TY - CONF A1 - Rhode, Michael T1 - Welding (and joining) technologies for the hydrogen economy - a short overview N2 - This study gives an overview on the important field of joining processes for component fabrication in hydrogen technologies. The current main issues and future perspectives are highlighted for the different technological field of hydrogen generation, storage, transport and use. In addition, the emerging field of additive manufacturing is included. Some remarks are given for standardization and regulations. T2 - Meeting of the European Welding Association (EWA), Executive Committee (EC) 1 CY - Frankfurt am Main, Germany DA - 22.03.2023 KW - Hydrogen KW - Welding KW - Research KW - Study PY - 2023 AN - OPUS4-57222 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Bewertung und Vermeidung von schweißverarbeitungsbedingten Rissen in hochfesten Baustählen N2 - Die vorliegende Präsentation fasst die Ergebnisse von drei laufenden bzw. beendeten AiF/IGF-Projekten zusammen, die über die Forschungsvereinigung Stahlanwendung FOSTA e.V. an der BAM bearbeitet wurden zum Thema: Bewertung und Vermeidung von schweißverarbeitungsbedingten Rissen in hochfesten Baustählen. T2 - FOSTA Tagung: Hochfester Stahl im Stahl und Anlagenbau CY - Essen, Germany DA - 16.05.2023 KW - Studie KW - Schweißen KW - Hochfester Stahl KW - Riss KW - Forschung PY - 2023 AN - OPUS4-57517 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Kromm, Arne A1 - Mente, Tobias A1 - Czeskleba, Denis A1 - Brackrock, Daniel A1 - Kannengießer, Thomas T1 - Bauteilversuch zur Bewertung der wasserstoffunterstützten Rissanfälligkeit geschweißter, dickwandiger Offshore-Gründungsstrukturen N2 - Offshore-Windenergieanlagen erfordern Gründungskonzepte aus unterpulver-(UP-)geschweißten Dickblechen (bspw. der Güte S420ML). Während der Schweißfertigung kann eine zeitverzögerte wasserstoffunterstützte Kaltrissbildung auftreten, deren Bewertung aufgrund der Bauteilgröße von Offshore-Strukturen sehr komplex ist. Deswegen wurde eine bauteilähnliche Geometrie (Mock-Up) entwickelt, um reale Steifigkeitsverhältnisse auf den Labormaßstab zu übertragen. Zusätzliche Versteifungen simulieren die Wirkung einer Einspannung bzw. Schrumpfbehinderung der Schweißnaht. Über die Verwendung von Schweißpulvern mit definierter Feuchte wurden zudem ein Extremszenario der Wasserstoffaufnahme simuliert. Entsprechend der vorgegebenen Mindestwartezeit für die ZfP von bis zu 48 h wurde die Schweißnaht zerstörungsfrei mit Phased-Array-Ultraschall-Prüfung (PAUT) geprüft und die Eigenspannungen über Röntgendiffraktometrie (XRD) bestimmt. Zusätzlich wurde die Wasserstoffverteilung in der Schweißverbindung numerisch simuliert. Außer zulässigen Defekten (wie Poren), wurde keine verzögerte Kaltrissbildung in den Mock-Ups festgestellt, was auf hohe Rissbeständigkeit hindeutet. T2 - Tagung Werkstoffprüfung 2023 CY - Berlin, Germany DA - 23.11.2023 KW - Kaltrissbildung KW - Wasserstoff KW - Offshore KW - Schweißen KW - Bauteiltest PY - 2023 DO - https://doi.org/10.48447/WP-2023-219 SP - 316 EP - 321 CY - Berlin AN - OPUS4-58908 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Bauteilversuch zur Bewertung der wasserstoffunterstützten Rissanfälligkeit geschweißter, dickwandiger Offshore Gründungsstrukturen N2 - Offshore-Windenergieanlagen erfordern Gründungskonzepte aus unterpulver-(UP-)geschweißten Dickblechen (bspw. der Güte S420ML). Während der Schweißfertigung kann eine zeitverzögerte wasserstoffunterstützte Kaltrissbildung auftreten, deren Bewertung aufgrund der Bauteilgröße von Offshore-Strukturen sehr komplex ist. Deswegen wurde eine bauteilähnliche Geometrie (Mock-Up) entwickelt, um reale Steifigkeitsverhältnisse auf den Labormaßstab zu übertragen. Zusätzliche Versteifungen simulieren die Wirkung einer Einspannung bzw. Schrumpfbehinderung der Schweißnaht. Über die Verwendung von Schweißpulvern mit definierter Feuchte wurden zudem ein Extremszenario der Wasserstoffaufnahme simuliert. Entsprechend der vorgegebenen Mindestwartezeit für die ZfP von bis zu 48 h wurde die Schweißnaht zerstörungsfrei mit Phased-Array-Ultraschall-Prüfung (PAUT) geprüft und die Eigenspannungen über Röntgendiffraktometrie (XRD) bestimmt. Zusätzlich wurde die Wasserstoffverteilung in der Schweißverbindung numerisch simuliert. Außer zulässigen Defekten (wie Poren), wurde keine verzögerte Kaltrissbildung in den Mock-Ups festgestellt, was auf hohe Rissbeständigkeit hindeutet. T2 - Tagung Werkstoffprüfung 2023 CY - Berlin, Germany DA - 23.11.2023 KW - Kaltrissbildung KW - Wasserstoff KW - Offshore KW - Bauteilversuch KW - Imperfektion PY - 2023 AN - OPUS4-58907 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Masoud Nia, Niloufar A1 - Nietzke, Jonathen A1 - Kannengiesser, Thomas T1 - Ti and Nb microalloying of HSLA steels and its effect on hydrogen diffusion and trapping N2 - Fine-grain, high-strength, low-alloy (HSLA) structural steels with yield strengths > 600 MPa are now the state of the art in construction applications such as mobile cranes and civil engineering. HSLA grades derive their strength from a combination of specific heat treatment and the underlying chemical composition. In this context, Ti or Nb are essential to obtain a fine-grained microstructure as well as the necessary carbides or nitrides for precipitation strengthening. In this context, the specific effect of Ti or Nb-rich compounds on hydrogen trapping and diffusion is well known for special laboratory cast alloys, but unknown for realistic steel compositions. For this reason, a series of S690Q-based alloys were synthesized, close to a real steel composition, but with well controlled Ti or Nb additions in different amounts. Specimens were obtained from these alloys by electrochemical discharge machining (EDM). The specimens were tested using the well-established electrochemical permeation technique. From the experimental results, the hydrogen diffusion coefficients and the analytical subsurface hydrogen concentration were calculated. In addition, the hydrogen trapping behavior at elevated temperatures was interpreted by thermal desorption analysis (TDA) using different heating rates of hydrogen charged samples. The results showed that in contrast to metallurgically "pure" laboratory cast alloys, realistic chemical compositions were similar in their hydrogen trapping behavior, despite some small differences. All investigated steel grades exhibited shallow and reversible hydrogen trapping, regardless of their chemical composition. Of course, the experiments only allowed the calculation of effective diffusion coefficients and trapping energies, which represent an average of the entire microstructure. Nevertheless, HSLA steels are typically joined by arc welding, which includes the risk of delayed hydrogen assisted cracking. From the point of view of welding practice, however, a more or less identical hydrogen diffusion behavior means that no special "metallurgically specific", justifiable measures need to be considered, despite the well-established processes such as "soaking" or dehydrogenation heat treatment. T2 - MPAC 2025 CY - Stuttgart, Germany DA - 06.10.2025 KW - HACC KW - Hydrogen KW - HSLA PY - 2025 AN - OPUS4-64337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Effect of Ti microalloying on the local strain behavior of cross-weld tensile samples determined by digital image correlation N2 - High-strength low-alloyed (HSLA) steels with yield strength / proof stress ≥ 600 MPa are the basis of modern light-weight steel constructions. Indeed, the economic and ecological benefits strongly depend on their processability in terms of welding. In this context, the use of highly productive welding processes and suitable welding consumables is of vital interest and requires a fundamental understanding of the microstructural changes in the HSLA steel and especially the heat-affected zone (HAZ) of the welded joint. Microalloying elements, such as Ti or Nb, are essential to achieve the desired mechanical properties. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the HAZ that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using cross-weld tensile specimens. Digital image correlation (DIC) was used for in-situ monitoring of the development and accumulation of the local strains in different HAZ regions during tensile testing. Using a specially designed mirror system, the local strains of the microstructure zones on the top and bottom of the weld were recorded simultaneously. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the reduction in area, the fracture position, and the overall fracture behavior. KW - High-strength structural steel KW - Microalloying influences KW - HAZ-softening KW - Digital Image Correlation KW - Constraint effect KW - Thermodynamic simulation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643558 DO - https://doi.org/10.1007/s40194-025-02185-1 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-64355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - A decarbonized future requires pipelines for CO2? A brief overview on perspectives and challenges N2 - Despite the use of hydrogen, for example, in various industrial production processes, CO2 emissions are still unavoidable in the medium term. For example, cement, lime and glass production or waste recycling (waste-to-energy plants) will continue to emit CO2 due to the processing involved chemical reactions. Conversely, the chemical industry with its value chains needs CO2 / carbon as a primary raw material for all compounds that fall within the organic chemistry. In this connection, carbon capture utilization (CCU) will play a key role here. In addition to “natural” methods (via reforestation and the dilution of moors), carbon capture storage (CSS) is already playing a major role, for example by injecting it into old natural gas underground caverns. The resulting quantities of CO2 have to be transported on a large scale and similar to hydrogen pipelines, there are concrete plans for CO2 pipeline networks. For this reason, this presentation provides an introduction to the topic and briefly outlines the associated challenges. On the one hand, these lie in the qualification (testing and construction) and especially in the operation of the pipelines with regard to strict monitoring of the gas quality (e.g. carbonic acid corrosion) and in the avoidance of critical service conditions (sudden pressure fluctuations), which can lead to localized condensation. Among other things, this can lead to the lowering of the typically welded low-alloyed steel pipes below the ductile brittle transition temperature (DBTT) and thus can have an impact on pipeline integrity. T2 - 49th MPA Conference CY - Stuttgart, Germany DA - 06.10.2025 KW - CO2 KW - Pipeline KW - Welding KW - Testing PY - 2025 AN - OPUS4-64316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Component test for simulation of in-service welding on hydrogen pipelines N2 - Hydrogen is set as the energy carrier of tomorrow and most countries will achieve large-scale hydrogen transport through the conversion of the natural gas (NG) grid and the construction of new pipelines. The interaction between hydrogen and the pipeline materials differs fundamentally from that of NG, as hydrogen is readily absorbed into the material. Considering the possible hydrogen embrittlement (HE), the compatibility of the pipeline materials (low-alloyed steels with a wide strength/thickness range) must be investigated. However, pipelines require intervention for maintenance, repair, or grid expansion with welding on/onto the pipelines while in service, i.e. the well-known "hot tapping" and "stoppling". The challenges compared to NG can be broadly divided into the possible austenitization of the inner pipe material exposed to hydrogen and the welding itself. Both result in a significant increase in hydrogen solubility and could potentially pose challenges in terms of HE. Emphasis is placed on the word "could" because knowledge of "hot tapping" on hydrogen pipelines is scarce due a lack of service experience. To this end, this study proposes a concept for a component-like demonstrator with the objectives: (1) safe feasibility of "hot tapping" on pressurized model hydrogen pipeline sections, (2) facilitate ex-post sample extraction for the purpose of quantifying the absorbed hydrogen concentrations, and (3) ensure in-situ temperature measurement during welding to monitor the pipeline surface temperature. For safety reasons in the event of an unintentional "burn-through", a solid cylinder was inserted in the demonstrator to restrict the hydrogen gas volume to a small, pressurized layer. Reference pipeline surface temperature measurements were ensured on comparable, unpressurized geometries. The investigated range of welding conditions was investigated for representative material/thickness combinations (DN60 to DN300), suggesting the feasibility of the demonstrator for the determination of reliable in-service welding conditions for both installed and new pipelines for hydrogen service. T2 - 49th MPA Conference CY - Stuttgart, Germany DA - 06.10.2025 KW - Hydrogen KW - Pipeline KW - In-service welding KW - Component test PY - 2025 AN - OPUS4-64317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Ti and Nb influence on the HAZ microstructures of weld-simulated high-strength structural steel S690QL N2 - High-strength low-alloyed (HSLA) steels with yield strength / proof stress ≥ 600 MPa are the basis of modern light-weight steel constructions. Indeed, the economic and ecological benefits strongly depend on their processability in terms of welding. In this context, the use of highly productive welding processes, suitable welding consumables is of vital interest and requires a fundamental understanding of the microstructural changes in the HSLA steel and especially the heat-affected zone (HAZ) of the welded joint. Microalloying elements, such as Ti or Nb, are essential to achieve the desired mechanical properties. In this context, the underlying standards (such as EN 10025-6) only specify maximum values, resulting in different manufacturer customized microalloy concepts. Furthermore, even small deviations can have a drastic effect expressed by an excessive hardening or softening despite identical welding conditions and filler metal. The reason is the different thermal stability of the Ti and Nb-related precipitates (typically carbides or carbon nitrides). As a result, it is difficult (or even impossible) to adequately predict the weldability. Against this background, different microalloying routes with varying Ti and Nb contents for a S690QL reference grade were systematically investigated in terms of lab-cast alloys close to realistic chemical compositions. To investigate the influence of the welding heat input on the HAZ microstructure formation, physical simulations were carried with specified peak temperatures and cooling times (by a dilatometry). The focus was the identification of the occurring phase transformations during cooling and the final HAZ microstructure. In this context, a double welding cycle was simulated to further identify the behavior of the so-called intercritical HAZ (where softening is likely to occur) in case of the common multi-layer welding for thick plates. The results showed: (1) microalloying has significant influence on the formation of the individual HAZ dependent on (2) the thermal stability of the Ti or Nb-precipitates and (3) synergistic effects of further elements such as Mo and their effect on phase transformations in the HAZ. The results represent a microstructure-based validation of welding processing of such HSLA-steels e.g. in terms of preferred microalloy and weld heat input combinations. T2 - 49th MPA Conference CY - Stuttgart, Germany DA - 06.10.2025 KW - High-strength steel KW - Microalloy elements KW - Welding KW - Weld simulation KW - Microstructure PY - 2025 AN - OPUS4-64319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Welding of high-entropy alloys - New material concept vs. old challenges N2 - HEAs represent a relatively new class of materials. The the alloy concept is fundamentally different from the most conventional materials and alloys that are used today. Recently, the focus of HEA designs is more application-based. For that purpose, the elements of interest are carefully selected and multiple phases as well as micro-structures are deliberately adjusted. Currently, only limited attention has been paid to weldability of HEA. This encompasses possible effects on metallurgy and its influence on the desired properties. It remains open if welding causes e.g. considerable number of intermetallic phases or segregations and their effect on weld joint properties. For that reason, the scope of this study is to summarize already available studies on welding of HEAs with respect to the HEA-type, the applied welding process and its influence on the weld joint properties. T2 - IIW Annual Assembly, Meeting of Commission II-A CY - Online meeting DA - 20.07.2020 KW - High-entropy alloy KW - Welding KW - Review PY - 2020 AN - OPUS4-51116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffdiffusion und lokale Volta-Potentiale in Hoch- und Mittelentropie-Legierungen N2 - Hochentropie-Legierungen (HEAs) zeichnen sich durch einen Mischkristall-System aus mindestens fünf und Mittelentropie-Legierungen (MEAs) durch mindestens drei Hauptlegierungselemente aus, in äquiatomarer Zusammensetzung. Sie zeigen außergewöhnliche Anwendungseigenschaften, wie z.B. hohe Festigkeit, Duktilität oder Korrosionsbeständigkeit. Zukünftige HEA/MEA-Komponenten aufgrund ihrer Eigenschaften für wasserstoffhaltige Umgebungen (wie Behälter für kryogene oder Hochdruckspeicherung) von Interesse. Daher ist die Bewertung der Wasserstoffabsorption und die Diffusion in diesen Materialien von großer Bedeutung. Dazu wurden in unserer Studie eine CoCrFeMnNi-HEA und eine CoCrNi-MEA untersucht. Die Proben wurden elektrochemisch mit Wasserstoff beladen. Für die Ermittlung des Wasserstoffdiffusionsverhaltens wurde die thermische Desorptionsanalyse (TDA) mit unterschiedlichen Heizraten bis zu 0,250 K/s angewandt. Die nachfolgende Peakentfaltung der Signale führte zu Hochtemperatur-Desorptionsspitzen und Wasserstofftrapping auch über 280°C. Eine resultierende Gesamtwasserstoffkonzentration > 40 ppm wurde für den MEA ermittelt und > 100 ppm für den HEA. Dies deutet auf zwei wichtige Effekte hin: (1) verzögerte Wasserstoffdiffusion und (2) eine beträchtliche Menge an getrapptem Wasserstoff auch bei hoher Temperatur. Beide Effekte können hinsichtlich einer wasserstoffunterstützten Rissbildung kritisch werden, dies erfordert jedoch weitere Untersuchungen. Zusätzlich erfolgte die Bestimmung des lokalen Volta-Potentials mittels hochauflösender Kelvin-Sonden-Kraft-Mikroskopie (SKPFM). Die ermittelten Scans zeigen einen bestimmten Einfluss der Wasserstoffbeladung auf die Potentiale. T2 - Symposium on Materials and Joining Technology CY - Online meeting DA - 07.09.2020 KW - Wasserstoff KW - High-entropy alloy KW - Diffusion KW - Scanning kelvin probe force microscopy KW - Thermal desorption analysis PY - 2020 AN - OPUS4-51187 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Steger, Jörg A1 - Böllinghaus, Thomas A1 - Kannengießer, Thomas ED - Lippold, J. ED - Böllinghaus, Thomas ED - Richardson, I. M. T1 - Hydrogen degradation effects on mechanical properties in T24 weld microstructures N2 - Spectacular failure cases of fossil power stations in the recent years exhibited severe cracking in T24 welds. The results show that hydrogen-assisted cracking up to 200 °C cannot be excluded. Hence, it is important to gain a basic understanding on how hydrogen might affect the basic material properties in the respective weld microstructures. The present study focuses on hydrogen degradation of the respective weld microstructures, i.e., the weld metal and the coarse grained heat affected zone, where actually cracking appeared in practice. Tensile tests were carried out for coarse grain heataffected zone (CGHAZ) and the weld metal in uncharged and electrochemically hydrogen-charged condition. It turned out that both microstructures show distinct tendency for gradual degradation of mechanical properties in the presence of increasing hydrogen concentration. Already for a hydrogen concentration about and above 2 ml/100 g Fe, a significant ductility reduction has been observed. SEM investigations revealed that the fracture topography changes from ductile topography in uncharged condition to intergranular topography for the CGHAZ and to ductile-brittle mix for the weld metal (WM) in hydrogen charged condition. Ti-rich inclusions were identified as central regions of quasi-cleavage fracture areas in the WM. An approximation procedure is applied to quantify the degradation intensity. KW - Low alloy steels KW - Hydrogen embrittlement KW - Heat affected zone KW - Microstructure KW - Creep resisting materials PY - 2016 UR - http://link.springer.com/article/10.1007/s40194-015-0285-5 DO - https://doi.org/10.1007/s40194-015-0285-5 SN - 0043-2288 VL - 60 IS - 2 SP - 201 EP - 216 PB - Springer-Verlag GmbH CY - Heidelberg AN - OPUS4-35390 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schaupp, Thomas A1 - Rhode, Michael A1 - Kannengießer, Thomas ED - Lippold, J. ED - Böllinghaus, Thomas ED - Richardson, I. T1 - Influence of welding parameters on diffusible hydrogen content in high-strength steel welds using modified spray arc process N2 - In order to satisfy the growing requirements towards lightweight design and resource efficiency in modern steel constructions, e.g., mobile cranes and bridges, high-strength steels with typical yield strength ≥ 690 MPa are coming into use to an increasing extent. However, these steels require special treatment in welding. The susceptibility for degradation of the mechanical properties in the presence of hydrogen increases significantly with increasing yield strength. In case of missing knowledge about how and the amount of hydrogen that is uptaken during welding, hydrogen-assisted cracking (HAC) can be a negative consequence. Moreover, modern weld technology like the modified spray arc process enables welding of narrower weld seams. In this context, a reduced number of weld beads, volume, and total heat input are technical and economical benefits. This work presents the influence of welding parameters on the diffusible hydrogen content in both (1) single-pass and (2) multi-layer welds. Different hydrogen concentrations were detected by varied contact tube distance, wire feed speed, arc length, and varied arc type (transitional arc and modified spray arc). The results show that all welding parameters have significant influence on the diffusible hydrogen concentration in the single-pass welds. By increasing the number of weld beads in case of multi-layer welding, the hydrogen concentration has been reduced. Whereby, differences in hydrogen concentrations between both arc types are present. KW - Hydrogen KW - MAG welding KW - High-strength steels KW - Process parameters PY - 2018 DO - https://doi.org/10.1007/s40194-017-0535-9 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 1 SP - 9 EP - 18 PB - Springer CY - Berlin Heidelberg AN - OPUS4-43864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Modeling of hydrogen-assisted cracking (HAC) in duplex stainless steels (DSS) N2 - Modeling of Hydrogen-Assisted Cracking (HAC) in Duplex Stainless Steels (DSS): - Hydrogen causes significant degradation in DSS and consequently HAC - Mechanisms of HAC have not been fully understood in two-phase microstructures - Mesoscale numerical modeling for HAC in DSS was created, coupled to the macroscale, enabling simulation of HAC in both phases independent from predefined crack paths T2 - International Hydrogen Conference - Material Performance in Hydrogen Environments CY - Jackson Lake Lodge, Moran, Wyoming, USA DA - 11.09.2016 KW - Hydrogen KW - Numerical modeling KW - Duplex stainless steel KW - Hydrogen assisted cracking PY - 2016 AN - OPUS4-37404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Böllinghaus, Thomas T1 - Hydrogen absorption and diffusion in T24 steel weld joints and effect on mechanical properties N2 - The present contribution summarizes results obtained from experiments with low-alloyed boiler steel grades T24 (CrMoV alloy), T22 (CrMo) and thermally simulated T24 HAZ microstructure and pure weld metal. The hydrogen absorption and diffusion behavior was investigated by permeation experiments and thermal desorption analysis (TDA). The results showed significant weld microstructure influence on diffusion by hydrogen trapping. Trapped hydrogen was determined in the T24 BM at temperatures up to 120 °C compared to 75 °C in the T22. In addition, the T24 HAZ showed decreased diffusion coefficients (at room temperature) of approximately one magnitude compared to the BM. For the mechanical properties, tensile tests were conducted with electrochemically hydrogen charged specimens and compared to results obtained from slow strain rate tests (SSRT) in high-temperature water up to 200 °C. The as-welded HAZ had remarkably increased susceptibility compared to the BM already at low hydrogen concentration of 1-2 ppm. The SSRT were conducted for free corrosion and acidic environment and confirmed this behavior at elevated temperatures for both HAZ microstructures of T24 and T22. Summarized, each weld microstructure has specific diffusion coefficients and shows different susceptibility to degradation of the mechanical properties, i.e. delayed hydrogen assisted cracking or stress corrosion cracking. T2 - NACE Italia - 2nd Conference & Expo 2018 CY - Genoa, Italy DA - 28.05.2018 KW - Hydrogen KW - Stress corrosion cracking KW - Welding KW - Creep-resistant steel PY - 2018 SP - Paper 10, 1 EP - 7 AN - OPUS4-45081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - "On how to influence your results" - A review on carrier gas hot extraction parameters for hydrogen determination in welded specimens N2 - Carrier gas hot extraction (CGHE) is a commonly applied technique for determination of hydrogen in welded joints using a thermal conductivity device (TCD) for quantitative measurement. The CGHE is based on the accelerated hydrogen effusion due to thermal activation at elevated temperatures. The ISO 3690 standard suggests different specimen geometries as well as necessary minimum extraction time vs. temperature. They have the biggest influence on precise hydrogen determination. The present study summarizes the results and experience of numerous test runs with different specimen temperatures, geometries and factors that additionally influence hydrogen determination. They are namely: specimen surface (polished/as-welded), limited TCD sensitivity vs. specimen volume, temperature measurement vs. effects of PID-furnace controller as well as errors due to insufficient data assessment. Summarized, the temperature is the driving force of the CGHE. Two different methods are suggested to increase the heating rate up the reach the desired extraction temperature without changing the experimental equipment. Suggestions are made to improve the reliability of hydrogen determination depended on the hydrogen signal stability during extraction accompanied by evaluation of the recorded data. Generally, independent temperature measurement with calibration specimens is useful for further data analysis, especially if this data is used for calculation of trapping kinetics by thermal desorption analysis (TDA). T2 - IIW Annual Assembly and International Conference 2018, Meeting of Commission II-E CY - Nusa Dua, Bali Island, Indonesia DA - 15.07.2018 KW - Carrier gas hot extraction (CGHE) KW - Welding KW - ISO 3690 KW - Hydrogen KW - Experimental design PY - 2018 AN - OPUS4-45520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Rhode, Michael A1 - Boerner, Andreas A1 - Saliwan Neumann, Romeo A1 - Schneider, M. A1 - Laplanche, G. T1 - Influence of machining on the surface integrity of high- and medium-entropy alloys N2 - High- and medium-entropy alloys (HEAs) are a quite new class of materials. They have a high potential for applications from low to high temperatures due to the excellent combination of their structural properties. Concerning their application as components; processing properties, such as machinability, have hardly been investigated so far. Hence, machinability analyses with a focus on the influence of the milling process and its basic parameters (cutting speed, feed per cutting edge) on the resulting surface integrity of specimens from an equiatomic high- (CoCrFeMnNi) and a medium- (CoCrNi) entropy alloy have been carried out. A highly innovative milling process with ultrasonic assistance (USAM) was compared to conventional milling processes. Recent studies have shown that USAM has a high potential to significantly reduce the mechanical load on the tool and workpiece surface during milling. In this study, the basic machining and ultrasonic parameters were systematically varied. After machining, the surface integrity of the alloys was analyzed in terms of topography, defects, subsurface damage, and residual stresses. It was observed that USAM reduces the cutting forces and increases the surface integrity in terms of lower tensile residual stresses and defect density near the surfaces for the CoCrFeMnNi alloy. It was shown that the cutting forces and the metallurgical influence in the sub surface region are reduced by increasing the cutting speed and reducing the feed rate per cutting edge. With the CoCrNi alloy, the tool revealed severe wear. As a result, for this alloy no influence of the parameters on the machinability could be determined. KW - High Entropy Alloy KW - Medium Entropy Alloys KW - Ultrasonic assited machining PY - 2022 DO - https://doi.org/10.1016/j.matchemphys.2021.125271 SN - 0254-0584 VL - 275 SP - 125271 PB - Elsevier B.V. AN - OPUS4-53606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Mechanische Eigenschaften der Längschweißnaht einer X65-Pipeline in Druckwasserstoffatmosphäre N2 - Im folgenden Beitrag werden die Ergebnisse der mechanischen Eigenschaften unter 200 bar Druckwasserstoff des Werkstoffes 316L (1.4404) vorgestellt. Dazu wurden Hohlzugproben aus konventionellem, kaltgezogenem Material herausgearbeitet und per SLM-PBF additiv gefertigten Hohlzugproben gegenübergestellt. Die Proben wurden da-bei unter Druckwasserstoff einer SSRT-Prüfung mit einer Dehnrate von 1E-5/s unterzogen. Zusätzlich zum Werkstoffzustand wurde der Einfluss des Oberflächenzustandes charakterisiert: (1) additiv gefertigten Proben mit endkonturnaher Form „as-printed“ oh-ne zusätzliche Bohrung, (2) Bohren und (3) zusätzliches Honen. Die gemessene Degradation der mechanischen Eigenschaften unter Wasserstoff hing dabei in erster Linie von der Oberfläche ab und damit indirekt vom Werkstoffzustand „as-printed“ oder kaltgezogen ab. Während die Proben mit gebohrter und/oder gehonter Oberfläche eine RRA (Relative Reduction of Area) 78 % aufwiesen, zeigten die AM-Proben eine deutlich höhere RRA von 90 %. Ein möglicher Grund dafür sind während der Fertigung ausbildende Oxidschichten, die sich durch geringe Mengen an Restsauerstoff während des AM-Prozesses ausbilden. Zur abschließenden Charakterisierung sind weitere Untersuchungen erforderlich, insbesondere für ein größeres Parameterfeld an Prüftemperaturen (Oxideinwirkung) und Dehnraten (mechanische Beständigkeit der Oxidschicht ähnlich den Einflüssen auf „klassische“ Spannungsrisskorrosion). T2 - DGM Arbeitskreis Wasserstoff CY - Neu-Isenburg, Germany DA - 26.05.2025 KW - Pipeline KW - Wasserstoff KW - Hohlzugprobe PY - 2025 AN - OPUS4-63236 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Additive gefertigte 316L-Hohlzugproben unter Druckwasserstoff - Einfluss der Oberfläche und des Werkstoffzustandes N2 - Im folgenden Beitrag werden die Ergebnisse der mechanischen Eigenschaften unter 200 bar Druckwasserstoff des Werkstoffes 316L (1.4404) vorgestellt. Dazu wurden Hohlzugproben aus konventionellem, kaltgezogenem Material herausgearbeitet und per SLM-PBF additiv gefertigten Hohlzugproben gegenübergestellt. Die Proben wurden da-bei unter Druckwasserstoff einer SSRT-Prüfung mit einer Dehnrate von 1E-5/s unterzogen. Zusätzlich zum Werkstoffzustand wurde der Einfluss des Oberflächenzustandes charakterisiert: (1) additiv gefertigten Proben mit endkonturnaher Form „as-printed“ oh-ne zusätzliche Bohrung, (2) Bohren und (3) zusätzliches Honen. Die gemessene Degra-dation der mechanischen Eigenschaften unter Wasserstoff hing dabei in erster Linie von der Oberfläche ab und damit indirekt vom Werkstoffzustand „as-printed“ oder kaltgezogen ab. Während die Proben mit gebohrter und/oder gehonter Oberfläche eine RRA (Relative Reduction of Area) 78 % aufwiesen, zeigten die AM-Proben eine deutlich höhere RRA von 90 %. Ein möglicher Grund dafür sind während der Fertigung ausbildende Oxidschichten, die sich durch geringe Mengen an Restsauerstoff während des AM-Prozesses ausbilden. Zur abschließenden Charakterisierung sind weitere Untersuchungen erforderlich, insbesondere für ein größeres Parameterfeld an Prüftemperaturen (Oxideinwirkung) und Dehnraten (mechanische Beständigkeit der Oxidschicht ähnlich den Einflüssen auf „klassische“ Spannungsrisskorrosion). T2 - DGM Arbeitskreis Wasserstoff CY - Neu-Isenburg, Germany DA - 26.05.2025 KW - Wasserstoff KW - Additive Fertigung KW - Hohlzugprobe KW - Austentitischer Stahl PY - 2025 AN - OPUS4-63239 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Richter, Tim A1 - Mayr, P. A1 - Nitsche, A. A1 - Mente, Tobias A1 - Böllinghaus, Thomas T1 - Hydrogen diffusion in creep-resistant 9% Cr P91 multi-layer weld metal N2 - Welded components of P91 9% Cr steel demand for careful welding fabrication with necessary post weld heat treatment (PWHT). Before the PWHT, a hydrogen removal heat treatment is necessary for avoidance of hydrogen assisted cracking (HAC). In this context, the microstructure and temperature-dependent hydrogen diffusion is important, and reliable diffusion coefficients of P91 weld metal are rare. For that reason, the diffusion behavior of P91 multi-layer weld metal was investigated for as-welded (AW) and PWHT condition by electrochemical permeation experiments at room temperature and carrier gas hot extraction (CGHE) from 100 to 400 °C. Hydrogen diffusion coefficients were calculated, and the corresponding hydrogen concentration was measured. It was ascertained that both heat treatment conditions show significant differences. At room temperature the AW condition showed significant hydrogen trapping expressed by to seven times lower diffusion coefficients. A preferred diffusion direction was found in perpendicular direction expressed by high permeability. The CGHE experiments revealed lower diffusion coefficients for the AW condition up to 400 °C. In this context, a hydrogen concentration of approximately 21 ml/100 g was still trapped at 100 °C. For that reason, a certain HAC susceptibility of as-welded P91 weld metal cannot be excluded, and hydrogen removal should be done before PWHT. KW - Creep resisting materials KW - Diffusion KW - Hydrogen KW - Weld metal KW - Post weld heat treatment KW - Microstructure PY - 2020 DO - https://doi.org/10.1007/s40194-019-00828-8 SN - 0043-2288 VL - 64 IS - 2 SP - 267 EP - 281 PB - Springer AN - OPUS4-50471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -