TY - CONF A1 - Mente, Tobias A1 - Grimault de Freitas, Tomás A1 - Nietzke, Jonathan A1 - Konert, Florian A1 - Sobol, Oded A1 - Wackermann, Ken A1 - Ruchti, Peter A1 - Elsen-Humberg, Stefan A1 - Systermans, Thomas ED - Zimmermann, Martina T1 - Hohlzugprüfung als kostengünstige Methode zur Werkstoffcharakterisierung für die Wasserstoffwirtschaft N2 - Wasserstoff ist ein notwendiger Baustein zur Erreichung zukünftiger Klimaziele. Für eine schnell hochlaufende Wasserstoffwirtschaft ist es daher notwendig sowohl bestehende Infrastruktur als auch neue Werkstoffe für den sicheren und nachhaltigen Einsatz in Wasserstofftechnologien zu qualifizieren. Die akzeptierten und standardisierten Prüfverfahren zur Ermittlung des Einflusses gasförmigen Wasserstoffs auf die mechanischen Eigenschaften metallischer Werkstoffe sind meist sehr komplex, mit hohem technologischem und finanziellem Aufwand verbunden und stehen nur Wenigen Instituten weltweit zur Verfügung. Die Hohlzugprüftechnik bietet hier eine kostengünstige und einfach zu realisierende Alternative. Mit der im Jahr 2024 erstmals veröffentlichten ISO 7039 wurde diese Prüftechnik auch für die Wirtschaft anwendbar gemacht. Der Standard gilt allgemein für die Prüfung mit gasförmigen Medien, weist jedoch in Bezug auf die Prüfung mit gasförmigem Wasserstoff noch einige Wissenslücken auf. Im Teilvorhaben H2HohlZug des Leitprojekt TransHyDE werden die Lücken zum Einfluss der Geometrie, Oberflächenqualität sowie Gasreinheit in einzelnen Arbeitspaketen geschlossen und die Erkenntnisse in einen Standard überführt. T2 - 43. Vortrags- und Diskussionstagung Werkstoffprüfung 2025 - Werkstoffe und Bauteile auf dem Prüfstand CY - Dresden, Germany DA - 27.11.2025 KW - Hohlzugprüfung KW - Druckwasserstoff KW - ISO 7039 KW - H2HohlZug - TransHyDE PY - 2025 SN - 978-3-88355-454-9 SP - 11 EP - 17 PB - Deutsche Gesellschaft für Materialkunde e.V. (DGM) CY - Dresden AN - OPUS4-64937 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böllinghaus, Thomas A1 - Mente, Tobias T1 - Vermeidung von Rissen beim Schweissen von Rohrleitungen N2 - Schadensfälle in den letzten zehn Jahren mit teilweise katastrophalen Folgen belegen, dass der Vermeidung von Rissen beim Schweißen von Rohrleitungen besondere Aufmerksamkeit zu schenken ist. In der Analyse solcher Schäden ist zu unterscheiden, ob die Risse bereits während oder kurz nach der schweißtechnischen Fertigung der Rohrkomponenten oder während des anschließenden Betriebes entstanden sind. Im vorliegenden Beitrag wird sich vor allem auf die Vermeidung einer Heiß- und Kaltrissbildung beim Schweißen von Rohrleitungen konzentriert und es werden weitere Forschungsperspektiven abgeleitet. T2 - DVM-Tag 2011 - Bauteilzuverlässigkeit - Schäden und ihre Vermeidung CY - Berlin, Germany DA - 04.05.2011 KW - Rissvermeidung KW - Heißrissbildung KW - Wasserstoffunterstützte Kaltrissbildung (HACC) KW - Pipelineschweißungen PY - 2011 SN - 0946-5987 N1 - Serientitel: DVM-Bericht – Series title: DVM-Bericht IS - 678 SP - 81 EP - 90 AN - OPUS4-26113 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Mesoscale Crack Model for Duplex Stainless Steel Microstructures T2 - IIW Intermediate Meeting 2012 CY - Cambridge, England DA - 2012-02-20 PY - 2012 AN - OPUS4-25537 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Hohlzugprüfung - Kostengünstige Methode zur Werkstoffcharakterisierung für die Wasserstoffwirtschaft N2 - Wasserstoff ist ein notwendiger Baustein zur Erreichung zukünftiger Klimaziele. Für eine schnell hochlaufende Wasserstoffwirtschaft ist es daher notwendig sowohl bestehende Infrastruktur als auch neue Werkstoffe für den sicheren und nachhaltigen Einsatz in Wasserstofftechnologien zu qualifizieren. Die akzeptierten und standardisierten Prüfverfahren zur Ermittlung des Einflusses gasförmigen Wasserstoffs auf die mechanischen Eigenschaften metallischer Werkstoffe sind meist sehr komplex, mit hohem technologischem und finanziellem Aufwand verbunden und stehen nur Wenigen Instituten weltweit zur Verfügung. Die Hohlzugprüftechnik bietet hier eine kostengünstige und einfach zu realisierende Alternative. Mit der im Jahr 2024 erstmals veröf-fentlichten ISO 7039 wurde diese Prüftechnik auch für die Wirtschaft anwendbar gemacht. Der Standard gilt allgemein für die Prüfung mit gasförmigen Medien, weist jedoch in Bezug auf die Prüfung mit gasförmigem Wasserstoff noch einige Wissenslücken auf. Im Teilvorhaben H2HohlZug des Leitprojekt TransHyDE werden die Lücken zum Einfluss der Geometrie, Ober-flächenqualität sowie Gasreinheit in einzelnen Arbeitspaketen geschlossen und die Erkenntnisse in einen Standard überführt. T2 - 43. Vortrags- und Diskussionstagung Werkstoffprüfung 2025 - Werkstoffe und Bauteile auf dem Prüfstand CY - Dresden, Germany DA - 27.11.2025 KW - Hohlzugprüfung KW - Druckwasserstoff KW - ISO 7039 KW - H2HohlZug - TransHyDE PY - 2025 AN - OPUS4-64936 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Richter, Tim A1 - Mayr, P. A1 - Nitsche, A. A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Hydrogen diffusion in creep-resistant 9% Cr P91 multi-layer weld metal N2 - Welded components of P91 9% Cr steel demand for careful welding fabrication with necessary post weld heat treatment (PWHT). Before the PWHT, a hydrogen removal heat treatment is necessary for avoidance of hydrogen assisted cracking (HAC). In this context, the microstructure and temperature-dependent hydrogen diffusion is important, and reliable diffusion coefficients of P91 weld metal are rare. For that reason, the diffusion behavior of P91 multi-layer weld metal was investigated for as-welded (AW) and PWHT condition by electrochemical permeation experiments at room temperature and carrier gas hot extraction (CGHE) from 100 to 400 °C. Hydrogen diffusion coefficients were calculated, and the corresponding hydrogen concentration was measured. It was ascertained that both heat treatment conditions show significant differences. At room temperature the AW condition showed significant hydrogen trapping expressed by to seven times lower diffusion coefficients. A preferred diffusion direction was found in perpendicular direction expressed by high permeability. The CGHE experiments revealed lower diffusion coefficients for the AW condition up to 400 °C. In this context, a hydrogen concentration of approximately 21 ml/100 g was still trapped at 100 °C. For that reason, a certain HAC susceptibility of as-welded P91 weld metal cannot be excluded, and hydrogen removal should be done before PWHT. KW - Creep resisting materials KW - Diffusion KW - Hydrogen KW - Weld metal KW - Post weld heat treatment KW - Microstructure PY - 2020 DO - https://doi.org/10.1007/s40194-019-00828-8 SN - 0043-2288 VL - 64 IS - 2 SP - 267 EP - 281 PB - Springer AN - OPUS4-50471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Schadensprävention durch Werkstoff- und Komponentenprüfung unter Druckwasserstoff N2 - Historischer Schadensfall Wasserstoff-Gasflaschen von A. Martens aus dem Jahr 1894 / Kurzvorstellung H2Safety und ModuH2Pipe / Prüfung von Hohlzugproben unter Druckwasserstoff T2 - 49. VDI-Jahrestagung Schadensanalyse - Schadensprävention bei Druckwasserstoff und Schadensprävention für Kunststoff- und Elastomerprodukte CY - Würzburg, Germany DA - 18.10.2023 KW - Hohlzugprobe KW - Wasserstoff KW - H2Safety@BAM KW - MatCom KW - ModuH2Pipe@BAM PY - 2023 AN - OPUS4-58624 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Schadensprävention durch Werkstoff- und Komponentenprüfung unter Druckwasserstoff N2 - Historischer Schadensfall Wasserstoff-Gasflaschen von A. Martens aus dem Jahr 1894 .Prüfung von Hohlzugproben unter Druckwasserstoff - Herausforderungen und Umsetzung. T2 - Forum Schadenverhütung der Arbeitsgemeinschaft Berlin Brandenburg (AGS) in Kooperation mit der AGBB Berlin e.V. CY - Berlin, Germany DA - 12.10.2023 KW - Hohlzugprobe KW - Wasserstoff PY - 2023 AN - OPUS4-58623 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - kModeling of hydrogen distribution in a duplex stainless steel N2 - Quite a number of models for hydrogen distribution in steels and welds have been developed in the past 20 years. They reach from simple analytical models to more complex two and three dimensional finite element simulations. So far, these models have been used to simulate hydrogen distribution in homogeneous microstructure. This paper contributes to numerical simulation of hydrogen distribution in heterogeneous microstructure, e. g. in a duplex stainless steel microstructure consisting of two phase fractions. Under appropriate conditions, such as cathodic protection, it is possible that hydrogen is absorbed leading to material embrittlement and possibly initiating hydrogen assisted cracking. In order to avoid hydrogen assisted cracking in duplex stainless steels, it is of great interest to know more about the diffusion behavior of the ferrite and austenite phase. A numerical model has been developed that operates on the mesoscale and enables simulation of hydrogen transport in the various phases of a metallic material. As a first application of this model, hydrogen distribution in a duplex stainless steel 1.4462, consisting of approximately equal portions of ferrite and austenite, was simulated using the finite element program package ANSYS. The results reflect the dependency of hydrogen distribution on the microstructural alignment of the ferrite and austenite phase fractions. Crack-critical areas can thus be identified, provided the critical strain-hydrogen combination is known for the respective microstructural phase. KW - Finite element KW - Simulation KW - Duplex stainless steel KW - Hydrogen KW - Diffusion KW - Weld metal KW - Microstructure PY - 2012 SN - 0043-2288 SN - 1878-6669 VL - 56 IS - 11/12 SP - 66 EP - 78 PB - Springer CY - Oxford AN - OPUS4-27483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Wasserstoffunterstützte Rissbildung in geschweißten hochfesten Feinkornbaustählen T2 - 17. LWE Seminar - "Schweißen im Mobilkranbau" CY - Ehingen, Germany DA - 2012-11-08 PY - 2012 AN - OPUS4-27043 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Stand der Technik des Schweißens hoch- und ultrahochfester Feinkornbaustähle T2 - 1st Alform Welding Day CY - Linz, Austria DA - 2012-06-05 PY - 2012 AN - OPUS4-26032 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Sommitsch, C. ED - Enzinger, N. T1 - Numerical model for hydrogen assisted cracking in duplex stainless steel microstructures N2 - Duplex stainless steels (DSS) are used in various industrial applications, e.g. in offshore construction as well as in chemical industry. But, at specific conditions, as for instance arc welding fabrication, cathodic protection or exposure to sour service environments, such materials can take up hydrogen which may cause significant property degradation particularly in terms of ductility losses which, in turn, may entail hydrogen assisted cracking (HAC). If HAC occurs in a duplex stainless steel the cracking mechanism is different from steels having only one phase, because hydrogen diffusion, stress-strain distribution and crack propagation are totally different in the austenite or ferrite phase. Whereas, the mechanism of hydrogen assisted crack initiation and propagation as well as hydrogen trapping in DSS have not been fully understood up to the present, as in most two-phase microstructures. In order to better understand the mechanisms of hydrogen assisted cracking in duplex stainless steels, knowledge of the diffusion behavior and of the stress-strain distribution in the ferritic and austenitic phase is of great interest. A numerical mesoscale model was created with a view to studying the hydrogen transport and the stresses and strains in each phase of duplex stainless steel. The material investigated in this work was DSS 1.4462, consisting of approximately equal portions of ferrite and austenite. Hydrogen diffusion in the duplex base metal was studied using the finite element program ANSYS. Stress-strain distribution as well as hydrogen assisted cracking in the ferritic and austenitic phase fractions were additionally investigated. The results of numerical simulation of the hydrogen diffusion process as well as structural analyses enable the identification of crack critical areas in the DSS microstructure. Numerical simulations qualitatively reflect the crack initiation and propagation process in ferrite. Crack critical combinations of hydrogen concentrations and local mechanical loads initiating HAC can be identified. T2 - 10th International seminar numerical analysis of weldability CY - Leibnitz, Austria DA - 24.09.2012 KW - Schweißen KW - Mathematisches Modell KW - Numerische Mathematik PY - 2013 SN - 978-3-85125-293-4 VL - 10 SP - 337 EP - 356 PB - Verlag der Technischen Universität Graz AN - OPUS4-29987 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Böllinghaus, Thomas A1 - Steppan, Enrico A1 - Mente, Tobias ED - Böllinghaus, Thomas ED - Lippold, J. C. ED - Cross, C. E. T1 - Hydrogen assisted cracking of a subsea-flowline N2 - Since the mid-nineties, supermartensitic stainless steels (SMSS) have increasingly been applied to welded subsea-pipeline systems in the North Sea oil and gas fields, especially to flowlines at mild sour service conditions. However, in 2001 cracking and leaks occurred during installation and service start-up of two SMSS flowlines in the Norwegian Tune gas condensate field, welded with a new developed matching filler wire. Brittle transgranular cracking started especially at inter-run lack of fusion and propagated brittle, predominantly through the weld metal. The present paper provides a brief overview of the original failure case and respective sequence of events leading to complete replacement of the SMSS by carbon steel flowlines in 2002. Then, detailed investigations of a circumferential weld sample of the failed Tune flowline are highlighted, targeted at comparison of the failure appearance to previous investigations of this filler material type and to search for possible explanations for the brittle fracture at the crack initiation area. SEM investigations of the fracture surface revealed brittle areas only in the direction towards the top side of the weld while the major part of the investigated surface exhibited ductile fracture. As an approach to clarify, if the fracture was a consequence of hydrogen assisted cracking, five small sized specimens have been cut out of the original sample. Cracking has been introduced parallel to the original fracture surface in these specimens at respective saw cuts and bending. The results show that brittle transgranular cracking appeared only in the specimen cooled down to very low temperatures by liquid nitrogen and in the sample charged with hydrogen to an average concentration of about 15 ml/100 g. However, a fracture similar to the original surface was observed only in the hydrogenized specimen. As a further result, very similar fracture surfaces of supermartensitic stainless steel weld metals had been observed on specimens subjected to hydrogen assisted cold cracking (HACC) as well as to hydrogen assisted stress corrosion cracking (HASCC). In total, the results indicate that brittle fracture starting at the inter-run lack of fusion were not initiated by high notch tip deformation rates, but rather influenced by hydrogen, probably taken up during welding. KW - supermartensitic stainless steel KW - hydrogen assisted cracking KW - fracture topography PY - 2016 UR - http://link.springer.com/chapter/10.1007/978-3-319-28434-7_17 UR - http://www.springer.com/us/book/9783319284323 SN - 978-3-319-28432-3 SN - 978-3-319-28434-7 DO - https://doi.org/10.1007/978-3-319-28434-7_17 SP - Part V, 361 EP - 379 PB - Springer International Publishing CY - Switzerland ET - 1 AN - OPUS4-35592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - MatCom - Materialeigenschaften und Kompatibilität für Wasserstofftechnologien - MatCom 1 - Metallische Werkstoffe N2 - Aufbauend auf dem historischen Schadensfall von A. Martens im Jahr 1894 zur Explosion von H2-Gasflaschen auf dem Tempelhofer Feld und den dabei durchgeführten Untersuchungen wird im Hauptteil des Vortrages auf die Standardisierung der Hohlzugprüftechnik eingegangen. Dabei wird zunächst auf die Vor- und Nachteile unterschiedlicher Prüfmöglichkeiten zur Wasserstoffkompatibilität metallischer Werkstoffe und deren Schweißverbindungen eingegangen und im Weiteren die Umsetzung der Prüftechnik an der BAM beschrieben. Für die Standardisierung der Hohlzugprüftechnik wurden verschiedene Randbedingungen mit Einfluss auf die Ergebnisqualität überprüft. Dabei wurde der Pipelinestahl X65 als auch der additiv gefertigte Werkstoff 316L genutzt. Abschließend wird auf die Verwaltungspartnerschaft mit Namibia eingegangen und die umzusetzenden Projekte mit Bezug zur Schweißtechnik dargestellt. T2 - BAM-PTB Workshop CY - Magdeburg, Germany DA - 04.09.2024 KW - MatCom1 KW - H2Safety@BAM KW - Hohlzugprobe PY - 2024 AN - OPUS4-61036 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Somerday, B. P. ED - Sofronis, P. T1 - Mesoscale Numerical Simulation of Hydrogen-Assisted Cracking in Duplex Stainless Steels N2 - A two-dimensional numerical mesoscale model has been created representing a microstructure of a typical 2205/1.4462 duplex stainless steel to further elucidate the mechanisms of hydrogen-assisted crack initiation and propagation in multiphase non-hydride forming metallic microstructures. Hydrogen-assisted cracking (HAC) was simulated by considering different stress and strain behavior as well as different diffusion behavior in both phases. For simulation of crack initiation and propagation, the element elimination technique has been applied. The model allows the simulation of path-free crack propagation which contributes to a better understanding of the HAC process in two-phase microstructures. As a particular result, the analyses revealed that a global macroscopic elastic deformation might already cause plastic deformation in both phases entailing respective HAC. T2 - International Hydrogen Conference CY - Jakson Lake Lodge, Wyoming, USA DA - 11.09.2016 KW - Computer simulation KW - Cracking (Materials) KW - Fracture (Process) KW - Hydrogen KW - Stainless steel PY - 2017 SN - 978-0-7918-6138-7 DO - https://doi.org/10.1115/1.861387_ch67 SP - 589 EP - 596 PB - The American Society of Mechanical Engineers (ASME) CY - New York AN - OPUS4-45680 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böllinghaus, Thomas A1 - Mente, Tobias T1 - Schadensfälle geschweißter Rohrleitungen und Maßnahmen zur Vermeidung N2 - Aus wirtschaftlich-technischer Perspektive ergeben sich in den letzten zehn Jahren hinsichtlich der Werkstoffinnovation und -auswahl für geschweißte Rohrleitungen im Wesentlichen zwei Entwicklungsrichtungen: Im Bereich der niedriglegierten Stähle werden immer höher festere Feinkombaustähle mit Streckgrenzen von inzwischen über 900 MPa verwendet. Wirtschaftliches Ziel ist hierbei eine möglichst hohe Kosteneinsparung durch Reduktion der Wanddicke. Für korrosionsbeanspruchte Komponenten, unter anderem im Petrochemie- und Energieanlagenbau besteht das wirtschaftliche Ziel primär darin, eine höhere Kosteneinsparung durch neue Legierungskonzepte zu erzielen und zwar möglichst so, dass bei mindestens gleicher Festigkeit auf die Verwendung von teuren Elementen, wie beispielsweise Nickel, verzichtet werden kann. Beispiele hierfür sind insbesondere hochlegierte martensitische Cr-V-Stähle, supermartensitische Stähle, Lean-Duplexstähle, superaustenitische Stähle und austenitische Cr-Mn-Stähle. Für einige der neu eingeführten Grundwerkstoffe sind die Zusatzwerkstoffe noch in der Entwicklung. In jedem Fall stellen diese Werkstoffinnovationen besondere Ansprüche hinsichtlich einer Rissvermeidung während der schweißtechnischen Verarbeitung, um von vornherein riss- bzw. fehlerfreie Rohrleitungen herzustellen, die eine hohe Sicherheit gegen ein Versagen während der Inbetriebnahme und im Verlauf der vorgesehenen Lebensdauer aufweisen. Fast alle dieser neu eingeführten Rohrleitungswerkstoffe weisen eine reduzierte Heiß- oder Kaltrissresistenz vor allem während des Schweißens mit modernen Hochleistungsprozessen, bspw. Laserhybridschweißen, auf. Dabei besteht nach wie vor Forschungsbedarf hinsichtlich der jeweiligen Entstehungsmechanismen. Da es in den letzten zehn Jahren immer häufiger zu Produktionsausfällen und Schadensfällen mit teilweise katastrophalen Konsequenzen gekommen ist, werden die Ursachen und die Vermeidung fertigungsbedingter Heiß- und Kaltrisse im Folgenden zusammengefasst. T2 - 14. Sommerkurs Werkstoffe und Fügen CY - Magdeburg, Germany DA - 23.09.2011 PY - 2011 SN - 978-3-940961-56-3 SP - 45 EP - 54 CY - Magdeburg AN - OPUS4-26196 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Heat treatment effects on the reduction of hydrogen in multi-layer high-strength weld joints KW - Cold cracking KW - Heat treatment KW - High strength steels KW - Hydrogen KW - Numerical simulation KW - Structural steels PY - 2012 SN - 0043-2288 SN - 1878-6669 VL - 56 IS - 7/8 SP - 26 EP - 36 PB - Springer CY - Oxford AN - OPUS4-26055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Udomkichdecha, W. ED - Mononukul, A. ED - Böllinghaus, Thomas ED - Lexow, Jürgen T1 - Numerical investigations on hydrogen-assisted cracking (HAC) in duplex stainless steels N2 - Duplex stainless steels have been used for a long time in the offshore industry, since they have higher strength than conventional austenitic stainless steels and they exhibit a better ductility as well as an improved corrosion resistance in harsh environments compared to ferritic stainless steels. However, despite these good properties the literature shows some failure cases of duplex stainless steels in which hydrogen plays a crucial role for the cause of the damage. Numerical simulations can give a significant contribution in clarifying the damage mechanisms. Therefore, a numerical model of a duplex stainless steel microstructure was developed enabling simulation of crack initiation and propagation in both phases. The phase specific stress strain analysis revealed that local plastic deformation occurs in both austenite and δ-ferrite already in the macroscopically elastic range. Altogether, phase specific hydrogen-assisted material damage was simulated for the first time taking into account all main factors influencing hydrogen assisted cracking process. The results agree well with experimental observations and thus allow a better insight in the mechanism of hydrogen-assisted material damage. T2 - 4th WMRIF Young scientists workshop CY - Boulder, CO, USA DA - 2014-09-08 KW - Hydrogen-assisted cracking (HAC) KW - Numerical simulation KW - FEM KW - Duplex stainless steel (DSS) KW - Mesoscale model PY - 2016 SN - 978-981-287-723-9 SN - 978-981-287-724-6 DO - https://doi.org/10.1007/978-981-287-724-6_3 SP - 21 EP - 31 PB - Springer AN - OPUS4-35075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Rhode, Michael A1 - Münster, C. A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Somerday, B.P. ED - Sofronis, P. T1 - Influence of experimental conditions and calculation method on hydrogen diffusion coefficient evaluation at elevated temperatures N2 - Literature provides a wide range of hydrogen diffusion coefficients for low alloyed steels used in power plants. In fact, experimental boundary conditions and calculation methods have influence on the determination of these coefficients. The diffusion and trapping behavior in creep-resistant steel 7CrMoVTiB10-10 has been studied. Based on experimental carrier gas hot extraction (CGHE) data, a numerical model has been developed to describe the hydrogen transport and respective hydrogen distribution at elevated temperatures. The numerical results suggest that common calculation methods for diffusion coefficients are limited for experimental data analysis. The sample preparation time before CGHE experiment influences the determined diffusion coefficients with the consequence that non-homogeneous hydrogen concentration profiles have to be considered in the simulations. KW - Temperature effect KW - Hydrogen diffusion KW - Creep-resistant steel KW - Hydrogen assisted cracking KW - Carrier gas hot extraction PY - 2017 SN - 978-0-7918-6138-7 DO - https://doi.org/10.1115/1.861387_ch56 SP - 495 EP - 503 PB - ASME CY - New York, USA ET - 1 AN - OPUS4-42502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Numerical simulation of hydrogen assisted cold cracking in welded joints of High strength structural steels T2 - IIW Annual Assembly CY - Denver, CO, USA DA - 2012-07-09 PY - 2012 AN - OPUS4-26164 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straub, Franka A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang A1 - Mente, Tobias ED - Somerday, B. P. ED - Sofronis, P. T1 - In-situ detection of Deuterium in duplex stainless steels by time-of-flight secondary ion mass spectrometry (TOF-SIMS) N2 - Local in-situ measurements of hydrogen distribution in the microstructure become increasingly important to elucidate the degradation mechanisms. In contrast to other attempts, modern TOF-SIMS instruments might provide precise element and phase mappings at sub-μm lateral resolution, enabling imaging of the microstructure and analysis of the chemical composition. Such technique has thus been applied to image the deuterium distribution in duplex stainless steel microstructures. After electrochemical charging, accumulations of deuterium have been detected in the austenite grains, causing parallel cracking in this phase which up to the present has been regarded as less prone to hydrogen or deuterium deterioration in comparison to the δ-ferrite. Hydrogen and deuterium behave quite similarly in metallic microstructures. TOF-SIMS imaging of Deuterium and Hydrogen might thus significantly contribute to elucidate respective metallurgical failure mechanisms. Such imaging also represents a valuable tool to validate respective numerical analyses of hydrogen distributions. T2 - Hydrogen-materials interactions - 2012 International hydrogen conference CY - Moran, WY, USA DA - 09.09.2012 PY - 2014 SN - 978-0-7918-6029-8 SP - 505 EP - 512 PB - ASME CY - New York AN - OPUS4-27669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Mesoscale modelling of hydrogen diffusion in duplex stainless steels T2 - IIW Annual Assembly CY - Chennai, India DA - 2011-07-17 PY - 2011 AN - OPUS4-25035 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Böllinghaus, Thomas ED - Lippold, J. C. ED - Cross, C. E. T1 - Numerical investigations on hydrogen-assisted cracking in duplex stainless steel microstructures N2 - Duplex stainless steels (DSS) are used in various industrial applications, e.g. in offshore constructions as well as in chemical industry. DSS reach higher strength than commercial austenitic stainless steels at still acceptable ductility. Additionally, they exhibit an improved corrosion resistance against pitting corrosion and corrosion cracking in harsh environments. Nevertheless, at specific conditions, as for instance arc welding, cathodic protection or exposure to sour service environments, such materials can take up hydrogen which may cause significant property degradation particularly in terms of ductility losses which, in turn, may entail hydrogen-assisted cracking (HAC). The cracking mechanism in DSS is different from steels having only a single phase, because hydrogen diffusion, stress-strain distribution and crack propagation are different in the austenite or ferrite phase. Therefore, the mechanism of HAC initiation and propagation as well as hydrogen trapping in DSS have not been fully clarified up to the present, as for most of the two-phase microstructures. At this point the numerical simulation can bridge the gap to a better insight in the cracking mechanism regarding the stress-strain distribution as well as hydrogen distribution between the phases, both austenite and ferrite, of the DSS. For that purpose, a two dimensional numerical mesoscale model was created representing the microstructure of the duplex stainless steel 1.4462, consisting of approximately equal portions of austenite and ferrite. Hydrogen assisted cracking was simulated considering stresses and strains as well as hydrogen concentration in both phases. Regarding the mechanical properties of austenite and ferrite different statements can be found in the literature, dependent on chemical composition and thermal treatment. Thus, various stress-strain curves were applied for austenite and ferrite simulating the HAC process in the DSS microstructure. By using the element elimination technique crack critical areas can be identified in both phases of the DSS regarding the local hydrogen concentration and the local mechanical load. The results clearly show different cracking behavior with varying mechanical properties of austenite and ferrite. Comparison of the results of the numerical simulation to those of experimental investigations on DSS will improve understanding of the HAC process in two phase microstructures. KW - duplex stainless steel 1.4462 (2205) KW - numerical simulation KW - hydrogen assisted cracking KW - diffusion PY - 2016 UR - http://link.springer.com/chapter/10.1007%2F978-3-319-28434-7_16 UR - http://www.springer.com/us/book/9783319284323 SN - 978-3-319-28432-3 SN - 978-3-319-28434-7 DO - https://doi.org/10.1007/978-3-319-28434-7_16 SP - Part V, 329 EP - 359 PB - Springer International Publishing CY - Switzerland ET - 1 AN - OPUS4-35591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Mesoscale modeling of hydrogen-assisted cracking in duplex stainless steels N2 - Quite a number of numerical models for hydrogen-assisted cracking in different kind of steels are existing reaching from simple analytical models to more complex two- and three-dimensional finite element simulations. These numerical models have been used to simulate the processes of hydrogen-assisted cracking in homogeneous microstructure. This paper contributes to numerical simulation of hydrogen-assisted cracking in heterogeneous microstructure, e.g., in a duplex stainless steel microstructure consisting of two phase fractions. If hydrogen is absorbed during welding or during service, i.e., due to cathodic protection, hydrogen is leading to material embrittlement and leads to hydrogen-assisted cracking. In order to improve understanding of the mechanisms of hydrogen-assisted cracking in duplex stainless steels, a numerical model has been created that operates at the mesoscale and enables simulation of stress–strain distribution as well as cracking in the various phases of a metallic material. Stress–strain distribution and hydrogen-assisted cracking in the duplex stainless steel 1.4462, consisting of approximately equal portions of ferrite and austenite, was simulated using the finite element program ANSYS. It was shown by numerical simulation that higher local stresses and strains are present at ferrite and austenite than the global stresses and strains in the duplex stainless steel, while the highest plastic deformations occur at austenite and the highest stresses can be found in small ferrite bars surrounded by ductile austenitic islands. By analyzing the stress–strain distribution in the duplex microstructure, crack critical areas in the ferrite can be identified. Hydrogen-assisted cracking was modeled assuming high hydrogen concentrations and regarding the local mechanical load in each phase of the duplex stainless steel. The mesoscale model qualitatively reflects the crack initiation and propagation process in the ferritic and austenitic phase of the duplex stainless steel. KW - Finite element analysis KW - Simulating KW - Duplex stainless steels KW - Stress distribution KW - Strain KW - Mathematical models KW - Hydrogen-assisted cracking KW - Hydrogen PY - 2014 DO - https://doi.org/10.1007/s40194-013-0106-7 SN - 0043-2288 SN - 1878-6669 VL - 58 IS - 2 SP - 205 EP - 216 PB - Springer CY - Oxford AN - OPUS4-29442 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Numerical Simulation of Hydrogen Assisted Cold Cracking in welded Joints of High Strength Structural Steels T2 - IIW Intermediate Meeting 2012 CY - Cambridge, England DA - 2012-02-20 PY - 2012 AN - OPUS4-25538 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Steppan, Enrico A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Numerical investigations on cold cracking avoidance in fillet welds of high-strength steels N2 - Industry faces a growing demand for high-strength structural steels with yield strengths of up to 1,300 MPa in order to cope with increasingly higher strength requirements in engineering. Higher strength levels are achieved by a special coordinated production process and an adapted chemical composition. Nevertheless, disastrous damage cases with high-strength steels have occurred in the past. The sensitivity to mechanical property degradation by hydrogen increases dramatically with strength. This phenomenon leads to hydrogen-assisted cold cracking. T-joints with fillet welds made from one side with an included angle of 60° were examined for their cold cracking behavior. Based on the T-joint, a modified heat input, even interpass temperature, plate thickness, and length ones were examined. The diffusion behavior and the effectiveness of different post-weld heat treatments in joints were simulated. The results of post-weld heat treatments are illustrated in practical hydrogen removal heat treatment diagrams. It is noticed that the T-joint is subject to a very high risk of hydrogen-assisted cold cracking (HACC). Contrary to other joints, its most critical area for cracking is not the weld metal but the heat-affected zone surrounding area of the root pass. The simulation shows that HACC in the T-joint can only be avoided by applying a sufficient post-weld heat treatment. KW - High-strength structural steels KW - Hydrogen diffusion KW - Numerical simulation KW - Hydrogen-assisted cold cracking (HACC) KW - T joints KW - Fillet welds KW - Post-weld heat treatment KW - Hydrogen removal heat treatment diagramm (HRHT) PY - 2013 DO - https://doi.org/10.1007/s40194-013-0036-4 SN - 0043-2288 SN - 1878-6669 VL - 57 IS - 3 SP - 359 EP - 371 PB - Springer CY - Oxford AN - OPUS4-27952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Mente, Tobias T1 - Numerische Simulation der wasserstoffunterstützten Rissbildung in austenitisch-ferritischen Duplexstählen N2 - In der Offshore-Industrie werden seit langer Zeit austenitisch-ferritische Duplexstähle eingesetzt, da sie im Vergleich zu herkömmlichen austenitischen hochlegierten Stählen bessere Festigkeitseigenschaften aufweisen und gegenüber rein ferritischen hochlegierten Stählen eine bessere Verformbarkeit bei gleichzeitig verbesserter Korrosionsbeständigkeit, auch in aggressiver Umgebung, bieten. Dennoch zeigt das Schrifttum, dass es trotz dieser guten Eigenschaften zum Versagen von Bauteilen kommen kann, bei dem Wasserstoff für die Schadensursache eine entscheidende Rolle spielt. Zur Klärung der Schädigungsmechanismen unter Einfluss von Wasserstoff kann die numerische Simulation einen entscheidenden Beitrag leisten, da sich experimentelle Ergebnisse besser deuten und zwischen Labortests bis hin zu Bauteilversuchen übertragen lassen. Bisher wurden jedoch meistens makroskopische numerische Betrachtungen zur wasserstoffunterstützten Werkstoffschädigung in Duplexstählen durchgeführt. Die Duplexstähle bestehen jedoch nahezu aus gleichen Teilen an austenitischer und ferritischer Phase, welche unterschiedliche mechanische Eigenschaften als auch Transporteigenschaften für Wasserstoff aufweisen. Zugleich bedingt dies eine unterschiedliche Empfindlichkeit für eine wasserstoffunterstützte Werkstoffschädigung. Daher bestand die Aufgabe dieser Arbeit in der Erstellung eines numerischen Mesomodells eines realen Duplexgefüges, mit dem die Abbildung des Wasserstofftransportverhaltens, der mechanischen Spannungen und Dehnungen sowie der Rissinitiierung und des Rissfortschrittes in den einzelnen Phasen möglich ist. Zudem werden moderne Röntgenbeugungsexperimente genutzt, um den Einfluss von Wasserstoff auf die phasenspezifischen mechanischen Eigenschaften zu bestimmen. Für den Transport von Wasserstoff konnte eine deutliche Abhängigkeit von der Orientierung der austenitischen und ferritischen Phase im Gefüge gezeigt werden, wobei der Wasserstofftransport vornehmlich über die ferritische Phase erfolgt und der Wasserstoff im Austenit stärker getrappt wird. Die numerische Analyse der mechanischen Spannungen und Dehnungen in den Phasen des Duplexstahls zeigte, dass bei einer makroskopisch elastischen Beanspruchung des Duplexgefüges bereits lokal in den Phasen plastische Verformungen auftreten können. Damit verbunden ist ein erhöhtes Risiko für eine wasserstoffunterstützte Werkstoffschädigung bereits im makroskopisch elastischen Bereich, wenn ausreichend hohe Wasserstoffkonzentrationen im Duplexgefüge vorliegen. Die Ergebnisse der numerischen Simulation entsprechen den experimentellen Beobachtungen zum Wasserstofftransport und den lokalen Beanspruchungen in realen Duplexgefügen. Das Modell erlaubt somit die Identifikation risskritischer Bereiche und kritischer Kombinationen von Wasserstoffkonzentration und lokaler Beanspruchung im Duplexgefüge. Die Ergebnisse der simulierten wasserstoffunterstützten Werkstofftrennung stimmen mit experimentellen Beobachtungen zugehöriger Bruchtopographien überein. Insgesamt wird erstmalig eine numerische Simulation der wasserstoffunterstützten Werkstoffschädigung im Duplexstahl, unter Berücksichtigung der lokalen Beanspruchung und Wasserstoffverteilung in den spezifischen Phasen (Austenit / δ-Ferrit), durchgeführt. Die Ergebnisse korrelieren mit experimentellen Beobachtungen und erlauben somit ein besseres Verständnis für die Mechanismen der wasserstoffunterstützten Werkstoffschädigung in Duplexstählen. Die Simulationen unterstützen die Deutung experimenteller Ergebnisse und ermöglichen die Übertragbarkeit auf reale Bauteile. N2 - Duplex stainless steels have been used for a long time in the offshore industry, since they have higher strength than conventional austenitic stainless steels and they exhibit a better ductility as well as an improved corrosion resistance in harsh environments compared to ferritic stainless steels. However, despite these good properties the literature shows some failure cases of duplex stainless steels in which hydrogen plays a crucial role for the cause of the damage. Numerical simulations can give a significant contribution in clarifying the damage mechanisms. Because they help to interpret experimental results as well as help to transfer results from laboratory tests to component tests and vice versa. So far, most numerical simulations of hydrogen-assisted material damage in duplex stainless steels were performed at the macroscopic scale. However, duplex stainless steels consist of approximately equal portions of austenite and δ-ferrite. Both phases have different mechanical properties as well as hydrogen transport properties. Thus, the sensitivity for hydrogen-assisted damage is different in both phases, too. Therefore, the objective of this research was to develop a numerical model of a duplex stainless steel microstructure enabling simulation of hydrogen transport, mechanical stresses and strains as well as crack initiation and propagation in both phases. Additionally, modern x-ray diffraction experiments were used in order to evaluate the influence of hydrogen on the phase specific mechanical properties. For the numerical simulation of the hydrogen transport it was shown, that hydrogen Diffusion strongly depends on the alignment of austenite and δ-ferrite in the Duplex stainless steel microstructure. Also, it was proven that the hydrogen transport is mainly realized by the ferritic phase and hydrogen is trapped in the austenitic phase. The numerical analysis of phase specific mechanical stresses and strains revealed that if the duplex stainless steel is macroscopically loaded in the elastic range local plastic deformation occurs in both Austenite and δ-ferrite phase. Thus, there will be an increasing risk for hydrogen-assisted damage already in the macroscopic elastic range, if sufficiently high hydrogen concentrations are present in the microstructure. The results of the numerical simulations correlate well with experimental observations of the hydrogen transport and local stresses and strains in the duplex stainless steel microstructure. Therefore, the model allows identification of crack critical areas as well as crack critical combinations of local hydrogen concentration and local phase specific mechanical load. The results of the numerical fracture analyses agrees well with experimental observations on hydrogen-assisted cracking in duplex stainless steel with corresponding fracture topographies. Altogether, hydrogen-assisted material damage at the mesoscale level was simulated for the first time taking into account the local stresses and strains as well as the hydrogen distribution in the specific phases (austenite / δ-ferrite) of the duplex stainless steels. The results correlate well with experimental observations and thus allow a better insight in the mechanism of hydrogen-assisted material damage. The numerical simulations support the interpretation of experimental results and allow transferring results of laboratory tests to real components. T3 - BAM Dissertationsreihe - 129 KW - Duplexstahl KW - Numerische Simulation KW - Finite-Elemente-Methode KW - wasserstoffunterstützte Rissbildung PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-5006 SN - 978-3-9816668-9-2 VL - 129 SP - 1 EP - 225 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-500 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias T1 - Mesoscale Crack Model for Duplex Stainless Steels Microstructures T2 - IIW Annual Assembly CY - Denver, CO, USA DA - 2012-07-09 PY - 2012 AN - OPUS4-26165 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böllinghaus, Thomas A1 - Mente, Tobias A1 - Dabah, Eitan ED - Kulkarni, D.V. ED - Samant, M. ED - Krishnan, S. ED - De, A. ED - Krishnan, J. ED - Patel, H. ED - Bhaduri, A.K. T1 - Trends in investigating hydrogen cracking and diffusion in steel welds N2 - The present contribution highlights recent trends in investigating hydrogen diffusion and cracking in steel welds. For such studies, supermartensitic stainless steels (SMSS) have exemplarily been selected. These materials have been used for offshore and marine constructions for about two decades now. They present a versatility of improved properties such as high strength to thickness ratio, good weldability and good corrosion resistance. However, as shown by respective failure cases, SMSS welds might become prone to hydrogen assisted cracking and the degradation phenomena are more easily to investigate due to the nearly homogeneous martensitic microstructure than in other materials. Generally, it has to be distinguished between cracking that occurs during or shortly after fabrication welding, or during subsequent operation of SMSS components. In order to achieve crack avoidance during fabrication and service, conclusive test sequences have to be applied, ranging from field tests at real components and full scale tests investigating the materials behavior under real service conditions to basic and small scale tests, such as tensile and corrosion tests, oriented more towards a materials ranking. Considerable testing of SMSS welds has been carried out and the present paper particularly summarizes spotlights on 1:1 scale component testing of welded tubulars, slow strain rate testing and basic tests oriented to elucidate the hydrogen behavior and degradation in SMSS weld microstructures. Also, permeation tests, hydrogen dependent degradation of mechanical properties and thermal desorption spectroscopy are adressed. As a specific item, first results of lately conducted investigations for tracking hydrogen movement in such weld microstructures by using high energy synchrotron radiation are elucidated. T2 - IIW International conference on global trends in joining, cutting and surfacing technology CY - Chennai, India DA - 21.07.2011 PY - 2011 SN - 978-81-8487-152-4 SP - 49 EP - 55 PB - Narosa Publ. House AN - OPUS4-26114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Münster, C. A1 - Mente, Tobias A1 - Rhode, Michael A1 - Böllinghaus, Thomas ED - Sommitsch, C. ED - Enzinger, N. ED - Mayr, P. T1 - Modelling of hydrogen diffusion in power station steels and influence of experimental conditions on the determination of diffusion coefficients N2 - In the field of modelling hydrogen assisted cracking (HAC) phenomenon, hydrogen diffusivity is an important input parameter for numerical simulation. In terms of hydrogen diffusion coefficients, they have great impact on realistic assessment of the evolution of possible crack critical hydrogen concentrations. In addition, the chemical compositions of steels can have a strong effect on hydrogen diffusion. Unfortunately, literature provides a wide range of available hydrogen diffusion coefficients even for similar microstructures and equal temperatures. The scattering of the data can lead to significant deviations in the results of simulating the evolving hydrogen concentrations due to hydrogen uptake (by fabrication or service). Thus, the application of such data to crack-models or for component life tie predictions can be realized up to the present only by considering envelope curves of such value, corresponding to a work or bench case scenario, respectively. For improved reliability of numerical simulaitons, it is necessary to minimize the mentioned deviation of these data. Hence, this work focuses on the validation of hydrogen diffusion coefficients obtained from permeation experiments at room temperature. Two baintic steels with different alloying concepts were investigated, the creep-resistant 7CrMoVTiB10-10 and the reactor pressure vessel grade 20MnMoNi4-5. A numerical model is presented for simulation of the corresponding hydrogen diffusion during permeation experiments using the finite element software ANSYS. Three different diffusion coefficients (obtained from different common calculation methods) are considered and compared to numerical results. The vases of thes calculation methods are permeation transients which are a direct measure for hydrogen. The results of the simulated hydrogen diffusion coefficients show that only one procedure for calculation of diffusion coefficitnes is suitable in comparision to the experimental values. Thus, it is suggested to use this method for analysis of experimental results in case of hydrogen diffusion during permeation experiments. Furthermore, this work supplies validated values for the hydrogen diffusion coefficients of both steel grades. KW - Hydrogen KW - Diffusion Coefficient KW - Numerical Simulation KW - Permeation KW - Creep-resistant Steel KW - Pressure Vessel Steel PY - 2016 SN - 978-3-85125-490-7 SN - 2410-0544 SP - 435 EP - 457 PB - Technische Universität Graz CY - Graz AN - OPUS4-38917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jamro, R. A1 - Mente, Tobias A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Al-Falahat, Ala'A. M. A1 - Woracek, R. A1 - Manke, I. A1 - Griesche, Axel T1 - Temperature distribution during welding measured by neutron imaging N2 - This study was carried out to investigate the neutron transmission signal as a function of sample temperature during a welding process. A theoretical description that includes the Debye-Waller factor was used to describe the temperature influence on the neutron crosssections. Neutron imaging using a monochromatic beam helps to observe transmission variations related to the material temperature. In-situ neutron imaging of welding experiments show the distribution of the temperature in bulk steel samples. The performed finite element modelling of expected temperature distributions shows good agreement with the obtained experimental data. KW - Neutron imaging KW - Debye-Waller-Faktor PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586268 DO - https://doi.org/10.1088/1742-6596/2605/1/012026 VL - 2605 SP - 1 EP - 10 PB - IOP Publishing Ltd. AN - OPUS4-58626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Schaupp, Thomas A1 - Münster, C. A1 - Mente, Tobias A1 - Kannengießer, Thomas A1 - Böllinghaus, Thomas T1 - Hydrogen determination in welded specimens by carrier gas hot extraction - a review on the main parameters and their effects on hydrogen measurement N2 - Carrier gas hot extraction (CGHE) is a commonly applied technique for determination of hydrogen in weld joints using a thermal conductivity detector (TCD) for hydrogen measurement. The CGHE is based on the accelerated hydrogen effusion due to thermal activation at elevated temperatures. The ISO 3690 standard suggests different specimen geometries as well as necessary minimum extraction time vs. temperature. They have the biggest influence on precise hydrogen determination. The present study summarizes the results and experience of numerous test runs with different specimen temperatures, geometries (ISO 3690 type B and small cylindrical samples), and factors that additionally influence hydrogen determination. They are namely specimen surface (polished/as-welded), limited TCD sensitivity vs. specimen volume, temperature measurement vs. effects of PI-furnace controller, as well as errors due to insufficient data assessment. Summarized, the temperature is the driving force of the CGHE. Two different methods are suggested to increase the heating rate up to the desired extraction temperature without changing the experimental equipment. Suggestions are made to improve the reliability of hydrogen determination depended on the hydrogen signal stability during extraction accompanied by Evaluation of the recorded data. Generally, independent temperature measurement with dummy specimens is useful for further data analysis, especially if this data is used for calculation of trapping kinetics by thermal desorption analysis (TDA). KW - Hydrogen KW - Carrier gas hot extraction KW - Experimental design KW - Thermal conductivity device PY - 2019 DO - https://doi.org/10.1007/s40194-018-0664-9 SN - 0043-2288 VL - 63 IS - 2 SP - 511 EP - 526 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-47603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madigan, Maria A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Sommitsch, C. ED - Enzinger, N. ED - Mayr, P. T1 - Numerical Simulation of Hydrogen Assisted Stress Corrosion Cracking Originating from Pits N2 - Supermartensitic stainless steels (SMSS) are a commonly used material nowadays for building offshore structures, i.e. pipelines in the oil and gas industry. The harsh and corrosive environments in oil and gas applications require the correct combination of alloys to attain the desired properties of steel, including high strength and good corrosion properties, even in severe sour service conditions. Welding is the most commonly used method in joining offshore components, depending on requirements requiring strength or fitting. It has been shown that the heat affected zone (HAZ) is more susceptible to certain types of corrosion, including pitting corrosion, especially during severe sour service where a high pH and lower H2S values in the flow medium can lead to pitting corrosion in the HAZ of welded structures. Subsequent hydrogen uptake in the pits can cause cracks to initiate and propagate, leading to rupture of pipelines or catastrophic failures of structures, even at low mechanical loads. Offshore standards allow a certain amount of corrosion, including pitting, to be present before action is required, however the extent of pitting corrosion is not identified by performing visual inspection alone as the subsurface pit diameter may be vastly greater than the pit diameter at the surface. The critical conditions which lead to crack initiation and propagation from a pit with hydrogen uptake are currently not known. Therefore, pitting corrosion and subsequent crack initiation are a danger to the safety of structures. The interest in this phenomenon has resulted in many experimental studies and numerical simulations. Several numerical models of pitting corrosion and hydrogen uptake resulting in crack initiation are already in existence, but these two phenomena are regularly modelled individually. Thus, a model enabling simulation of both phenomena simultaneously would be of great benefit. Hence, the goal of this study is to develop a model enabling simulation of pit growth and crack initiation, considering hydrogen uptake in the pit from a corrosive environment. As a first step, this paper presents an investigation into various parameters, which influence crack initiation at pits. These crack critical parameters include: pit geometry, pit location, mechanical load and hydrogen transport into the microstructure. The results will help to identify critical conditions for crack initiation starting at the pit and developing measures to avoid hydrogen assisted cracking (HAC). T2 - 12th International Seminar Numerical Analysis of Weldability CY - Graz, Austria DA - 23.09.2018 KW - Hydrogen Assisted Cracking (HAC) KW - Pitting KW - Supermartensitic Stainless Steel (SMSS) KW - Numerical Simulation PY - 2019 SN - 978-3-85125-615-4 SN - 978-3-85125-616-1 SN - 2410-0544 VL - 12 SP - 443 EP - 464 PB - Verlag der Technischen Universität Graz CY - Graz (Österreich) AN - OPUS4-48721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Mente, Tobias A1 - Markötter, Henning A1 - Al-Falahat, M. A1 - Kardjilov, N. T1 - Neutron Bragg edge imaging for in situ mapping of crystallographic phase-transformations and of temperature distributions during GTAW of supermartensitic stainless steel N2 - In Neutron-Bragg-Edge Imaging (NBEI) experiments, we studied the phase transition during butt-welding of supermartensitic steel plates. Gas tungsten arc welding (GTAW) was used with a motorized torch allowing for automated weldments. The austenitization in the heat affected zone (HAZ) underneath the welding head could be clearly visualized at λ = 0.39 nm, a wavelength smaller than the Bragg edge wavelengths of both austenite and martensite. Also, the re-transformation into the martensitic phase upon cooling was detected. However, we observed an unexpected additional change in transmission at λ = 0.44 nm that is a wavelength larger than the wavelength of the Bragg edges of both the martensitic and austenitic phases. We attribute this change to the Deybe-Waller-Factor that describes the temperature dependence of coherent scattering at a crystal lattice. The observed two-dimensional attenuation map corresponds well with a temperature distribution modelling by software macros in ANSYS. Here, the absolute temperature values could be achieved by calibrating the modelled attenuation with help of a thermocouple placed at the steel plate. This allows in return for a direct two-dimensional temperature reading based on the Debye-Waller-relation between neutron attenuation and sample temperature. T2 - ITMNR-9 CY - Buenos Aires, Argentina DA - 12.10.2022 KW - Debye-Waller-Faktor PY - 2023 AN - OPUS4-58627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -