TY - JOUR A1 - Beyer, Katrin A1 - Kannengießer, Thomas A1 - Griesche, Axel A1 - Schillinger, B. T1 - Neutron radiography study of hydrogen desorption in technical iron N2 - 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. KW - Neutron radiography KW - Hydrogen PY - 2011 DO - https://doi.org/10.1007/s10853-011-5450-7 SN - 0022-2461 SN - 1573-4803 VL - 46 IS - 15 SP - 5171 EP - 5175 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-25150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuskin, D. A1 - Kargl, F. A1 - Griesche, Axel A1 - Stenzel, C. A1 - Mitschke, D. A1 - Bräuer, D. A1 - Meyer, A. T1 - MSL compatible isothermal furnace insert for high temperature shear-cell diffusion experiments N2 - For long-time diffusion experiments shear-cell techniques offer more favourable terms than the traditional long capillary techniques. Here, we present a further developed shear-cell that enables the measurement of diffusion coefficients up to temperatures of 1600 °C. Hence, diffusion experiments can be carried out at temperatures not accessible until now by conventional capillary or shear-cell techniques. The modified shear-cell, which can contain up to six samples of a total length of 90mm and a diameter of 1.5 mm, is built of 30 shear discs of 3mm thickness each. It is operated in an isothermal furnace insert which can be accommodated in the Materials Science Laboratory of the International Space Station. This provides the opportunity that the shear-cell can be applied to microgravity and to ground-based experiments, respectively. The heater insert with an overall length of 518mm and a diameter of 210mm consists of four heating zones with a total power of 3.5 kW. Temperature homogeneity along the graphite sample compartment is better than 2K at 1600°C. Details of the new design are discussed and results of first successfully performed heating and shearing cycles are presented. KW - Microgravity KW - Diffusion KW - Shear cell KW - Melt KW - Alloy PY - 2011 DO - https://doi.org/10.1088/1742-6596/327/1/012053 SN - 1742-6588 SN - 1742-6596 VL - 327 IS - 012053 SP - 1 EP - 8 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-24994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Dabah, Eitan A1 - Hilger, A. A1 - Kardjilov, N. A1 - Manke, I. A1 - Kannengießer, Thomas T1 - Neutron imaging of hydrogen in steels T2 - Materials Science & Technology (MS&T) 2013 CY - Montreal, Quebec, Canada DA - 2013-10-27 KW - Neutron radiography KW - Hydrogen KW - Diffusion KW - Steel PY - 2013 SP - 945 EP - 950 PB - Curran CY - Red Hook, NY AN - OPUS4-29506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Zhang, B. A1 - Solórzano, E. A1 - Garcia-Moreno, F. T1 - Note: X-ray radiography for measuring chemical diffusion in metallic melts N2 - A x-ray radioscopy technique for measuring in situ chemical diffusion coefficients in metallic melts is presented. The long-capillary diffusion measurement method is combined with imaging techniques using microfocus tubes and flat panel detectors in order to visualize and quantitatively analyze diffusive mixing of two melts of different chemical composition. The interdiffusion coefficient as function of temperature and time is obtained by applying Fick’s diffusion laws. Tracking the time dependence of the mean square penetration depth of the mixing process allows to detect changes in the mass transport caused by convective flow. The possibility to sort out convective mass transport contributions from analysis enhances significantly the accuracy compared to the conventional long-capillary diffusion measurement method with postmortem analysis. The performance of this novel diffusion measurement method with x-ray radiography technique is demonstrated by a diffusion experiment in an Al-Ni melt. KW - Diffusion KW - Metal KW - Aluminium KW - Nickel KW - Melt KW - In-situ KW - Radiography KW - Capillary KW - Aluminium-alloys KW - Chemical analysis KW - Chemical interdiffusion KW - Convection KW - Liquid alloys KW - Mass transfer KW - Nickel alloys KW - X-ray apparatus PY - 2010 DO - https://doi.org/10.1063/1.3427256 SN - 0034-6748 SN - 1089-7623 VL - 81 SP - 056104-1 - 056104-3 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-21333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kargl, F. A1 - Engelhardt, M. A1 - Yang, F. A1 - Weis, H. A1 - Schmakat, P. A1 - Schillinger, B. A1 - Griesche, Axel A1 - Meyer, A. T1 - In situ studies of mass transport in liquid alloys by means of neutron radiography N2 - When in situ techniques became available in recent years this led to a breakthrough in accurately determining diffusion coefficients for liquid alloys. Here we discuss how neutron radiography can be used to measure chemical diffusion in a ternary AlCuAg alloy. Neutron radiography hereby gives complementary information to x-ray radiography used for measuring chemical diffusion and to quasielastic neutron scattering used mainly for determining self-diffusion. A novel Al2O3 based furnace that enables one to study diffusion processes by means of neutron radiography is discussed. A chemical diffusion coefficient of Ag against Al around the eutectic composition Al68.6Cu13.8Ag17.6 at.% was obtained. It is demonstrated that the in situ technique of neutron radiography is a powerful means to study mass transport properties in situ in binary and ternary alloys that show poor x-ray contrast. KW - Neutron radiography KW - Diffusion KW - Liquid alloys KW - Shear cell PY - 2011 DO - https://doi.org/10.1088/0953-8984/23/25/254201 SN - 0953-8984 SN - 1361-648X VL - 23 IS - 25 SP - 254201-1 EP - 254201-8 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-23854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Lexow, Jürgen T1 - Research on materials simulation and the promotion of global databases - activities within the world materials research institute forum (WMRIF) T2 - Materials Science & Technology (MS&T) 2013 CY - Montreal, Quebec, Canada DA - 2013-10-27 KW - ICME KW - WMRIF KW - VAMAS KW - M-ERA.net KW - Materials simulation KW - Global databases PY - 2013 SP - 2551 EP - 2554 PB - Curran CY - Red Hook, NY AN - OPUS4-29718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Solórzano, E. A1 - Beyer, Katrin A1 - Kannengießer, Thomas T1 - The advantage of using in-situ methods for studying hydrogen mass transport: Neutron radiography vs. carrier gas hot extraction N2 - 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. KW - Hydrogen diffusion KW - In-situ KW - Neutron radiography KW - Carrier gas hot extraction KW - Imaging PY - 2013 DO - https://doi.org/10.1016/j.ijhydene.2013.08.145 SN - 0360-3199 VL - 38 IS - 34 SP - 14725 EP - 14729 PB - Elsevier CY - Oxford AN - OPUS4-29413 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Kannengießer, Thomas T1 - Spatially resolved EDS, XRF and LIBS measurements of the chemical composition of duplex stainless steel welds: A comparison of methods N2 - Duplex stainless steels (DSS) are used in all industries where corrosion problems play a major role. Examples include the chemical industry, the food industry and shipping industries. DSS have a balanced phase ratio of ferrite (α) and austenite (γ). Unlike single-phase stainless steels, DSS combine the advantages of these and can therefore fit many industry requirements, such as weight saving or high mechanical strength. When these steels are welded, alloying elements can burn off and condense as thin layers on cold surface regions. This loss of chemical elements can lead to changes in the microstructure. With the help of Laser-Induced Breakdown Spectroscopy (LIBS), chemical element distributions were visualized. The results were compared with those of conventional measurement methods, such as energy dispersive X-ray analysis (EDS) and X-ray fluorescence analysis (XRF), and the results from LIBS could be validated. LIBS is suitable as a fast, straightforward measurement method for producing line scans along the weld seam and provides spatially resolved information on accumulation phenomena of burned off alloying elements. LIBS is very well suited for the detection of sub-surface elements due to the exclusively superficial ablation of the material. In addition, the measurement method has been calibrated so that quantitative statements about element concentrations can also be made. T2 - EMSLIBS 2021 CY - Online Meeting DA - 25.11.2021 KW - LIBS KW - TIG welding KW - Duplex stainless steel KW - XRF KW - EDS PY - 2022 DO - https://doi.org/10.1016/j.sab.2022.106439 SN - 0584-8547 VL - 193 SP - 1 EP - 8 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-54837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Laquai, René A1 - Schaupp, Thomas A1 - Griesche, Axel A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Hannemann, Andreas A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - Quantitative analysis of hydrogen-assisted microcracking in duplex stainless steel through X-ray refraction 3D imaging N2 - While the problem of the identification of mechanisms of hydrogen assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field-of-views and high spatial resolution. Synchrotron X-ray refraction techniques do possess both features. In this work, we show how synchrotron X-ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X-ray absorption computed tomography. As already reported in literature, but this time using a non-destructive technique, we show that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen-charged specimens, we deduce that cracks in the specimen bulk are due to the rolling process rather than hydrogen-assisted. We show that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and we deduce that a significant crack propagation can only be observed short before rupture. KW - 2101 duplex stainless steel KW - Hydrogen embrittlement KW - Synchrotron radiation KW - X-ray refraction KW - Computed tomography KW - Microcracking PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542811 DO - https://doi.org/10.1002/adem.202101287 SN - 1438-1656 SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54281 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Pfretzschner, B. A1 - Taparli, Ugur Alp A1 - Kardjilov, N. T1 - Time-Resolved Neutron Bragg-Edge Imaging: A Case Study by Observing Martensitic Phase Formation in Low Temperature Transformation (LTT) Steel during GTAW N2 - Polychromatic and wavelength-selective neutron transmission radiography were applied during bead-on-plate welding on 5 mm thick sheets on the face side of martensitic low transformation temperature (LTT) steel plates using gas tungsten arc welding (GTAW). The in situ visualization of austenitization upon welding and subsequent α’-martensite formation during cooling could be achieved with a temporal resolution of 2 s for monochromatic imaging using a single neutron wavelength and of 0.5 s for polychromatic imaging using the full spectrum of the beam (white beam). The spatial resolution achieved in the experiments was approximately 200 µm. The transmitted monochromatic neutron beam intensity at a wavelength of λ = 0.395 nm was significantly reduced during cooling below the martensitic start temperature Ms since the emerging martensitic phase has a ~10% higher attenuation coefficient than the austenitic phase. Neutron imaging was significantly influenced by coherent neutron scattering caused by the thermal motion of the crystal lattice (Debye–Waller factor), resulting in a reduction in the neutron transmission by approx. 15% for monochromatic and by approx. 4% for polychromatic imaging. KW - Austenite-to-martensite transformation KW - Neutron radiography KW - Bragg-edge imaging KW - Gas tungsten arc welding (GTAW) KW - Debye–Waller factor KW - Low transformation temperature (LTT) steel PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538016 DO - https://doi.org/10.3390/app112210886 VL - 11 IS - 22 SP - 10886 PB - MDPI CY - Basel AN - OPUS4-53801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -