5 Werkstofftechnik
Filtern
Dokumenttyp
- Beitrag zu einem Tagungsband (60) (entfernen)
Sprache
- Englisch (60) (entfernen)
Schlagworte
- Corrosion (13)
- CCS (6)
- CO2 (5)
- Fatigue (4)
- Steel (4)
- Aluminium (3)
- CCUS (3)
- CO2 quality (3)
- Carbon steel (3)
- Geothermal (3)
- Impurities (3)
- Martensitic steel (3)
- Pipeline (3)
- Pipeline network (3)
- Additive manufacturing (2)
- Adiabatic calorimeter (2)
- Alloy 2618A (2)
- CCU (2)
- CO2-storage (2)
- Carbon steels (2)
- Coarsening (2)
- Crack growth (2)
- Creep (2)
- EN AW-2618A (2)
- Glass fiber reinforced polymers (2)
- Hydrogen (2)
- Inconel 686 (2)
- P92 (2)
- Phase change material (2)
- Polyaniline (2)
- Recommendations (2)
- Salt eutectics (2)
- SiO2 (2)
- Superaustenite steel (2)
- Supercritical CO2 (2)
- Supercritical/dense phase CO2 (2)
- Tempered Martensite Ferritic Steels (2)
- Thermal energy storage (2)
- Thermomechanical fatigue (2)
- Transmission electron microscopy (2)
- Utilization (2)
- Whole-chain CCS scenario (2)
- Wind turbine blades (2)
- AISI 304L (1)
- Additive Manufacturing (1)
- Aggressive environment (1)
- Air-coupled ultrasonic testing (1)
- Airborne ultrasonic testing (1)
- Alloy 2818A (1)
- Alumina (1)
- Aluminium alloy (1)
- Aluminum alloys (1)
- Anisotropy (1)
- Austenitic stainless steel (1)
- Automated finite element analysis (1)
- Automatische Finite Element Simulation (1)
- Biofilm (1)
- Burst test (1)
- CO2 Corrosion (1)
- CO2 corrosion (1)
- Capture (1)
- Carbon (1)
- Carbon capture (1)
- Carbon capture storage (1)
- Casting (1)
- Cement (1)
- Coating (1)
- Coatings (1)
- Composite (1)
- Composite pressure vessels (1)
- Composite structures (1)
- Composites (1)
- Concrete (1)
- Condensation (1)
- Continnum damage model (1)
- Corrosion and storage (CCUS) technology (1)
- Crack tip opening displacement (1)
- Creep data (1)
- Creep-Fatigue (1)
- Crevice corrosion (1)
- Cross linking (1)
- Crystal plasticity (1)
- Cure process (1)
- Cyclic loading (1)
- Damage (1)
- Data Mapping (1)
- Degradation (1)
- Dense phase (1)
- Dielectric properties (1)
- Digital material representation (1)
- Distributed fibre optic sensors (1)
- Distribution function (1)
- Droplet (1)
- Droplet corrosion (1)
- Dynamic mechanical analysis (DMA) (1)
- EBSD (1)
- EIS (1)
- Electrochemical dressing (1)
- Electropolishing (1)
- Epoxy (1)
- FAIR Data (1)
- Fatigue of sandwich shell structures (1)
- Fe-Al alloys (1)
- Ferritic-martensitic steels (1)
- Ferroelectret (1)
- Fiber reinforced polymer (1)
- First year students (1)
- Flipped classroom (1)
- Fractography (1)
- Fracture (1)
- High - temperature corrosion (1)
- High alloyed steel (1)
- High alloyed steels (1)
- High cycle fatigue (1)
- High temperature corrosion (1)
- High temperature mechanical properties (1)
- Honing (1)
- Honing Stone (1)
- IN718 (1)
- ISRU (1)
- Infrastructure (1)
- Injection (1)
- Intermetallics (1)
- Inverted classroom (1)
- Iron aluminides (1)
- Irregular topography (1)
- Knowledge Graph (1)
- LTCC (1)
- Laminography (1)
- Laser Scanning Microscopy (1)
- Lecture videos (1)
- Lightweight materials (1)
- Long-term behavior (1)
- Low Cycle Fatigue (1)
- Lunar habitat (1)
- Machine Learning (1)
- Material degradation (1)
- Metal seal (1)
- Micromechanical model (1)
- Microstructure evolution (1)
- Microstructure-property-correlation (1)
- Monte-Carlo Simulation (1)
- Monte-Carlo-Analysis (1)
- Net zero (1)
- Neutron diffraction (1)
- Nickel based coatings (1)
- Non-destructive testing (1)
- Online teaching (1)
- Ontology (1)
- Optical backscatter reflectometry (1)
- Optical fibre (1)
- Oxide scale (1)
- Paving (1)
- Photon counting detector (1)
- Pipelines (1)
- Pitting (1)
- Protective coating (1)
- Repair patch (1)
- Residual Stresses (1)
- Residual stress (1)
- Residual stresses (1)
- Rissausbreitung (1)
- Rotor blade (1)
- Roughness (1)
- S-phase (1)
- Sandwich (1)
- Scale-bridging (1)
- Scarf repairs (1)
- Selective Laser Melting (1)
- Selective laser melting (1)
- Self-healing (1)
- Sibayak (1)
- Silver nanoparticle (1)
- Simulation of concrete (1)
- Sol-gel coating (1)
- Solar sintering (1)
- Starch (1)
- Starch nanoparticle (1)
- Storage (1)
- Structural health monitoring (SHM) (1)
- Surface (1)
- Swept wavelength interferometry (SWI) (1)
- Synchrotron Tomography (1)
- TEM (1)
- Temperature (1)
- Tensile data (1)
- Thermal Spray (1)
- Thermo-Mechanical Fatigue (1)
- Thermomechanics (1)
- Thermomechanische Ermüdung (1)
- Thermoplastic (1)
- Thermoset polymers (1)
- ToF-SIMS (1)
- Transducers (1)
- Under cyclic loading (1)
- Vickers Hardness (1)
- Virtual experiments (1)
- Weibull Distribution (1)
- Wind energy (1)
- Wind turbine (1)
- X-ray laminography (1)
- laser cladding (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (60)
- 5.1 Mikrostruktur Design und Degradation (28)
- 5.2 Metallische Hochtemperaturwerkstoffe (17)
- 7 Bauwerkssicherheit (16)
- 7.6 Korrosion und Korrosionsschutz (14)
- 5.3 Polymere Verbundwerkstoffe (10)
- 5.5 Materialmodellierung (9)
- 8 Zerstörungsfreie Prüfung (7)
- 3 Gefahrgutumschließungen; Energiespeicher (3)
- 5.4 Multimateriale Fertigungsprozesse (3)
In Germany spent nuclear fuel and high level radioactive waste is stored in interim storage containers with double lid systems. Those lids are equipped with metal seals (e.g. Helicoflex®) that ensure the safe enclosure of the inventory. The used metal seals consist of three components as can be seen in the cross-sectional view in Figure 1. The innermost part is a helical spring that is surrounded by an inner jacket made of stainless steel. The outer jacket that is made of a softer material which in case of assembly in the aforementioned storage containers is silver or aluminum (i.e. Al 99.5). During application the seal is compressed and due to the restoring force of the helical spring, the outer jacket is plastically deformed and adapts to the sealing surface. Hence, leakage paths are closed and the sealing function is generated. In Germany the above-mentioned containers are licensed for up to 40 years of interim storage, which in case extended storage becomes necessary before a final repository is available will have to be extended to even longer periods. Therefore, the evaluation of the long-term behavior of the seals is necessary, taking into account storage conditions, decay heat and possible mechanical loads as well.
At Bundesanstalt für Materialforschung und –prüfung (BAM) long-term investigations are being conducted in which seals are assembled in test flanges and aged at temperatures ranging from room temperature to 150°C for accelerated aging. The aged seals are tested semi-annually (after the first 6 months in which the seals are tested more frequently) regarding the sealing performance, the remaining seal force, and the useable resilience upon decompression. Results of these investigations have been published over the past years (e.g. Grelle, Wolff, Probst, Jaunich, & Völzke, 2017; Völzke, Wolff, Probst, Nagelschmidt, & Schulz, 2014). It was found that the seal force and the useable resilience decrease with time and temperature, which is in agreement with the result of other studies (Sassoulas et al., 2006; Wataru et al., 2016) as well. Geometry change of the outer jacket has been identified as the main reason for this seal behavior. At the prevailing operating temperatures and stresses the aluminum is subjected to creep deformation leading to a thinning of the outer jacket. Since the seal groove depth remains unchanged the helical spring expands, which in turn leads to a decrease of the generated spring and seal force.
Although the main reason for the change of seal parameters over time and temperature is known, a detailed characterization of the seal behavior and a reliable prediction of the parameter development for aging times that exceed the experimental time frame have not been possible, yet.
For deeper understanding of the aging processes, an Investigation program, which is covered in this contribution, is conducted at Bundesanstalt für Materialforschung und –prüfung (BAM) that focusses on the behavior of the aluminum jacket and its influence on the long-term sealing performance. The program investigates properties of material samples as well as the behavior of the seal as a component.
Original sheet material of the same aluminum that is used for manufacturing of the seals is investigated in compression creep tests. For this, a DMA (dynamic mechanical analysis) machine is employed (here used for static tests) that allows for a measurement of the specimens deformation under forces of up to 500 N. The advantage of this method is that the original material can be tested in the same shape as used for the seals which is 0.5 mm thick sheet material. For investigation of tensile creep standard specimens are used, that were machined from surrogate material of the same composition and annealing condition.
Furthermore, aluminum seals that are cut into smaller segments are assembled in flanges and placed in heating chambers at temperatures ranging from 23°C to 150°C. After different periods of time from 3 days to 300 days the segments are taken out of the flanges and are investigated, thus giving information on different states of aging. Measurements of the development of the seal contact width and the aluminum jacket thickness are done with an optical microscope. Further investigations on the segments will include metallography and hardness measurements.
From the detailed material and component behavior including the results of the long-term seal force and useable resilience investigations a better understanding of the overall seal behavior can be gained. The aim is to contribute to the development of material models and analytical approaches for the prediction of the sealing behavior in dependence of time and temperature.
Cyclic fatigue behavior of glass fiber reinforced epoxy resin at ambient and elevated temperatures
(2018)
The fatigue behavior of ±45° glass fiber reinforced epoxy resin under cyclic mechanical and constant thermal loading is investigated in this study. Tests at three different temperature levels in the range 296 K to 343 K have been performed in order to create S-N curves for each temperature level. The specimen damage is measured in-situ using optical grayscale analysis. The characteristic damage state (CDS) is evaluated for each specimen. It is shown that the point of CDS is suitable as a failure criterion to compare the resulting S-N curves. With micromechanical formulations, the temperature-dependent matrix effort is calculated for each stress-temperature level. In terms of matrix effort, the longest fatigue life is reached at high temperatures, while, in terms of stress, the lowest fatigue life is reached at the highest temperatures.
The current competitive situation on electricity markets forces power plants into cyclic operation regimes with frequent load shifts and starts/shutdowns. In the present work, the cyclic mechanical behavior of ferritic-martensitic 9-12 % Cr steels under isothermal and thermomechanical loading was investigated for the example of grade P92 material. A continuous softening was observed under all loading conditions. The introduction of hold periods to the applied cycles reduced material lifetime, with most prominent effects at technologically relevant small strain levels. The microstructural characterization reveals a coarsening of the original “martensitic” lath-type microstructure to a structure with polygonal subgrains and reduced dislocation density. The microstructural data forms the input for a physically-based modelling approach.
The current competitive situation on electricity markets forces power plants into cyclic operation regimes with frequent load shifts and starts/shutdowns. In the present work, the cyclic mechanical behavior of ferritic-martensitic 9-12 % Cr steels under isothermal and thermomechanical loading was investigated for the example of grade P92 material. A continuous softening was observed under all loading conditions. The introduction of hold periods to the applied cycles reduced material lifetime, with most prominent effects at technologically relevant small strain levels. The microstructural characterization reveals a coarsening of the original “martensitic” lath-type microstructure to a structure with polygonal subgrains and reduced dislocation density. The microstructural data forms the input for a physically-based modelling approach, both of which are presented in “Part 2: Microstructural Evolution during Cyclic Loading and its Representation in a Physically-based Micromechanical Model“.
The current competitive situation on electricity markets forces conventional power plants into cyclic operation regimes with frequent load shifts and starts/shutdowns. In the present work, the cyclic mechanical behavior of ferritic-martensitic 9-12 % Cr steels under isothermal and thermomechanical loading was investigated for the example of grade P92 material. A continuous softening was observed under all loading conditions. The introduction of hold periods to the applied cycles reduced material lifetime, with most prominent effects at technologically relevant small strain levels. The microstructural characterization reveals a coarsening of the original “martensitic” lath-type microstructure to a structure with polygonal subgrains and reduced dislocation density. The microstructural data forms the input for a physically-based modelling approach.
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 Kolmogorov-Smirnov 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) Norm-Log 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.
Development and characterization of starch film and the incorporation of silver nanoparticles
(2020)
Starch is one of the biopolymers being used for bioplastic synthesis. For production, starch can be combined with different plasticizers, starches from different plant sources and even with nanomaterials to improve or to add film properties. The challenge of adding these, e.g. in the form of silver nanoparticles (AgNp) is to determine the concentration so as to avoid impairing the properties of the film, agglomeration or altering the visual characteristics of the film. In this study, a starch film synthesis route and the incorporation of silver nanoparticles has been proposed in order not to alter the properties of the film while maintaining the transparency and a clear colour of the starch film. The results showed that the proposed synthesis route is promising, efficient, reproducible, fast and the film has good mechanical properties.
This work examined the droplet corrosion of CO2 pipeline steels caused by impurities in CO2 supercritical/dense phase at 278 K, simulating the underground transport condition. The wetting properties of carbon steels (X52 and X70) as well as martensitic steel UNS S41500, and superaustenite UNS N08031 were studied by contact angle measurement, revealing reactive wetting behavior of carbon steels. Exposure tests with CO2 saturated water droplet on steel surface showed that the impurities (220 ppmv SO2 and 6700 ppmv O2) diffused into the droplet and then reacted with metal coupons in supercritical/dense phase condition, forming the corrosion product instantly during pumping process. Due to the active wetting behavior, the carbon steels suffered from heavily attack, while negligible corrosion product was observed in cases of martensitic steel UNS S41500 and superaustenite UNS 08031 coupons. Condensation experiments that were carried out on fresh polished coupons in CO2 with 1200 ppmv H2O showed that the formation and aggregation of droplet is dependent on the presence of impurities. Without SO2 and O2, the same concentration of H2O did not cause observable corrosion process after a week of exposure. With 220 ppmv SO2 and 6700 ppmv O2 even low water concentration (5-30 ppmv) still resulted in heterogeneous nucleation and subsequent growth of droplets, leading to corrosive process on carbon steel surface albeit to a lesser extent.
In this work, the focus was set on the corrosion process of condensate as drops on the surface of carbon steels (X52, X70), martensitic steel UNS S41500, and superaustenite UNS N08031 in CO2 atmosphere with impurities at 278 K (to simulate the transportation condition in a buried pipeline). Exposure tests were performed at both normal pressure and high pressure where CO2 is supercritical or in dense phase. The drop, 1 ‑ 10 μL in volume, was prepared by dropping CO2 saturated ultra-pure water onto the surface of steel coupons in a one-liter-autoclave. The CO2 gas stream, simulating the oxyfuel flue gas with varying concentration of impurities (SO2 and O2 ), was then pumped into the autoclave to observe the condensation and corrosion impacts of impurities. Comparable exposure tests were carried out with the same gas mixture and the same volume of water as vapor to observe the drop formation and the corrosion process that follows. The wettability and stability of drops on the surface of steel coupons in CO2 supercritical/dense phase environment was evaluated additionally by contact angle measurement.