TY - CONF A1 - Giese, Marcel A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Local strain behaviour in cross weld tensile specimens of microalloyed high strength steels using digital image correlation N2 - This study specifically examines the role of the microalloying element titanium (Ti) in achieving the desired mechanical properties of quenched and tempered high-strength fine-grain structural steels, with a nominal yield strength of ≥ 690 MPa. Current specifications limit chemical composition only by defining upper thresholds, but even minor variations in Ti content can substantially alter mechanical properties. Consequently, accurate prediction of weldability and welded joint integrity becomes challenging, as variations in Ti lead to distinct microstructural characteristics, potentially causing undesirable softening or hardening effects in the heat-affected zone (HAZ). To address these complexities, two distinct titanium concentrations were systematically investigated for the first time using specially developed laboratory-cast alloys. Both alloying configurations were based on the standard S690QL grade, with consistent chemical composition and heat treatment parameters maintained across the samples. For the weldability analysis, three-layer welds were executed using gas metal arc welding (GMAW), allowing for the identification of critical microstructural zones within the HAZ that exhibit significant softening or hardening. The influence of the softened HAZ region on failure mechanisms was assessed through transverse tensile tests. Digital image correlation (DIC) was employed to capture local strain variations across different HAZ regions in situ. With a custom-developed mirror system, local strains in microstructural zones on both the top and bottom surfaces of the weld were recorded simultaneously. This setup enabled a detailed analysis of how weld seam geometry (e.g., V-groove configuration) influences strain gradients. Additionally, the investigation of localized deformation provided insights into how variations in Ti content within the HAZ affect global strain, fracture constriction, fracture location, and overall fracture behavior. T2 - MPA Seminar 2024 Materials Processes Applications CY - Stuttgart, Germany DA - 08.10.2024 KW - HAZ-Softening KW - Digital Image Correlation KW - Cross weld tensile test PY - 2024 AN - OPUS4-61488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kaiser, Sebastian A1 - Rhode, Michael 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. Particularly important is the decarbonization of heavy industry. Therefore, a reliable supply of hydrogen must be guaranteed. A hydrogen pipeline grid can achieve this purpose. 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. For 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, which in most cases isn’t possible from an economic standpoint. The EIGA 121/14 guideline already pointed out in 2014 that “A hydrogen hot-tap shall not be considered a rou-tine 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 properties, 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 hydrogen uptake due to a large heat input and microstructural changes in the material needs to be considered. Therefore, material degradation must be investigated to determine whether modifications of repair procedures are necessary to ensure a reliable and safe hydrogen transportation via pipelines. 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 weld-ed 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 II-A "Metallurgy of Weld Metals" CY - Ixia, Rhodes Island, Greece DA - 07.07.2024 KW - Hydrogen KW - Pipeline KW - In-Service Welding PY - 2024 AN - OPUS4-60757 LA - eng 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 - Hydrogen trapping in T24 steel weld joints – Microstructure influence vs. experimental design effect on activation energy for diffusion N2 - 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. T2 - Forschungsseminar Fügetechnik des IWF, Otto-von-Guericke-Universität CY - Magdeburg, Germany DA - 25.04.2018 KW - Creep-resisting materials KW - Diffusion KW - Weld metal KW - Hydrogen embrittlement PY - 2018 AN - OPUS4-44879 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Effect of microalloy elements on austenite grain growth and microstructure evolution in simulated heat affected zones of S690QL steel T2 - IIW - Annual Assembly 2014: Meeting of Sub-Comission II-A (Metallurgy iof Weld Metal) CY - Seoul, South Korea DA - 2014-07-14 PY - 2014 AN - OPUS4-31117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Mechanische Eigenschaften von warmfesten Behälterstählen unter Einfluss von Wasserstoff T2 - Sitzung des DIN AG A 4.1 "Wasserstoffunterstützte Rissbildung" und des NA 092-00-05 GA "Gemeinschaftsarbeits-ausschuss NAS/NMP: Zerstörende Prüfung von Schweißverbindungen (DVS AG Q 4)" CY - Magdeburg, Germany DA - 2013-04-11 PY - 2013 AN - OPUS4-28051 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael 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. Particularly important is the decarbonization of heavy industry. Therefore, a reliable supply of hydrogen must be guaranteed. A hydrogen pipeline grid can achieve this purpose. 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. 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, which in most cases isn’t possible from an economic standpoint. 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. Therefore, material degradation must be investigated to determine whether modifications of repair procedures are necessary to ensure a reliable and safe hydrogen transportation via pipelines. 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. The focus hereby lies on possible methods of material testing and modeling. Its current difficulties, limits and possible solution will be discussed. T2 - IIW Intermediate Meeting, Com. II-A CY - Incheon, Republic of Korea DA - 12.03.2024 KW - Hydrogen KW - Repair welding KW - Pipelines KW - In-service PY - 2024 AN - OPUS4-59674 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Combined effect of heating rate and restraint condition on stress relief cracking susceptibility during PWHT of thick-walled Cr-Mo-V steel submerged arc welded joints N2 - Contemporary steels creep-resistant steels like the 13CrMoV9-10 are used as thick plates e.g., for applications in hydrocrackers. The large plate thickness requires high efficiency welding processes like submerged arc welding (SAW) and a mandatory post weld heat treatment (PWHT). The PWHT-parameters stem from a combination of empirical knowledge and traditional experiments on free shrinking (FS) welds. In that connection, the formation of so-called stress-relief cracking (SRC) must be anticipated. The SRC susceptibility of a welded component is a complex combination and interaction of com-ponent specific, thermal, and metallurgical factors. Many of which have to date not been conclusively researched. For example, it is well known that SRCs develop during PWHT due to formation and growth of carbides on prior austenite grain boundaries, resulting in a significant hardness increase (secondary hardening) and toughness decrease. This leads to a high SRC susceptibility of the coarse grain heat-affected zone (CGHAZ) of the last weld bead during PWHT. This is intensified in case of high residual stresses from the component-specific, structurally induced stiffness. In combination with multi-layer welding this leads to a multiaxial stress distribution. Nonetheless, the combined effect of PWHT and high-residual stresses on the SRC formation is merely unknown. For that reason, this study presents the effect of different heating rates in conjunction with a certain component stiffness. For that reason, SAW joints of 13CrMoV9-10 steel were investigated under FS and defined external restraint condition. T2 - IIW Intermediate Meeting, Com. II-A CY - Incheon, Republic of Korea DA - 12.03.2024 KW - Stress relief cracking KW - Welding KW - Post weld heat treatment KW - Submerged arc welding KW - Cr-Mo-V steel KW - Creep-resisting steel PY - 2024 AN - OPUS4-59673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Simulation der Wasserstoffverteilung in UP-geschweißten Grobblechen als Bewertungstool für die Kaltrissanfälligkeit von Offshorestrukturen N2 - Gründungsstrukturen für Offshore-Windkraftanlagen bestehen in der Regel aus hochfesten Stahlgrobblechen, die im UP-Verfahren geschweißt werden, durch den u.U. größere Mengen an Wasserstoff eingebracht werden können. Die große Blechdicke führt zudem zu langen Diffusionswegen und einer verlängerten Diffusionszeit für den Wasserstoff. Infolgedessen kann sich der Wasserstoff in Bereichen mit hoher mechanischer Spannung und Dehnung ansammeln und daher zu einer verzögerten Kaltrissbildung führen. Aufgrund der verzögerten Diffusion muss daher eine Mindestwartezeit von bis zu 48 h eingehalten werden, bevor eine zerstörungsfreie Prüfung durchgeführt wird. Darüber hinaus ist die Beurteilung möglicher Kaltrissstellen sehr komplex. Es wurde daher ein numerisches Modell zur Abbildung einer bauteilähnlichen Schweißnahtprüfung entwickelt. Dazu wurde das Temperaturfeld während des Schweißens und der anschließenden Abkühlung experimentell bestimmt und numerisch simuliert. Auf dieser Grundlage wurde Diffusionsmodell zur numerischen Simulation der zeitlich-örtlichen Wasserstoffkonzentration erstellt. Mit diesem Modell wurden zwei Anwendungsfälle simuliert: (1) Veränderung der Wasserstoffverteilung als Funktion des Temperaturzyklus während des Mehrlagenschweißens und (2) für das Wartezeitintervall ≤ 48 h. Ein Vorteil des Diffusionsmodells ist die Simulation einer normierten Konzentration, d.h. zwischen „0“ (kein Wasserstoff) und „1“ (max. Konzentration), die auf experimentell ermittelte Wasserstoffkonzentrationen skaliert werden kann. T2 - 6. Symposium Materialtechnik CY - Clausthal-Zellerfeld, Germany DA - 20.02.2025 KW - Gründungsstrukturen KW - Offshore KW - Kaltrissbildung KW - Wasserstoff KW - Numerische Simulation PY - 2025 AN - OPUS4-62616 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Fügetechnik für Wasserstofftechnologien: Ausgewählte Themen und Herausforderungen N2 - Die Präsentation fasst die Bedeutung der Fügetechnik für Wasserstofftechnologien im Rahmen der Arbeiten für einer Studie (DVS-Berichte Nr. 373) mit besonderer Berücksichtigung der Normung und Regelwerkssetzung zusammen. T2 - Sitzung des DIN-Gemeinschaftsarbeitsausschusses NA 092 00 05 GA, NAS/NMP: Zerstörende Prüfung von Schweißverbindungen CY - Online meeting DA - 10.03.2022 KW - Wasserstoff KW - Fügetechnik KW - Schweißen KW - Wasserstofftechnologien KW - Bedeutung PY - 2022 AN - OPUS4-54447 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Bewertungsmethode zur Interaktion von Metallurgie und Reaktionskräften beim PWHT warmfester Stähle N2 - Die Präsentation fasst die Entwicklung einer Ersatzprüfmethode für sogenannte Stress-Relief-Cracks (SRC) bei dickwandigen und kriechfesten geschweißten Stahlkomponenten zusammen. Über die Kombination von gezielter mechanischer Beanspruchung unter hoher Temperaturbeanspruchung werden die Effekte des Post Weld Heat Treatments auf SRC realistisch erstmal auf Laborskala nachgebildet. T2 - Sitzung des DIN-Gemeinschaftsarbeitsausschusses NA 092 00 05 GA, NAS/NMP: Zerstörende Prüfung von Schweißverbindungen CY - Online meeting DA - 10.03.2022 KW - PWHT KW - Warmfeste Stähle KW - UP Schweißen KW - Metallurgie KW - Stress relief cracking PY - 2022 AN - OPUS4-54448 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Reliable hydrogen determination in metallic materials and their weld joints: Parameters and challenges N2 - In the course of tomorrow's hydrogen-based energy transition, the construction of the corresponding infrastructure will play a central role. The majority of materials used to date are typically welded for component fabrication. In that context, steels are widely applied and can be prone to hydrogen embrittlement. This includes the classical delayed cold cracking during welding processing as well as embrittlement phenomena during operation. For the evaluation of any hydrogen effect on, for example, the mechanical properties of a welded metallic material, the hydrogen content must be precisely determined. In the case of welds, for example, according to ISO 3690, this is the isothermal carrier gas hot extraction (CGHE). CGHE is based on accelerated hydrogen degassing due to thermal activation of hydrogen at elevated temperatures. In addition to the pure quantification of hydrogen, thermal desorption analysis (TDA) with varied heating rates can be used to determine and evaluate the bonding state at microstructural defects in the material. For both techniques, experimental and measurement influences have to be considered, which have a great effect on the result. For CGHE, for example, ISO 3690 suggests different sample geometries as well as minimum extraction times. The present study summarizes results and experiences of numerous investigations with different sample temperatures and geometries (ISO 3690 type B and cylindrical TDA samples) regarding: the influence of the sample surface (polished/welded), measurement accuracies depending on the sample volume as well as the insufficient monitoring of the effect of the PI controller on the extraction temperature. In particular, a deviating extraction temperature to the set temperature, can significantly falsify the measurement results. Based on the results, methods are shown to quickly reach the desired extraction temperature without having to physically interfere with the measurement equipment. This serves to substantially improve the reliability of hydrogen measurement through increased signal stability and accelerated hydrogen desorption. In general, an independent temperature measurement with dummy samples for the selected heating procedure is advisable to exclude possible unwanted temperature influences already before the measurement. In addition (and way more important), the methods described can be transferred directly to industrial applications. T2 - 47th MPA-Seminar CY - Stuttgart, Germany DA - 10.10.2023 KW - Hydrogen assisted cracking KW - Carrier gas hot extraction KW - Welding KW - ISO 3690 KW - Metals PY - 2023 AN - OPUS4-58677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen trap characterization in 200 and 1,000 bar charged CoCrNi medium entropy alloy compared to steel AISI 316L N2 - Multiple principal element alloys (MPEAs) represent a new class of metallic materials. MPEAs, such as the CoCrNi medium entropy alloy (MEA), have attracted considerable research attention as potential materials to replace, for example, austenitic steels in high-pressure hydrogen environments. Due to the relatively new alloy concept, studies on the specific hydrogen diffusion and trapping behavior of high-pressure hydrogen-charged CoCrNi MEAs are rare so far. For this reason, a CoCrNi-MEA was investigated and compared to an austenitic stainless steel, AISI 316L. Both materials were subjected to high pressure hydrogen loading for two different pressures: 200 bar and 1,000 bar. After charging, thermal desorption analysis (TDA) was used with three heating rates from 0.125 K/s to 0.500 K/s to clarify the specific hydrogen desorption and trapping behavior. To the best of our knowledge, this study is the first to characterize hydrogen diffusion and trapping in 1,000 bar high-pressure charged CoCrNi. For this purpose, the underlying TDA spectra were analyzed in terms of peak deconvolution into a metallurgically justifiable number of defined peaks. The individual peak temperatures and activation energies “EA” were calculated. The following conclusions can be drawn from the results obtained: (1) Exposure to 200 bar or 1,000 bar leads to an increase in hydrogen absorption, regardless of the material investigated, expressed by a significantly increased desorption rate at 1,000 bar. However, the effusion peaks typically occur only at high temperatures. The (2) TDA showed that a four-peak deconvolution scenario was sufficient to describe the trapping behavior and the "EA" indicated the dominance of irreversible traps. In addition, the average trapping energy is higher than in the 316L. The (3) charge pressure related hydrogen solubility was in the order of: CoCrNi-MEA < 316L for both pressures and (4) charging at 1000 bar results in an average concentration of 49 wt.ppm (CoCrNi-MEA) and > 75 wt.ppm (316L). In summary, the CoCrNi-MEA was characterized by a reduced solubility, but very deep entrapment compared to the 316L. For this reason, further application potentials of the MEA may arise. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - Medium entropy alloy KW - Hydrogen KW - Trapping KW - Diffusion KW - High-pressure charging PY - 2025 AN - OPUS4-64160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Effect of Ti and Nb on hydrogen trapping in welded S690 HSLA steel and effect on delayed cold cracking 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. Of course, a closer look at the heat-affected zone (HAZ) or the weld metal of the specific welds is necessary. However, especially in the case of thick-walled welds, it is assumed that the weld metal and HAZ are similar to the base material due to the multi-layer welding, which results in multiple annealing cycles of the weld metal and HAZ. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - Hydrogen assisted cracking KW - HSLA KW - Diffusion KW - Electrochemical permeation PY - 2025 AN - OPUS4-64156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Component test for the assessment of in-service welding on/onto pressurized hydrogen pipelines N2 - Hydrogen is the energy carrier of tomorrow and requires a reliable large-scale transport infrastructure. In addition to new pipelines, the conversion of existing natural gas (NG) pipeline grids is an essential part. The transport of hydrogen is fundamentally different from that of NG, as hydrogen can be absorbed into the pipeline material. Given the effects of hydrogen embrittlement, the material compatibility (low alloy steels in a wide range of strengths and thicknesses) must be investigated. However, pipelines e.g. require maintenance or the need for installation of additional outlets with the necessity of welding on/onto the pipelines while they are still in service, i.e. with gas flow under high pressure, such as the well-known "hot tapping". This in-service welding poses challenges for hydrogen operations. The challenge can be roughly divided into the possible austenitization of the inner pipe material exposed to hydrogen, the welding itself, which causes an increased temperature range. Both lead to a significant increase in hydrogen solubility and diffusivity compared to room temperature. In addition, possible surface reactions of the present iron oxides (e.g. magnetite or hematite) with the hot hydrogen should be considered. In this context, the knowledge of hydrogen pipelines is scarce due to the lack of operational experience. Fundamental experimental investigations are required to investigate the transferability from NG to hydrogen pipeline grids. For this reason, the present study presents a specially designed mock-up / demonstrator concept for the realistic assessment of the welding process conditions. The mock-up was designed to allow in-situ temperature measurement during the welding process as well as ex-post sample extraction for quantification of the absorbed hydrogen concentration. For safety reasons, the required volume of pressurized hydrogen was limited by inserting a solid cylinder to ensure a 1 cm thick layer of hydrogen gas. Welding experiments on the DN60 and DN200 pressurized mock-ups showed the possibility of safe welding on or onto pressurized hydrogen pipelines. Indeed, the austenitizing temperature was reached on the inner surface of the pipeline, especially on thinner-walled pipelines, using current welding parameter recommendations. This corresponded to an increased hydrogen uptake in the welded area of several ppm. From this point of view, the suggested component concept is a viable strategy for the screening of several materials and welding parameter combinations under realistic operational conditions. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - In-service welding KW - Pipeline KW - Hydrogen KW - Component test PY - 2025 AN - OPUS4-64159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Combined effect of heating rate and restraint condition on stress relief cracking susceptibility during PWHT of thick walled Cr Mo V steel submerged arc welded joints N2 - Contemporary steels creep-resistant steels like the 13CrMoV9-10 are used as thick plates e.g., for applications in hydrocrackers. The large plate thickness requires high efficiency welding processes like submerged arc welding (SAW) and a mandatory post weld heat treatment (PWHT). The PWHT-parameters stem from a combination of empirical knowledge and traditional experiments on free shrinking (FS) welds. In that connection, the formation of so-called stress-relief cracking (SRC) must be anticipated. The SRC susceptibility of a welded component is a complex combination and interaction of com-ponent specific, thermal, and metallurgical factors. Many of which have to date not been conclusively researched. For example, it is well known that SRCs develop during PWHT due to formation and growth of carbides on prior austenite grain boundaries, resulting in a significant hardness increase (secondary hardening) and toughness decrease. This leads to a high SRC susceptibility of the coarse grain heat-affected zone (CGHAZ) of the last weld bead during PWHT. This is intensified in case of high residual stresses from the component-specific, structurally induced stiffness. In combination with multi-layer welding this leads to a multiaxial stress distribution. Nonetheless, the combined effect of PWHT and high-residual stresses on the SRC formation is merely unknown. For that reason, this study presents the effect of different heating rates in conjunction with a certain component stiffness. For that reason, SAW joints of 13CrMoV9-10 steel were investigated under FS and defined external restraint condition. T2 - 77th IIW Annual Assembly and International Conference, Meeting of Commission II-A CY - Ixia, Rhodes, Greece DA - 07.07.2024 KW - Stress relief cracking KW - Submerged arc welding KW - Post weld heat treatment KW - Cr-Mo-V steel PY - 2024 AN - OPUS4-60675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Joining technologies for hydrogen components: current need and future perspectives N2 - The study provides an overview of the aspects of joining and its importance in manufacturing of components for the more and more important field of hydrogen as key factor for the energy transition to a decarburized future. To this end, the fundamentals of the technology fields of hydrogen production, storage, transport, and application are presented and the state of the art of manufacturing of components for hydrogen technologies by joining is summarized. Based on representative examples from practice, research and development, the importance of joining technology in hydrogen technologies is clearly highlighted and perspectives for the future are derived. From a macroeconomic perspective, the focal points, or trends of joining technologies here include: the erection of new infrastructure for hydrogen storage and transport, and the safe conversion of existing natural gas infrastructure and its challenges for welded materials. In addition, we show the problems that are anticipated with in-service repair welding of hydrogen pipelines. In hydrogen applications, the efficient mass production of fuel cells and electrolysers is becoming increasingly important. For that reason, the importance of additive manufacturing is highlighted. Finally, the challenges for technical regulations and standardization by using hydrogen are shown. T2 - AJP 2023: 3rd International Conference on Advanced Joining Processes 2023 CY - Braga, Portugal DA - 19.10.2023 KW - Hydrogen KW - Infractstructure KW - Joining KW - Welding KW - Research PY - 2023 AN - OPUS4-58674 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Quantitative Bestimmung von Wasserstoff durch Heißgasextraktion: Erfahrungen und Grenzen N2 - Die Trägergas-Heißextraktion (TGHE) mit Warmauslagerung (d.h. ohne Schmelzen der Proben) ist eine häufig angewandte Technik zur Bestimmung von Wasserstoff, u.a. für Schweißverbindungen aber auch allgemein für Metalle geeignet. Die TGHE basiert auf der beschleunigten Wasserstoffausgasung aufgrund der thermischen Aktivierung bei erhöhten Temperaturen. Die Norm ISO 3690 schlägt hierzu verschiedene Probengeometrien sowie die erforderliche Mindestextraktionszeit in Abhängigkeit der Temperatur vor. Die vorliegende Präsentation fasst die Ergebnisse und Erfahrungen zahlreicher Testläufe an der BAM der letzten 15 Jahre mit unterschiedlichen Probentemperaturen, Geometrien, etc. zusammen, die die Wasserstoffbestimmung beeinflussen können. Dabei handelt es sich insbesondere um die Bewertung des Absorptionskoeffizienten für Infrarotstrahlung der Probenoberfläche, die begrenzte Empfindlichkeit von WLD im Vergleich zum MS, die Temperaturmessung, u.v.m. Zusammenfassend lässt sich sagen, dass die Temperatur die treibende Kraft der TGHE ist. Es werden Vorschläge zur Verbesserung der Zuverlässigkeit der Wasserstoffbestimmung gemacht, die von der Stabilität des Wasserstoffsignals während der Extraktion und der Auswertung der aufgezeichneten Daten abhängt. Im Allgemeinen ist eine unabhängige Temperaturmessung mit Dummy-Proben für die weitere Datenanalyse nützlich, insbesondere wenn diese Daten für die Berechnung der Einfangkinetik verwendet werden. T2 - Herbstsitzung des DGM Arbeitskreises "Materialprüfung unter Wasserstoff" CY - Dortmund, Germany DA - 19.11.2024 KW - Wasserstoff KW - Trägergasheißextraktion KW - Messung KW - Massenspektrometrie KW - Schweißen PY - 2024 AN - OPUS4-61721 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Evaluation of local strain behavior of cross-weld tensile specimens of micro-alloyed high-strength steels by digital image correlation N2 - Microalloying elements such as Nb and Ti play a decisive function in achieving the desired mechanical strength of quenched and tempered, high-strength fine-grain structural steels with a nominal yield strength ≥ 690 MPa. The current specifications for the chemical composition only provide manufacturers with upper limits. However, even minor deviations in the alloy concept can have a significant impact on the mechanical properties. Consequently, accurate prediction of weldability and the integrity of welded joints becomes difficult or even impossible due to differences in composition and the resulting microstructures. Undesirable consequences include a possible softening of the heat-affected zone (HAZ) or, conversely, hardening effects. In view of these challenges, various microalloying strategies with different Ti and Nb contents are being systematically investigated for the first time using specially developed laboratory casting alloys. Each alloying route is based on the common S690QL, maintaining both the chemical composition and the heat treatment parameters. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the heat-affected zone (HAZ) that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using transverse tensile specimens. Digital image correlation (DIC) is used to image changes in local strains in different HAZ regions in situ. Using a specially developed mirror system, the local strains of the microstructure zones on the top and bottom of the weld are recorded simultaneously. This makes it possible to analyse how the weld seam geometry (e.g., V-seam) influences the strain gradients. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the fracture constriction, the fracture position, and the overall fracture behavior. T2 - IIW Intermediate Meeting, Com. II-A CY - Incheon, Republic of Korea DA - 12.03.2024 KW - Welding KW - High-strength steel KW - Alloy concept KW - Cross-weld tensile sample KW - Mechanical properties PY - 2024 AN - OPUS4-59675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Welding of in service hydrogen pipelines for repair and maintenance purposes Concepts and Challenges N2 - Hydrogen will make a decisive contribution to a sustainable large-scale energy supply, the transport of which will be based on long-distance pipeline grids. Previous material compatibility studies have shown that the currently used low-alloy pipe steels are generally suitable for hydrogen pipelines. However, this cannot be directly transferred to the case of repair welding. For technical and economic reasons, welding work on hydrogen pipelines in service is usually carried out during operation under continuous pressure and gas flow. In this context, concepts such as hot tapping and stoppling are well established in natural gas (NG) grids and crude oil transportation. In hot tapping, a pressurized pipeline is drilled by flanging a sealed, pressure-tight system consisting of a shut-off valve and drilling equipment. For this purpose, sleeves (made of preformed cylindrical half-shells) must be welded by longitudinal seams and then welded to the product-carrying pipeline by circumferential girth welds. Preheat temperatures of approximately 100 °C must be maintained for most manual metal arc (MMA) / shielded metal arc welding (SMAW) and 250 °C for the interpass temperature in multi-pass welding. This is particularly important for thin-walled pipelines because the austenitizing temperature is exceeded on the inside of the pipeline when the girth welds are welded. As a result, significantly higher hydrogen absorption in the pipeline steel is expected, with possible degradation of mechanical properties or cracking. T2 - MSE 2024: International Materials Science and Engineering Congress CY - Darmstadt, Germany DA - 24.09.2024 KW - Hydrogen KW - Repair welding KW - Pipelines KW - In-service PY - 2024 AN - OPUS4-61155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Strom ohne Ende? Herausforderungen für die Fügetechnik im Zuge der Energieerzeugung im 21. Jahrhundert N2 - Die Energiewirtschaft ist bereits jetzt in massivem Umbruch. Herausforderungen der Energiewende sind u.a. die Einbindung von regenerativen Energiequellen und deren Speicherung. Dieses stellt auch die Fügetechnik, als zentrale Produktionstechnologie für die Komponentenfertigung, vor neue Aufgaben. Der Vortrag gibt zu ausgewählten Themen einen kurzen Überblick. T2 - Vortragsreihe des DVS Bezirksverbandes Berlin CY - Berlin, Germany DA - 31.10.2018 KW - Fügetechnik KW - Energieerzeugung KW - Schweißen KW - Komponenten PY - 2018 AN - OPUS4-46483 LA - deu 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 Annual Assembly, Meeting of Commission IX-C CY - Online meeting DA - 15.07.2021 KW - Creep-resistant steel KW - Diffusion KW - Electrochemical permeation KW - Hydrogen KW - Welding PY - 2021 AN - OPUS4-53048 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen embrittlement of steels N2 - Hydrogen assisted cracking of metals is a serious issue in the safety of components, espcially in case of welding. The current presentation gives an overview on specialized testing procedures at Department 9 including the quantitative determination of hydrogen. T2 - HYDROGENIUS BAM Joint Hydrogen Symposium CY - Online meeting DA - 06.07.2021 KW - Hydrogen KW - Embrittlement KW - Degradation KW - Carrier gas hot extraction KW - Welding PY - 2021 AN - OPUS4-53049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Kurzvorstellung des DVGW-geförderten Projektes “H2SuD” - Einfluss des Schweißens auf die Wasserstoffaufnahme und Degradation im Betrieb befindlicher H2-Gasleitungen N2 - Die Wasserstoffinfrastruktur ist eine zentraler Bestandteil der erfolgreichen Umsetzung der wasserstoffbasierten Energiewende. Dabei bilden Ferngasleitungen quasi das "Rückgrat" der Transportinfrastruktur großer Gasmengen. Dabei müssen unter Umständen Reparaturen an den Pipelines durchgeführt werden. Dabei ist in der Erdgasinfrastruktur das Schweißen an in Betrieb befindlichen (d.h. von Gas durchflossenen) Pipelines Stand der Technik. Es ist jedoch vollkommen offen, inwieweit diese Technik auf die reine Wasserstoffpipelines übertragbar sind. Hierzu leistet das Projekt H2SuD wichtige Beiträge zur Aufklärung des Einfluss eines Reparaturschweißprozesses auf die Wasserstoffaufnahme und Degradation im Betrieb befindlicher H2 Gasleitungen. T2 - Sitzung des Unterarbeitskreises / UAK 2.1.1 "Rohrleitungen" im Rahmen der Normungsroadmap Wasserstofftechnologien CY - Online meeting DA - 16.06.2023 KW - Wasserstoff KW - Schweißen KW - Pipeline KW - Reparatur KW - Prüfverfahren PY - 2023 AN - OPUS4-57714 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffabhängige mechanische Eigenschaften der Schweißnahtgefüge niedriglegierter Stähle für Ferngasleitungen N2 - Der Vortrag stellt aktuelle Ergebnisse des Fosta-Forschungsprojektes P1668 vor. Ziel ist hier, die Wasserstoffresistenz geschweißter Mikrostrukturen gängiger und neuer Pipeline-Stählen zu untersuchen. Im Fokus stehen hierbei durch physikalische Simulation nachgebildete, schweißnahtähnliche Mikrostrukturen in Form von (1) Wärmeeinflusszonen mit unterschiedlicher Abkühlgeschwindigkeit und (2) angelassene Zonen zur Simulation der typischen Mehrlagenschweißungen. Aus diesen repräsentativen Mikrostrukturen werden Zugproben extrahiert welche elektrochemisch oder mit Druckwasserstoff beladen werden. Aus diesen wird dann eine Datenbasis der spezifischen mechanische Eigenschaften unter Wasserstoff bereitgestellt. Die so entwickelte, praxisorientierte Prüfstrategie ermöglicht die schnelle und zuverlässige Bewertung sowohl in Betrieb befindlicher als auch neuer Rohrleitungswerkstoffe. T2 - Herbstsitzung des DGM Arbeitskreises "Materialprüfung unter Wasserstoff" CY - Dortmund, Germany DA - 19.11.2024 KW - Wasserstoff KW - Pipeline KW - Mechanische Kennwerte KW - Schweißen KW - Prüfung PY - 2024 AN - OPUS4-61750 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Standardization and examples for R & D activities on hydrogen technologies with respect to testing procedures in Germany N2 - This contribution briefly summarizes the standardization activities in accordance with the "Nationale Roadmap Wasserstofftechnologien" and presents selected results on the activities in Germany with scope on hydrogen transport in pipelines. The talk was given during a panel discussion to set-up a steering committee for standardization for hydrogen pipelines and welding , coordinated by the International Institute of Welding. T2 - IIW Annual Assembly, Meeting of Commission XI CY - Singapore DA - 19.07.2023 KW - Hydrogen KW - Welding KW - Pipelines KW - Standardization KW - Research PY - 2023 AN - OPUS4-57976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Intended weld repair of in service hydrogen pipelines N2 - In the course of tomorrow's hydrogen-based energy transition, the construction of the corresponding infrastructure will play a central role. In that context, large diameter long-distance transmission pipelines for hydrogen will be the backbone in the European Union with service pressures from 70 to 90 bar (e.g., de-pending on national regulations). It is a major goal to repurposing the existing natural gas (NG) infrastructure despite the necessity of new pipelines. From that point of view repair welding or further welding of branch pipe etc. can be necessary during in-service, i.e., permanent flow of pressurized hydrogen. The reason is that a shut-down of large diameter pipelines is not easy or sometimes merely impossible. At the moment, it is entirely open if current repair welding procedures for NG pipe-lines can be transferred to pure hydrogen pipelines. For that reason, a collaborative project between BAM, DVGW (German Association for Gas and Water Professions) and a large number of gas grid operators, pipeline manufacturers and construction companies was initiated in 2023 to answer questions on: (1) How many hydrogen is additionally absorbed during the preheating and maintaining at interpass temperature under remaining operational pressures? (2) Is the hydrogen concentration sufficient to reach a critical condition? (3)Which material and weld microstructure are the most susceptible? (4) Is there a difference in the repair welding behavior of NG pipelines with materials in “used” condition? (5) Which welding parameters and joint dimensions must be ensured for safe repair welding? The final aim of this project is the publication of a recommended practice for repair welding of in-service hydrogen pipelines. For that reason, the present study gives an overview on: (A) current practice in repair welding of in-service pipelines and (b) plans for hydrogen pipelines and first results of international research projects. T2 - IIW Annual Assembly, Meeting of Commission XI CY - Singapore DA - 19.07.2023 KW - Hydrogen KW - Repair Welding KW - Pipelines KW - Research PY - 2023 AN - OPUS4-57975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Unter Druck gesetzt: Die unterschätzte Bedeutung des In-Service-Schweißen für die Wasserstoffinfrastruktur der Zukunft N2 - Wasserstoff leistet als Energieträger der Zukunft einen entscheidenden Beitrag zur nachhaltigen Energieversorgung. Der Transport wird vorwiegend durch das europäische Ferngasleitungsnetz erfolgen. Bisherige Untersuchungen zeigen, dass bisher verwendete Rohrstähle grundsätzlich für den Wasserstofftransport geeignet sind. Diese Eignung ist nicht direkt auf Reparaturfragestellungen im Betrieb übertragbar, da Schweißungen aus technisch-ökonomischen Gründen oft unter fortwährendem Gasfluss durchgeführt werden. Ein im Erdgasnetz angewandtes Konzept ist das Anbohren druckführender Pipelines („Hot Tapping“). Dazu werden Zylinderhalbschalen zuerst durch Längs- und dann per Rohrrundnähten an die Pipeline geschweißt. Essenziell ist dabei die maßgeschneiderte Wärmeeinbringung, um das „Durchbrennen“ in die Pipeline zu vermeiden. Für zukünftige Wasserstoffpipelines liegt der Fokus u.a. auf dünnwandigen Leitungen. Im Gegensatz zu Erdgas, führen die beim Schweißen erreichten hohen Temperaturen an der Innenseite der Pipeline zu einer zusätzlichen Wasserstoffaufnahme in den Rohrstahl mit möglicher Materialdegradation. Zur praktischen Lösung der Fragestellung, sind internationale Aktivitäten im Gang. Diese umfassen bspw. die Möglichkeiten und Weiterentwicklung von realistischen Prüfkonzepten (u.a. durch maßstäbliche Bauteilversuche). Dazu untersucht die Bundesanstalt für Materialforschung und -prüfung (BAM) in einem DVGW-geförderten Kooperationsprojekt zusammen mit den grossen Gasnetzbetreibern, die Frage der Übertragbarkeit der Schweißkonzepte der Erdgastechnik auf zukünftiger Wasserstoffpipelines. T2 - Herbstsitzung des DGM Arbeitskreises "Materialprüfung unter Wasserstoff" CY - Dortmund, Germany DA - 19.11.2024 KW - Wasserstoff KW - Pipeline KW - Reparaturschweißen KW - Komponententest PY - 2024 AN - OPUS4-61723 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Large scale hydrogen assisted cracking test for thick walled SAW joints for offshore applications N2 - Offshore wind turbines continuously increase in size and weight and demand adequate offshore foundations concepts like monopiles, tripods or jackets. These components are typically submerged arc welded (SAW) high-strength thick steel plates like the S420ML. During welding, the occurrence of delayed hydrogen assisted cracking (HAC) must be anticipated. HAC is a critical combination of the local hydrogen concentration within a susceptible microstructure under certain mechanical load, i.e., the occurring (welding) residual stresses. The welding sequence of the thick-walled plates complicate the residual stress distribution due to the necessary repeated thermal cycling, i.e., welding seam / layer deposition to fill the joint. For that purpose, SAW with two-wire-technique was used to weld a specially designed and prototype-like mock-up of a real component with a thickness of 50 mm, filled with 22 passes and a seam length of 1,000 mm. Additional welded stiffeners simu-lated the effect of a high restraint, to stimulate critical HAC conditions. The necessity of a minimum waiting time (MWT) before the NDT can be conducted (to exclude HAC) was critically verified by the application of ultrasonic testing of the welded joint at different time-steps of the NDT of 48 h after welding. The residual stresses were determined by a robot XRD goniometer. Tensile residual stresses up to the yield limit are found both in the weld metal and in the heat-affected zone. Numerical modelling allowed the qualitative estimation of the hydrogen diffusion in the weld. A remarkable HAC occurrence was not identified and proves both, a certain resistance of the weld joint to HAC and the (questionable) duration of the MWT. T2 - IIW Annual Assembly, Meeting of Commission II-C CY - Singapore DA - 19.07.2023 KW - Mock-up KW - Hydrogen assisted cracking KW - Submerged arc welding KW - Offshore KW - Steel PY - 2023 AN - OPUS4-57977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffunterstützte Kaltrissbildung in Schweißnähten hochfester Stahlgüten - Anforderungen an die Prüfung N2 - Die Vortrag gibt einen Überblick, warum Kaltrissprüfung von geschweißten Stählen ständig weiterentwickelt werden muss. Am Beispiel des Implant- und Tekken-Tests werden die Einsatz- u. Anwendungsgrenzen bewertet. Zu berücksichtigen ist, dass beim Schweißen eine äußere mechan. Beanspruchung durch bauteilspezifische Steifigkeitsverhältnisse wirksam ist. Zusätzlich werden weiterführende Prüfverfahren zur Bestimmung der Wasserstoffkonzentration und -diffusion in Schweißnähten vorgestellt, wie die Trägergasheißextraktion (TGHE) für die Ermittlung der Wasserstoffkonzentration (ISO 3690) oder Hochtemperaturdiffusionskoeffizienten. Diese Werte sind für die schweißtechnische Praxis von großer Bedeutung, um Haltezeiten z.B. für das Wasserstoffarmglühen abzuleiten. T2 - Tagung Werkstoffprüfung 2021 CY - Online meeting DA - 02.12.2021 KW - Wasserstoff KW - Kaltrissprüfung KW - Schweißen KW - Stahl KW - Hochfest PY - 2021 AN - OPUS4-53902 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Adaption of Heat Control Concepts for Welding Stress Optimization in High-strength Steel Components N2 - High-strength structural steels from 690 MPa are increasingly applied at present. Major reasons are lightweight design trends and potential cost reductions. The structural design of welds and their manufacturing become more challenging with increasing material strength. By reasons of a higher yield ratio of these steels, the development of high residual stresses has to be avoided, since they are detrimental to the components safety and performance. Local restraint stresses and welding loads due to external shrinkage restraints occur. Frequently, this leads to critical tensile residual stresses in the weld and HAZ. In this study, influences of welding process parameters and restraint conditions on the residual stress state in welded components of high-strength steels were investigated. Multilayer GMAW tests under free shrinkage and experiments under well-defined restraints in special in-house developed testing facilities were accomplished. The tests permitted analyses of the resulting local residual stresses measured by means of X-ray diffraction and global reaction stress build-up while welding and cooling. Significant effects were found for heat control, seam configuration and restraint condition. Besides high restraints, elevated preheating and interpass temperatures lead to increased welding stresses. An adaption of welding parameters considering heat control, weld run sequence and seam configuration proved to be beneficial. T2 - 10th Conference on Trends in Welding Research CY - Tokyo, Japan DA - 11.10.2016 KW - Weld heat input KW - Residual Stress KW - High-strength Steel KW - Welding KW - Component Test PY - 2016 AN - OPUS4-37828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Trapping in T24 steel weld joints – Effects on activation energy for hydrogen diffusion during TDA N2 - Failure cases in the past decade exhibited severe cracking in T24 welds and showed that generally hydrogen-assisted cracking (HAC) occurring up to 200°C cannot be excluded. A basic understanding is necessary on how hydrogen diffusion is influenced by the weld process. In this regard, both weld microstructures HAZ and weld metal have particular influence on hydrogen diffusion compared to the base material. In general, hydrogen diffusion at a certain temperature is described by diffusion coefficients representing an effective value of combined lattice diffusion and effects of reversible hydrogen traps. Those traps are typically precipitates, interstitials, grain boundaries and so on. A common approach to describe the trap character and its effect on diffusion is the determination of so-called activation energy. This can be done by respective thermal desorption analysis (TDA) with linear heating. In the present study, different T24 as-welded microstructures (BM, HAZ, WM) were investigated. For that purpose, electrochemically hydrogen charged specimens were analyzed by TDA with linear heating using a mass spectrometer for detection of ultra-low hydrogen amounts. The results showed that typically the as-welded HAZ had higher energy traps than the tempered base material. Nonetheless two important effects were ascertained: (1) it is strictly necessary to monitor the sample temperature due to its great impact on the hydrogen desorption peak temperature and (2) the real heating rate in the specimen vs. the applied heating rate has to be considered. Both influence the calculated activation energy, i.e. the assigned hydrogen trap character (moderate or strong trap), which changed up to a factor of two in terms of the calculated activation energy. This effect can be much more important compared to the microstructure effect itself. Hence, suitable experimental boundary conditions should be mandatory for the determination of hydrogen trap kinetics. T2 - Intermediate Meeting of IIW Commission C-II-A "Metallurgy of Weld Metal" CY - Trollhättan, Sweden DA - 06.03.2017 KW - Hydrogen KW - Trapping and diffusion KW - Thermal desorption analysis KW - Microstructure KW - Activation energy PY - 2017 AN - OPUS4-39401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen trapping in T24 steel weld joints - microstructure influence vs. experimental design effect on activation energy for diffusion N2 - In general, hydrogen assisted cracking is a result of a critical combination of local microstructure, mechanical load and hydrogen concentration. In that connection, welded microstructures of low-alloyed creep-resistant steels can show different hydrogen trapping kinetics. That influences the adsorbed hydrogen concentration as well as the diffusion itself in terms of moderate or strong trapping. A common approach to describe trapping is by the activation energy that is necessary to release hydrogen from a specific trap site. In the present study, T24 base material and weld metal were investigated. For that purpose, electrochemically hydrogen charged specimens were analyzed by thermal desorption analysis(TDA) with linear heating using a mass spectrometer. The results showed a microstructure effect on hydrogen trapping kinetics at elevated temperatures. Additionally, it is necessary to monitor the specimen temperature. A comparison between idealized temperature profile and real specimen temperature showed that the calculated activation energy varied up to a factor of two. Thus, the assigned trap character(moderate or strong) changed. In case of high temperature peaks, this effect could be more important compared to the microstructure effect itself. T2 - 70th IIW Annual Assembly, Commission II-A CY - Shanghai, People's Republic of China DA - 25.06.2017 KW - Creep resisting materials KW - Welding KW - Hydrogen diffusion KW - Thermal desorption analysis KW - Microstructure KW - Experimental design PY - 2017 AN - OPUS4-40954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffdiffusion und mechanische Eigenschaften in der thermisch simulierten WEZ (Wärmeeinflusszone) eines Druckbehälterstahls T2 - MDDK Magdeburg CY - Magdeburg, Germany DA - 2013-11-14 PY - 2013 AN - OPUS4-29601 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen effect on degradation of mechanical properties in T24 weld metal and simulated coarse grained HAZ T2 - IIW - Annual Assembly 2014: Joint meeting of Commission II, IX and XI CY - Seoul, South Korea DA - 2014-07-14 PY - 2014 AN - OPUS4-31118 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Effect of hydrogen on the mechancial properties of the simulated HAZ of a reactor pressure vessel steel grade (SA508CI.3) T2 - IIW Intermediate Meeting 2015, Commission II-A CY - Istanbul, Turkey DA - 2015-03-02 PY - 2015 AN - OPUS4-32757 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - HAZ softening behavior in Ti- and Nb-containing quenched and tempered high strength steels T2 - IIW Intermediate Meeting 2015, Commission II-A CY - Istanbul, Turkey DA - 2015-03-02 PY - 2015 AN - OPUS4-32756 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Experimental determination and investigation of thermal fields and residual stresses in weld joints during and after welding T2 - Kick-off Meeting: "New resistance model for high strength steels I-shape and box sections based on experimental investigations and numerical simulation" CY - Warsaw, Poland DA - 2015-01-16 PY - 2015 AN - OPUS4-32817 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen diffusivity in low alloyed steels - Experimental determination with mass spectrometry and application of data in numerical analysis T2 - Bruker Elementals - International Sales Meeting 2015 CY - Düsseldorf, Germany DA - 2015-06-15 PY - 2015 AN - OPUS4-33477 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Effect of hydrogen on the mechanical properties of simulated HAZ microstructures of a RPV (reactor pressure vessel) steel grade T2 - IIW Annual Assembly 2015, Commission II-A CY - Helsinki, Finland DA - 2015-06-29 PY - 2015 AN - OPUS4-33677 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - HAZ softening in Nb-, Ti- and Ti+V-bearing quenched and tempered high strength steel welds T2 - IIW Annual Assembly 2015, Commission II-A CY - Helsinki, Finland DA - 2015-06-29 PY - 2015 AN - OPUS4-33676 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Zuverlässige Wasserstoffbestimmung in Metallen und ihren Schweißverbindungen: Parameter, Einflüsse, Grenzen N2 - Im Zuge der wasserstoffbasierten Energiewirtschaft von morgen, kommt der Errichtung der dementsprechenden Infrastruktur die zentrale Rolle zu. Der überwiegende Teil bisher eingesetzter und meist geschweißter Werkstoffe, wie Stähle, kann unter bestimmten Bedingungen zur Wasserstoffversprödung neigen. Dies umfasst die klassische verzögerte Kaltrissbildung während der Schweißverarbeitung als auch Versprödungsphänomene während des Betriebs. Für die Bewertung eines jeden Wasserstoffeffektes auf bspw. die mechanischen Eigenschaften eines geschweißten metallischen Werkstoffes, muss der Wasserstoffgehalt präzise bestimmt werden, Im Fall von Schweißnähten ist die beispielsweise nach der ISO 3690, die klassische isotherme Trägergas-Heißextraktion (TGHE). Die TGHE basiert dabei auf der beschleunigten Wasserstoffentgasung aufgrund der thermischen Aktivierung des Wasserstoffs bei erhöhten Temperaturen. Neben der reinen Quantifizierung des Wasserstoffs, kann über die thermische Desorptionsanalyse (TDA) mit variierten Heizraten, der Bindungszustand an mikrostrukturellen Defekten im Material festgestellt und bewertet werden. Für beide Techniken sind experimentelle und messtechnische Einflüsse zu beachten, die großen Effekt auf das Ergebnis haben. Für die TGHE schlägt die ISO 3690 schlägt beispielswiese verschiedene Probengeometrien sowie Mindestextraktionszeiten vor. Die vorliegende Studie fasst Ergebnisse und Erfahrungen zahlreicher Untersuchungen an der Bundesanstalt für Materialforschung und -prüfung (BAM) mit unterschiedlichen Probentemperaturen und Geometrien (ISO 3690 Typ B und zylindrische TDA-Proben) zusammen hinsichtlich: Einfluss der Probenoberfläche (poliert/geschweißt), Messgenauigkeiten in Abhängigkeit des Probenvolumens sowie die unzureichende Überwachung des Effektes des PI-Reglers auf die Extraktionstemperatur. Insbesondere eine abweichende Extraktionstemperatur zur eingestellten Temperatur, kann die Messergebnisse wesentlich verfälschen. Basierend auf den Ergebnissen werden Methoden aufgezeigt, um schnell die gewünschte Extraktionstemperatur zu erreichen, ohne physisch in das Messequipment eingreifen zu müssen. Dies dient der wesentlichen Verbesserung der Zuverlässigkeit der Wasserstoffmessung durch erhöhte Signalstabilität und beschleunigte Wasserstoffdesorption. Im Allgemeinen ist eine unabhängige Temperaturmessung mit Dummy-Proben für die gewählte Heizprozedur angeraten, um mögliche unerwünschte Temperatureinflüsse bereits vor der Messung auszuschließen. Die beschriebenen Methoden können ohne großen Aufwand direkt in die industrielle Anwendung überführt werden. T2 - DVS Congress 2023 CY - Essen, Germany DA - 11.09.2023 KW - Wasserstoff KW - Messung KW - Trägergasheißextraktion KW - ISO 3690 KW - Schweißverbindung PY - 2023 AN - OPUS4-58307 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Thermal desoprtion analysis of hydrogen trapping in micro-alloyed high strength steels N2 - Hydrogen can cause unexpected material failure under consideration of stresses (external/internal) during manufacturing, processing or service of the materials. This failure is mostly based on a certain degradation of the mechanical properties. Thus, the correlation of hydrogen trapping vs. a respective microstructure is necessary for high strength steels. Thus, the scope of this work is the improvement of existing hydrogen trap models by verification of activation energies for hydrogen traps as well as the influence of the determination method. In this scope, the thermal desorption method is appropriate to distinguish between different hydrogen traps. Nevertheless, the specimen temperature has to be accounted very carefully in case of calculating the necessary trap energy. T2 - IIW Intermediate Meeting, Meeting of commission II-A CY - Madrid, Spain DA - 29.02.2016 KW - Thermal desorption analysis (TDA) KW - Hydrogen trapping KW - High strength steels KW - Degradation KW - Heat treatment condition PY - 2016 AN - OPUS4-35544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Experimental simulation of dissimilar weld metal in high manganese steels by arc metling technique N2 - High manganese steels have great potential for use in automotive lightweight constructions (like car body structures) due to their superior strength and formability. In this scope, welding is the most common joining technique for sheet metal with challenges especially of dissimilar weld joints. In this case, the formation of martensite has to be considered resulting in a certain propability of brittle fracture in a respective load condition. In addition, no reliable weld metal microstructure prediction is possible with currently available constitution diagrams like the Schaeffler or WRC1992-diagram. Thus, the arc melting technique offers the possibility to investigate the effects of dilution on microstructures and properties of weld metal of high manganese steels. The results suggested that a complex indentification of microstructures is possible by directed experiments using the arc metling technique T2 - IIW Intermediate Meeting, Meeting of commission II-A CY - Madrid, Spain DA - 29.02.2016 KW - Arc melting technique KW - Dissimilar weld joints KW - High manganese steel KW - Constitution diagram PY - 2016 AN - OPUS4-35546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Laboratory experiments on press hardened steels in different delievered states exposed to hydrogen T2 - 5th International conference on hot sheet metal forming of high perfomance steel CY - Toronto, Canada DA - 2015-05-31 PY - 2015 AN - OPUS4-33440 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Thermal desorption spectroscopy for identification of diffusion and trapping in CoCrFeMnNi high-entropy alloy at 1,000 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). 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. Despite the activation energy, 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 - 1st Conference on Hydrogen in Materials Science and Engineering (H2-MSE) CY - Freiburg, Germany DA - 11.02.2025 KW - High-entropy alloy KW - Hydrogen diffusion KW - High-pressure charging KW - Thermal desorption analysis PY - 2025 AN - OPUS4-62543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Mechanische Eigenschaften eines warmfesten Behälterstahles unter Einfluss von Wasserstoff T2 - Sitzung des Arbeitskreises Energietechnik (AKE) in der Gesellschaft für Korrosionsschutzes e.V. (GfKorr) CY - Frankfurt am Main, Germany DA - 2013-01-30 PY - 2013 AN - OPUS4-28050 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffdiffusion und mechanische Eigenschaften in den schweißnahtspezifischen Gefügen eines Druckbehälterstahls T2 - MDDK Magdeburg CY - Magdeburg, Germany DA - 2013-05-30 PY - 2013 AN - OPUS4-28624 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Fügetechnik in Wasserstofftechnologien: Erzeugung, Transport, Speicherung, Nutzung N2 - Der Vortrag gibt einen kurzen Überblick über die Bedeutung der Fügetechnik in Wasserstofftechnologien und über zukünftige FuE-Bereiche. Fügetechnologien 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 Berlin CY - Berlin, Germany DA - 22.02.2023 KW - Wasserstoff KW - Fügetechnik KW - Forschung KW - Review PY - 2023 AN - OPUS4-57040 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen effect on degradation of mechanical properties of T24 weld metal and simulated coarse grained HAZ T2 - IIW International Meeting - Commission IX-C (Creep and heat resistant welds) CY - Berlin, Germany DA - 2014-04-05 PY - 2014 AN - OPUS4-30538 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -