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 -