TY - JOUR A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Mente, Tobias A1 - Richter, Tim A1 - Kannengießer, Thomas T1 - Characterization of Hydrogen Diffusion in Offshore Steel S420G2+M Multi-layer Submerged Arc Welded Joint N2 - As onshore installation capacity is limited, the increase in the number of offshore wind turbines (OWT) is a major goal. In that connection, the OWTs continuously increase in size and weight and demand adequate foundations concepts like monopiles or tripods. These components are typically manufactured from welded mild steel plates with thickness up to 200 mm. The predominant welding technique is submerged arc welding (SAW). In accordance with the standards, the occurrence of hydrogen-assisted cracking is anticipated by either a minimum waiting time (MWT, before non-destructive testing of the welded joint is allowed) at ambient or a hydrogen removal heat treatment (HRHT) at elevated temperatures. The effectiveness of both can be estimated by calculation of the diffusion time, i.e., diffusion coefficients. In this study, these coefficients are obtained for the first time for a thick-walled S420G2+M offshore steel grade and its multi-layer SAW joint. The electrochemical permeation technique at ambient temperature is used for the determination of diffusion coefficients for both the base material and the weld metal. The coefficients are within a range of 1025 to 1024 mm2/s (whereas the weld metal had the lowest) and are used for an analytical and numerical calculation of the hydrogen diffusion and the related MWT. The results showed that long MWT can occur, which would be necessary to significantly decrease the hydrogen concentration. Weld metal diffusion coefficients at elevated temperatures were calculated from hydrogen desorption experiments by carrier gas hot extraction. They are within a range of 1023 mm2/s and used for the characterization of a HRHT dwell-time. The analytical calculation shows the same tendency of long necessary times also at elevated temperatures. That means the necessary time is strongly influenced by the considered plate thickness and the estimation of any MWT/HRHT via diffusion coefficients should be critically discussed. T2 - European Congress and Exhibition on Advanced Materials and Process - Euromat 2021 CY - Online meeting DA - 13.09.2021 KW - Thick-walled KW - Hydrogen diffusion KW - Offshore KW - Steel KW - Submerged arc welding PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544127 DO - https://doi.org/10.1007/s11665-022-06679-7 SN - 1059-9495 SP - 1 EP - 13 PB - Springer Nature AN - OPUS4-54412 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen diffusion in thick-walled S690 SAW joints: Part 1 - Experimental determination of microstructure dependent diffusion coefficients N2 - S690 steels are widely used in heavy-duty applications, such as structural components, mobile cranes, and industrial plant construction, owing to their high strength and weldability. However, thick-plate submerged arc welding (SAW) can introduce elevated hydrogen levels and residual stresses that promote time-delayed hydro-gen-assisted cold cracking (HACC). Accurate, microstructure-specific diffusion data are scarce, limiting pre-dictive HACC assessments. This study presents an experimental determination of hydrogen diffusion coeffi-cients (DH) in two S690 variants: thermomechanically rolled (S690MC) and quenched and tempered (S690Q). Multi-layer SAW welds were produced from 30 mm-thick plate material at three heat input levels, and diffusion membranes were extracted from weld metal (WM), heat-affected zone (HAZ), and base material (BM). Hydro-gen permeation tests, conducted in accordance with DIN EN ISO 17081, yielded time-normalized flux curves from which DH was derived using the inflection-point method. At room temperature, DH values ranged from 6 × 10⁻⁵ to 9 × 10⁻⁵ mm²/s across all regions and heat inputs, with no significant difference between S690MC and S690Q. Weld metal exhibited marginally lower DH, attributed to enhanced hydrogen trapping, while base mate-rial measurements showed greater variability. These microstructure-resolved diffusion coefficients fill a critical data gap and provide essential input for the numerical simulations presented in Part 2. The results also support practical guidelines for mitigating HACC risk through the optimization of welding parameters. T2 - 78th IIW Annual Assembly, Meeting of Commission II-C CY - Genoa, Italy DA - 22.06.2025 KW - Hydrogen assisted cracking KW - Submerged arc welding KW - High strength steels KW - Hydrogen Diffusion KW - Electrochemical permeation PY - 2025 AN - OPUS4-63540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Weld heat input effect on microstructure and hydrogen diffusion in thick-walled S690 submerged arc welded joints N2 - High-strength, low-alloy (HLSA) steels such as S690 are an attractive option for heavy industries such as offshore wind turbines and peripheral equipment due to their combination of excellent mechanical properties and weldability. The construction of these thick-walled structures requires highly efficient welding processes such as submerged arc welding (SAW). However, SAW faces challenges related to delayed hydrogen assisted cold cracking (HACC). Despite its importance, the effect of different diffusion coefficients on the cold cracking susceptibility of different microstructures within SAW-welded S690 steels is not fully understood. For this reason, the present study focuses on comparing the cold cracking susceptibility of thermomechanically rolled (TM) or quenched and tempered (QL) variants of S690 steel. Submerged arc welding was performed on both steel grades at different welding heat inputs. From these thick-walled welds, metallic membranes were extracted from the weld metal, the heat-affected zone (HAZ), and the two base metals. The specimens were subjected to electrochemical hydrogen permeation tests (according to ISO 17081) to determine the microstructure-specific hydrogen diffusion coefficients. In general, increased welding heat input and thickness decreased the hydrogen diffusion coefficients, i.e., the time required for hydrogen diffusion increased. In addition, the results showed that the TM grade exhibited slightly accelerated hydrogen diffusion coefficients compared to the QL grade, which is beneficial for hydrogen reduction and increases the HACC resistance. As a result, the microstructure-specific assessment of hydrogen diffusion in the BM, HAZ or WM of the SAW joint was less important for a given set of welding parameters compared to other welding processes such as gas metal arc welding (GMAW). The reason is that in multilayer SAW, the relatively large welding heat input and multiple annealing resulted in similar microstructures, resulting in very close hydrogen diffusion coefficients. From this point of view, it is sufficient to characterize the hydrogen diffusion coefficients of both the weld metal and the base material. T2 - 78th IIW Annual Assembly and International Conference CY - Genoa, Italy DA - 26.06.2025 KW - Hydrogen assisted cracking KW - Submerged arc welding KW - Diffusion KW - Electrochemical permeation KW - Microstructure PY - 2025 AN - OPUS4-63543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen diffusion in thick-walled S690 SAW joints: Part 2 - Predictive modeling of welding heat input and microstructure influence N2 - High-strength low-alloy (HSLA) steels such as S690 are widely employed in thick-walled welded structures, where hydrogen-assisted cold cracking (HACC) remains a persistent concern. While microstructure-specific hydrogen diffusion coefficients (DH) for weld metal (WM), heat-affected zone (HAZ), and base material (BM) were experimentally established in Part 1 of this study, their quantitative influence on hydrogen accumulation and effusion has not yet been fully clarified. This work presents a transient, spatially resolved numerical model for simulating hydrogen transport in multi-pass submerged arc welds. The model integrates experimentally determined DH values with realistic thermal cycles and temperature-dependent boundary conditions. Developed in Python, the simulation tool is purpose-built for hydrogen diffusion in welded joints and offers a focused, transparent alternative to general-purpose finite element platforms. Parametric analyses demonstrate that, although the diffusion coefficients vary by up to 50 %, their impact on overall hydrogen retention is minor. In contrast, welding parameters such as plate thickness, bead geometry, cooling time (t₈/₅), and interpass tem-perature exert a dominant influence on hydrogen distribution. Despite clear microstructural differences between the thermomechanically rolled (S690MC) and quenched and tempered (S690Q) variants, including hardness softening versus hardening in the heat-affected zone of the (pen)ultimate weld bead, the simulations confirm that their diffusion behavior and hydrogen solubility are closely aligned. Consequently, differences in diffusivity and solubility exert only a minor influence on hydrogen retention compared to thermal exposure and joint geometry. These findings support the interchangeable use of both steel grades in terms of HACC risk due to hydrogen diffusion kinetics, under comparable welding conditions. T2 - 78th IIW Annual Assembly, Meeting of Commission II-C CY - Genoa, Italy DA - 22.06.2025 KW - Hydrogen assisted cracking KW - Numerical simulation KW - Hydrogen diffusion PY - 2025 AN - OPUS4-63541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erxleben, Kjell A1 - Kaiser, Sebastian A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne T1 - Reparaturschweißen zukünftiger, in Betrieb befindlicher Wasserstoffpipelines N2 - Wasserstoff leistet als Energieträger der Zukunft einen entscheidenden Beitrag zur nachhaltigen Energieversorgung, wobei der Transport auf Basis des europäischen Ferngasleitungsnetzes erfolgen wird. Bisherige Untersuchungen zur Werkstoffkompatibilität zeigen, dass die hier verwendeten, niedriglegierten Rohrstähle für Wasserstofftransport unter normalen Betriebsbedingungen (≤ 60 °C, max. 100 bar) grundsätzlich geeignet sind. Die Eignung kann nicht ohne Weiteres übertragen werden, sobald Reparaturschweißungen beispielsweise aufgrund von Wartungsarbeiten an druckführenden, in Betrieb befindlichen, Hochdruckgasleitungen erfolgen. Aus technisch-ökonomischen Gründen werden Schweißarbeiten dabei im Betrieb unter fortwährendem Druck und Gasfluss durchgeführt. Dies soll auch bei Wasserstoffpipelines erfolgen. Dazu im Erdgasnetz angewandte und etablierte Konzepte sind beispielsweise das „Hot-Tapping“ und „Stoppling“. Beim „Hot-Tapping“ wird eine druckführende Pipeline durch Anflanschen eines abgeschlossenen, druckdichten Systems aus Absperrventil und Bohrvorrichtung angebohrt. Dazu müssen sogenannte Überschieber (aus vorgeformten Zylinderhalbschalen) durch Längsnaht verbunden und dann mit Rohrrundnähten am Produktrohr verbunden werden. Für das zum überwiegenden Teil durchgeführte E-Hand-Schweißen sind dabei Vorwärmtemperaturen von ca. 100 °C bzw. 250 °C für die maximale Zwischenlagentemperatur einzuhalten. Besonderer Fokus liegt auf der Betrachtung dünnwandiger Leitungen, da hier beim Schweißen der Rundnähte die Austenitisierungstemperatur an der Innenseite der Pipeline überschritten wird. Dadurch wird eine signifikant höhere Wasserstoffaufnahme in den Leitungsstahl vermutet, mit einer möglichen Degradation der mechanischen Kennwerte bzw. Rissbildung. Durch die langen Schweiß- und Abkühlzeiten wird der Rohrleitungsstahl zudem teilweise stundenlang Temperaturen von bis zu 250 °C ausgesetzt. Neben der klassischen „Versprödung“ muss daher eventuell auch ein sogenannter Hochtemperatur-Wasserstoffangriff betrachtet werden. Diese vorliegende Studie gibt Einblick zur Übertragbarkeit der bekannten Konzepte aus der Erdgastechnik zum Reparaturschweißen. Dazu werden Möglichkeiten und Grenzen momentaner Prüfkonzepte sowie deren Weiterentwicklungen aufgezeigt. Dies umfasst bspw. geeignete Methodiken zur Werkstoffprüfung als auch skalierte Bauteilversuche unter realistischen Druckgas-Betriebsbedingungen einer Pipeline. In diesem Rahmen erfolgt auch die Kurzvorstellung des Kooperationsprojektes von BAM, DVGW und Ferngasnetzbetreibern „H2-SuD“ zum Einfluss der Temperaturführung und Rohrgeometrie auf die Wasserstoffaufnahme. T2 - DVS CONGRESS 2024 CY - Erfurt, Germany DA - 16.09.2024 KW - Reparaturschweißen KW - Pipeline KW - Wasserstoff KW - Im Betrieb PY - 2024 SN - 978-3-96144-269-0 VL - 395 SP - 341 EP - 349 AN - OPUS4-61478 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kaiser, Sebastian A1 - Erxleben, Kjell A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Herausforderungen beim Schweißen im Betrieb an Wasserstoff-Ferngasleitungen N2 - Als Energieträger der Zukunft kommt grünem Wasserstoff große Bedeutung bei der Energiewende und der zukünftigen, nachhaltigen Energieversorgung zu Teil. Zum effizienten und sicheren Transport des Wasserstoffs ist die Bereitstellung einer Pipeline-Infrastruktur geplant. Die meisten Länder verfolgen hierbei die Strategie der Umwidmung bestehender Erdgastransportleitungen, ergänzt durch Errichtung neuer Pipelines. Die bestehenden Erdgasnetze sind dabei aus unterschiedlichsten Rohrgeometrien und Materialien zusammengesetzt. Bei der Umwidmung von Erdgaspipelines zum Transport von Wasserstoff müssen daher Fragen der Materialverträglichkeit hinsichtlich des als Wasserstoffversprödung bekannten Phänomens der Beeinträchtigung der mechanischen Eigenschaften metallischer Werkstoffe durch Wasserstoff betrachtet werden. Bisherige Forschungsergebnisse und Feldversuche deuten darauf hin, dass die niedriglegierten, ferritischen Stähle, aus denen die Ferngasleitungen des Erdgasnetzes überwiegend bestehen, für den Transport von Wasserstoff unter normalen Betriebsbedingungen geeignet sind. Eine Frage, die bislang weniger Aufmerksamkeit erhielt, ist die, wie sich das Schweißen im Betrieb an Wasserstoffpipelines auf die Materialkompatibilität auswirkt. Im Erdgasnetz sind etablierte Verfahren wie beispielsweise das „Hot-Tapping“ unumgänglich für die Instandhaltung und Erweiterung des Netzes. Hierbei werden an eine im Betrieb befindliche Pipeline geteilte T-Stücke aufgeschweißt, über die die Pipeline dann mit geeigneten Bohrvorrichtungen während eines ununterbrochenen Betriebs angebohrt werden kann. Um zu beurteilen, ob diese Verfahren gefahrlos auf Wasserstoffpipelines übertragen werden können, müssen Problemstellungen betrachtet werden, die sich durch den Wärmeeintrag ins Material beim Schweißen ergeben. Wasserstofflöslichkeit und Diffusionsgeschwindigkeit sind temperaturabhängig. Erhöhte Temperaturen könnten eine Wasserstoffaufnahme ins Material bewirken, die zu einer kritischen Degradation der mechanischen Eigenschaften des Materials führen könnte. Die Temperaturen, die beim Schweißen erreicht werden, führen lokal zur Überschreitung der Austenitisierungstemperatur. Austenit weist eine deutlich höhere Löslichkeit von Wasserstoff auf, während die Diffusionsgeschwindigkeit des Wasserstoffs in dieser Phase deutlich herabgesetzt ist. Es wird vermutet, dass dies zu einer lokal erhöhten Wasserstoffkonzentration führt. Damit geht ein erhöhtes Risiko einer kritischen Materialdegradation einher. Durch die lange Zeitdauer beim Schweißen von mehrlagigen Rundkehlnähten an großen Pipelines, einschließlich einer möglichen Vorwärmprozedur, ist weiterhin zu klären, ob der aus Anwendungsfällen in der Petrochemie bekannte Hochtemperaturwasserstoffangriff auftritt. Der vorliegende Beitrag liefert einen Überblick über das Schweißen im Betrieb an Gaspipelines, hierbei auftretenden Herausforderungen bei der möglichen Anwendung auf Wasserstoffleitungen. Dabei werden auch aktuelle Forschungsprojekte zum Thema Schweißen an Wasserstoffpipelines im Betrieb eingehend diskutiert. In diesem Zusammenhang werden erste Ergebnisse des gemeinschaftlichen Forschungsprojektes „H2-SuD: Einfluss des Schweißens auf die Wasserstoffaufnahme und Degradation im Betrieb befindlicher H2-Ferngasleitungen“ des Deutschen Vereins des Gas- und Wasserfaches (DVGW), der Bundesanstalt für Materialforschung und -prüfung (BAM) und deutscher Gasnetzbetreiber (Open Grid Europe, ONTRAS Gastransport, u.v.m.) präsentiert. T2 - 53. Sondertagung - Schweißen im Anlagen-und Behälterbau 2025 CY - Munich, Germany DA - 18.03.2025 KW - Materialdegradation KW - Pipeline KW - Schweißen KW - Wasserstoff PY - 2025 SN - 978-3-96144-290-4 (Print) SN - 978-3-96144-291-1 (E-Book) VL - 2025 SP - 106 EP - 115 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-62911 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Schweißen im Wasserstoffanlagen- und Behälterbau - Eine Kurzübersicht N2 - Wasserstoff erfüllt die zentrale Rolle für die Umwandlung der bisherigen fossil-basierten Energieerzeugung und -nutzung auf eine dekarbonisierte, nachhaltige Form. Dazu muss der Wasserstoff erzeugt, gespeichert, transportiert werden, bevor er wieder der Nutzung zugeführt wird. Hierzu sind entlang der gesamtem Prozesskette Wasserstofftechnologien notwendig, die einen sicheren Betrieb erfordern. Hierbei kommt dem schweißtechnischen Anlagen- und Behälterbau wesentliche Bedeutung zu, insbesondere (aber nicht ausschließlich) für Speicherung und Transport des Wasserstoffes. Der vorliegende Beitrag gibt einen kurzen Überblick, wo und wie die konventionelle Schweißtechnik hierzu wichtige Beiträge leistet. Die additive Fertigung, also das „Drucken“ von Bauteilen wird dabei zunehmend wichtiger, entlang der gesamtem Prozesskette der Wasserstofftechnologien. Gleichwohl darf nicht unterschätzt werden, dass auch wesentlicher Bedarf an der Erweiterung und teilweiser Neufassung von bestehenden Regel- und Normenwerken besteht. T2 - 51. Sondertagung "Schweißen im Behälter- und Anlagenbau" CY - Munich, Germany DA - 01.03.2023 KW - Wasserstoff KW - Anlagenbau KW - Schweißen KW - Studie KW - Pipeline PY - 2023 SN - 978-3-96144-219-5 VL - 387 SP - 83 EP - 88 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-57075 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Characterization of hydrogen trapping in a CoCrFeMnNi high-entropy alloy charged up to 1000 bar high-pressure hydrogen N2 - First studies on the mechanical behavior of high-entropy alloys (HEAs) in high-pressure hydrogen environment are available. In contrast, the underlying hydrogen absorption, diffusion and trapping in these HEAs like the Cantor-alloy was less in the scientific scope so far. For that reason, the CoCrFeMnNi-HEA was compared to a conventional AISI 316L austenitic steel, by exposing to high-pressure hydrogen charging at 200 bar and very-high pressure at 1,000 bar. Thermal desorption analysis (TDA) was applied with different heating rates (0.125 K/s to 0.500 K/s), see Fig. 1a to d. The underlying TDA spectra were analyzed in terms of a reasonable peak deconvolution to into a defined number of peaks and the calculation of the activation energies for the respective and predominant hydrogen trap sites. Both materials show a comparable hydrogen diffusivity. The obtained activation energies suggest that in case of the CoCrFeMnNi-HEAs an interaction of the austenitic phase as well as the direct atomic bonding of hydrogen to the metal atoms are the dominant traps, since “impurities” such as carbides or inclusions are only present in trace amounts. Available literature suggests that the Cr and Mn-content is here of special interest for the direct hydrogen bonding at solute atoms. In addition, the trap occupancy rate must be considered in terms of a pressure-related hydrogen absorption. The derived apparent hydrogen solubility was in the order: 316L < CoCrFeMnNi-HEA for both charging pressures. Especially, the 1,000 bar values lead to noteworthy results with > 70 wt.ppm for the AISI 316L and >130 wt.ppm for the CoCrFeMnNi. In fact, both the hydrogen diffusion and trapping data on gaseous high-pressure hydrogen charged HEAs are rare so far. The results of the present study allow a deeper understanding of hydrogen trapping in the regarded CoCrFeMnNi-system. T2 - 78th IIW Annual Assembly and International Conference CY - Genoa, Italy DA - 26.06.2025 KW - Hydrogen KW - Thermal desorption analysis KW - High-pressure charging KW - Trapping KW - Diffusion PY - 2025 AN - OPUS4-63542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kaiser, Sebastian A1 - Erxleben, Kjell A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Schweißen im Betrieb an Wasserstoff-Ferngasleitungen N2 - Wasserstoff gilt als Energieträger für die Erreichung der Klimaziele und einer nachhaltigen zukünftigen Energieversorgung. Für den notwendigen Transport des Wasserstoffs in großem Maßstab und über weite Entfernungen ist eine zuverlässige Pipeline-Infrastruktur erforderlich. Umfassende weltweite Forschungsprojekte deuten auf die allgemeine Kompatibilität der verwendeten überwiegend ferritischen Stähle für die vorgesehenen Betriebsbedingungen von bis zu 60 °C bei 100 bar Wasserstoff hin. Dies ist jedoch nicht direkt übertragbar auf schweißtechnische Reparatur- und Wartungsarbeiten an im Betrieb befindlichen Pipelines. Ein im Erdgasnetz etabliertes Verfahren stellt das „Hot-Tapping“ dar, bei dem eine unter Druck stehende Pipeline im Betrieb angebohrt wird. Hierfür kommt ein an die Rohrleitung geschweißtes Formstück zum Einsatz, das die Montage der Bohr-/Lochschneidemaschine ermöglicht. In den Richtlinien EIGA 121/14 bzw. AIGA 033/14 wird darauf hingewiesen, dass das Anbohren von Wasserstoffleitungen kein Routineverfahren darstellt: “[…] a hydrogen hot-tap shall not be considered a routine procedure […]“. Dieser Aussage liegt unter anderem zugrunde, dass das Anschweißen des Formstücks an das Rohr und alle zu erwartenden Wärmebehandlungen vor und nach dem Schweißen eine lokale Temperaturerhöhung verursachen. Insbesondere auch an der Rohrinnenfläche, die dem Wasserstoff ausgesetzt ist. Diese erhöhten Temperaturen begünstigen die Absorption und Diffusion von Wasserstoff in das Material. Besonders zu beachten ist außerdem die lokal auftretende kurzzeitige Austenitisierung des Materials, die eine lokal stark erhöhte Wasserstoffkonzentration verursachen kann. Aus den genannten Gründen gibt diese Studie einen kurzen Überblick über die derzeit weltweit verfügbaren Forschungsprojekte zum Schweißen von Wasserstoff-Pipelines im Betrieb. Vorgestellt werden unter anderem erste Ergebnisse des Kooperationsforschungsprojektes H2SuD, das derzeit an der BAM bearbeitet wird. T2 - 6. Symposium Materialtechnik CY - Clausthal-Zellerfeld, Germany DA - 20.02.2025 KW - Materialdegradation KW - Pipeline KW - Schweißen KW - Wasserstoff PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632731 SN - 978-3-8440-9961-4 SN - 978-3-8191-0041-3 DO - https://doi.org/10.21268/20250506-12 SN - 2364-0804 SN - 3052-3524 N1 - Serientitel: Fortschrittsberichte der Materialforschung und Werkstofftechnik – Series title: Bulletin of Materials Research and Engineering VL - 15 SP - 381 EP - 390 PB - Shaker Verlag CY - Düren AN - OPUS4-63273 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Mente, Tobias A1 - Kannengießer, Thomas T1 - Parameters and challenges for reliable hydrogen determination in welded joints by carrier gas hot extraction N2 - For the hydrogen-based energy economy of tomorrow, the construction of the necessary infrastructure will play a central role. Most materials used to date, such as welded steels, can be prone to hydrogen embrittlement under certain conditions. This includes the classic delayed cold cracking during welding as well as degradation phenomena during service of components in hydrogen-containing environment. For the evaluation of any hydrogen effect, for example, on the mechanical properties of a welded metallic material, the hydrogen content must be precisely determined. In the case of weld seams, the carrier gas hot extraction (CGHE) according to ISO 3690 is meanwhile state-of-the-art. CGHE is based on accelerated hydrogen degassing due to the thermal activation of hydrogen at elevated temperatures. In addition to the quantification of hydrogen, thermal desorption analysis (TDA) with varying heating rates can be used to determine and evaluate the hydrogen trapping at microstructural defects in the material. For both techniques, experimental and metrological influences must be considered, which have a major effect on the result. For example, ISO 3690 suggests different sample geometries and minimum extraction times for CGHE. This study summarizes the results and experiences of numerous investigations at the Federal Institute for Materials Research and Testing (BAM) with different sample temperatures and geometries (ISO 3690 type B and cylindrical TDA samples) regarding the influence of the sample surface (polished/welded), measurement accuracy depending on the sample volume and the insufficient monitoring of the effect of PI control on the extraction temperature. A deviating extraction temperature from the target temperature can significantly falsify the measurement results. Based on the results, methods are shown which allow the desired extraction temperature to be reached quickly without physically interfering with the measuring equipment. This serves to significantly improve the reliability of the hydrogen measurement through increased signal stability and accelerated hydrogen desorption. In general, an independent temperature measurement with dummy samples is recommended for the heating procedure of choice to exclude possible undesired temperature influences before the measurement. The methods described can be transferred directly to industrial applications KW - Welding KW - Hydrogen measurement KW - ISO 3690 KW - Carrier gas hot extraction PY - 2024 DO - https://doi.org/10.37434/tpwj2024.04.01 SN - 0957-798X VL - 4 SP - 3 EP - 10 PB - International Association Welding AN - OPUS4-60071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Rhode, Michael A1 - Mente, Tobias A1 - Kannengießer, Thomas A1 - Czeskleba, Denis T1 - Simulation of hydrogen distribution in submerged arc welded heavy plates as tool for evaluating cold cracking sensitivity for offshore structures N2 - Foundation structures for offshore wind turbines are typically made of heavy plate struc-tural steels, such as S420ML, welded by submerged arc welding. Due to the welding process conditions, higher amounts of hydrogen can be introduced. In this context, large plate thicknesses result in long diffusion paths and a prolonged diffusion time for hydrogen at ambient temperature and possible delayed hydrogen-assisted cold cracking. As a result, hydrogen can accumulate in areas of high mechanical stress and strain. Due to the delayed diffusion, a minimum waiting time of up to 48 h must be observed before non-destructive testing can be performed. In addition, the assessment of possible cold crack locations is very complex. For this reason, a numerical model of a component-like weld test was developed to simulate the temperature field during welding and subsequent cooling. A hydrogen diffusion model based on the temporal-local temperature distribution was established. It was applied to simulate the change of hydrogen distribution as a function of temperature cycle during multi-layer welding and further for the entire waiting time interval ≤ 48 h. As a result, crack critical areas could be evaluated in terms of accu-mulated hydrogen. An advantage of the diffusion model is the simulation of a normalized concentration, i.e. between "0" (no hydrogen) and "1" (max. concentration), which can be scaled to experimentally determined hydrogen concentrations. Finally, selected results for increased real hydrogen ingress are presented, which confirm the relatively high crack resistance of the S420 submerged arc welded joint. KW - Hydrogen assisted cracking KW - Diffusion KW - Numerical simulation KW - Offshore steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632416 DO - https://doi.org/10.21268/20250507-6 SP - 1 EP - 12 PB - Technische Universität Clausthal CY - Clausthal-Zellerfeld, Deutschland AN - OPUS4-63241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erxleben, Kjell A1 - Kaiser, Sebastian A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Hadick, C. A1 - Schu, K. T1 - Component test concept for evaluation of in-service welding on pressurized hydrogen pipelines N2 - Hydrogen is set as the energy carrier of tomorrow and most countries will achieve large-scale hydrogen transport through the conversion of the natural gas (NG) grid and the construction of new pipelines. The interaction between hydrogen and the pipeline materials differs fundamentally from that of NG, as hydrogen is readily absorbed into the material. Considering the possible hydrogen embrittlement (HE), the compatibility of the pipeline materials (low-alloyed steels with a wide strength/thickness range) must be investigated. However, pipelines require intervention for maintenance, repair, or grid expansion with welding on/onto the pipelines while in service, i.e. the well-known "hot tapping" and "plugging" or “stoppling”. The challenges compared to NG can be broadly divided into the possible austenitization of the inner pipe material exposed to hydrogen and the welding itself. Both result in a significant increase in hydrogen solubility and could potentially pose challenges in terms of HE. Emphasis is placed on the word "could" because knowledge of "hot tapping" on hydrogen pipelines is scarce due a lack of service experience. To this end, this study proposes a concept for a component-like demonstrator with the objectives: (1) safe feasibility of "hot tapping" on pressurized model hydrogen pipeline sections, (2) facilitate ex-post sample extraction for the purpose of quantifying the absorbed hydrogen concentrations, and (3) ensure in-situ temperature measurement during welding to monitor the pipeline surface temperature. For safety reasons in the event of an unintentional "burn-through", a solid cylinder was inserted in the demonstrator to restrict the hydrogen gas volume to a small, pressurized layer. Reference pipeline surface temperature measurements were ensured on comparable, unpressurized geometries. The investigated range of welding conditions was investigated for representative material/thickness combinations (DN50 to DN200), suggesting the feasibility of the demonstrator for the determination of reliable in-service welding conditions for both installed and new pipelines for hydrogen service. T2 - 20th Pipeline Technology Conference ptc2025 CY - Berlin, Germany DA - 06.05.2025 KW - In-service KW - Hydrogen KW - Pipeline KW - Repair welding KW - component test PY - 2025 SP - 1 EP - 11 AN - OPUS4-63168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Thickness and microstructure effect on hydrogen diffusion in creep-resistant 9 % Cr P92 steel and P91 weld metal N2 - Martensitic 9 %-Cr steels like P91 and P92 show susceptibility to delayed hydrogen assisted cracking depending on their microstructure. In that connection, effective hydrogen diffusion coefficients are used to assess the possible time-delay. The small number of available diffusion coefficients varies already at room temperature by several orders of magnitude (mostly regarded as result of present microstructure). Especially P91 weld metal diffusion coefficients are rare so far. For that reason, electrochemical permeation experiments had been conducted using P92 base metal and P91 weld metal (in as-welded and heat-treated condition) with different thicknesses. The diffusion coefficients are calculated by two methods (time-lag and inflection point method) were performed. The results show that, despite of microstructural effects, the sample thickness must be considered as it influences the calculated diffusion coefficients. Finally, the comparison of calculated and measured hydrogen concentrations (determined by carrier gas hot extraction) enables the identification of realistic diffusion coefficients. T2 - IIW Intermediate Meeting, Comm. IX-C "Welding of creep and heat-resistant materials" CY - Online meeting DA - 08.03.2021 KW - Hydrogen KW - Welding KW - Diffusion KW - Creep-resistant steel KW - Electrochemical permeation PY - 2021 AN - OPUS4-52239 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Preuß, Bianca A1 - Lindner, Thomas A1 - Hanisch, Niclas A1 - Giese, Marcel A1 - Schröpfer, Dirk A1 - Richter, Tim A1 - Rhode, Michael A1 - Lampke, Thomas T1 - Surface Functionalization of Novel Work‐Hardening Multi‐Principal‐Element Alloys by Ultrasonic Assisted Milling N2 - The development of multi‐principal‐element alloys (MPEAs) with unique characteristics such as high work hardening capacity similar to well‐known alloy systems like Hadfield steel X120Mn12 (ASTM A128) is a promising approach. Hence, by exploiting the core effects of MPEAs, the application range of conventional alloy systems can be extended. In the present study, work‐hardening MPEAs based on the equimolar composition CoFeNi are developed. Mn and C are alloyed in the same ratio as for X120Mn12. The production route consists of cast manufacturing by an electric arc furnace and surface functionalization via mechanical finishing using ultrasonic‐assisted milling (USAM) to initiate work hardening. The microstructure evolution, the hardness as well as the resulting oscillating wear resistance are detected. A pronounced lattice strain and grain refinement due to the plastic deformation during the USAM is recorded for the MPEA CoFeNi‐Mn12C1.2. Consequently, hardness increases by ≈380 HV0.025 in combination with a higher oscillating wear resistance compared to the X120Mn12. This shows the promising approach for developing work‐hardening alloys based on novel alloy concepts such as MPEAs. KW - Electric arc furnace KW - Finish milling KW - High manganese steels KW - Multi-principal element alloy KW - Ultrasonic-assisted milling KW - Work hardening PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608008 DO - https://doi.org/10.1002/adem.202400339 SN - 1438-1656 SP - 1 EP - 12 PB - Wiley VHC-Verlag AN - OPUS4-60800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rhode, Michael T1 - Normungsroadmap Wasserstofftechnologien 2024 N2 - Im Auftrag des Bundesministeriums für Wirtschaft und Klimaschutz (BMWK) wurden Anfang 2023 unter Leitung der Projektpartner DIN, DKE, DVGW, NWB, VDA, VDI und VDMA die Arbeiten an der Normungsroadmap Wasserstofftechnologien (NRM H2) begonnen. Ziel des Verbundprojekts war es, einen strategischen Fahrplan für eine schnelle und gezielte Erweiterung und Anpassung des technischen Regelwerks im Bereich der Wasserstofftechnologien auszuarbeiten und die aufgezeigten Lücken effizient zu schließen. Die Erarbeitung erfolgte in 39 Arbeitsgruppen mit einer Beteiligung von mehr als 600 Expertinnen und Experten. Die Clusterung erfolgte auf Basis von fünf großen Themenfeldern, die die gesamte Wertschöpfungskette abdecken: - Erzeugung - Infrastruktur - Anwendung - Qualitätsinfrastruktur - Weiterbildung, Zertifizierung und Sicherheit. Im Rahmen der des AK Infrastruktur erfolgte die Mitarbeit in der Arbeitsgruppe „Rohrleitungen“ (AG 2.1.1). Die AG war zuständig für die Ermittlung der Normungsbedarfe auf dem Gebiet der industriellen Rohrleitungen zur Werksversorgung sowie dem Gebiet der Flansche und ihren Verbindungen wie auch Prozessleitungen. Dies umfasst unter anderem Anforderungen für oberirdische oder in Kanälen verlegte oder erdgedeckte Rohrleitungen aus metallischen und nichtmetallischen Werkstoffen für Wasserstoff und -gemische. Mit dem Ziel, sicherer Betriebsbedingungen, waren hierbei insbesondere Anforderungen für industrielle Rohrleitungssysteme von Bedeutung (z. B. Normenreihe DIN EN 13480). Dabei unterscheiden sich die industriellen Rohrleitungssysteme von Fern- bzw. Transportleitungen, außerhalb der industriellen Werke, bspw. Raffinerien. Diese waren Bestandteil der AG 2.1.2 „Transportleitungen“. KW - Normung KW - Wasserstoff KW - Rohrleitungen KW - Metallische Werkstoffe KW - Regelwerke PY - 2024 SP - 49 EP - 54 AN - OPUS4-62442 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Diffusion in high-pressure hydrogen charged multi-principal element alloys CoCrFeMnNi and CoCrNi vs. AISI 316L N2 - Multi-principal element alloys (MPEAs) are innovative materials that have attracted extensive research attention within the last decade. MPEAs are characterized by a solid solution of equiatomic metallic elements. Depending on the number of elements, they are also referred as high entropy alloys (HEAs with n ≥ 4 elements like CoCrFeMnNi) and medium-entropy alloys (MEA with n = 3 elements CoCrNi). Depending on the alloy concept, MPEAs show exceptional properties in terms of mechanical performance or corrosion resistance at extreme environments. In that connection, hydrogen and its challenges for the most metallic materials gets more and more important. MPEAs are candidate materials for the substitution of conventional materials like austenitic stainless steels e.g., at very high-pressure up to 1000 bar. Those pressures are typically reached in valves or compressors for refueling of tanks with operational pressure of 700 bar. So far, the susceptibility of HEA/MEAs to hydrogen assisted cracking (if any) and the especially the underlying hydrogen uptake and diffusion was not within the scientific scope and not investigated in detail yet. For that reason, we focused on the hydrogen absorption the characterization of the hydrogen diffusion and trapping at elevated temperatures in a CoCrFeMnNi-HEA (each element with 20 at.-%) and CoCrNi-MEA, each element with 33.3 at.-%). As reference grade, the commercially available austenitic stainless steel AISI 316L was investigated. High-pressure hydrogen charging was conducted at different pressures in autoclave environment with maximum value of 1,000 bar. Thermal desorption analysis (TDA) via carrier gas hot extraction with coupled mass spectrometry was used with a max. heating rate of 0.5 K/s up to 650 °C. The measured desorption spectra of the different samples were deconvoluted into a defined number of individual peaks. The individually calculated peak temperatures allowed the definition of activation energies for predominant trap sites in the respective materials as well as the percentage share of the totally absorbed hydrogen concentration. The results present for the first time the complex interaction of both MPEAs and high-pressure hydrogen charging. A deconvolution of four peaks was selected and a main desorption peak was identified the dominant hydrogen trap containing the biggest share of the absorbed hydrogen concentration. The chemical composition an austenitic phase of both MPEAs is responsible for delayed hydrogen diffusion and strong, but mostly reversible, trapping. The comparison with the 316L samples showed significantly higher activation energies in the MPEAs, whereas hydrogen was also trapped at very high extraction temperatures. The absorbed maximum hydrogen concentration at 1,000 bar was 130 ppm for the CoCrFeMnNi-HEA, 50 ppm for the CoCrNi-MEA and 80 ppm for the 316L. It is interesting that the CoCrFeMnNi-HEA has obviously a way higher trapping capability compared to the conventional austenitic 316L, which could be a major advantage in terms of resistance to hydrogen assisted cracking. T2 - 47th MPA-Seminar CY - Stuttgart, Germany DA - 10.10.2023 KW - High-entropy alloy KW - Hydrogen KW - Diffusion KW - Thermal desorption analysis KW - Multiple-principal element alloy PY - 2023 AN - OPUS4-58675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Richter, Tim A1 - Mente, Tobias A1 - Mayr, P. A1 - Nitsche, A. T1 - Thickness and microstructure effect on hydrogen diffusion in creep‑resistant 9% Cr P92 steel and P91 weld metal N2 - Martensitic 9% Cr steels like P91 and P92 show susceptibility to delayed hydrogen assisted cracking depending on their microstructure. In that connection, effective hydrogen diffusion coefficients are used to assess the possible time-delay. Limited data on room temperature diffusion coefficients reported in literature vary widely by several orders of magnitude (mostly attributed to variation in microstructure). Especially P91 weld metal diffusion coefficients are rare so far. For that reason, electrochemical permeation experiments had been conducted using P92 base metal and P91 weld metal (in as-welded and heat-treated condition) with different thicknesses. From the results obtained, diffusion coefficients were calculated using to different methods, time-lag, and inflection point. Results show that, despite microstructural effects, the sample thickness must be considered as it influences the calculated diffusion coefficients. Finally, the comparison of calculated and measured hydrogen concentrations (determined by carrier gas hot extraction) enables the identification of realistic diffusion coefficients. KW - Creep-resistant steel KW - Diffusion KW - Hydrogen assisted cracking KW - Welding KW - Electrochemical permeation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540645 DO - https://doi.org/10.1007/s40194-021-01218-9 SN - 0043-2288 SP - 1 EP - 16 PB - Springer Nature Switzerland AG AN - OPUS4-54064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Wetzel, Annica A1 - Oczan, Ozlem A1 - Nietzke, Jonathan A1 - Richter, Tim A1 - Schröpfer, Dirk T1 - Hydrogen diffusion and local Volta potential in high- and medium-entropy alloys N2 - High-entropy alloys (HEAs) are characterized by a solid solution of minimum five and medium-entropy alloys (MEAs) of minimum three principal alloying elements in equiatomic proportions. They show exceptional application properties, such as high-strength and ductility or corrosion resistance. Future HEA/MEA-components could be exposed to hydrogen containing environments like vessels for cryogenic or high-pressure storage where the hydrogen absorption and diffusion in these materials is of interest. In our study, we investigated the HEA Co20Cr20Fe20Mn20Ni20 and the MEA Co33.3Cr33.3Ni33.3. For hydrogen ingress, cathodic charging was applied and diffusion kinetic was measured by high-resolution thermal desorption spectros-copy using different heating rates up to 0.250 K/s. Peak deconvolution resulted in high-temperature desorption peaks and hydrogen trapping above 280 °C. A total hydrogen concentration > 40 ppm was identified for the MEA and > 100 ppm for HEA. This indicates two important effects: (1) delayed hydrogen diffusion and (2) considerable amount of trapped hydrogen that must be anticipated for hydrogen assisted cracking phenomenon. Local electrochemical Volta potential maps had been measured for the hydrogen free condition by means of high-resolution Scanning Kelvin Probe Force Microscopy (SKPFM). T2 - Symposium on Materials and Joining Technology CY - Online meeting DA - 07.09.2020 KW - Hydrogen KW - High-entropy alloy KW - Diffusion KW - Scanning kelvin probe force microscopy KW - Corrosion PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511684 DO - https://doi.org/10.1088/1757-899X/882/1/012015 VL - 882 SP - 1 EP - 15 PB - IOP Publishing CY - Bristol AN - OPUS4-51168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Rhode, Michael A1 - Börner, Andreas T1 - Influence of modern machining processes on the surface integrity of high-entropy alloys N2 - High Entropy Alloys (HEAs) are a recent class of materials. In contrast to conventional alloys, HEAs consist of five alloying elements in equiatomic equilibrium. The high entropy effect is due, among other things, to the increased configuration entropy, which promotes solid solution formation. Many HEAs have enormous application potential due to excellent structural property combinations from very low to high temperatures. For the introduction of HEAs in real components, however, the question of the applicability of machining production technologies for component manufacture is of central importance. This has so far received Little attention in global materials research. Reliable and safe processing is essential for the demand of economical component production for potential areas of application, e.g. in power plant technology. For metals, milling is the standard machining process. This article presents the results of machining analyses. It focuses on the surface integrity resulting from the milling process on a Co20Cr20Fe20Mn20Ni20-HEA. For this purpose, investigations were carried out using ball nose end milling tools for conventional milling process in comparison to an innovative hybrid process available at BAM Berlin, Ultrasonic-Assisted Milling (USAM). USAM promises a lower Degradation of the surface properties due to lower loads on the workpiece surface during machining. For this purpose, basic milling parameters (cutting speed and tooth feed) were systematically varied and cutting forces were measured during the milling experiments. The subsequent Analysis of these forces allows an understanding of the mechanical loads acting on the tool and component surface. These loads cause topographical, mechanical and microstructural influences on the surface and consequently on the surface integrity. For their characterization, light and scanning electron microscopy were used, and the roughness and residual stresses via X-ray diffraction were measured. The results indicate significant advantages using USAM, especially due to reduced cutting forces compared to the conventional milling process. This causes lower mechanical loads on the tool and surface, combined with lower tensile residual stresses on and below the surface, and ultimately results in a significantly enhanced surface integrity. T2 - Symposium on Materials and Joining Magdeburg 2020 CY - Online meeting DA - 07.09.2020 KW - High entropy alloy KW - Machining KW - Ultrasonic machining PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512958 DO - https://doi.org/10.1088/1757-899X/882/1/012016 VL - 882 IS - 012016 SP - 1 EP - 11 PB - Institute of Physics CY - London AN - OPUS4-51295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Richter, Tim A1 - Mente, Tobias A1 - Mayr, P A1 - Nitsche, A T1 - Hydrogen effect on mechanical properties and cracking of creep‑resistant 9% Cr P92 steel and P91 weld metal N2 - Martensitic 9% Cr steels like P91 and P92 can show an increased susceptibility to delayed hydrogen-assisted cracking. The focus of this study was the microstructure and heat treatment efect on the mechanical properties of P92 base material and P91 multi-layer weld metal in both as-welded and post weld heat treated (PWHT) condition. Tensile tests with hydrogen free reference samples and electrochemically hydrogen charged samples were carried out; the mechanical properties were assessed and supported by detailed fractographic analysis. Finally, a hydrogen and microstructure-dependent fracture criterion is established. All investigated microstructures showed a hydrogen-infuenced degradation of the mechanical properties compared to the hydrogen-free reference samples. The as-welded martensitic P91 weld metal had the highest degree of degradation in the presence of hydrogen. The P91 PWHT weld metal and the P92 base material had comparable properties. From that point of view, a signifcantly increased risk for hydrogen-assisted cold cracking during welding fabrication of P91 weld joints must be considered before any heat treatment is conducted. T2 - IIW Annual Assembly, Meeting of Commission IX-C CY - Tokyo, Japan DA - 16.07.2022 KW - Creep-resisting materials KW - Welding KW - Hydrogen assisted cracking KW - Hydrogen embrittlement KW - Mechanical properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564070 DO - https://doi.org/10.1007/s40194-022-01410-5 SN - 0043-2288 SP - 1 EP - 12 PB - Springer Nature CY - Basel (CH) AN - OPUS4-56407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Rhode, Michael T1 - Residual stresses in a high- and a medium-entropy alloy due to TIG and friction stir welding N2 - The new alloying concept of multi-element systems with defined entropy (HEA—high-entropy alloy; MEA—medium-entropy alloy) is gaining increasing importance in materials research. Significantly improved properties or combinations of properties are shown by some HEA/MEA systems. Thus, primarily the production and resulting microstructures of HEA, as well as its properties, have been investigated so far. Furthermore, processing is a main issue in transferring HEA systems from the laboratory to real components. Since welding is the most important joining process for metals, it is crucial to investigate the influence of welding to guarantee component integrity. Welding leads to residual stresses, which significantly affect the component integrity. Hence, the focus of this study is the residual stress formation and distribution in a CoCrFeMnNi HEA and ternary CoCrNi MEA using two different welding processes: tungsten inert gas (TIG) welding and solid-state friction stir welding (FSW). As a pathway for the application of HEA in this investigation, for the first time, residual stress analyses in realistic near-component specimens were performed. The residual stresses were determined by X-ray diffraction (XRD) on the surfaces of top and root weld side. The results were correlated with the local welding microstructures. The results show that both FSW and TIG generate significant tensile residual stresses on the weld surfaces in, and transverse to, the welding direction. In the case of FSW of the CoCrFeMnNi HEA, the longitudinal residual stresses are in the range of the yield strength of approx. 260 MPa in the weld zone. KW - High entropy alloy KW - Welding KW - Residual stresses KW - Microstructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567039 DO - https://doi.org/10.3390/jmmp6060147 SN - 2504-4494 VL - 6 IS - 6 SP - 1 EP - 11 PB - MDPI CY - Basel AN - OPUS4-56703 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Richter, Tim T1 - Hydrogen diffusion and desorption characteristics of a CoCrFeMnNi high entropy and a CoCrNi medium entropy alloy N2 - High-entropy alloys (HEAs) are innovative high-performance materials that have attracted more and more research attention. HEAs are characterized by a solid solution of typically five equiatomic metallic elements. In addition, medium-entropy alloys (MEA, with three elements) are of interest and become more and more important. Depending on the alloy concept, HEAs and MEAs show exceptional mechanical properties, especially high-strength and ductility combinations at both cryogenic and elevated temperatures combined with excellent corrosion resistance. Future structural HEA/MEA components can be exposed to potential applications with hydrogen containing environments like high-temperature water in pressurized nuclear reactors or aerospace structures. Other potential applications could be in materials for vessel walls in the field of cryogenic and high-pressure hydrogen storage. So far, the susceptibility of HEAs/MEAs to hydrogen assisted cracking (if any) and the hydrogen diffusion is not investigated in detail yet and can limit or extend possible applications of HEA/MEA as structural materials. In our work, we focused on the hydrogen absorption, diffusion, and distribution in a HEA (CoCrFeMnNi the original Cantor-alloy) and a MEA (CoCrNi). Cathodic hydrogen charging was carried out for the hydrogen ingress, and thermal desorption analysis (TDA) revealed complex hydrogen trapping in both alloy types up to 300 °C. The absorbed total hydrogen concentrations were > 100 ppm for the HEA and > 40 ppm for MEA. In addition, the assessment of the peak deconvolution is not trivial and must consider both experimental and microstructure influences. T2 - 4th International Conference on Metals and Hydrogen - Steely & Hydrogen 2022 CY - Ghent, Belgium DA - 11.10.2022 KW - Hydrogen KW - High-entropy alloy KW - Multiple principal element alloy KW - Thermal desorption analysis KW - Diffusion PY - 2022 SP - 1 EP - 11 CY - Ghent, Belgium AN - OPUS4-56076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Ausscheidungsverhalten und Eigenschaften der schweißbedingten Wärmeeinflusszonen hochfester Stähle in Abhängigkeit der Mikrolegierungsroute N2 - Für eine signifikante Festigkeitssteigerung von vergüteten, hochfesten Feinkornbaustählen mit einer Nominalstreckgrenze ≥ 690 MPa, ist die Zugabe von Mikrolegierungselementen, wie Nb und Ti, unerlässlich. Die Normvorgaben zur chemischen Zusammensetzung dieser Stähle (bspw. in DIN EN 10025-6) geben zur Erzielung der vorgeschriebenen Eigenschaften dabei oft nur Grenzgehalte für die Hersteller vor. Die Wirkung der Legierungselemente in der WEZ ist teilweise komplett konträr. Somit wird eine adäquate Vorhersage der Chargenabhängigkeit hinsichtlich der Schweißeignung und des Tragverhaltens der Schweißverbindung erschwert. Neben metallographischen Untersuchungen einzelner WEZ-Bereiche wurden unter Variation der chemischen Zusammensetzung, thermodynamische Phasenberechnungen mittels ThermoCalc durchgeführt. Hierdurch wird ein Verständnis zur Phasentransformation, Ausscheidungswachstum und -auflösung während des Schweißens in Abhängigkeit von Temperatur und Abkühlbedingungen geschaffen. T2 - 40. Vortrags- und Diskussionstagung Werkstoffprüfung 2022 CY - Dresden, Germany DA - 27.10.2022 KW - WEZ-Erweichung KW - Mikrolegierungseinflüsse KW - Thermodynamische Modellierung PY - 2022 SP - 1 EP - 6 AN - OPUS4-56168 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Assessment of in-service welding conditions for pressurized hydrogen pipelines via component test N2 - Hydrogen is the energy carrier of tomorrow. This requires a reliable transport infrastructure with the ability to carry large amounts of hydrogen e.g. for steel industry or chemical industry. The conversion of existing natural gas (NG) grids is an essential part of the worldwide hydrogen strategies, in addition to the construction of new pipelines. In this context, the transportation of hydrogen is fundamental different from NG as hydrogen can be absorbed into the pipeline material. Given the well-known effects of hydrogen embrittlement, the compatibility of the materials for the intended pipelines must be investigated (typically low alloy steels in a wide range of strengths and thicknesses). However, pipelines require frequent maintenance, repair or the need for installation for further outlets. In some cases, it is necessary to perform welding on or onto the pipelines while they are still in service, i.e. with active gas flow under high pressure, e.g. such as the well-known “hot tapping”, see Fig. 1a. This in-service welding causes challenges for hydrogen operations in terms of additional hydrogen absorption during welding and the material compatibility. The challenge can be roughly divided into the possible austenitization of the inner pipe material exposed to hydrogen, which can lead to sufficient hydrogen absorption, and the welding itself, which causes an increased temperature range. Both lead to a significant increase in hydrogen solubility and diffusivity of the respective materials compared to room temperature. In this context, knowledge about hot tapping on hydrogen pipelines is scarce due to the lack of operating experience. Fundamental experimental investigations are required to investigate the transferability from NG to hydrogen pipeline grids. For this reason, the present study introduces a specially designed mock-up / demonstrator concept for the realistic assessment of the welding processing conditions, see Fig. 1b. The mock-up was designed to enable in-situ temperature measurement during welding as well as ex-post extraction of samples for the quantification of the absorbed hydrogen concentration, see Fig. 1c. For safety measures, the necessary pressurized hydrogen volume was limited by the insertion of a solid cylinder ensuring a 1 cm hydrogen gas layer. Welding experiments on the pressurized mock-ups with the diameters DN50 and DN200 have shown that the austenitization temperature can be reached on the inner surface of the pipeline, especially on thinner-walled pipelines, using current welding practices. This corresponds to an increased hydrogen uptake in the welded area of several ppm T2 - 1st Conference on Hydrogen in Materials Science and Engineering (H2-MSE) CY - Siegburg, Germany DA - 11.02.2025 KW - Hydrogen KW - Pipeline KW - In-service welding KW - Component test PY - 2025 AN - OPUS4-62544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Mente, Tobias A1 - Steppan, E. A1 - Kannengießer, Thomas A1 - Steger, J. T1 - Hydrogen trapping in T24 Cr-Mo-V steel weld joints - microstructure effect vs. experimental influence on activation energy for diffusion N2 - Hydrogen-assisted cracking is a critical combination of local microstructure, mechanical load and hydrogen concentration. Welded microstructures of low-alloyed creep-resistant Cr-Mo-V steels show different hydrogen trapping kinetics. This influences the adsorbed hydrogen concentration as well as the diffusion by moderate or strong trapping. A common approach to describe hydrogen traps is by their activation energy that is necessary to release hydrogen from the trap. In the present study, Cr-Mo-V steel T24 (7CrMoVTiB10-10) base material and TIG weld metal were investigated. Electrochemically hydrogen charged specimens were analyzed by thermal desorption analysis (TDA) with different linear heating rates. The results show two different effects. At first, the microstructure effect on trapping is evident in terms of higher hydrogen concentrations in the weld metal and increased activation energy for hydrogen release. Secondly, it is necessary to monitor the real specimen temperature. A comparison between the adjusted heating rate and the real specimen temperature shows that the calculated activation energy varies by factor two. Thus, the trap character in case of the base material changes to irreversible at decreased temperature. Hence, the effect of the experimental procedure must be considered as well if evaluating TDA results. Finally, realistic temperature assessment is mandatory for calculation of activation energy via TDA. KW - Creep-resistant steel KW - Hydrogen assisted cracking KW - Thermal desorption analysis KW - Welding KW - Microstructure KW - Diffusion PY - 2018 DO - https://doi.org/10.1007/s40194-017-0546-6 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 2 SP - 277 EP - 287 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-44505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Determination of inner pipe surface temperatures during in-service welding on hydrogen pipelines by means of component-like mock up experiments N2 - Hydrogen is considered as one of the most important energy carriers in the future. The necessary large-scale transport over long distances requires a suitable pipeline infrastructure. Current plannings encompass a dual-way strategy of repurposing existing natural gas (NG) pipelines, supplemented by the construction of new hydrogen pipelines. In some cases, such as necessary grid extensions or installation of bypasses in case of repair work, techniques like “hot tapping” are applied. These techniques include so-called in-service welding on pressurized pipelines and are state-of-the-art for NG grids and oil pipelines. The existing NG pipeline grid consists of a wide range of materials with different strengths, diameters, and wall thicknesses. In this context, the material compatibility is crucial. The main difference between hydrogen and NG is that hydrogen can both penetrate the material and cause hydrogen embrittlement. In that connection, in-service welding encompasses elevated temperatures for a certain time during the typically multi-layer welding process. Locally even austenitization temperature can be reached or surpassed. Austenite has a higher hydrogen solubility at a significantly lower diffusion rate, which could lead to a critical hydrogen accumulation. Especially the inner pipe surface temperature is from utmost interest, as this interface is exposed to the pressurized hydrogen (up to 100 bar). However, direct measurement of the locally occurring temperatures is very challenging. For this reason, a component-like geometry was developed. The geometry consists of a pipeline segment with a metal sheet joined to the pipe segment, representing similar heat dissipation conditions as in the field. In addition, typical welding parameters were applied that are currently used in the NG grid. This allows the welding of realistic multi-layer fillet welds on the outer pipe wall with simultaneous temperature measurement using manifold thermocouples at defined positions: (1) adjacent to the weld seam on the outer pipe surface, (2) on the inner pipe surface and (3) on the welded metal sheet. To ensure realistic conditions, manual shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) was investigated. The effects of different wall thicknesses and welding heat inputs on the temperature distribution and peak temperatures achieved on the inner pipe surface during welding vary depending on the chosen method. Peak temperatures above austenitization temperature up to 1078 °C have been measured on L245 pipes with wall thickness of 3.6 mm. For pipes made from higher strength materials, such as L485, with a wall thickness of 8 mm, peak temperatures between 607 °C and 755 °C were recorded. Temperature and austenitization directly affects hydrogen diffusivity and solubility, showing the importance of the findings. The temperature profile and cooling conditions influence the mechanical properties of the material as well. For this reason, metallurgical investigations are carried out to assess the hardness and microstructure of the welds. Hardening up to 248 HV10 was detected in the heat-affected zone (HAZ) of the top layer, which could lead to a locally increased susceptibility to hydrogen assisted cracking. Meanwhile, the minimum hardness found in the HAZ of the root layer was as low as 144 HV10, indicating a softening. The results of this study provide valuable insights into the suitability of existing materials and geometries for hydrogen transport. Secondly, the data collected will serve as a basis for planned numerical simulations to further improve knowledge and optimize welding processes to ensure the integrity and safety of hydrogen pipelines. T2 - IIW Intermediate Meeting, Com. II-A CY - Trollhättan, Sweden DA - 10.03.2025 KW - Testing KW - In-service welding KW - Hydrogen KW - Pipelines PY - 2025 AN - OPUS4-62690 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Update on "Call for interested people to contribute to series of comprehensive papers on welding and joining of components for sustainable energy systems" N2 - Based on the initial call in March 2024, an update time-frame is introduced on the working plan for a comprehensive review paper series on joining and welding technologies for the manufacturing of components and parts used in sustainable energy generation, conversion, and transport with focus on hydrogen and wind energy. T2 - 77th IIW Annual Assembly and International Conference, Meeting of Commission II-A CY - Ixia, Rhodes, Greece DA - 07.07.2024 KW - Review paper KW - Research study KW - Hydrogen KW - Joining KW - Welding PY - 2024 AN - OPUS4-60674 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Evaluation of the wear protection of modified NiMoCrSi alloy and machinability using ultrasonic-assisted milling N2 - The development of technologies for climate-neutral energy generation is an important contribution to reducing CO2 emissions, whereby the efficient use of material systems is a key factor. Wear-resistant coatings are required for highly efficient and economical steel components in energy, process and power plant engineering in order to withstand the high corrosive, tribological, thermal and mechanical loads. Considering price and supply risks as well as the increasing demands on corrosive resistance at high temperatures, conventional cobalt alloys are to be replaced by nickel alloys. In addition, there is a growing demand for defined surfaces of high quality or functional surfaces of these protective coatings. The milling required for this is often not economically feasible, especially for SMEs, due to high tool wear. A joint project of BAM and ISAF of TU Clausthal (Fosta P1550/IGF 21959 N) investigates the optimization of these challenging machining conditions by means of alloy modifications of the welding powder for plasma transferred arc cladding, without reducing the wear protection potential and using innovative ultrasonic assisted milling process for better machinability without reducing wear resistance. This article presents the results of investigations into the relationships between different alloy modifications (Ti, Al, Nb Mo and Hf with wX ≤ 0.01), the resulting microstructure and precipitation morphology, the machinability and the wear protection properties using a NiCrMoSiFeB alloy (trade name: Colmonoy 56 PTA). Tests using cast samples have already shown that the addition of Nb leads to a finer distribution of the hard phases and that this results in a reduction in cutting forces and tool wear during ultrasonic-assisted milling. The change in the microstructure morphology through the addition of Al, on the other hand, causes a significant increase in the cutting forces that occur. T2 - IIW Intermediate meeting of Commission II-A CY - Online meeting DA - 12.03.2024 KW - Ultrasonic assisted milling KW - Surface integrity PY - 2024 AN - OPUS4-61924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Fügetechnik für die neue Wasserstoffökonomie – Werkstoffe, Schweißtechnologien, Perspektiven – N2 - Die Studie gibt einen Überblick über die Aspekte der Fügetechnik und ihrer Bedeutung in Wasserstofftechnologien. Dazu werden die Grundlagen der Technologiefelder Wasserstofferzeugung, -speicherung, -transport und -nutzung vorgestellt und der Stand der Technik der fügetechnischen Fertigung von Komponenten in Wasserstofftechnologien zusammengefasst. Dabei werden nicht nur exklusiv Metalle betrachtet. Anhand repräsentativer Beispiele aus der Praxis, Forschung und Entwicklung wird die Bedeutung der Fügetechnik in Wasserstofftechnologien klar herausgestellt und mögliche Perspektiven für die Zukunft abgeleitet. Hier ist ersichtlich, dass Fügetechnologien wesentliche Bedeutung für die erfolgreiche Umsetzung von technischen Komponenten der Wasserstofftechnologien haben, von der Erzeugung bis zur Anwendung. Aus gesamtwirtschaftlicher Sicht umfassen die Schwerpunkte bzw. Trends der Fügetechnik dabei: die Erstellung neuer Infrastruktur für Wasserstoffspeicherung und -transport sowie die sichere Umnutzung der bestehenden Erdgasinfrastruktur. Bei der Wasserstoffanwendung wird die effiziente massentaugliche Produktion von Brennstoffzellen immer wichtiger. Es ist zudem klar ersichtlich, dass die additive Fertigung bereits jetzt ein hohes Potential für Komponenten von Wasserstofftechnologien besitzen und dieses wachsen wird. Aus den perspektivischen Anwendungen ergeben sich zudem Herausforderungen und Forschungsbedarfe für die notwendigen nationalen und internationalen Regelwerke und technischen Normen. Schwerpunktmäßig sind hierbei die bereits bestehenden Empfehlungen und kodifizierten Regeln vollständig zu adaptieren und in die Aus- und Weiterbildung von fügetechnischem Fachpersonal einzubetten. KW - Fügetechnik KW - Wasserstoff KW - Werkstoffe KW - Prozesse KW - Perspektiven PY - 2021 UR - https://www.dvs-media.eu/de/neuerscheinungen/4425/dvs-studie-zur-fuegetechnik-fuer-die-neue-wasserstoffoekonomie-werkstoffe-schweisstechnologien-perspektiven SN - 978-3-96144-157-0 SN - 978-3-96144-158-7 VL - 373 SP - 1 EP - 59 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-53498 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schroeder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Ausscheidungsverhalten und Eigenschaften der schweißbedingten Wärmeeinflusszonen hochfester Stähle in Abhängigkeit der Mikrolegierungsroute N2 - Für eine signifikante Festigkeitssteigerung von vergüteten, hochfesten Feinkornbaustäh-len mit einer Nominalstreckgrenze ≥ 690 MPa, ist die Zugabe von Mikrolegierungselementen, wie Nb und Ti, unerlässlich. Die Normvorgaben zur chemischen Zusammensetzung dieser Stähle (bspw. in DIN EN 10025-6) geben zur Erzielung der vorgeschriebenen Eigenschaften dabei oft nur Grenzgehalte für die Hersteller vor. Die Wirkung der Legierungselemente in der WEZ ist teilweise komplett konträr. Somit wird eine adäquate Vorhersage der Chargenabhängigkeit hinsichtlich der Schweißeignung und des Tragver-haltens der Schweißverbindung erschwert. Neben metallographischen Untersuchungen einzelner WEZ-Bereiche wurden unter Variation der chemischen Zusammensetzung, thermodynamische Phasenberech-nungen mittels ThermoCalc durchgeführt. Hierdurch wird ein Verständnis zur Phasentransformation, Aus-scheidungswachstum und -auflösung während des Schweißens in Abhängigkeit von Temperatur und Ab-kühlbedingungen geschaffen. T2 - Forschungsseminar BAM, BMDK CY - Magdeburg, Germany DA - 05.12.2022 KW - WEZ-Erweichung KW - Thermodynamische Simulation KW - Mikrolegierungseinfluss KW - Hochfester Feinkornbaustahl KW - Modifizierter Sprühlichtbogen PY - 2023 AN - OPUS4-56837 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kannengießer, Thomas A1 - Rhode, Michael T1 - Fügetechnik in Wasserstofftechnologien - Forschungsbedarf für die Branche N2 - Die Studie gibt einen kurzen Überblick über die jetzige Bedeutung der Fügetechnik in Wasserstofftechnologien und über zukünftige Forschungsbedarfe für die Branche in den einzelnen Technologiefeldern Wasserstofferzeu-gung, -speicherung, -transport und -nutzung. Fügetechnologien haben dabei wesentliche Bedeutung für die er-folgreiche Umsetzung von technischen Komponenten der Wasserstofftechnologien. Die Schwerpunkte bzw. For-schungsbedarfe ergeben sich bspw. durch die Erstellung neuer Infrastruktur für Wasserstoffspeicherung und -transport sowie durch Umnutzung der bestehenden Erdgasinfrastruktur. Bei der Wasserstofferzeugung und -anwendung wird z.B. die Entwicklung effiziente Massenproduktionsmethoden von Elektrolyseuren und Brennstoff-zellen einen wichtigen Meilenstein bilden und laserbasierte Fügetechnologien sind hier zum Teil schon etabliert. Die additive Fertigung nimmt dabei eine Querschnittsposition ein und besitzt hohes Anwendungspotential für die Zukunft z.B. für die Fertigung von Komponenten in Gasturbinen. Aus den technischen Fragestellungen und For-schungsbedarfen ergeben sich zudem Herausforderungen für die notwendige Neu- und Weiterentwicklung von technischen Regelwerken und Normen und den Eingang in die Aus- und Weiterbildung von fügetechnischem Fachpersonal. T2 - DVS Congress 2021 CY - Essen, Germany DA - 14.09.2021 KW - Wasserstoff KW - Fügetechnik KW - Forschung KW - Technologie PY - 2021 AN - OPUS4-53321 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Joining Processes in Hydrogen Technologies - Current need and future R&D activites, a review N2 - This study gives an overview on the important field of joining processes for component fabrication in hydrogen technologies. For that reason, the current need and future research and developement activites are highlighted for the different technological field of hydrogen generation, storage, transport and use. In addition, the emerging field of additive manufacturing is included. Finally, some remarks are given for necessary changes in the standardization and its challenges. T2 - 46th Seminar - Additive Manufacturing, Hydrogen, Energy, Integrity CY - Online meeting DA - 12.10.2021 KW - Hydrogen KW - Joining process KW - Welding KW - Review KW - Research and Development PY - 2021 AN - OPUS4-53554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Mente, Tobias A1 - Kannengießer, Thomas T1 - Diffusionsmessungen in UP-Mehrlagenschweißgut als effektives Tool gegen verzögerte Kaltrissbildung in Dickblechschweißungen N2 - Offshore-Windenergieanlagen bilden einen zentralen Bestandteil der zukünftigen Energieerzeugung. Hierzu notwendige Gründungs- und Turmstrukturen werden vorrangig aus UP-geschweißten Blechen aus hochfesten niedriglegierten Stählen mit Dicken bis zu 200 mm hergestellt. Die großen Blechdicken begünstigen hohe Schweißeigenspannungen und lange Diffusionswege für z. B. über den Schweißprozess eingebrachten Wasserstoff. Damit steigt das Risiko für eine wasserstoffunterstützte Kaltrissbildung (WKB) an. Zum sichereren Ausschluss von WKB in den geschweißten Komponenten wird in Abhängigkeit der Nahtgröße, Wärmeeinbringung und Stahlsorte eine Mindestwartezeit (MWZ) von bis zu 48 h empfohlen, bevor die zerstörungsfreie Prüfung durchgeführt wird. Es ist allerdings offen, ob die empfohlene MWZ zu konservativ ist. Einflüsse sind hier bspw. die schwierige Bewertung des Wasserstoffdiffusionsverhaltens im heterogenen UP-Mehrlagen-Schweißgut (SG) im Vergleich zum Grundwerkstoff (GW). Zudem sind nur sehr begrenzt H-Diffusionskoeffizienten für UP-Mehrlagen-SG als Grundlage zur Abschätzung des Zeitintervalls einer möglichen verzögerten Kaltrissbildung (somit MWZ) oder auch für Nachwärmprozeduren zur Wasserstoffreduktion (keine MWZ) verfügbar. Verlässliche H-Diffusionskoeffizienten sind daher ein adäquates Tool zur Bewertung des Risikos einer verzögerten WKB. Dieser Beitrag beschreibt Untersuchungen zur Charakterisierung der Wasserstoffdiffusionsverhalten in UP-Mehrlagen-SG eines 60 mm dicken Bleches einer Offshore-Stahlgüte. Dazu wurden Proben unterschiedlicher Dicke aus dem reinen Schweißgut extrahiert und über elektrochemische Permeation und Trägergasheißextraktion im Temperaturbereich bis 400 °C sehr interessante Ergebnisse zu den korrespondierenden Diffusionskoeffizienten erarbeitet. T2 - DVS Congress 2021 CY - Online meeting DA - 14.09.2021 KW - UP-Schweißen KW - Wasserstoff KW - Kaltriss KW - Permeation KW - Diffusion PY - 2021 SN - 978-3-96144-146-4 VL - 371 SP - 448 EP - 459 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-53369 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Joining processes for components in hydrogen technologies: Current need and future importance N2 - This presentation gives an overview on the importance of joining processes for component fabrication in hydrogen technologies. For that reason, the current need and future research and developement activites are highlighted for the three technological fields: hydrogen storage, transport and use (in terms of the emerging field of additive manufacturing). Finally, some remarks are given for necessary changes in the standardization. T2 - IIW Intermediate Meeting, Comm. II-A "Welding Metallurgy" CY - Online meeting DA - 17.03.2022 KW - Hydrogen KW - Welding KW - Research KW - Review KW - Additive manufacturing PY - 2022 AN - OPUS4-54488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Kaiser, Sebastian T1 - Repair welding of pressurized in-service hydrogen pipelines: A review on current challenges and strategies N2 - As energy carrier of the future, green hydrogen can make a decisive contribution to a sustainable energy supply. In Europe concrete plans for a hydrogen pipeline grid already exist, as the so called “European Hydrogen backbone”. As building a completely new pipeline grid is economically not justifiable, a dual-way strategy of repurposing natural gas (NG) pipelines and newly built pipelines is intended. Long distance pipeline grids require regular maintenance and repairs. In that conection, for natural gas (NG) pipelines in-service welding is state of the art. Concepts such as hot-tapping (drilling into pressurized pipelines) and “stoppling” (sealing off pipeline sections after installing bypasses or pressure relieves) allow the repair of damaged pipeline sections or the installation of new branches without shutting the pipeline down. The EIGA 121/14 guideline already pointed out in 2014 that “a hydrogen hot-tap shall not be considered a routine procedure”. This shows that the determination of the transferability of these repair concepts to hydrogen pipelines is of utmost importance. Due to the degrading effects of hydrogen on mechanical proper-ties, commonly referred to as “hydrogen embrittlement” it is necessary to understand and investigate the occurring effects. In the special case of repair welding on in-service hydrogen pipelines an increased hydro-gen uptake due to a large heat input and microstructural changes in the material needs to be considered. For this reason, this paper gives an overview on existing weld repair concepts and its risks and limitations in terms of hydrogen absorption and possible embrittlement effects when transferred to hydrogen pipelines. The complexity lies in a large variety of materials (low alloyed steels), pipeline diameters and corresponding welded joints. The material compatibility of materials in used (repurposed NG-pipelines) and new condition must be investigated. Particularly for repurposed/used pipelines the effect of a pre-matured/corroded inner surface and sometimes insufficient documentation of the material “history” needs to be considered. An overview on ongoing and completed R&D-projects with respect to repair concepts for hydrogen pipelines and hydrogen effects on pipeline materials is given. T2 - 77th IIW Annual Assembly and International Conference, Meeting of Commission XI "Pressure Vessels and Piping" CY - Ixia, Rhodes, Greece DA - 07.07.2024 KW - Hydrogen KW - Repair welding KW - Pipelines KW - Study PY - 2024 AN - OPUS4-60673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Fügetechnik in Wasserstofftechnologien Ein aktueller Überblick N2 - Der Vortrag gibt einen kurzen Überblick über die Bedeutung der Fügetechnik in Wasserstofftechnologien und über zukünftige Herausforderungen. Fügetechnologien, insbesondere die Schweißtechnik, haben dabei wesentliche Bedeutung für die Umsetzung von technischen Komponenten der Wasserstofftechnologien. Forschungsschwerpunkte ergeben sich insbesondere für die Erzeugung und den Transport des Wasserstoffs. T2 - Vortragsreihe des DVS Bezirksverbandes Mannheim-Ludwigshafen CY - Online meeting DA - 27.04.2023 KW - Wasserstoff KW - Schweißen KW - Studie PY - 2023 AN - OPUS4-57411 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Welding (and joining) technologies for the hydrogen economy - a short overview N2 - This study gives an overview on the important field of joining processes for component fabrication in hydrogen technologies. The current main issues and future perspectives are highlighted for the different technological field of hydrogen generation, storage, transport and use. In addition, the emerging field of additive manufacturing is included. Some remarks are given for standardization and regulations. T2 - Meeting of the European Welding Association (EWA), Executive Committee (EC) 1 CY - Frankfurt am Main, Germany DA - 22.03.2023 KW - Hydrogen KW - Welding KW - Research KW - Study PY - 2023 AN - OPUS4-57222 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Bewertung und Vermeidung von schweißverarbeitungsbedingten Rissen in hochfesten Baustählen N2 - Die vorliegende Präsentation fasst die Ergebnisse von drei laufenden bzw. beendeten AiF/IGF-Projekten zusammen, die über die Forschungsvereinigung Stahlanwendung FOSTA e.V. an der BAM bearbeitet wurden zum Thema: Bewertung und Vermeidung von schweißverarbeitungsbedingten Rissen in hochfesten Baustählen. T2 - FOSTA Tagung: Hochfester Stahl im Stahl und Anlagenbau CY - Essen, Germany DA - 16.05.2023 KW - Studie KW - Schweißen KW - Hochfester Stahl KW - Riss KW - Forschung PY - 2023 AN - OPUS4-57517 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Masoud Nia, Niloufar A1 - Nietzke, Jonathen A1 - Kannengiesser, Thomas T1 - Ti and Nb microalloying of HSLA steels and its effect on hydrogen diffusion and trapping N2 - Fine-grain, high-strength, low-alloy (HSLA) structural steels with yield strengths > 600 MPa are now the state of the art in construction applications such as mobile cranes and civil engineering. HSLA grades derive their strength from a combination of specific heat treatment and the underlying chemical composition. In this context, Ti or Nb are essential to obtain a fine-grained microstructure as well as the necessary carbides or nitrides for precipitation strengthening. In this context, the specific effect of Ti or Nb-rich compounds on hydrogen trapping and diffusion is well known for special laboratory cast alloys, but unknown for realistic steel compositions. For this reason, a series of S690Q-based alloys were synthesized, close to a real steel composition, but with well controlled Ti or Nb additions in different amounts. Specimens were obtained from these alloys by electrochemical discharge machining (EDM). The specimens were tested using the well-established electrochemical permeation technique. From the experimental results, the hydrogen diffusion coefficients and the analytical subsurface hydrogen concentration were calculated. In addition, the hydrogen trapping behavior at elevated temperatures was interpreted by thermal desorption analysis (TDA) using different heating rates of hydrogen charged samples. The results showed that in contrast to metallurgically "pure" laboratory cast alloys, realistic chemical compositions were similar in their hydrogen trapping behavior, despite some small differences. All investigated steel grades exhibited shallow and reversible hydrogen trapping, regardless of their chemical composition. Of course, the experiments only allowed the calculation of effective diffusion coefficients and trapping energies, which represent an average of the entire microstructure. Nevertheless, HSLA steels are typically joined by arc welding, which includes the risk of delayed hydrogen assisted cracking. From the point of view of welding practice, however, a more or less identical hydrogen diffusion behavior means that no special "metallurgically specific", justifiable measures need to be considered, despite the well-established processes such as "soaking" or dehydrogenation heat treatment. T2 - MPAC 2025 CY - Stuttgart, Germany DA - 06.10.2025 KW - HACC KW - Hydrogen KW - HSLA PY - 2025 AN - OPUS4-64337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Effect of Ti microalloying on the local strain behavior of cross-weld tensile samples determined by digital image correlation N2 - High-strength low-alloyed (HSLA) steels with yield strength / proof stress ≥ 600 MPa are the basis of modern light-weight steel constructions. Indeed, the economic and ecological benefits strongly depend on their processability in terms of welding. In this context, the use of highly productive welding processes and suitable welding consumables is of vital interest and requires a fundamental understanding of the microstructural changes in the HSLA steel and especially the heat-affected zone (HAZ) of the welded joint. Microalloying elements, such as Ti or Nb, are essential to achieve the desired mechanical properties. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the HAZ that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using cross-weld tensile specimens. Digital image correlation (DIC) was used for in-situ monitoring of the development and accumulation of the local strains in different HAZ regions during tensile testing. Using a specially designed mirror system, the local strains of the microstructure zones on the top and bottom of the weld were recorded simultaneously. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the reduction in area, the fracture position, and the overall fracture behavior. KW - High-strength structural steel KW - Microalloying influences KW - HAZ-softening KW - Digital Image Correlation KW - Constraint effect KW - Thermodynamic simulation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643558 DO - https://doi.org/10.1007/s40194-025-02185-1 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-64355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Component test for simulation of in-service welding on hydrogen pipelines N2 - Hydrogen is set as the energy carrier of tomorrow and most countries will achieve large-scale hydrogen transport through the conversion of the natural gas (NG) grid and the construction of new pipelines. The interaction between hydrogen and the pipeline materials differs fundamentally from that of NG, as hydrogen is readily absorbed into the material. Considering the possible hydrogen embrittlement (HE), the compatibility of the pipeline materials (low-alloyed steels with a wide strength/thickness range) must be investigated. However, pipelines require intervention for maintenance, repair, or grid expansion with welding on/onto the pipelines while in service, i.e. the well-known "hot tapping" and "stoppling". The challenges compared to NG can be broadly divided into the possible austenitization of the inner pipe material exposed to hydrogen and the welding itself. Both result in a significant increase in hydrogen solubility and could potentially pose challenges in terms of HE. Emphasis is placed on the word "could" because knowledge of "hot tapping" on hydrogen pipelines is scarce due a lack of service experience. To this end, this study proposes a concept for a component-like demonstrator with the objectives: (1) safe feasibility of "hot tapping" on pressurized model hydrogen pipeline sections, (2) facilitate ex-post sample extraction for the purpose of quantifying the absorbed hydrogen concentrations, and (3) ensure in-situ temperature measurement during welding to monitor the pipeline surface temperature. For safety reasons in the event of an unintentional "burn-through", a solid cylinder was inserted in the demonstrator to restrict the hydrogen gas volume to a small, pressurized layer. Reference pipeline surface temperature measurements were ensured on comparable, unpressurized geometries. The investigated range of welding conditions was investigated for representative material/thickness combinations (DN60 to DN300), suggesting the feasibility of the demonstrator for the determination of reliable in-service welding conditions for both installed and new pipelines for hydrogen service. T2 - 49th MPA Conference CY - Stuttgart, Germany DA - 06.10.2025 KW - Hydrogen KW - Pipeline KW - In-service welding KW - Component test PY - 2025 AN - OPUS4-64317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Mechanische Eigenschaften der Längschweißnaht einer X65-Pipeline in Druckwasserstoffatmosphäre N2 - Im folgenden Beitrag werden die Ergebnisse der mechanischen Eigenschaften unter 200 bar Druckwasserstoff des Werkstoffes 316L (1.4404) vorgestellt. Dazu wurden Hohlzugproben aus konventionellem, kaltgezogenem Material herausgearbeitet und per SLM-PBF additiv gefertigten Hohlzugproben gegenübergestellt. Die Proben wurden da-bei unter Druckwasserstoff einer SSRT-Prüfung mit einer Dehnrate von 1E-5/s unterzogen. Zusätzlich zum Werkstoffzustand wurde der Einfluss des Oberflächenzustandes charakterisiert: (1) additiv gefertigten Proben mit endkonturnaher Form „as-printed“ oh-ne zusätzliche Bohrung, (2) Bohren und (3) zusätzliches Honen. Die gemessene Degradation der mechanischen Eigenschaften unter Wasserstoff hing dabei in erster Linie von der Oberfläche ab und damit indirekt vom Werkstoffzustand „as-printed“ oder kaltgezogen ab. Während die Proben mit gebohrter und/oder gehonter Oberfläche eine RRA (Relative Reduction of Area) 78 % aufwiesen, zeigten die AM-Proben eine deutlich höhere RRA von 90 %. Ein möglicher Grund dafür sind während der Fertigung ausbildende Oxidschichten, die sich durch geringe Mengen an Restsauerstoff während des AM-Prozesses ausbilden. Zur abschließenden Charakterisierung sind weitere Untersuchungen erforderlich, insbesondere für ein größeres Parameterfeld an Prüftemperaturen (Oxideinwirkung) und Dehnraten (mechanische Beständigkeit der Oxidschicht ähnlich den Einflüssen auf „klassische“ Spannungsrisskorrosion). T2 - DGM Arbeitskreis Wasserstoff CY - Neu-Isenburg, Germany DA - 26.05.2025 KW - Pipeline KW - Wasserstoff KW - Hohlzugprobe PY - 2025 AN - OPUS4-63236 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Additive gefertigte 316L-Hohlzugproben unter Druckwasserstoff - Einfluss der Oberfläche und des Werkstoffzustandes N2 - Im folgenden Beitrag werden die Ergebnisse der mechanischen Eigenschaften unter 200 bar Druckwasserstoff des Werkstoffes 316L (1.4404) vorgestellt. Dazu wurden Hohlzugproben aus konventionellem, kaltgezogenem Material herausgearbeitet und per SLM-PBF additiv gefertigten Hohlzugproben gegenübergestellt. Die Proben wurden da-bei unter Druckwasserstoff einer SSRT-Prüfung mit einer Dehnrate von 1E-5/s unterzogen. Zusätzlich zum Werkstoffzustand wurde der Einfluss des Oberflächenzustandes charakterisiert: (1) additiv gefertigten Proben mit endkonturnaher Form „as-printed“ oh-ne zusätzliche Bohrung, (2) Bohren und (3) zusätzliches Honen. Die gemessene Degra-dation der mechanischen Eigenschaften unter Wasserstoff hing dabei in erster Linie von der Oberfläche ab und damit indirekt vom Werkstoffzustand „as-printed“ oder kaltgezogen ab. Während die Proben mit gebohrter und/oder gehonter Oberfläche eine RRA (Relative Reduction of Area) 78 % aufwiesen, zeigten die AM-Proben eine deutlich höhere RRA von 90 %. Ein möglicher Grund dafür sind während der Fertigung ausbildende Oxidschichten, die sich durch geringe Mengen an Restsauerstoff während des AM-Prozesses ausbilden. Zur abschließenden Charakterisierung sind weitere Untersuchungen erforderlich, insbesondere für ein größeres Parameterfeld an Prüftemperaturen (Oxideinwirkung) und Dehnraten (mechanische Beständigkeit der Oxidschicht ähnlich den Einflüssen auf „klassische“ Spannungsrisskorrosion). T2 - DGM Arbeitskreis Wasserstoff CY - Neu-Isenburg, Germany DA - 26.05.2025 KW - Wasserstoff KW - Additive Fertigung KW - Hohlzugprobe KW - Austentitischer Stahl PY - 2025 AN - OPUS4-63239 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 - Rhode, Michael T1 - Additive manufacturing for components in hydrogen technologies N2 - With the introduction of a hydrogen-based energy and national economy, safety-relevant components for hydrogen technologies are becoming increasingly important. Characteristic of hydrogen technologies are, for example, harsh environmental conditions such as cryogenic or high-pressure storage, corrosion issues in fuel cells and electrolyzers, turbines, and many more. Additive manufacturing of components is becoming increasingly important and irreplaceable for the production of complex technical systems. Using the case studies of burners for gas turbines and electrodes and membranes for polymer (PEMFC) and solid oxide (SOFC) fuel cells, this article shows the potential of additive manufacturing of components. At the same time, however, the challenge of considering divergent mechanical properties depending on the direction of assembly in a "hydrogen-compatible" manner is also highlighted. Finally, the challenges posed by additive manufacturing and hydrogen for materials testing are highlighted under scenarios that are as realistic as possible. T2 - MPA-Workshop Hydrogen CY - Online meeting DA - 10.11.2022 KW - Additive manufacturing KW - Hydrogen KW - Technologies KW - Overview KW - Component PY - 2022 AN - OPUS4-56233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Processing and application properties of multiple principal element alloys (MPEA) N2 - The presentation gives an overview of BAM's activities on processing influences and application properties of MPEAs in the form of joined and machined high and medium entropy alloys (CoCrFeMnNi and CoCrNi). In the case of welding, the focus is on defect-free welded joints with sufficient mechanical properties. In the case of machining, the focus is on the possible influence on the surface quality of the materials through adequate milling parameters. In addition, the hydrogen absorption and diffusion properties as well as the electrochemical corrosion behavior are fundamentally examined. T2 - FAU-Department Werkstoffwissenschaften, Seminar: Aktuelle Probleme der Werkstoffwissenschaften CY - Erlangen, Germany DA - 25.04.2024 KW - Welding KW - Application properties KW - Machining KW - High-entropy alloy KW - Hydrogen PY - 2024 AN - OPUS4-59975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen diffusion in creep-resistant 9%-Cr P91 steel weld metal N2 - 9 %-Cr steel P91 is widely used in power plants due to the excellent creep-resistance. Components of this steel are typically welded and demand for careful welding fabrication, whereas a so-called post weld heat treatment (PWHT), must be conducted to increase the toughness and decrease the hardness of the martensitic as-welded (AW) microstructure. Before the PWHT, a hydrogen removal (or dehydrogenation) heat treatment is necessary as hardened AW martensitic microstructure is generally prone to delayed hydrogen assisted cracking (HAC). The microstructure and temperature dependent hydrogen diffusion is an important issue as it determines how long a potential crack-critical hydrogen concentration could remain in the microstructure. In this context, reliable hydrogen diffusion coefficients of P91 weld metal are rare. Hence, the diffusion behavior of P91 multi-layer weld metal was investigated in two different microstructure conditions: AW and further PWHT (760 °C for 4 h). Two different experimental techniques were used to cover a wide range of hydrogen diffusion temperatures: the electrochemical permeation technique (PT) at room temperature and the carrier gas hot extraction (CGHE) for a temperature range from 100 to 400 °C. From both techniques typical hydrogen diffusion coefficients were calculated and the corresponding hydrogen concentration was measured. It was ascertained that both heat treatment conditions show significant differences in hydrogen diffusivity. The biggest deviations were identified for room temperature. In this case, the AW condition shows significant hydrogen trapping and up to seven times lower diffusion coefficients. Additionally, PT investigations showed a preferred diffusion direction of hydrogen in the weld metal expressed by the diffusion coefficients and the permeability for both heat treatment conditions. The CGHE generally revealed lower diffusion coefficients for the AW microstructure up to 200 °C. In addition, the AW condition showed hydrogen concentrations up to 50 ml/100 g (considering electrochemical charging). Nonetheless, this hydrogen was not permanently (reversibly) trapped. Nonetheless, this temperature is approximately 100 °C below recommended dehydrogenation heat treatment (DHT). This has two main consequences: (I) in case of welding is interrupted or no DHT is conducted, a HAC susceptibility of hardened martensitic P91 weld metal cannot be excluded and (II) DHT can be conducted at temperatures around 200 °C below the recommended temperatures. T2 - IIW Annual Assembly, Meeting of Commission IX-C "Creep and heat resistant welds" CY - Bratislava, Slovakia DA - 07.07.2019 KW - Hydrogen KW - Diffusion KW - Weld metal KW - Microstructure KW - Post weld heat treatment PY - 2019 AN - OPUS4-48449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drexler, A.-K. A1 - Konert, Florian A1 - Nietzke, Jonathan A1 - Hodžić, E. A1 - Pastore, S. A1 - Domitner, J. A1 - Rhode, Michael A1 - Sommitsch, C. A1 - Böllinghaus, Thomas T1 - Effect of Tensile Loading and Temperature on the Hydrogen Solubility of Steels at High Gas Pressure N2 - The hydrogen solubility in ferritic and martensitic steels is affected by hydrostatic stress, pressure, and temperature. In general, compressive stresses decrease but tensile stresses increase the hydrogen solubility. This important aspect must be considered when qualifying materials for high‐pressure hydrogen applications (e.g., for pipelines or tanks) by using autoclave systems. In this work, a pressure equivalent for compensating the effect of compressive stresses on the hydrogen solubility inside of closed autoclaves is proposed to achieve solubilities that are equivalent to those in pipelines and tanks subjected to tensile stresses. Moreover, it is shown that the temperature effect becomes critical at low temperatures (e.g., under cryogenic conditions for storing liquid hydrogen). Trapping of hydrogen in the microstructure can increase the hydrogen solubility with decreasing temperature, having a solubility minimum at about room temperature. To demonstrate this effect, the generalized law of the hydrogen solubility is parameterized for different steels using measured contents of gaseous hydrogen. The constant parameter sets are verified and critically discussed with respect to the high‐pressure hydrogen experiments. KW - Hydrogen KW - Solubility KW - Temperature KW - Tensile loading KW - Analytical calculation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586701 DO - https://doi.org/10.1002/srin.202300493 SN - 1611-3683 SP - 1 EP - 9 PB - Wiley AN - OPUS4-58670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drexler, A A1 - Konert, Florian A1 - Sobol, Oded A1 - Rhode, Michael A1 - Domitner, J A1 - Sommitsch, C A1 - Böllinghaus, Thomas T1 - Enhanced gaseous hydrogen solubility in ferritic and martensitic steels at low temperatures N2 - Metals that are exposed to high pressure hydrogen gas may undergo detrimental failure by embrittlement. Understanding the mechanisms and driving forces of hydrogen absorption on the surface of metals is crucial for avoiding hydrogen embrittlement. In this study, the effect of stress-enhanced gaseous hydrogen uptake in bulk metals is investigated in detail. For that purpose, a generalized form of Sievert's law is derived from thermodynamic potentials considering the effect of microstructural trapping sites and multiaxial stresses. This new equation is parametrized and verified using experimental data for carbon steels, which were charged under gaseous hydrogen atmosphere at pressures up to 1000 bar. The role of microstructural trapping sites on the parameter identification is critically discussed. KW - Hydrogen KW - Thermodynamic modelling KW - Pressure-dependent solubility KW - Steel KW - Trapping PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559307 DO - https://doi.org/10.1016/j.ijhydene.2022.09.109 SN - 0360-3199 VL - 47 IS - 93 SP - 39639 EP - 39653 PB - Elsevier Ltd. AN - OPUS4-55930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Konert, Florian A1 - Nietzke, Jonathan A1 - Grimault de Freitas, Tomás A1 - Rhode, Michael A1 - Sobol, Oded A1 - Böllinghaus, Thomas T1 - Investigation of resistance to gaseous hydrogen of a longitudinal weld seam in a X65 pipeline using the hollow specimen technique N2 - The constantly increasing demand for renewable energy sources leads to the necessity of transporting large amounts of hydrogen. Since pipelines enable a cost-effective way for the distribution of gaseous hydrogen, the interaction of hydrogen and the pipeline materials must be carefully investigated as hydrogen can cause a degradation of the mechanical properties under certain conditions. Especially welds, which are assumed to be more susceptible to the degradation enhanced by hydrogen, are of great interest. The aim of this study is to investigate the effect of gaseous hydrogen on the mechanical properties of an X65 pipeline, and the longitudinal submerged arc welding (SAW) welded joint. The tests are conducted using the hollow specimen technique on two types of specimens: one extracted from the base material (BM) and the other extracted as a cross-weld (CW) specimen consisting of BM and weld seam. The specimens are charged in situ under a pressure of 60 bar and tested using slow strain rate (SSR) tensile tests with a nominal strain rate of 10−5 s−1. The properties obtained of specimens tested in hydrogen atmosphere are compared to the properties of comparable specimen in inert argon atmosphere as a reference. The performed tests showed a decrease of the reduction of area (RA) from 72% in inert atmosphere to 52% in hydrogen atmosphere for the CW specimen and a decrease from 73% in inert atmosphere to 51% for the BM. Metallographic analyses showed the crack initiation between fine-grained heat-affected zone (FGHAZ) and BM for the specimens tested in hydrogen atmosphere as well as for the reference specimens. This leads to the conclusion that the location of the crack initiation does not change due to the presence of gaseous hydrogen. KW - Hydrogen KW - Hollow specimen technique KW - Pipeline KW - SSRT KW - Hydrogen embrittlement KW - Cross-weld specimen PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624658 DO - https://doi.org/10.1007/s40194-025-01953-3 SN - 0043-2288 SN - 1878-6669 VL - 69 IS - 3 SP - 861 EP - 870 PB - Springer CY - Berlin AN - OPUS4-62465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen in Welded Microstructures of T24 Steel: Effect on Mechanical Properties and Corresponding Hydrogen Diffusion N2 - Low-alloyed CrMoV steels, such as T24, are widely used for welded components in fossil power stations due to their excellent creep-strength. Spectacular failure cases in the recent years exhibited severe cracking in T24 welds. The results showed that hydrogen-assisted cracking (HAC) occurring up to 200 degree Celsius cannot be excluded. Hence, a basic understanding is necessary on how hydrogen affects the material properties of welded microstructures. In this regard, each weld microstructure (HAZ and weld metal) has influence on the HAC susceptibility and respective hydrogen diffusion. Thus, the present contribution summarizes different results obtained from experiments with grades T24 (CrMoV alloy) and T22 (CrMo) and thermally simulated HAZ. Tensile tests were conducted with hydrogen charged specimens and compared to hydrogen-assisted stress corrosion cracking results obtained from slow strain rate tests (SSRT) up to 200 degree Celsius. Electrochemical permeation and degassing experiments were performed to identify a particular weld microstructure influence on hydrogen diffusion and trapping (especially in the HAZ). The results showed that T24 base material has improved resistance to hydrogen-assisted degradation/cracking. In contrast, the as-welded HAZ had remarkably increased susceptibility (tesnile tests at hydrogen concentration of 1 to 2 ppm). SSRT experiments confirmed this at elevated temperatures for both the T24 and the T22. Hence, the evaluation of a particular degradation of the mechanical properties should be performed independently for each weld microstructure. In addition, the HAZ showed decreased diffusion coefficients (at room temperature) of approximately one magnitude compared to the base materials. Trapped hydrogen was determined in the T24 at temperatures up to 120 degree Celsius compared to 75 degree Celsius in the T22. This has to be considered in case of changing operational temperatures, e.g. in the case of start-up and shutdown processes of boiler components. T2 - 10th Conference on Trends in Welding Research CY - Tokyo, Japan DA - 11.10.2016 KW - Degradation of Mechanical Properties KW - Hydrogen KW - Creep-resistant Steel KW - Weld Joint KW - Diffusion PY - 2016 AN - OPUS4-37827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czeskleba, Denis A1 - Rhode, Michael A1 - Wandtke, Karsten A1 - Irfan, Muhammad Dary A1 - Kannengiesser, Thomas T1 - Hydrogen diffusion in thick-walled S690 saw joints: part 1—experimental determination of microstructure-dependent diffusion coefficients N2 - High-strength low-alloyed steel S690 is widely used in heavy-duty applications, such as structural components, mobile cranes, and industrial plant construction, owing to their high strength and weldability. However, thick-plate submerged arc welding (SAW) can introduce elevated hydrogen levels and residual stresses that promote time-delayed hydrogen-assisted cold cracking (HACC). Accurate, microstructure-specific diffusion data are scarce, limiting predictive HACC assessments. This study presents an experimental determination of hydrogen diffusion coefficients (DH) in two S690 variants: thermomechanically rolled (S690MC) and quenched and tempered (S690Q). Multi-layer SAW welds were produced from 30 mm thick plate material at three heat input levels, and diffusion membranes were extracted from weld metal (WM), heat-affected zone (HAZ), and base material (BM). Hydrogen permeation tests, conducted in accordance with DIN En ISO 17081, yielded flux curves normalized in time from which DH was derived using the inflection-point method. At room temperature, DH values ranged from 6 × 10−5 mm2/s to 9 × 10−5 mm2/s across all regions and heat inputs, with no significant difference between S690MC and S690Q. Weld metal exhibited marginally lower DH, attributed to enhanced hydrogen trapping, while base material measurements showed greater variability. These microstructure-resolved diffusion coefficients add quantitative data for modern S690 SAW welds and provide internally consistent input parameters for the numerical simulations presented in part 2. The results support improved parameterization for subsequent assessments of HACC risk through the optimization of welding parameters. KW - Hydrogen assisted cracking KW - Submerged arc welding KW - Diffusion KW - Electrochemical permeation KW - Microstructure PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655711 DO - https://doi.org/10.1007/s40194-026-02400-7 SN - 0043-2288 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-65571 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czeskleba, Denis A1 - Rhode, Michael A1 - Wandtke, Karsten A1 - Irfan, Muhammad Dary A1 - Kannengiesser, Thomas T1 - Hydrogen diffusion in thick-walled S690 SAW joints: part 2 – predictive modeling of heat input and microstructure influence N2 - High-strength low-alloy (HSLA) steels such as S690 are widely employed in thick-walled welded structures, where hydrogen-assisted cold cracking (HACC) remains a persistent concern. While microstructure-specific hydrogen diffusion coefficients (DH) for weld metal (WM), heat-affected zone (HAZ), and base material (BM) were experimentally established in Part 1 of this study, their quantitative influence on hydrogen accumulation and effusion has not yet been fully clarified. This work presents a transient, spatially resolved numerical model for simulating hydrogen transport in multi-pass submerged arc welds. The model integrates experimentally determined DH values with realistic thermal cycles and temperature-dependent boundary conditions. Developed in Python, the simulation tool is purpose-built for hydrogen diffusion in welded joints. It offers a focused, transparent alternative. It offers a focused, transparent alternative to general-purpose finite element platforms. Parametric analyses demonstrate that, although the diffusion coefficients vary by up to 50%, their impact on overall hydrogen retention is minor. In contrast, plate thickness, bead geometry, cooling time (t₈/₅), and interpass temperature exert a dominant influence on hydrogen distribution. Despite clear microstructural differences between the thermomechanically rolled (S690MC) and quenched and tempered (S690Q) variants, including opposite HAZ hardness responses (softening in S690MC, hardening in S690Q) in the (pen)ultimate weld bead, the simulations confirm that their diffusion behavior and hydrogen solubility are closely aligned. Consequently, differences in DH and solubility exert only a minor influence on hydrogen retention compared to thermal exposure and joint geometry. These findings support the interchangeable use of both steel grades in terms of HACC risk due to hydrogen diffusion kinetics under comparable welding conditions. KW - Hydrogen assisted cracking KW - Numerical simulation KW - Diffusion KW - Submerged arc welding PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655721 DO - https://doi.org/10.1007/s40194-026-02395-1 SN - 0043-2288 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-65572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Determination, Assessment and Quantification of Hydrogen in Multi-pass / Multi-layer Weld Joints by Adapted ISO 3690 Samples - DEAQuade - N2 - High-strength, low-alloy (HSLA) structural steels, such as S690 and higher grades, are used in numerous applications, enabling sustainable, lightweight structural construction. However, the welded joints of these steels can be susceptible to hydrogen-assisted cold cracking (HACC), especially in the hardened weld metal (WM) or heat-affected zone (HAZ). HACC in high-strength welds basically involves a critical combination of local, mutually dependent parameters consisting of: (1) a crack-critical microstructure; (2) sufficiently high mechanical stress; and (3) a diffusible hydrogen concentration (HD). In this context, thick-walled steel weld joints typically involve multi-layer welding with several passes. This leads to an effective, empirically known reduction in the global HD in the weld seam. This reduction is due to the repeated reheating of subsequently welded beads or layers, which reduces the local HD in the individual weld beads or layers. However, this has not yet been adequately quantified or described. Bead-on-plate tests, such as ISO 3690, cannot correctly reproduce the local HD distribution in individual welding passes (and thus, the global HD in the entire seam). Therefore, these tests lead to an extremely conservative evaluation of hydrogen ingress and the potential for "self-reduction" of HD due to increased interpass temperature during multi-layer welding, which has not yet been adequately addressed in the literature. Ideally, the local HD in each pass and the global (average) HD of the multi-layer weld would be known immediately after welding. For this reason, the study proposes an approach to address the local, track-, and layer-dependent, as well as global, hardness (HD) of multi-layer welds via a modified ISO 3690 test. To this end, representative welding parameter combinations for selected practical welding processes (e.g., SAW, GMAW, or SMAW) will be carried out as conventional bead-on-plate samples. These samples will be systematically extended by an increasing number of welding passes. Several sample series with an increasing number of beads or layers will be examined. Additionally, the initial HD is varied by methods such as targeted shielding gas variation (e.g., addition of hydrogen in GMAW) or moistened flux/coating (e.g., SAW/SMAW). Based on experimental data (temperature field measurements during welding and determination of temperature-dependent HD coefficients), a numerical hydrogen diffusion model is created. This model calculates the local HD (in the beads) and the HD across the weld cross-section. Additional variation calculations represent heat transfer conditions that were not recorded experimentally and their influence on HD distribution. Finally, we investigate the potential use of the modified ISO 3690 multi-layer geometry for application cases such as (1) predicting the effectiveness and necessity of hydrogen removal heat treatment procedures for given welding parameter sets and (2) extending the HD classification definition (e.g., allowing HD10 use for HSLA steels with RP0.2 > 690 MPa instead of HD5). Finally, an international round robin should be initiated once the concept has been successfully confirmed and verified. T2 - IIW Intermediate Meeting, Com. II-A CY - Bangkok, Thailand DA - 17.03.2026 KW - Hydrogen assisted cracking KW - Multi-pass welding KW - Diffusion KW - Cold cracking test PY - 2026 AN - OPUS4-65716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Praktikable Prüfung der Wasserstoffverteilung in Mehrlagenschweißungen in Anlehnung an die DIN EN ISO 3690 N2 - Das Forschungsvorhaben adressiert eine zentrale Lücke und damit einhergehende Einschränkung für geschweißte hochfeste Werkstoffe in der aktuellen Normung: Die DIN EN ISO 3690 erlaubt ausschließlich die Bestimmung des diffusiblen Wasserstoffs in einlagigen Prüfraupen und bildet damit die realen Bedingungen in mehrlagigen Schweißnähten hochfester Stähle nicht ab. Durch das mehrfache wiederholte Aufwärmen wird die eingebrachte Wasserstoffkonzentration deutlich unter die konservativen, einlagigen Prüfraupen bereits während des Schweißens abgesenkt. Hierzu fehlt jedoch eine einfache, experimentelle Methoden, um die tatsächliche lokale lagenabhängige bzw. globale Wasserstoffverteilung quantifizieren zu können. Das Vorhaben entwickelt daher erstmals eine Versuchsmethodik, der reale Diffusions- und Entgasungsbedingungen von Mehrlagenschweißungen experimentell reproduziert. Dadurch werden die Nachteile der ISO 3690 (einlagige Prüfraupe, konservative Bewertung) aufgehoben und mit dem Hauptvorteil (robuste, einfache Handhabung) kombiniert. Durch gezielte Variation von Wärmeführung, Zwischenlagentemperaturen und Wasserstoffangebot werden lokale und globale Wasserstoffverteilungen quantifiziert. Ergänzt durch ein numerisches Diffusionsmodell entsteht ein skalierbares Bewertungswerkzeug, das die experimentellen Daten generalisiert und auf reale Schweißnähte überträgt. Die Ergebnisse ermöglichen: (1) eine realitätsnahe Bewertung verbleibender Wasserstoffgehalte, Kaltrisssicherheit, damit die (2) die mögliche Ausweitung der HD Klassifizierung hochfester Schweißzusätze, und (3) die Beurteilung der Effektivität und Notwendigkeit von Wärmenachbehandlungs-maßnahmen (wie „Wasserstoffarmglühen“). T2 - Sitzung des NA 092-00-05 GA Gemeinschaftsarbeitsausschuss NAS/NMP: Zerstörende Prüfung von Schweißverbindungen (DVS AG Q 4/Q 4.1) CY - Berlin, Germany DA - 24.03.2026 KW - Schweißen KW - Wasserstoff KW - ISO 3690 KW - Prüfung KW - Mehrlagennaht PY - 2026 AN - OPUS4-65784 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -