2 - Laser powder bed fusion of metals (PBF-LB/M) offers great potential for the production of new and spare parts for stationary gas turbines made of nickel superalloys such as Inconel 939 (IN939). In order to enable integration into existing assemblies and overcome design limitations, the additive manufacturing process chain must be expanded by suitable joining techniques. This study compares the electron beam welding of cast IN939 sheets and sheets produced additively using PBF-LB/M. The investigation focuses on the achievable seam quality with regard to geometric irregularities and internal defects in the form of liquation cracks on the microscale in the heat-affected zone. The evaluation of the welded samples shows no differences in the formation of the seam shape between the additively manufactured material and the cast material. For both materials, the highest quality category for beam-welded seams according to DIN EN ISO 13,919–1 was achieved at high welding speeds of 20 mm/s. Regardless of the manufacturing method, both materials show an increase in crack formation with increasing welding speed. However, due to its microstructure, the PBF-LB/M material exhibits significantly fewer microcracks overall. Final crack propagation tests on welded PBF-LB/M samples that were treated using HIP also show stable crack growth without sudden failure, which opens up potential for practical application.
KW - Electron beam welding
KW - Inconel 939
KW - PBF-LB/M
KW - Liquation cracking
KW - Fatigue crack propagation
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657015
DO - https://doi.org/10.1016/j.jajp.2026.100389
SN - 2666-3309
VL - 13
SP - 1
EP - 10
PB - Elsevier B.V.
AN - OPUS4-65701
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -