5 Werkstofftechnik
Filtern
Erscheinungsjahr
- 2019 (187) (entfernen)
Dokumenttyp
- Vortrag (73)
- Zeitschriftenartikel (55)
- Posterpräsentation (31)
- Beitrag zu einem Tagungsband (19)
- Buchkapitel (2)
- Sonstiges (2)
- Forschungsbericht (2)
- Monografie (1)
- Dissertation (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (156)
- Deutsch (30)
- Mehrsprachig (1)
Schlagworte
- Corrosion (17)
- Additive Manufacturing (14)
- Glass (12)
- Carbon steel (8)
- Low Cycle Fatigue (8)
- Microstructure (7)
- CO2 (6)
- Degradation (6)
- Fatigue (6)
- Water content (6)
- Additive manufacturing (5)
- CCS (5)
- Ceramic (5)
- Crack growth (5)
- Crystallization (5)
- EBSD (5)
- Oxidation (5)
- 3D printing (4)
- LCF (4)
- Mikrostruktur (4)
- P92 (4)
- Ti-6Al-4V (4)
- Transmission electron microscopy (4)
- 316L (3)
- Alloy 2618A (3)
- Anisotropy (3)
- Carbon capture (3)
- Ceramic spring (3)
- Ceramics (3)
- DCB (3)
- Diesel (3)
- Diffraction (3)
- Diopside (3)
- Full-Notch Creep Test (FNCT) (3)
- High temperature corrosion (3)
- In situ (3)
- Modeling (3)
- Orientation (3)
- Pitting (3)
- Polymer (3)
- Sandwich (3)
- Simulation (3)
- Sintering (3)
- Slurry (3)
- Steel (3)
- Sulfidation (3)
- Tempered Martensite Ferritic Steels (3)
- Thermo-Mechanical Fatigue (3)
- Utilization (3)
- Water speciation (3)
- µ-gravity (3)
- 3D (2)
- AISI 316L (2)
- Additive Fertigung (2)
- Al-Cu-Li alloys (2)
- Alterung (2)
- Aluminium (2)
- Betriebsfestigkeit (2)
- Bioactive glass (2)
- Bioceramics (2)
- CCU (2)
- CCUS (2)
- CT (2)
- Capture (2)
- Carbon (2)
- Coarsening (2)
- Composite (2)
- Computed Tomography (2)
- Condensate (2)
- Condensation (2)
- Corrosion Fatigue (2)
- Crack Propagation (2)
- Crack propagation (2)
- Creep-Fatigue (2)
- Crevice corrosion (2)
- Crystal plasticity (2)
- Dehnungsfehler (2)
- Digital material representation (2)
- Distribution function (2)
- Ductile iron (2)
- Early oxidation (2)
- Elastic constants (2)
- Electron energy (2)
- Energy distribution (2)
- Extensometer (2)
- FeCr- alloys (2)
- Fiber reinforced polymer (2)
- Fracture surface analysis (2)
- Fraktografie (2)
- Geothermal (2)
- Glas (2)
- Glass fiber reinforced polymers (2)
- Glass-ceramic (2)
- High Alloyed Steel (2)
- High Temperature Testing (2)
- High temperature (2)
- IN 718 (2)
- IR (2)
- Impurities (2)
- Internal friction (2)
- Kavitation (2)
- Kikuchi pattern (2)
- Kleinprobenprüfung (2)
- Laminography (2)
- Layerwise (2)
- Layerwise slurry deposition (2)
- Lightweight materials (2)
- Material degradation (2)
- Microhardness (2)
- Mixed Ca-K-Na phosphates (2)
- Monte-Carlo Simulation (2)
- NMR spectroscopy (2)
- Na and K rhenanites (2)
- Niobium alloying (2)
- Non-destructive testing (2)
- Phase diagram (2)
- Phase transformations (2)
- Photon counting detector (2)
- Pipelines (2)
- Polyethylene, PE-HD (2)
- Polymer matrix composites (2)
- Pores (2)
- Powder (2)
- Probengrößeneffekt (2)
- Roughness (2)
- Röntgenbeugung (2)
- Röntgenrefraktion (2)
- Scale-bridging (2)
- Schadensanalyse (2)
- Schädigung (2)
- Selective laser melting (2)
- Silicon Carbide (2)
- Soda-lime silicate glass (2)
- Soda-lime-silica glass (2)
- Storage (2)
- Surface (2)
- Surface crystallization (2)
- Synthetic air (2)
- TMF (2)
- Temperaturschwankungen (2)
- Tensile Properties (2)
- Ti64 (2)
- TiAl5V4 (2)
- Titan (2)
- Titanium (2)
- Topografie (2)
- Utilization, and storage (CCUS) technology (2)
- VSSA (2)
- Vickers indentation (2)
- Virtual experiments (2)
- Weibull Distribution (2)
- Werkstoffprüfung (2)
- Wind energy (2)
- Wind turbine blades (2)
- Zero-g (2)
- Zugeigenschaften (2)
- Zugversuch (2)
- 3D imaging (1)
- 5G (1)
- AFM based test methods (1)
- AISI 304L (1)
- AM (1)
- Abrasion (1)
- Aggressive environment (1)
- Alkali-activated materials (1)
- Alumina (1)
- Aluminosilicate glasses (1)
- Analytische Zentrifuge (1)
- Anwendungen (1)
- Aquifer (1)
- Artificial weathering (1)
- Atomization (1)
- Aufbau von Festkörpern (1)
- Aussonderugnsrate (1)
- BTS (1)
- Berstdruck (1)
- Biodiesel (1)
- Biogeochemical cycling (1)
- Biomineralisation (1)
- Biopolymer (1)
- Blähen (1)
- Breakdown strength (1)
- Brittle fracture (1)
- Bruchflächenanalyse (1)
- Bubble formation (1)
- C. lap-shear (1)
- CALPHAD (1)
- CALPHAD databases analysis (1)
- CFRP (1)
- CO2 Corrosion (1)
- CO2 separation membranes (1)
- CO2-Speicherung (1)
- CO2-storage (1)
- Calcination (1)
- Calcium cobaltite (1)
- Calibration (1)
- Carbidic austempered ductile iron (1)
- Carbon Capture, Utilization and Storage (CCUS) (1)
- Carbon capture, utilization and storage technology (1)
- Carbon fibres (1)
- Carbon storage (1)
- Cavitation (1)
- Cellulose (1)
- Cement (1)
- Certification Standard 22 (1)
- Chalcogenides (1)
- Characterisation (1)
- Chemically Complex Alloy (1)
- Chemische Analyse (1)
- Chemo-mechanical coupling (1)
- Co-axial monitoring (1)
- Coefficient of thermal expansion (1)
- Complex concentrated alloy (CCA) (1)
- Contact angle (1)
- Contact fatigue (1)
- Copper vacancies (1)
- Corrosion and storage (CCUS) technology (1)
- Corrosion pits (1)
- Corrosion resistance (1)
- Crack arrest (1)
- Crack healing (1)
- Creep (1)
- Crosslinking (1)
- Crystal Plasticity Modelling (1)
- Crystal Texture (1)
- Crystal orientation (1)
- Cyclic softening (1)
- D. aging (1)
- D. creep D. viscoelasticity (1)
- DED-L (1)
- Damage (1)
- Dark-field transmission electron microscopy (DFTEM) (1)
- Data storage (1)
- Defects (1)
- Deformation behavior (1)
- Dense phase (1)
- Destabilization (1)
- Deuterium (1)
- Dielectric breakdown (1)
- Dielectric strength (1)
- Diesel Fuel (1)
- Dislocation (1)
- Dislocations (1)
- Distributed fiber optic sensing (1)
- Distributed fiber optic sensors (1)
- Droplet (1)
- Droplet corrosion (1)
- Druckgasspeicher (1)
- Dual-energy (1)
- Dynamic mechanical analysis (1)
- Dynamisch Mechanische Analyse (1)
- EASA (1)
- EIS (1)
- Early sulfidation (1)
- Eigenschaften (1)
- Electrochemical characterisation (1)
- Electrochemical deposition (1)
- Electrochemical dressing (1)
- Electrochemical impedance spectroscopy (1)
- Electromicroscopy (1)
- Electron backscattered diffraction (EBSD) (1)
- Electron microscopy (1)
- Electropolishing (1)
- Endurance Limit (1)
- Energiespeicherung (1)
- Environment (1)
- Environmental Stress Cracking (ESC) (1)
- Environmental stress cracking (1)
- Environmental stress cracking (ESC) (1)
- Environmentally assisted cracking (1)
- Ermüdung (1)
- Erneuerbare Energien (1)
- Explosionsschutz (1)
- Exposed metal sites (1)
- FSDC (1)
- Fabrication (1)
- Facilitated activation (1)
- Failure test (1)
- Faser-Kunststoff-Verbunde (1)
- Faserkunststoffverbunde (1)
- Fatigue Life Evaluation (1)
- Fatigue Testing (1)
- Fatigue crack propagation stages (1)
- Ferritic steels (1)
- Ferritic–martensitic steel (1)
- Fiber reinforced polymers (1)
- Fine Powder (1)
- Finite element analysis (1)
- Flowability (1)
- Foaming (1)
- Focused Ion Beam (1)
- Force-distance diagram (1)
- Four-point bending test (1)
- Fracture (1)
- Fracture mechanics (1)
- Freeze Drying (1)
- Freeze casting (1)
- Fresnoit (1)
- Friction Stir Welding (1)
- Frozen state photopolymerization (1)
- GFRP (1)
- Gasdetektion (1)
- Gassensorik (1)
- Gefügeuntersuchung (1)
- Glass ceramic (1)
- Glass matrix composite (1)
- Glass powder (1)
- Glass screening device (1)
- Glasspeicher (1)
- Gleichgewicht (1)
- Gold (1)
- Grain boundary (1)
- Grünfolieneigenschaften (1)
- HDPE Soprption (1)
- HDPE Sorption (1)
- Hard machining (1)
- Hardness (1)
- Heat treatment (1)
- Heißgasextraktion (1)
- Heißgaskorrosion (1)
- Hierarchical porosities (1)
- High alloyed steel (1)
- High entropy alloys (1)
- High pressure (1)
- High-entropy alloys (1)
- High-temperature corrosion (1)
- High-temperature oxidation (1)
- High-temperature properties (1)
- High-voltage testing (1)
- Hochentropielegierungen (1)
- Hochtemperaturermüdung (1)
- Honing (1)
- Honing Stone (1)
- Hydrogel (1)
- Hydrogen (1)
- Hydrogen diffusivity (1)
- Hygrothermal (1)
- Impact damage (1)
- In-situ Process Monitoring (1)
- Inclusion cluster (1)
- Inclusion size (1)
- Inconel 625 (1)
- Inconel 686 (1)
- Incremental lifetime models (1)
- Infrared nano AFM (1)
- Infrared spectroscopy (1)
- Intermodulation AFM (1)
- Internal Surfaces (1)
- Internal oxidation (1)
- Interphase (1)
- Ionic porosity (1)
- Iron meteorite (1)
- Irregular topography (1)
- Keramikfeder (1)
- Keramische Folien (1)
- Korrosion (1)
- Kreislaufwirtschaft (1)
- Kriechen (1)
- Kristallisation (1)
- Kristallsystem (1)
- Kurzfaser-verstärkte Thermoplaste (1)
- LMD (1)
- LSD print (1)
- LTCC multilayer (1)
- Langzeitstabilität (1)
- Laser Beam Melting (1)
- Laser Scanning Microscopy (1)
- Laser Scanning Microscopy (LSM) (1)
- Laser beam melting (1)
- Laser cladding (1)
- Laser-induced slip casting (1)
- Laserbearbeitung (1)
- Laserscanningmikroskopie (LSM) (1)
- Layer system (1)
- Layerwise Slurry Deposition (1)
- Lebensdauer (1)
- Long-term storage (1)
- Low cycle fatigue (1)
- MOF-74 (1)
- Machine Learning (1)
- Magmatic and hydrothermal processes (1)
- Magnetic domains (1)
- Magnetische Domänen (1)
- Magnetoelastic effect (1)
- Magnetoelastischer Effekt (1)
- Martensite (1)
- Mass transport (1)
- Materialkreislauf (1)
- Materialprüfung (1)
- Materials science (1)
- Mechanical behavior (1)
- Mechanical properties (1)
- Mehrachsige Verformung (1)
- Metal powder characterization (1)
- Metrology (1)
- Micro-shrinkages (1)
- Micromechanical model (1)
- Microstructure analysis (1)
- Microstructure characterisation (1)
- Microstructure evolution (1)
- Microstructure modification (1)
- Mikrostrukturuntersuchung (1)
- Mindedestberstdruck (1)
- Mini-UAV (1)
- Mis-match (1)
- Mixed-linkers (1)
- Modell (1)
- Moisture (1)
- Mortel (1)
- Multiaxial deformation (1)
- Multiple cracks (1)
- NDT (1)
- NMR (1)
- Nano particle (1)
- Nano screening (1)
- Nanocomposites (1)
- Nanomaterial (1)
- Nanoparticles (1)
- Natural (1)
- Neutron diffraction (1)
- New standards (1)
- Ni-Resist (1)
- Nitride (1)
- Non-destructive Materials (1)
- Non-metallic inclusions (1)
- Nondestructive testing (1)
- Normung (1)
- Ooxidation (1)
- Optical criterion (1)
- Orientation relationship (1)
- Oxidation protection (1)
- PE-HD Sorption (1)
- Parabolic flight (1)
- Particle size (1)
- Partikelgrößenverteilung (1)
- Permeability (1)
- Phase transformation (1)
- Phase-field (1)
- Phase-field simulation (1)
- Phosphate (1)
- Physically based material model (1)
- Pipeline (1)
- Pitting corrosion (1)
- Plastic deformation (1)
- Platinum-group-metals (1)
- Polyaniline (1)
- Polyethylen hoher Dichte (1)
- Polyurethane (1)
- Power plant (1)
- Power-to-Gas (1)
- Preceramic polymer (1)
- Pressure-assisted sintering (1)
- Process Monitoring (1)
- Process development (1)
- Process monitoring (1)
- Processing window (1)
- Pultruded fiber rods (1)
- REM (1)
- Referenzmaterial (1)
- Referenzorganismus (1)
- Referenzverfahren (1)
- Relaxation fatigue (1)
- Repair patch (1)
- Residual stress (1)
- Resonance testing (1)
- Restberstfestigkeit (1)
- Risikoanalyse (1)
- Rohrprobekörper (1)
- SDC (1)
- STEM (1)
- Safety (1)
- Sailplane Development Panel (1)
- Salt melt (1)
- Samarium doped ceria (1)
- Sample preparation (1)
- Sandwich structures (1)
- Scaffolds (1)
- Scanning Electron Microscopy (SEM) (1)
- Scanning electron microscopy (1)
- Scavenging effect of iron (1)
- Scratches (1)
- Semiconductor materials (1)
- Sensor (1)
- Sensorik (1)
- Silicoborate glasses (1)
- Silver glass paste (1)
- Sintern (1)
- Slip-rolling (1)
- Slow Crack Growth (SCG) (1)
- Slow crack growth (1)
- Soda-lime-silica (1)
- Sodium ion batteries (1)
- Sol-gel coating (1)
- Sorption (1)
- Spannungs-Dehnungs-Verhalten (1)
- Spannungsriss (1)
- Spar cap design (1)
- Spectroscopy (1)
- Spring constant (1)
- Spring constant (1)
- Standardisation (1)
- Stanzen (1)
- Statistics (1)
- Stress intensity factor (1)
- Stress-strain behavior (1)
- Streuung (1)
- Structural composites (1)
- Structural defects (1)
- Structural health monitoring (1)
- Structural steel (1)
- Struktur (1)
- Subcritical crack growth (1)
- Superalloy (1)
- Superconducting magnet (1)
- Supercritical CO2 (1)
- Supercritical/dense phase CO2 (1)
- Surface treatments (1)
- Swept wavelength interferometry (1)
- Synthesis (1)
- TEM (1)
- Tempered martensite ferritic steel (1)
- Tempered martensite ferritic steels (1)
- Tensile testing (1)
- Thermodynamic analysis (1)
- Thermoelectric properties (1)
- Thermomechanics (1)
- Thermomechanik (1)
- Thiol-ene click chemistry (1)
- ToF-SIMS (1)
- Transmission electron microscopy (TEM) (1)
- Tribologie (1)
- Tungsten-Rhenium (1)
- Ultrasound (1)
- Ungleichgewicht (1)
- Unlegierter Baustahl (1)
- VM12 SHC (1)
- Vacuum hot extraction (1)
- Vickers (1)
- Viscoelastic model (1)
- Viscous sintering (1)
- Viskoplastisch (1)
- WAXS (1)
- Wasserstoff (1)
- Wasserstofferzeugung (1)
- Werkstoffmechanische Prüfung (1)
- Wetting (1)
- Wind turbine blade shells (1)
- Windenergie (1)
- X-ray absorption spectroscopy (1)
- X-ray refraction (1)
- XRD (1)
- Young´s modulus (1)
- Zerstörungsfreie Prüfung (1)
- ZnO (1)
- Zug-Druck-Schubprüfung (1)
- alumina (1)
- arbidic austempered ductile iron (1)
- arbon capture (1)
- ausfgallfreie Lastwechsel (1)
- bioactive (1)
- biomaterials (1)
- bone (1)
- carbon steel (1)
- ceramics (1)
- coarsening (1)
- condensate (1)
- corrosion (1)
- electrochemical characterization (1)
- hardness (1)
- high pressure (1)
- impurities (1)
- infrared spectroscopy (1)
- microstructure analysis (1)
- phosphate glasses (1)
- pitting corrosion (1)
- selective laser melting (1)
- statistische Auswertung (1)
- utilization, and storage (CCUS) technology (1)
- volume resistivity (1)
- water speciation (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (187) (entfernen)
Eingeladener Vortrag
- nein (73)
Determination of Distribution Function used in MCS on Safety Analysis of Hydrogen Pressure Vessel
(2019)
The test data of static burst strength and load cycle strength of composite pressure vessels are often described by GAUSSian normal or WEIBULL distribution function to perform safety analyses. The goodness of assumed distribution function plays a significant role in the inferential statistics to predict the population properties by using limited test data. Often, GAUSSian and WEIBULL probability nets are empirical methods used to validate the distribution function; Anderson-Darling and KolmogorovSmirnov tests are the mostly favorable approaches for Goodness of Fit. However, the different approaches used to determine the parameters of distribution function lead mostly to different conclusions for safety assessments. In this study, six different methods are investigated to show the variations on the rates for accepting the composite pressure vessels according to GTR No. 13 life test procedure. The six methods are: a) NormLog based method, b) Least squares regression, c) Weighted least squares regression, d) A linear approach based on good linear unbiased estimators, e) Maximum likelihood estimation and f) The method of moments estimation. In addition, various approaches of ranking function are considered. In the study, Monte Carlo simulations are conducted to generate basic populations based on the distribution functions which are determined using different methods. Then the samples are extracted randomly from a population and evaluated to obtain acceptance rate. Here, the “populations” and “samples” are corresponding to the burst strength or load cycle strength of the pressure vessels made from composite material and a plastic liner (type 4) for the storage of hydrogen. To the end, the results are discussed, and the best reliable methods are proposed.
Carbidic Austempered Ductile Iron (CADI) microstructures containing eutectic carbides can be produced by the addition of carbide stabilizing elements, such as chromium. Carbides formed from the addition of Cr are eutectic of M3C type. The presence of such hard phases can enhance the abrasion wear resistance of ductile iron. A new CADI can be produced by the addition of Nb. Niobium carbide particles are formed in the beginning of solidification and remain stable once they are insoluble in solid iron matrix. The dry sand abrasive wear resistance of ductile irons alloyed with 1.0, 1.8, and 2.4 wt% Nb were tested in both “as-cast” and “heat treated” conditions using standard ASTM G65. Results were compared to abrasive wear data obtained on ductile iron alloyed with 1 wt% Cr, CADI (1 wt% Cr), and the basic composition of iron without carbide stabilizing elements. In the “ascast” condition, the addition of Nb did not lead to a reduction in wear, while CADI with Nb is a promising substitute for CADI with Cr addition, because both materials showed very similar values of abrasion resistance.
Micro-ploughing and micro-cutting mechanisms were observed on the worn surfaces of ductile irons. Abrasive wear resistance of these alloys was correlated with the volume fraction of carbides.
Die Untersuchung und Charakterisierung der Entwicklung/Änderung der Mikrostruktur, der mechanischen Eigenschaften sowie der Lebensdauer additiv gefertigter metallischer Werkstoffe hat bisher, vor allem im Hinblick auf die komplexe Belastungsfälle bei sicherheitsrelevanten Anwendungen, mit der rasanten Entwicklung der Fertigungstechniken nicht Schritt gehalten. Im Rahmen dieser Arbeit wurde eine Charakterisierung des Ermüdungsverhaltens von additiv gefertigten TiAl6V4 im Low-Cycle-Fatigue Bereich (niederzyklische Ermüdung) nach Norm ISO 12206 mit Dehnungsamplituden von 0.3 bis zu 1.0 % und bei Raumtemperatur, 250°C und 400°C durchgeführt. Die TiAl6V4 Proben wurden aus zylindrischen Halbzeugen gefertigt, welche durch Laser-Pulver-Auftragsschweißen mit einer optimierten Aufbaustrategie hergestellt wurden. Die optimierte Aufbaustrategie beinhaltet variierende Spurüberlappungsgraden, die die Fertigung der dünnen zylindrischen Körper ohne weitere Ausgleichslagen ermöglicht. Das Werkstoffverhalten wird anhand von Wechselverformungskurven sowie einer Darstellung der Lebensdauer in einem Wöhler-Diagramm beschrieben. Ein Fitting der Lebensdauer-Daten erfolgt anhand der Manson-Coffin-Basquin Beziehung. Eine Eingangscharakterisierung der mikrostrukturellen Merkmale inklusive Bindefehler aus dem Herstellungsprozess wird durch Lichtmikroskopie und hochauflösende Computertomographie (CT) durchgeführt. Der Versagensmechanismus während der Belastung wird anhand von Zwischenuntersuchungen mit CT und einem unterbrochenen Versuch mit ausgewählten Versuchsparametern beschrieben. Nach dem Versagen wurden die Proben am REM, mit Lichtmikroskopie und mit CT fraktographisch in Längs- und Querrichtung untersucht. Die erfassten Lebensdauern sind ähnlich zu denen aus herkömmlichen Studien und liegen unter derjenigen von dem konventionell hergestellten (geschmiedeten) Werkstoff. In dieser Arbeit wurden für den untersuchten Werkstoff bei anwendungs- und sicherheitsrelevanten Belastungszuständen (hohe Temperaturen, zyklische Plastizität) neue experimentelle Daten und Kennwerte ermittelt und Verständnis über das mechanische Verhalten und die Entwicklung der Mikrostruktur aufgebaut. Darüber hinaus wurde Verständnis über die Rolle von Bindefehlern und anderen typisch für AM auftretenden Gefügemerkmalen auf das Versagensverhalten von DED-L TiAl6V4 gewonnen.
The aim of this research is to study the influence of moisture absorption at low moisture contents on the creep behaviour of an epoxy adhesive in steel bonded joints. Single lap joints were manufactured using high strength steel adherends and a two-component epoxy adhesive. The single lap joints were tested at load Levels corresponding to average lap shear stresses of±5%, 15%, 30% and 45% of the dry lap shear strength in both 40 °C air and 40 °C distilled water. Specimens were not pre-aged to be able to analyse the coupled effect of moisture and loading. The test results show that an increase in the load level resulted in an increase in the instantaneous strain and in the creep strain rate. The creep strain of single lap joints loaded in water was generally larger than for the ones loaded in air. For joints loaded in water the creep behaviour was found to be dependent on the moisture concentration in the adhesive. At low moisture percentages creep was suppressed, resulting in a lower instantaneous strain. At higher moisture percentages creep was promoted, resulting in a larger strain rate. The suppression of creep at low moisture percentages is attributed to water molecules bonding to the epoxy macromolecules, resulting in a reduction in molecular mobility and a smaller creep strain. At higher moisture percentages the plasticizing effect of the water dominates, resulting in a larger creep strain. The Maxwell threeelement solid model and Kelvin-Voigt three-element solid model were used to simulate the creep behaviour of the single lap joints loaded in air and water. The models gave good representations of the creep Response across the different load levels in both water and air, they were however unable to give a correct representation of the instantaneous strain of the single lap joints loaded in water. This is attributed to the models being unable to account for the present short-term relaxation process that is dependent on the moisture concentration.
Die warmfeste austenitische Gusseisenlegierung EN-GJSA-XNiSiCr35-5-2 (häufig auch als Ni-Resist D-5S bezeichnet) wurde hinsichtlich ihres mechanischen Verhal-tens bei hoher Temperatur charakterisiert. Dazu wurden (isotherme) niederzyklische (LCF-) und (nicht-isotherme) thermomechanische Ermüdungsversuche (TMF) zwischen Raumtemperatur und 900 °C durchgeführt. Diese Ergebnisse dienten (zu-sammen mit weiteren Versuchsdaten) der Kalibrierung werkstoffmechanischer Modelle. Bei den höchsten Prüftemperaturen wurde Schädigung in Form von Kriechen beobachtet und metallographisch dokumentiert.
Die Untersuchung und Charakterisierung der Entwicklung/Änderung der Mikrostruktur, der mechanischen Eigenschaften sowie der Lebensdauer additiv gefertigter metallischer Werkstoffe hat bisher, vor allem im Hinblick auf die komplexe Belastungsfälle bei sicherheitsrelevanten Anwendungen, mit der rasanten Entwicklung der Fertigungstechniken nicht Schritt gehalten. Im Rahmen dieser Arbeit wurde eine Charakterisierung des Ermüdungsverhaltens von additiv gefertigten TiAl6V4 im Low-Cycle-Fatigue Bereich (niederzyklische Ermüdung) nach Norm ISO 12206 mit Dehnungsamplituden von 0.3 bis zu 1.0 % und bei Raumtemperatur, 250°C und 400°C durchgeführt. Die TiAl6V4 Proben wurden aus zylindrischen Halbzeugen gefertigt, welche durch Laser-Pulver-Auftragsschweißen mit einer optimierten Aufbaustrategie hergestellt wurden. Die optimierte Aufbaustrategie beinhaltet variierende Spurüberlappungsgraden, die die Fertigung der dünnen zylindrischen Körper ohne weitere Ausgleichslagen ermöglicht. Das Werkstoffverhalten wird anhand von Wechselverformungskurven sowie einer Darstellung der Lebensdauer in einem Wöhler-Diagramm beschrieben. Ein Fitting der Lebensdauer-Daten erfolgt anhand der Manson-Coffin-Basquin Beziehung. Eine Eingangscharakterisierung der mikrostrukturellen Merkmale inklusive Bindefehler aus dem Herstellungsprozess wird durch Lichtmikroskopie und hochauflösende Computertomographie (CT) durchgeführt. Der Versagensmechanismus während der Belastung wird anhand von Zwischenuntersuchungen mit CT und einem unterbrochenen Versuch mit ausgewählten Versuchsparametern beschrieben. Nach dem Versagen wurden die Proben am REM, mit Lichtmikroskopie und mit CT fraktographisch in Längs- und Querrichtung untersucht. Die erfassten Lebensdauern sind ähnlich zu denen aus herkömmlichen Studien und liegen unter derjenigen von dem konventionell hergestellten (geschmiedeten) Werkstoff. In dieser Arbeit wurden für den untersuchten Werkstoff bei anwendungs- und sicherheitsrelevanten Belastungszuständen (hohe Temperaturen, zyklische Plastizität) neue experimentelle Daten und Kennwerte ermittelt und Verständnis über das mechanische Verhalten und die Entwicklung der Mikrostruktur aufgebaut. Darüber hinaus wurde Verständnis über die Rolle von Bindefehlern und anderen typisch für AM auftretenden Gefügemerkmalen auf das Versagensverhalten von DED-L TiAl6V4 gewonnen.
The coefficient of thermal expansion (CTE) and the thermomechanical properties of the polymers used in superconducting magnets need to be known in order to predict their stress state under the different magnet assembly and operating conditions.
We have measured Young’s moduli of typically used polymers during in situ heat cycles with the dynamic resonancemethod. The dynamic test results are compared with Young’s moduli determined from quasi-static stress–strain measurements at room temperature, 77 K and 4.2 K. A moderate elastic anisotropy is found for the fiber reinforced polymers. CTEs are compared based on dilation experiments. TheCTEs of the fiber reinforced polymers studied are similar to those of copper or steel. In contrast, the pure resins exhibit relatively larger CTEs.
Electron backscatter diffraction (EBSD) is a technique to obtain microcrystallographic information from materials by collecting large-angle Kikuchi patterns in the scanning electron microscope (SEM). An important fundamental question concerns the scattering-angle dependent electron energy distribution, which is relevant for the formation of the Kikuchi diffraction patterns. Here we review the existing experimental data and explore the effective energy spectrum that is operative in the generation of backscatter Kikuchi patterns from silicon. We use a full pattern comparison of experimental data with dynamical electron diffraction simulations. Our energy-dependent cross-correlation based pattern matching approach establishes improved constraints on the effective Kikuchi pattern energy spectrum, which is relevant for high-resolution EBSD pattern simulations and their applications.
Though Ni-base superalloys show a high oxidation and corrosion resistance, coatings could still improve these properties, especially if used at temperatures up to 1000 °C. Here, a coating was prepared by applying a boehmite-sol via dip-coating and a subsequent heat treatment at 600 °C for 30 minutes. To evaluate the coating, the oxidation behavior of bare and alumina coated Ni-base alloy Inconel 625 in air at 900 °C was studied for up to 2000 h. Electron microscopic studies of sample surfaces and cross-sections showed that (i) in the 3.5 µm – 6.3 mm thick scale formed on the bare alloy, Fe and Ni are located as fine precipitates at the grain boundaries of the chromia-rich scale, (ii) Ni and Ti are concentrated to a minor degree at the grain boundaries of the scale, too; and for the coated sample: (iii) the only 1.8 µm thick sol-gel alumina coating slows down the formation of chromia on the alloy surface and reduces the outward diffusion of the alloy constituents. The protective effect of the coating was evidenced by (i) diminished chromium diffusion at grain boundaries resulting in less pronounced string-like protrusions at the outer surface of the coated IN 625, (ii) formation of a Cr-enriched zone above the alloy surface which was thinner than the scale on the uncoated sample, (iii) no detectable Cr-depleted zone at the alloy surface, and (iv) a narrower zone of formation of Kirkendall pores.
Alkali and alkaline earth chlorides are discussed as heat storage media and are characterized by their low price and high availability. Disadvantages are a high corrosion rate and formation of Cr6+ ions in the melt, as observed in various binary chlorine salt melts. In our work the system NaCl-KCl-MgCl2 is considered. The storage capacity in this salt system is between 2 and 3 MWh per 10 t salt, depending on composition, melting temperature and working temperature. At the same time the system offers a eutectic line, which allows a high variance of the composition and possibly different corrosion rates can be observed. Corrosion tests in melts were carried out and the corrosion layers investigated. The tests with chloride melts on 12% Cr steel show an inner corrosion zone of up to 40 µm depth after 96 hours. The corrosion mechanisms and potential solutions are discussed.