Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-25150 Zeitschriftenartikel Beyer, Katrin; Kannengießer, Thomas; Griesche, Axel; Schillinger, B. Neutron radiography study of hydrogen desorption in technical iron The purpose of the present study is to show the feasibility of examining hydrogen desorption in technical iron samples using neutron radiography at the ANTARES facility of the FRM II research reactor, Technische Universität München. It has been shown that this method is appropriate for in situ determination of hydrogen Desorption for concentrations as low as 20 ppmH. Experiments were carried out in the temperature range from room temperature up to 260 °C. Measurement was based on direct comparison between electrochemically hydrogen-loaded iron samples and hydrogen-free reference samples at the same temperature. This enables the determination of hydrogen concentration as a function of time and temperature. Ex situ carrier gas hot extraction experiments using the same temperature-time profiles as the neutron radiography experiments have been used to calibrate the greyscale values of the radiographs to defined hydrogen concentrations. It can be stated that hydrogen desorption correlates with sample temperature. Norwell, Mass. Springer Science + Business Media B.V. 2011 Journal of materials science 46 15 5171 5175 10.1007/s10853-011-5450-7 2016-02-19 OPUS4-23401 Zeitschriftenartikel Beyer, Katrin; Kannengießer, Thomas; Griesche, Axel; Schillinger, B. Study of hydrogen effusion in austenitic stainless steel by time-resolved in-situ measurements using neutron radiography The purpose of the present study was to show the feasibility of measuring hydrogen effusion in austenitic stainless steel (1.4301) using neutron radiography at the facility ANTARES of the research reactor FRM II of the Technische Universität München. This method is appropriate to measure in-situ hydrogen effusion for hydrogen concentrations as small as 20 ppmH. Experiments were carried out in the temperature range from room temperature up to 533 K. The measurement principle is based on the parallel comparison of electrochemically hydrogen charged specimen with hydrogen-free reference specimen at the same temperature. This allows the determination of the hydrogen concentration in the specimens as a function of time and temperature. Separate hot carrier gas extraction experiments using the same temperature-time profiles as the radiography experiments have been used to calibrate the grey values of the neutron transmission images into hydrogen concentrations. It can be stated that the hydrogen effusion correlates with the specimen temperature. Amsterdam North-Holland 2011 Nuclear instruments and methods in physics research A 651 1 211 215 10.1016/j.nima.2011.02.010 2016-02-19 OPUS4-25981 misc Griesche, Axel; Beyer, Katrin; Kannengießer, Thomas; Calzada, E. Hydrogen diffusion measurements in steels using neutron imaging Revealing hydrogen embrittlement mechanisms in steels is of great interest to scientists and engineers. Neutron radiography makes it possible to measure in-situ hydrogen diffusion with high spatial and temporal resolution at concentrations as low as 20 ppm. We compare hydrogen-charged specimens with hydrogen-free reference specimens and use calibration standards to normalize the hydrogen concentrations. This allows quantitative tracking of the hydrogen concentration evolution as a function of time, space and temperature. Furthermore, a view into the material with 'neutron eyes' facilitates the detection of cavities that contain molecular hydrogen. TU München 2012 Annual Report 2011 of the scientific cooperation at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) 50 51 2016-02-19 OPUS4-29506 Beitrag zu einem Tagungsband Griesche, Axel; Dabah, Eitan; Hilger, A.; Kardjilov, N.; Manke, I.; Kannengießer, Thomas Neutron imaging of hydrogen in steels Red Hook, NY Curran American Ceramic Society 2013 Materials Science & Technology (MS&T) 2013 (Proceedings) Materials Science & Technology (MS&T) 2013 Montreal, Quebec, Canada 2013-10-27 2013-10-31 945 950 2016-02-20 OPUS4-29413 Zeitschriftenartikel Griesche, Axel; Solórzano, E.; Beyer, Katrin; Kannengießer, Thomas The advantage of using in-situ methods for studying hydrogen mass transport: Neutron radiography vs. carrier gas hot extraction Neutron radiography (NR) is compared with the commonly used carrier gas hot extraction (CGHE) technique. We performed isothermal hydrogen effusion experiments at 623 K to study the mass transport kinetics. The investigated material was technical iron. The quantification of the hydrogen mass flow is done for NR by using concentration standards. The temporal hydrogen concentration evolution in the sample coincides well for both methods, i.e. NR and CGHE, and is in good agreement with literature. The advantages of the NR method are the non-destructive nature of measuring and the in-situ determination of hydrogen concentrations with high spatial and temporal resolution. Remaining hydrogen inside the sample can be identified directly by the NR method. Oxford Elsevier International Association for Hydrogen Energy 2013 International journal of hydrogen energy 38 34 14725 14729 10.1016/j.ijhydene.2013.08.145 2016-02-20 OPUS4-31357 Beitrag zu einem Sammelband Dabah, Eitan; Griesche, Axel; Beyer, Katrin; Solórzano, E.; Kannengießer, Thomas Kannengießer, Thomas; Babu, S. S.; Komizo, Y.; Ramirez, A.J. In situ measurements of hydrogen diffusion in duplex stainless steels by neutron radiography Hydrogen embrittlement (HE) is a widely known phenomenon and under investigation already for more than a century. This phenomenon, though thoroughly studied, is not yet completely understood, and so far, there are several suggested mechanisms that try to explain the occurrence of HE. One important factor of understanding the HE phenomenon and predicting hydrogen-assisted failure is the descent knowledge about the hydrogen transport behaviour in the material. Neutron radiography is a proven method for tracking hydrogen diffusion and it was applied successfully in various research studies. In the presented study, we examined the hydrogen effusion behaviour in duplex stainless steel by means of neutron radiography and calculated the effective diffusion coefficient from the obtained transmission images. Springer 2014 In-situ studies with photons, neutrons and electrons scattering II 978-3-319-06144-3 155 163 10.1007/978-3-319-06145-0_9 2016-02-20 OPUS4-31084 Zeitschriftenartikel Griesche, Axel; Dabah, Eitan; Kardjilov, N.; Hilger, A.; Manke, I.; Kannengießer, Thomas Imaging of hydrogen in steels using neutrons We investigated the hydrogen distribution spatially and temporally in technical iron at room temperature. Samples were charged electrochemically and subsequently analysed by means of neutron radiography and tomography. The radiographic images allowed for a time-resolved analysis of hydrogen fluxes. The three-dimensional distribution of hydrogen measured by neutron tomography delivered valuable information for the damage analysis of hydrogen-induced cracks. For the first time hydrogen concentration gradients inside the material could be detect directly together with the cracks. The neutron radiography and tomography results were gained at the Research Reactor BER II of the HZB in Berlin. München Carl Hanser Deutsche Gesellschaft für Materialkunde 2014 International journal of materials research 105 7 640 644 10.3139/146.111043 2016-02-20 OPUS4-31068 Zeitschriftenartikel Griesche, Axel; Dabah, Eitan; Kannengießer, Thomas; Kardjilov, N.; Hilger, A.; Manke, I. Three-dimensional imaging of hydrogen blister in iron with neutron tomography We investigated hydrogen embrittlement and blistering in electrochemically hydrogen-charged technical iron samples at room temperature. Hydrogen-stimulated cracks and blisters and the corresponding hydrogen distributions were observed by neutron tomography. Cold neutrons were provided by the research reactor BER II to picture the sample with a spatial resolution in the reconstructed three-dimensional model of ~25 µm. We made the unique observation that cracks were filled with molecular hydrogen and that cracks were surrounded by a 50 µm wide zone with a high hydrogen concentration. The zone contains up to ten times more hydrogen than the bulk material. The hydrogen enriched zone can be ascribed to a region of increased local defect density. Hydrogen also accumulated at the sample surface having the highest concentration at blistered areas. The surfaces of the brittle fractured cracks showed micropores visualized by scanning electron microscopy. The micropores were located at grain boundaries and were surrounded by stress fields detected by electron backscattered diffraction. The cracks clearly originated from the micropores. Kidlington Elsevier Science 2014 Acta materialia 78 14 22 10.1016/j.actamat.2014.06.034 2016-02-20 OPUS4-38278 Posterpräsentation Laquai, René; Schaupp, Thomas; Müller, Bernd R.; Griesche, Axel; Bruno, Giovanni; Kannengießer, Thomas 3D imaging of hydrogen assisted cracking using analyser-based imaging To better understand the mechanism of hydrogen assisted cracking (HAC), it is important to investigate the 3D structure of the cracks non-destructively. Since, cracks introduced by HAC are usually very small, conventional x-ray imaging methods often lack the required spatial resolution. However, the detection of those cracks can be enhanced by taking advantage of refraction at interfaces within the sample. To image this refractive deflection we employ analyser based imaging (ABI). In this work we aim at proving the enhanced crack detection of ABI by investigating an alluminum alloy weld. 2015 BESSY User Meeting 2015 Berlin, Germany 09.12.2015 11.12.2015 2016-11-16 OPUS4-34287 Beitrag zu einem Tagungsband Laquai, René; Schaupp, Thomas; Müller, Bernd R.; Griesche, Axel; Bruno, Giovanni; Kannengießer, Thomas 3D imaging of hydrogen assisted cracking in metals using refraction enhanced synchrotron CT Hydrogen in metals can cause a degradation of the mechanical properties with possible subsequent hydrogen assisted cracking (HAC). Though, the mechanism of HAC is not completely understood yet and thus suitable methods for in situ investigations to characterise the crack formation are needed. X-ray computed tomography (CT) is a well-known tool for analysing these properties. However, the effective resolution of the detector system limits the detection of small defects by CT. Analyser based imaging (ABI) takes advantage of x-ray refraction at interfaces between volumes of different density, i.e. of cracks, pores, inclusions, etc., within the sample to detect defects smaller than the resolution of the detector system. In this study, measurements on an aluminium alloy weld showed that ABI allows us to resolve the 3D structure of cracks undetected by absorption based CT. Prospective investigations will analyse HAC in steels. Technische Universität Berlin / Bundesanstalt für Materialforschung und -prüfung 2015 NDT-CE 2015 - International symposium non-destructive testing in civil engineering (Proceedings) NDT-CE 2015 - International symposium non-destructive testing in civil engineering Berlin, Germany 2015-09-15 2015-09-17 1217 1224 2016-02-20