5 Werkstofftechnik
Filtern
Erscheinungsjahr
- 2021 (168) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (71)
- Vortrag (71)
- Beitrag zu einem Tagungsband (11)
- Posterpräsentation (8)
- Dissertation (2)
- Sonstiges (2)
- Buchkapitel (1)
- Corrigendum (1)
- Forschungsdatensatz (1)
Schlagworte
- Corrosion (19)
- Additive manufacturing (10)
- Additive Manufacturing (8)
- Steel (8)
- EBSD (7)
- CCS (6)
- Microstructure (6)
- Fatigue (5)
- Mechanical properties (5)
- Residual stress (5)
- SEM (5)
- Carbon capture storage (4)
- Crack growth (4)
- Creep (4)
- Fraktographie (4)
- Geothermal (4)
- Laser powder bed fusion (4)
- Ontology (4)
- Sintering (4)
- Thermomechanical fatigue (4)
- Transmission electron microscopy (4)
- 316L (3)
- CO2 quality (3)
- Ceramics (3)
- Corrosion fatigue (3)
- Crack tip opening displacement (3)
- Creep behavior (3)
- Digitalisierung (3)
- Full Notch Creep Test (3)
- Glass fiber reinforced polymers (3)
- High alloyed steel (3)
- High-temperature corrosion (3)
- Impurities (3)
- Inverted classroom (3)
- Martensitic steel (3)
- Metallic glass (3)
- Microstrucrue Design (3)
- Oxidation (3)
- Pattern matching (3)
- Pipeline network (3)
- Recommendations (3)
- Thermoelectrics (3)
- Whole-chain CCS scenario (3)
- Wissensrepräsentation (3)
- Agglomerates (2)
- Aging (2)
- Al2O3 (2)
- Alkali ions (2)
- CALPHAD (2)
- CCU (2)
- CO2 (2)
- Carbon capture and storage (2)
- Characterization (2)
- Chemically complex alloy (2)
- Chromium oxide (2)
- Coatings (2)
- Composite (2)
- Crystal plasticity (2)
- Damage (2)
- Defects (2)
- Density-based Thermodynamics (2)
- Density-based model (2)
- Diffusion (2)
- Diopsid (2)
- Dispersion process (2)
- Electron diffraction (2)
- Environmental stress cracking (2)
- Fatigue performance (2)
- Fe-Al alloys (2)
- Fractography (2)
- Fracture surface (2)
- Fracture toughness (2)
- Glass (2)
- Glass forming (2)
- High entropy alloy (2)
- High entropy alloys (2)
- High-density polyethylene (2)
- High-entropy alloy (2)
- High-entropy alloys (2)
- Hydrogen (2)
- Intermetallics (2)
- Iron aluminides (2)
- Kikuchi diffraction (2)
- Manganese oxide (2)
- Microstructural analysis (2)
- Multilayertechnik (2)
- Nano-powder (2)
- Nanoindentation (2)
- Neutron diffraction (2)
- Nickel alloys (2)
- Nickel-base alloy (2)
- Nickel-base superalloys (2)
- Normung (2)
- Ontologie (2)
- Oxidation behavior (2)
- PMD (2)
- Phase-field simulation (2)
- Plasticity (2)
- Polyaniline (2)
- Protective coating (2)
- REM (2)
- Residual Stress (2)
- SIMS (2)
- Sample preparation (2)
- Semantic Web (2)
- Shear bands (2)
- SiO2 (2)
- Sibayak (2)
- Single-Crystal (2)
- Single-crystals (2)
- Sol-gel coating (2)
- Spectroscopy (2)
- Standardization (2)
- Superalloys (2)
- Tensile Test (2)
- Thermoelectric (2)
- Ti-6Al-4V (2)
- Transmission electron microscopy (TEM) (2)
- Viscosity (2)
- Wall thickness (2)
- Zugversuch (2)
- 3D REM (1)
- 3D etching (1)
- 3D printing (1)
- 3D-printing (1)
- 4-Dimensional scanning transmission (1)
- 9-12%Cr steel (1)
- AGIL (1)
- AISI 316L (1)
- AM (1)
- Additive Fertigung (1)
- Advanced high strength steels (1)
- Ageing (1)
- Al alloys (1)
- Al-Cu alloy (1)
- Alkali and alkaline earth silicate and borate glass (1)
- Alkali zinc borate glass (1)
- Analytical scanning electron microscopy (1)
- Analytical services (1)
- Anisotropy (1)
- Aquifer fluid (1)
- Atomistic simulations (1)
- Austenite-to-martensite phase transformation (1)
- Behmite (1)
- Binder Jetting (1)
- Bio-ceramic engineering (1)
- Bioactive glass (1)
- Blended learning (1)
- Borate glasses (1)
- Brittle fracture (1)
- Bruchflächen (1)
- Bruchflächenauswertung (1)
- Bulk metallic glasses (1)
- Bundesoberbehörden (1)
- Burst test (1)
- CO2-storage (1)
- Cabon capture and storage (1)
- Calculated intrinsic fracture toughness (1)
- Carbon dioxide (1)
- Carbon fibres (1)
- Carbon steel (1)
- Casing (1)
- Catalogue of services (1)
- Cellular substructure (1)
- Cement (1)
- Centrifugal casting (1)
- Ceramic (1)
- Ceramic multilayer (1)
- Ceramics 3D printing (1)
- Chemo-mechanical coupling (1)
- Coating (1)
- Complex borides (1)
- Composite pressure vessels (1)
- Composite recycling (1)
- Compositionally complex alloy (1)
- Compositionally complex alloys (1)
- Computed tomography (1)
- Contact mechanics (1)
- Contamination (1)
- Cooling simulations (1)
- Covid-19 (1)
- Cow stress (1)
- Cr2O3 (1)
- Crack growth in air (1)
- Crystal Defects (1)
- Crystallization (1)
- DCB (1)
- Damage Tolerance (1)
- Damage mechanisms (1)
- Datenbank (1)
- Datenmanagement (1)
- Deep learning (1)
- Defects engineering (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Deformation mechanisms (1)
- Densty-based Thermodynamics (1)
- Dental (1)
- Deposition microstructure (1)
- Die casting (1)
- Dielectric breakdown (1)
- Dielectric strength (1)
- Differential scanning calorimetry (DSC) (1)
- Diffraction (1)
- Digitization (1)
- Dislocation avalanches (1)
- Dislocation substructure (1)
- Diversity (1)
- Dry preparation (1)
- Drywood termite (1)
- EC4SafeNano (1)
- EDXRD (1)
- Elastic constants (1)
- Elastic energy (1)
- Elasticity (1)
- Electric field strength (1)
- Electrical insulators (1)
- Electron backscatter diffraction (1)
- Electron microscopy (1)
- Electron microscopy, transmission (1)
- Energy harvesting (1)
- Environmental Stress Cracking (1)
- Environmental stress cracking (ESC) (1)
- Ermüdung (1)
- Ermüdungsriss (1)
- European Centre (1)
- Eutectic (1)
- Failure mechanisms (1)
- Faser (1)
- Faser-Kunststoff-Verbund (1)
- Faser-Kunststoff-Verbunde (1)
- Fem (1)
- Ferritic Alloys (1)
- Fertigungsprozess (1)
- Fiber (1)
- Fibre/matrix bond (1)
- Fibre/matrix bonding (1)
- Finite element analysis (1)
- First year students (1)
- Flipped classroom (1)
- Flowability (1)
- Foaming (1)
- Focussed ion beam growth (1)
- Fracture (1)
- Fracture behavior (1)
- Fracture surfaces (1)
- Full notch creep test (FNCT) (1)
- Fullerite (1)
- Fungi (1)
- GFK (1)
- Gas storage (1)
- Gitterkonstanten (1)
- Glas (1)
- Glas fibre reinforced polymer (1)
- Glasmatrixkomposit (1)
- Glass Ceramic (1)
- Glass ceramic (1)
- Glass fiber reinforced polymer (1)
- Glass fibre (1)
- Glass fibre reinforced plastics (1)
- Glass powder (1)
- Glass structure (1)
- Glass-ceramics (1)
- Grain Boundary Phase Diagram (1)
- Grain boundary phase diagram (1)
- Grain boundary thermodynamics (1)
- HEA (1)
- HIP (1)
- HV-Insulation (1)
- Hard machining (1)
- Hardness (1)
- Heat accumulation (1)
- Heat treatment (1)
- Hertzian cracks (1)
- High Cycle Fatigue (1)
- High Temperature Corrosion (1)
- High alloyed steels (1)
- High entropy superalloys (1)
- High temperature (1)
- High temperature corrosion (1)
- High-Temperature Corrosion (1)
- Hochentropie-Legierung (1)
- Hochtemperaturbrennstoffzelle (1)
- Homogenization (1)
- Hot pressing (1)
- In-situ (1)
- In-situ process monitoring (1)
- Inter layer time (1)
- Interface (1)
- Interfacial Spinodal (1)
- Interfacial anisotropy (1)
- Interfacial free energy (1)
- Interfacial shear strength (1)
- Intermetallic (1)
- Investment casting (1)
- Ion beam erosion Sectioning (1)
- Iron (1)
- Iron oxide nanoparticles (1)
- Keramik (1)
- Kikuchi patterns (1)
- Knowledge Graphs (1)
- Korrosion (1)
- L-PBF (1)
- Laser beam melting (LBM) (1)
- Laser scanning microscopy (LSM) (1)
- Lattice parameters (1)
- Lattice structures (1)
- Layering misalignment (1)
- Layerwise Slurry Deposition (1)
- Lecture films (1)
- Lecture videos (1)
- Legierung mit komplexer Zusammensetzung (1)
- Lehrfilm (1)
- Lehrfilmformate (1)
- Liquid metal embrittlement (1)
- Lithography-based technologies (1)
- Long-term aging (1)
- Low Cycle Fatigue (1)
- Low strain (1)
- Lösungsmittel (1)
- MEA (1)
- Machine Learning (1)
- Martensite (1)
- Martensitic steels (1)
- Martensitic structure (1)
- Martensitic transformation (1)
- Materialmodell (1)
- Matrix (1)
- Mechanical anisotropy (1)
- Metallic glasses (1)
- Metallic silver precipitates (1)
- Microbiologically influenced corrosion (1)
- Micromanipulation (1)
- Microstructural orientation (1)
- Microstructure and texture (1)
- Milling (1)
- Misfitting precipitate (1)
- Missing acknowledgment (1)
- Molecular dynamics (1)
- Molten salt (1)
- Monte-Carlo-Analysis (1)
- Multilayer (1)
- Multilayers (1)
- Nano (1)
- Nano metal fluorides (1)
- Nano-composite (1)
- Nano-landscape (1)
- Nano-safety (1)
- Nanocrystalline alloys (1)
- Nanocrystalline structure (1)
- Nanomaterial (1)
- Nanomaterials (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Net zero (1)
- Neutron Diffraction (1)
- Nickel-based superalloys (1)
- Nimonic 75 (1)
- Non-desired foaming (1)
- Oberflächenaktive wässrige Medien (1)
- Online (1)
- Online teaching (1)
- Ontologien (1)
- Ontology development (1)
- Optic (1)
- Optical criterion of brittleness (1)
- Orientation-dependent microstructure (1)
- Ostwald ripening (1)
- Oxides (1)
- Parametric modeling (1)
- Particle size (1)
- Phase field model (1)
- Phase separation (1)
- Phasenidentifikation (1)
- Pipeline (1)
- Pitting (1)
- Plasma nanocoatings (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Plattform Material Digital (PMD) (1)
- Pole figures (1)
- Polyethylen hoher Dichte (1)
- Polyethylene (1)
- Polymer Matrix Composites (1)
- Polymer composite (1)
- Polymer-Ceramic-Composite (1)
- Polymer-ceramic mixtures (1)
- Porosity (1)
- Porous materials (1)
- Portfolio (1)
- Positron annihilation spectroscopy (1)
- Powder bed additive manufacturing (1)
- Powder bed density (1)
- Powder flow (1)
- Powder rheology (1)
- Powder-based processes (1)
- Power law (1)
- Precipitate shape (1)
- Precipitation (1)
- Preparation (1)
- Pressure assisted sintering (1)
- Principal stress components (1)
- Projekt AGIL - Alterung additiv gefertigter metallischer Materialien und Komponenten (1)
- Properties (1)
- Pull-out (1)
- Radon transform (1)
- Real-time deformation (1)
- Recycling (1)
- Reference data (1)
- Reference material (1)
- Reference material BCR-425 (1)
- Refractory chemically complex alloys (1)
- Residual strains (1)
- Residual stresses (1)
- Review (1)
- Rissheilung (1)
- S-phase (1)
- SEM micrography (1)
- SHM (1)
- Salzschmelzen (1)
- Sample holder (1)
- Scan strategies (1)
- Scarf joint (1)
- Scarf joint repair (1)
- Scarf repairs (1)
- Schadensanalyse (1)
- Schlickerdeposition (1)
- Schwingstreifen (1)
- Schädigung (1)
- Screen printing (1)
- Selective laser melting (SLM) (1)
- Self-organization (1)
- Semantisches Web (1)
- Sensorik (1)
- Shape memory alloy (1)
- Shape-memory alloys (1)
- Shear strain (1)
- Shear-band structure (1)
- Short-beam strength (1)
- Silicate glass (1)
- Silver diffusion (1)
- Silver-glass-metallization-paste (1)
- Sintering atmosphere (1)
- Size effect (1)
- Small angle x-ray scattering (1)
- Small-scale (1)
- Solid solution strengthening (1)
- Solidification (1)
- Solubility (1)
- Spinodal Decomposition (1)
- Spinodal decomposition (1)
- Spring constant (1)
- Standard (1)
- Standardisierung (1)
- Strain rate dependence (1)
- Stress intensity (1)
- Stress-corrosion (1)
- Sulfidation (1)
- Sulphidation (1)
- Supercritical CO2 (1)
- Superlegierung (1)
- Surface energy (1)
- Symbolik (1)
- Symmetric dwell periods (1)
- Synchrotron radiation (1)
- Synchrotron radiations (1)
- Technical Ceramics (1)
- Temperature (1)
- Tensile test (1)
- Termites (1)
- Tetragonal distortion (1)
- Thermal Cycling (1)
- Thermal expansion (1)
- Thermal stress (1)
- Thermo mechanical fatigue (1)
- Thermo-mechanical-loading (1)
- Thermo-mechanics (1)
- Thermoelektrischer Generator (1)
- Thermography (1)
- Thermomechanics (1)
- Thermomechanik (1)
- Thermoplastic matrix (1)
- Thermosetting resin (1)
- Thin films (1)
- Three-dimensional tomographies (1)
- Topographie (1)
- Transmission Kikuchi diffraction (1)
- Transmission electron microscope (TEM) (1)
- Triply Periodical Minimal Surface (1)
- Two-photon adsorption (1)
- Umgebungsbedingter Spannungsriss (1)
- Welding (1)
- Wind turbine blade shell structures (1)
- Wood protection (1)
- Work of adhesion (1)
- Wärmespeicher (1)
- X-ray tomographic (1)
- X-ray-diffraction (1)
- XRD (1)
- Young´s Modulus (1)
- Zirconia (1)
- Zyklische R-Kurve (1)
- electron microscopy (1)
- thermomechanische Beanspruchung (1)
- γ- и γ'-фазы, период кристаллической решетки (1)
- γ″ phase (1)
- θ′ phase (1)
- θ′-(Al2Cu) precipitate phase (1)
- высокие температуры (1)
- жаропрочные нике- левые сплавы (1)
- монокристалл (1)
- рентгеноструктурный анализ (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (168)
- 5.1 Mikrostruktur Design und Degradation (64)
- 5.2 Metallische Hochtemperaturwerkstoffe (39)
- 5.4 Multimateriale Fertigungsprozesse (28)
- 5.5 Materialmodellierung (23)
- 7 Bauwerkssicherheit (18)
- 5.0 Abteilungsleitung und andere (17)
- 5.3 Polymere Verbundwerkstoffe (17)
- 8 Zerstörungsfreie Prüfung (15)
- 5.6 Glas (14)
Eingeladener Vortrag
- nein (71)
The locally varying tetragonality in martensite grains of a high-carbon steel (1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD) with a spatial resolution in the order of 100 nm. Compared to spatially integrating X-ray diffraction, which yielded an average tetragonality fo c/a=1.05, the EBSD measurements in the scanning electron microscope allowed to image a local variation of the lattice papameter ration c/a in the range of 1.02 ≤ c/a ≤ 1.07. The local variation of tetragonality is confirmed by two different EBSD data analysis approaches based on the fitting of simulated to experimental EBSD patterns. The resulting EBSD-based tetragonality maps are pointing to a complex interaction of carbon concentration and local lattice distortions during the formation process of martensitic structures.
Texturing of calcium cobaltite for thermoelectric applications by pressure assisted sintering
(2021)
Thermoelectric materials can convert waste heat directly into electrical power by using the Seebeck effect. Calcium cobaltite (CCO) is considered as a promising thermoelectric p-type oxide for energy harvesting applications at temperatures above 500 °C. The properties and morphology of single-crystal CCO are strongly anisotropic because of its crystal structure of alternating layers of CoO2 and Ca2CoO3. By aligning the plate-like grains, the anisotropic properties of the grains can be assigned to the poly-crystalline parts.
In this study, the combination of tape casting and pressure-assisted sintering is used to texture and densify large scale components (50 cm²). Thereby, the influence of powder preparation and applied pressure during sintering on texturing and thermoelectric properties is investigated.
The analysis of XRD pole figures revealed that tape casting already leads to highly textured CCO. By pressure variation during sintering, the microstructure of CCO can be tailored either toward maximum power factor as required for energy harvesting or toward maximum figure of merit as required for energy recovery. Low pressure lead to a porous microstructure and maximum figure of merit and higher pressure to full densification and maximum power factor. The electrical and thermal conductivity of CCO seem depending on both texture and sinter density.
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer Matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF).
Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated.
Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load.
Results of an extended TMF test program on grade P92 steel in the temperature range of 620 °C - 300 °C, comprising in-phase (IP) and out-of-phase (OP) tests, partly performed with symmetric dwells at Tmax/Tmin, are presented. In contrast to previous studies, the low-strain regime is also illuminated, which approaches flexible operation in a power plant with start/stop cycles. At all strain amplitudes, the material performance is characterized by continuous cyclic softening, which is retarded in tests at lower strains but reaches similar magnitudes in the course of testing. In the investigated temperature range, the phase angle does not affect fatigue life in continuous experiments, whereas the IP condition is more detrimental in tests with dwells. Fractographic analyses indicate creep-dominated and fatigue-dominated damage for IP and OP, respectively. Analyses of the (micro)hardness distribution in the tested specimens suggest an enhanced microstructural softening in tests with dwell times for the low- but not for the high-strain regime. To rationalize the obtained fatigue data, the fracture-mechanics-based D_TMF concept, which was developed for TMF life assessment of ductile alloys, was applied. It is found that the D_TMF parameter correlates well with the measured fatigue lives, suggesting that subcritical growth of cracks (with sizes from a few microns to a few millimeters) governs failure in the investigated range of strain amplitudes.
Wind turbine rotor blades commonly fail before their projected 20-year lifespan largely due to defects that originate during manufacturing and are propagated by operational fatigue and environmental conditions. The cost-intensive replacement outcomes lead to a high loss of earnings, and are one of the inhibitors of wind turbine production. A potential repair alternative to restoring the mechanical properties of such lightweight fiber reinforced polymer (FRP) structures is to locally patch these areas with scarf joints. This type of repair allows for a smoother load distribution across the joint, and is favored especially on structures where minor aerodynamic contour changes are key. The effects of such repairs on the structural integrity, however, is still largely unknown. Building upon an understanding of the static load failure mechanism of GFRP scarf joints, presented at the ICCS23 Joint Event in 2020, the influence of the fiber orientation mismatch between parent and repair materials of 1:50 scarf joints on the failure mechanism of monolithic glass FRP specimens under cyclic fatigue load were examined in this study. Specimens with various layups were produced with the vacuum-assisted resin infusion (VARI) process using biaxial E-glass non-crimp fabric (NCF). The patch layers were then joined directly to the parent structure with the VARI using biaxial E-glass NCF with half the areal weight of the parent side to allow for better drapability. This mimics the soft-to-hard patch style utilized in wind turbine blade shell field repairs. The specimens were tested under uniaxial fatigue load, during which they were periodically monitored for damage onset. A comparison of the +45/-45° and 0/90° layups allowed for an understanding of the role of a highly mismatching fiber orientation in the transition zone between parent and patch material on the failure mechanism of the scarf joint. In addition to the tensile strength and stiffness property recovery assessment, a grayscale analysis using in-situ camera images determined the damage state leading to failure in each region across the scarf joint, which varied in the parent material versus scarf joint region, providing insight to the critical regions in this composite structure under cyclic loading.
As more industrial interests focusing on using salt caverns and repurposed gas or petroleum reservoirs for alternative fuel storage, i.e. CO2/H2, the question raises whether microorganisms may impact the infrastructure, gas purity and storage condition over time.
Environments with high salinity (> 1.5 Meq of NaCl) are resided by halophiles (salt-loving microorganisms). To compensate for the intensive osmotic stress, they have resorted to two main adaptation strategies: 1) production of compatible solutes and 2) accumulation of intracellular KCl. Microbial community analysis of several high salinity environments revealed a number of recurring genera, including Halomonas and Halanaerobium. However, the impact of halophiles on the overall integrity and stability of the storage facilities remain largely unknown.
To evaluate the suitability and stability of saline storage facilities, several model halophilic microorganisms, such as members of Halomonas, will be selected as testing subjects. First, the impact of halophiles on the infrastructure will be determined using an integrative approach by combining a number of techniques, including electrochemistry, TOF-SIMS, SEM/FIB/EDS and FIB-TEM. Second, the abilities of halophiles to alter the fuel composition (i.e. increase/decrease the fractions of H2) will be monitored using gas chromatography by growing them under high pressure.
As a result of climate change and the accompanying mandatory shift to renewable energy resources, microorganisms will continue to play an important role in the energy sector, both to their benefit and detriment. Thus, it is important to achieve a certain level of understanding regarding the activities and mechanisms of halophiles prior to large-scaled excursions.
The impact of the microstructure of Fe-16Cr-0.2C on high-temperature oxidation – sulphidation in SO2
(2021)
This study elucidates the impact of the microstructure of Fe-16Cr-0.2C on oxide layer formation at 650 ◦C in Ar-0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. The samples were characterised in detail from microstructural and chemical perspectives using scanning electron microscopy (SEM), X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microstructural modification of the alloy by heat-treatment was advantageous. It was found that Cr-carbides support chromia formation and reduce sulphidation when their area fraction is low and diameter is small.
The relaxation of macroscopic residual stresses in laser powder bed fused stainless steel 316L
(2021)
The processing of stainless steel 316L using the additive manufacturing process Laser Powder Bed Fusion (LPBF) can widen its field of application due to a strong increase in Yield strength, without making major compromises on the ductility nor its outstanding corrosion and oxidation properties. Furthermore, improved designs that either reduce the weight or optimise the function of a part can be obtained using LPBF. These benefits are however counterbalanced by the proneness of LPBF to inducing high Residual Stresses (RS) during manufacturing. The characterisation and monitoring of these RS are of paramount importance for the wider acceptance of the LPBF process. This study focuses on the relaxation of the initial macroscopic RS present in an LPBF 316L as-built prism that undergoes various routes of manufacturing steps to achieve different specimen geometries and stress relieving treatments. The RS are determined using Angle-Dispersive (AD) and Time-of-Flight (TOF) neutron diffraction. The results reveal high tensile RS close to the surfaces and compressive RS near the centre of the as-built parts. The reduction in size and change of geometry heavily impact the stress ranges of the remaining RS, with lower stress ranges in cylindrical shaped compared to rectangular shaped specimens. Also, the application of different stress relieving heat treatments showed that heat-treating temperatures above 800 °C are necessary to obtain a strong relaxation in LPBF 316L.
Glass fiber reinforced polymer (GFRP) materials in practical applications have to endure cyclic mechanical loading in a wide temperature range (e.g. aircraft applications, automotive, wind turbine blades). In this study the static strength and fatigue behavior of GFRP was investigated in a temperature range from 213 K to 343 K. Therefor the coefficients of thermal expansion of the composite as well as the matrix are measured in this temperature interval. The inverse laminate theory was extended and used to calculate the inter fiber-failure effort for a virtual UD-layer according to the layer wise strength approach. The experimentally determined results are compared with the micro-mechanical model according to Krimmer, which has been enhanced to include the effect of temperature and fiber-perpendicular failure modes. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve, as it was similar done for the fatigue behavior of CFRP and GFRP to very high load cycles at room temperature.
Tour de table - BAM
(2021)
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure evelopment and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for eachindividual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv)impurity combinations to be avoided.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure development and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on:
• corrosion of pipeline steel,
• pipeline network design and related transport costs,
• alteration of well bore cements,
• pressure development and rock integrity,
• geochemical reactions, and
• petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
Due to the diversity of materials and the processes associated with their production and use, the complexity of the lifecycles of materials and the multitude of academic and industrial researchers participating in generation of data for material design impose a huge challenge. The topical goal of digitalizing materials and processes can only be adequately addressed by consolidating the efforts of all stakeholders in this field. There are many scattered activities, but there is a demand for an elimination of redundancies as well as an advance in acceptance and a common basis in the digitalization of materials. Furthermore, data analysis methods play an important role in both, the experimental and simulation-based digital description of materials, but they have been poorly structured so far.
Therefore, the two joint projects Platform Material Digital (PMD, materialdigital.de) and Materials open Laboratory (Mat-o-Lab, matolab.de) aim to contribute to a standardized description of data processing methods in materials research. Besides stimulating the formation of a collaborative community in this respect, their main technical goals are the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications. In this regard, data management in accordance with the FAIR (findability, accessibility, interoperability, reuseability) principles is addressed. There is a common agreement in the scientific community following current discussions that data is supposed to be conform to these principles. This includes storage, processing and querying of data in a preferably standardized form.
To meet the challenge to contextualize material data in a way that is consistent with all stakeholders, all necessary information on the condition of the material including production and application-related changes have to be made available via a uniform, machine-readable description. For this purpose, ontologies are to be used since they allow for machine-understandable knowledge representations and conceptualizations that are needed for data management and the digitalization in the field of materials science.
As first efforts in PMD and Mat-o-Lab, application ontologies are created to explicitly describe processes and test methods. Thereby, the well-known tensile test of metals at room temperature was described ontologically in accordance with the respective ISO standard 6892-1:2019-11.
The efforts in creating this tensile test application ontology are shown in this presentation. Especially, the path of ontology development based on standards to be pursued is focused, which is in accordance with the generic recommendations for ontology development and which is supposed to be exemplary for the creation of other application ontologies.
This study reports on the stress relaxation potential of stress-relieving heat treatments for laser powder bed fused 316L. The residual stress is monitored non-destructively using neutron diffraction before and after the heat treatment. Moreover, the evolution of the microstructure is analysed using scanning electron microscopy. The results show, that a strong relaxation of the residual stress is obtained when applying a heat treatment temperature at 900°C. However, the loss of the cellular substructure needs to be considered when applying this heat treatment strategy.
Signal optimization for transmission Kikuchi diffraction (TKD) measurements in the scanning electron microscope is investigated by a comparison of different sample holder designs. An optimized design is presented, which uses a metal shield to efficiently trap the electron beam after transmission through the sample. For comparison, a second holder configuration allows a significant number of the transmitted electrons to scatter back from the surface of the sample holder onto the diffraction camera screen. It is shown that the secondary interaction with the sample holder leads to a significant increase in the background level, as well as to additional noise in the final Kikuchi diffraction signal. The clean TKD signal of the optimized holder design with reduced background scattering makes it possible to use small signal changes in the range of 2% of the camera full dynamic range. As is shown by an analysis of the power spectrum, the signal-to-noise ratio in the processed Kikuchi diffraction patterns is improved by an order of magnitude. As a result, the optimized design allows an increase in pattern signal to noise ratio which may lead to increase in measurement speed and indexing reliability.
In this study, the thermomechanical damage behavior of a glass fiber reinforced polymer material is investigated. The coefficients of thermal expansion of the composite as well as the matrix are measured in a wide temperature range. Quasi-static experiments with neat resin, unidirectional and multidirectional laminates are performed as well as fatigue experiments in a temperature range from 213 K to 343 K. This study focusses on the matrix damage due to fiber-parallel loading. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve.
The discovery of the high entropy concept at the beginning of the 3rd millennium lead to a worldwide increase in metallurgical research, as the possible element combinations seemed nearly endless and the range of applications wide. In the early years of research, one of the main goals was the discovery of a single-phase high entropy alloy. As research evolved, it was found that properties could be enhanced by opening the HE-concept towards multiphase alloys, and from the wide area of possibilities our group chose a tuning of the properties towards high temperature application.
Compositionally complex Al10Co25Cr8Fe15Ni36Ti6 alloy, which is single-phase at high temperature, around 1200°C, shows a three phase morphology at intermediate temperatures, around 800°C. A high temperature homogenization procedure has to be applied in order to decrease the segregation induced by the dendritic growth. Subsequent annealing promotes the formation of the strengthening γ' precipitates. The alloy shows a positive lattice misfit between the γ and the γ' phase, which can be an indicator for good creep properties.
The microstructure can be optimized by adding trace elements such as Mo and Hf, known as γ and γ' strengtheners in Ni-based superalloys, respectively. Atom probe measurements show that Mo segregates into the γ matrix, and Hf prefers the γ' precipitates, where it increases the lattice parameter and thus also the lattice misfit, by about 50%. The alloy family shows interesting mechanical properties, especially the Al9.5Co25Cr8Fe15Ni36Ti6Hf0,5 alloy – its tensile properties are better than those of commercial Alloy 800H and IN617 at temperatures up to 700°C.
Polyethylen hoher Dichte (PE-HD) ist ein weit verbreitetes Material für Transportbehälter, die oft für eine längere Nutzungsdauer vorgesehen sind. Insbesondere in diesem Fall können mikroskopische Schäden im Material auch weit unterhalb der Streckgrenze auftreten, die durch eine Spannungskonzentration verursacht werden, deren Ursprung in intrinsischen Materialfehlern oder äußeren Kratzern liegt. Mit fortschreitender Schädigung bilden sich Rissstrukturen, die von verstreckten Fibrillen aufgespannt werden, bis es zum Versagen dieser Fibrillen kommt und sich der Riss ausbreitet. Dieser Schadensmechanismus des langsamen Risswachstums kann durch eine Vielzahl von Umgebungsmedien beschleunigt werden und wird dann als "environmental stress cracking" (ESC) bezeichnet. Eine international normierte Methode zur Validierung der Spannungsrissbeständigkeit von PE-HD Materialien ist der „Full Notch Creep Test“ (FNCT).
Anhand von Bruchflächenauswertungen mittels Rasterelektronenmikroskopie und Laser-Scanning-Mikroskopie, werden die typischen Schädigungsstrukturen des ESC sichtbar. Die fibrillierten Strukturen des ESC auf der Bruchfläche von PE-HD ergeben sich besonders bei oberflächenaktiven wässrigen Umgebungsmedien. In Lösungsmittel-Umgebungsmedien, im Zusammenspiel mit PE-HD, kommt es aufgrund der plastifizierenden Wirkung zur Herabsetzung der Streckspannung und Bruchflächen aus dem FNCT veranschaulichen keine signifikanten Anzeichen des Schädigungsmechanismus ESC.
Crack growth velocity in alkali silicate glasses was measured in vacuum across 10 orders of magnitude with double cantilever beam technique. Measured and literature crack growth data were compared with calculated intrinsic fracture toughness data obtained from Young´s moduli and the theoretical fracture surface energy estimated from chemical bond energies. Data analysis reveals significant deviations from this intrinsic brittle fracture behavior. These deviations do not follow simple compositional trends. Two opposing processes may explain this finding: a decrease in the apparent fracture surface energy due to stress-induced chemical changes at the crack tip and its increase due to energy dissipation during fracture.