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 - CONF A1 - Laquai, René A1 - Schaupp, Thomas A1 - Müller, Bernd R. A1 - Griesche, Axel A1 - Bruno, Giovanni A1 - Kannengießer, Thomas T1 - 3D imaging of hydrogen assisted cracking in metals using refraction enhanced synchrotron CT N2 - 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. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 2015-09-15 KW - Wasserstoffversprödung KW - Wasserstoffunterstützte Rissbildung KW - Röntgenrefraktion KW - CT KW - Hydrogen embrittlement (HE) KW - Hydrogen assisted cracking (HAC) KW - Aluminium alloy KW - X-ray refraction KW - Analyser based imaging KW - Computed tomography (CT) KW - Synchrotron radiation PY - 2015 SN - 1435-4934 SP - 1217 EP - 1224 AN - OPUS4-34287 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Laquai, René A1 - Schaupp, Thomas A1 - Müller, Bernd R. A1 - Griesche, Axel A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - 3D Crack analysis in hydrogen charged lean duplex stainless steel with synchrotron refraction CT N2 - Hydrogen in metals can cause a degradation of the mechanical properties, the so-called hydrogen embrittlement. In combination with internal stresses, hydrogen assisted cracking (HAC) can occur. This phenomenon is not completely understood yet. To better characterise the cracking behaviour, it is important to gain information about the evolution of the 3D crack network. For this purpose samples of lean duplex stainless steel were loaded with hydrogen by means of electrochemical charging and investigated by means of synchrotron refraction CT and SEM fractography after uniaxial tensile loading. Synchrotron refraction CT is an analyser-based imaging (ABI) technique. It uses a Si (111) single crystal as analyser, which is placed into the beam path between sample and detector. According to Bragg’s law only incident x-rays within a narrow range around the Bragg-angle are diffracted from the analyser into the detector. Hence, the analyser acts as an angular filter for the transmitted beam. This filtering allows to turn the refraction and scattering of x-rays into image contrast. Refraction occurs at all interfaces, where the density of the material changes and is more sensitive to density changes than the attenuation. Therefore, it is possible to detect smaller cracks than with classical x-ray imaging techniques, like CT, with comparable spacial resolution. It also visualises the 3D structure of the cracks and gains quantitative information about their morphology and distribution. Since cracks introduced by HAC are usually very small and have a small opening displacement, synchrotron refraction CT is expected to be well suited for imaging this cracking mechanism and can be a valuable tool to characterise the formation and the evolution of a 3D crack network. T2 - WCNDT 2016 CY - München, Germany DA - 13.06.2016 KW - X-ray refraction KW - Computed tomography KW - Hydrogen assisted cracking KW - Duplex stainless steel PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-366481 SN - 978-3-940283-78-8 VL - BB 158 SP - Tu.4.B.3, 1 EP - 9 AN - OPUS4-36648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Pfretzschner, Beate A1 - Schaupp, Thomas A1 - Kannengießer, Thomas A1 - Kardjilov, N. ED - Somerday, B. P. ED - Sofronis, P. T1 - Measurement of hydrogen distributions in metals by neutron radiography and tomography N2 - Neutron imaging has become a valuable tool for measuring hydrogen distributions qualitatively and quantitatively in metals. Hydrogen mass flow can be measured inside cm thick Steel samples with 10 s temporal resolution. Hydrogen accumulations around craclcs in embrittled iron samples can be visualized three-dimensionally. The gas pressure of hydrogen in crack cavities has been measured to be in the ränge of 5 MPa to 15 MPa. This quality of information allows new insights for the analysis of damage mechanisms on a micrometer scale, e.g., of hydrogen blistering. Further, this method is nondestructive and provides local information in situ and in three dimensions with a spatial resolution of 20 µm - 30 µm. T2 - International Hydrogen Conference 2016 CY - Jackson Lake Lodge, Wyoming, USA DA - 11.09.2017 KW - Hydrogen KW - Neutron imaging KW - Neutron radiography KW - Neutron tomography PY - 2017 SN - 978-0-7918-6138-7 U6 - https://doi.org/10.1115/1.861387_ch46 SP - 416 EP - 422 AN - OPUS4-42505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Kannengießer, Thomas A1 - Treutler, K. A1 - Gehling, T. A1 - Eissel, A. A1 - Wesling, V. T1 - In situ Messung der chemischen Konzentration in der Schmelze während des WIG-Schweißens von Duplexstählen N2 - Duplexstähle besitzen ein zweiphasiges Gefüge und werden aufgrund ihrer verbesserten Schweißeignung gegenüber den Vollausteniten häufig im Anlagen- bzw. Apparatebau eingesetzt. Aufgrund der hohen Abkühlgeschwindigkeit und dem Abbrand von Legierungselementen kommt es zu einer Ferritisierung des Schweißguts und damit zu einer Degradation der mechanischen Eigenschaften. Zur Vorhersage des Phasenverhältnisses im Schweißgut wird das WRC1992-Diagramm genutzt. Dieses Diagramm zeigt einige Ungenauigkeiten und benötigt zur genaueren Vorhersage der Phasenverhältnisse eine Überarbeitung. Um den Einfluss einzelner Elemente auf das Schweißnahtmikrogefüge besser zu verstehen, wurden drahtförmige Schweißzusatzwerkstoffe mit dem Ferrit-Bildner Nb und dem Austenit-Bildner Cu beschichtet und für Schweißungen verwendet. Die Messmethode der Laser-induzierten Plasmaspektroskopie (LIBS) bietet hier eine gute Möglichkeit der in situ Überwachung der chemischen Konzentrationen, während des WIG-Schweißens von Duplexstählen. Die LIBS-Messergebnisse, konnten mit der Ferritnummer und der Schweißnahtmikrostruktur korreliert werden. T2 - Symposium Materialtechnik der TU Clausthal CY - Clausthal-Zellerfeld, Germany DA - 23.02.2023 KW - LIBS KW - In situ measurement KW - WRC 1992 diagram KW - Dduplex stainless steel KW - TIG welding PY - 2023 VL - 12 SP - 612 EP - 627 PB - Shaker CY - Aachen AN - OPUS4-57991 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -