TY - CONF A1 - Kardjilov, N. A1 - Hilger, A. A1 - Manke, I. A1 - Banhart, J. A1 - Griesche, Axel T1 - Imaging with Cold Neutrons at the CONRAD-2 Facility T2 - Physics Procedia N2 - CONRAD-2 is an imaging instrument using low-energy (cold) neutrons. The instrument is installed at the end of a curved neutron guide which avoids the direct line of sight towards the reactor core. This ensures a very low background of high-energy neutrons and. photons at the sample position. The cold neutron beam provides a wavelength range which is suitable for phase-and diffraction-contrast imaging such as grating interferometry and Bragg edge mapping. The instrument is well suited for high resolution imaging due to the high efficiency of the very thin scintillators that can be used for the detection of cold neutrons. An instrument upgrade was performed recently as a part of an upgrade program for the cold neutron instrumentation at HZB. The parameters of the instrument as well as some research highlights will be presented. T2 - 10th World Conference on Neutron Radiography (WCNR) CY - Grindelwald, SWITZERLAND DA - 05.10.2014 KW - iron embrittlement KW - neutron imaging KW - neutron instrumentation KW - cold neutrons PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-373239 DO - https://doi.org/10.1016/j.phpro.2015.07.008 SN - 1875-3892 VL - 69 SP - 60 EP - 66 PB - Elsevier B.V. CY - Amsterdam, NL AN - OPUS4-37323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Dabah, Eitan A1 - Kannengießer, Thomas A1 - Hilger, A. A1 - Kardjilov, N. A1 - Manke, I. A1 - Schillinger, B. T1 - Measuring hydrogen distributions in iron and steel using neutrons JF - Physics Procedia N2 - Neutron tomography has been applied to investigate the mechanism of hydrogen assisted cracking in technical iron and supermartensitic steel. Rectangular technical iron block samples showed blistering due to intense hydrogen charging and the tomographic method revealed in situ the spatial distribution of hydrogen and cracks. Hydrogen accumulated in a small region around cracks and the cracks are filled with hydrogen gas. Cracks close to the surface contained no hydrogen. Hydrogenous tensile test samples of supermartensitic steel were pulled until rupture and showed hydrogen accumulations at the notch base and in the plastically deformed region around the fracture surface. T2 - 10th World Conference on Neutron Radiography (WCNR) CY - Grindelwald, Switzerland DA - 05.10.2014 PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-348022 DO - https://doi.org/10.1016/j.phpro.2015.07.062 SN - 1875-3892 VL - 69 SP - 445 EP - 450 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-34802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Dabah, Eitan A1 - Kardjilov, N. A1 - Hilger, A. A1 - Manke, I. A1 - Kannengießer, Thomas T1 - Imaging of hydrogen in steels using neutrons JF - International journal of materials research N2 - 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. KW - Hydrogen embrittlement KW - Hydrogen diffusion KW - Neutron tomography KW - Blister PY - 2014 DO - https://doi.org/10.3139/146.111043 SN - 1862-5282 VL - 105 IS - 7 SP - 640 EP - 644 PB - Carl Hanser CY - München AN - OPUS4-31084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Griesche, Axel A1 - Dabah, Eitan A1 - Kannengießer, Thomas A1 - Kardjilov, N. A1 - Hilger, A. A1 - Manke, I. T1 - Three-dimensional imaging of hydrogen blister in iron with neutron tomography JF - Acta materialia N2 - 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. KW - Hydrogen embrittlement KW - Hydrogen diffusion KW - In situ KW - Neutron tomography KW - Iron PY - 2014 DO - https://doi.org/10.1016/j.actamat.2014.06.034 SN - 1359-6454 SN - 1873-2453 VL - 78 SP - 14 EP - 22 PB - Elsevier Science CY - Kidlington AN - OPUS4-31068 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 (Proceedings) 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 -