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 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-348022 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 - 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 U6 - 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 - Osterloh, Kurt A1 - Fratzscher, Daniel A1 - Schwabe, A. A1 - Schillinger, B. A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Radiography and partial tomography of wood with thermal neutrons N2 - The effective high neutron scattering absorption coefficient of hydrogen (48.5 cm²/g) due to the scattering allows neutrons to reveal hydrocarbon structures with more contrast than X-rays, but at the same time limits the sample size and thickness that can be investigated. Many planar shaped objects, particularly wood samples, are sufficiently thin to allow thermal neutrons to transmit through the sample in a direction perpendicular to the planar face but not in a parallel direction, due to increased thickness. Often, this is an obstacle that prevents some tomographic reconstruction algorithms from obtaining desired results because of inadequate information or presence of distracting artifacts due to missing projections. This can be true for samples such as the distribution of glue in glulam (boards of wooden layers glued together), or the course of partially visible annual rings in trees where the features of interest are parallel to the planar surface of the sample. However, it should be possible to study these features by rotating the specimen within a limited angular range. In principle, this approach has been shown previously in a study with fast neutrons [2]. A study of this kind was performed at the Antares facility of FRM II in Garching with a 2.6×107/cm² s thermal neutron beam. The limit of penetration was determined for a wooden step wedge carved from a 2 cm×4 cm block of wood in comparison to other materials such as heavy metals and Lucite as specimens rich in hydrogen. The depth of the steps was 1 cm, the height 0.5 cm. The annual ring structures were clearly detectable up to 2 cm thickness. Wooden specimens, i.e. shivers, from a sunken old ship have been subjected to tomography. Not visible from the outside, clear radial structures have been found that are typical for certain kinds of wood. This insight was impaired in a case where the specimen had been soaked with ethylene glycol. In another large sample study, a planar board made of glulam has been studied to show the glued layers. This study shows not only the limits of penetration in wood but also demonstrates access to structures perpendicular to the surface in larger planar objects by tomography with fast neutrons, even with incomplete sets of projection data that covers an angular range of only 90° or even 60°. KW - Neutron computed tomography KW - Limited angle tomography KW - Wood KW - Annual rings PY - 2011 U6 - https://doi.org/10.1016/j.nima.2011.02.095 SN - 0168-9002 SN - 0167-5087 VL - 651 IS - 1 SP - 236 EP - 239 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-24918 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 U6 - 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 - JOUR A1 - Beyer, Katrin A1 - Kannengießer, Thomas A1 - Griesche, Axel A1 - Schillinger, B. T1 - Study of hydrogen effusion in austenitic stainless steel by time-resolved in-situ measurements using neutron radiography N2 - 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. KW - Hydrogen effusion KW - Austenitic stainless steels KW - Neutron radiography PY - 2011 U6 - https://doi.org/10.1016/j.nima.2011.02.010 SN - 0168-9002 SN - 0167-5087 VL - 651 IS - 1 SP - 211 EP - 215 PB - North-Holland CY - Amsterdam AN - OPUS4-23401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -