TY - GEN A1 - Rhode, Michael A1 - Mente, Tobias A1 - Kannengießer, Thomas A1 - Czeskleba, Denis T1 - Simulation of hydrogen distribution in submerged arc welded heavy plates as tool for evaluating cold cracking sensitivity for offshore structures N2 - Foundation structures for offshore wind turbines are typically made of heavy plate struc-tural steels, such as S420ML, welded by submerged arc welding. Due to the welding process conditions, higher amounts of hydrogen can be introduced. In this context, large plate thicknesses result in long diffusion paths and a prolonged diffusion time for hydrogen at ambient temperature and possible delayed hydrogen-assisted cold cracking. As a result, hydrogen can accumulate in areas of high mechanical stress and strain. Due to the delayed diffusion, a minimum waiting time of up to 48 h must be observed before non-destructive testing can be performed. In addition, the assessment of possible cold crack locations is very complex. For this reason, a numerical model of a component-like weld test was developed to simulate the temperature field during welding and subsequent cooling. A hydrogen diffusion model based on the temporal-local temperature distribution was established. It was applied to simulate the change of hydrogen distribution as a function of temperature cycle during multi-layer welding and further for the entire waiting time interval ≤ 48 h. As a result, crack critical areas could be evaluated in terms of accu-mulated hydrogen. An advantage of the diffusion model is the simulation of a normalized concentration, i.e. between "0" (no hydrogen) and "1" (max. concentration), which can be scaled to experimentally determined hydrogen concentrations. Finally, selected results for increased real hydrogen ingress are presented, which confirm the relatively high crack resistance of the S420 submerged arc welded joint. KW - Hydrogen assisted cracking KW - Diffusion KW - Numerical simulation KW - Offshore steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632416 DO - https://doi.org/10.21268/20250507-6 SP - 1 EP - 12 PB - Technische Universität Clausthal CY - Clausthal-Zellerfeld, Deutschland AN - OPUS4-63241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Mente, Tobias A1 - Steppan, E. A1 - Kannengießer, Thomas A1 - Steger, J. T1 - Hydrogen trapping in T24 Cr-Mo-V steel weld joints - microstructure effect vs. experimental influence on activation energy for diffusion N2 - Hydrogen-assisted cracking is a critical combination of local microstructure, mechanical load and hydrogen concentration. Welded microstructures of low-alloyed creep-resistant Cr-Mo-V steels show different hydrogen trapping kinetics. This influences the adsorbed hydrogen concentration as well as the diffusion by moderate or strong trapping. A common approach to describe hydrogen traps is by their activation energy that is necessary to release hydrogen from the trap. In the present study, Cr-Mo-V steel T24 (7CrMoVTiB10-10) base material and TIG weld metal were investigated. Electrochemically hydrogen charged specimens were analyzed by thermal desorption analysis (TDA) with different linear heating rates. The results show two different effects. At first, the microstructure effect on trapping is evident in terms of higher hydrogen concentrations in the weld metal and increased activation energy for hydrogen release. Secondly, it is necessary to monitor the real specimen temperature. A comparison between the adjusted heating rate and the real specimen temperature shows that the calculated activation energy varies by factor two. Thus, the trap character in case of the base material changes to irreversible at decreased temperature. Hence, the effect of the experimental procedure must be considered as well if evaluating TDA results. Finally, realistic temperature assessment is mandatory for calculation of activation energy via TDA. KW - Creep-resistant steel KW - Hydrogen assisted cracking KW - Thermal desorption analysis KW - Welding KW - Microstructure KW - Diffusion PY - 2018 DO - https://doi.org/10.1007/s40194-017-0546-6 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 2 SP - 277 EP - 287 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-44505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael 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 - CHAP A1 - Rhode, Michael A1 - Münster, C. A1 - Mente, Tobias A1 - Böllinghaus, Thomas ED - Somerday, B.P. ED - Sofronis, P. T1 - Influence of experimental conditions and calculation method on hydrogen diffusion coefficient evaluation at elevated temperatures N2 - Literature provides a wide range of hydrogen diffusion coefficients for low alloyed steels used in power plants. In fact, experimental boundary conditions and calculation methods have influence on the determination of these coefficients. The diffusion and trapping behavior in creep-resistant steel 7CrMoVTiB10-10 has been studied. Based on experimental carrier gas hot extraction (CGHE) data, a numerical model has been developed to describe the hydrogen transport and respective hydrogen distribution at elevated temperatures. The numerical results suggest that common calculation methods for diffusion coefficients are limited for experimental data analysis. The sample preparation time before CGHE experiment influences the determined diffusion coefficients with the consequence that non-homogeneous hydrogen concentration profiles have to be considered in the simulations. KW - Temperature effect KW - Hydrogen diffusion KW - Creep-resistant steel KW - Hydrogen assisted cracking KW - Carrier gas hot extraction PY - 2017 SN - 978-0-7918-6138-7 DO - https://doi.org/10.1115/1.861387_ch56 SP - 495 EP - 503 PB - ASME CY - New York, USA ET - 1 AN - OPUS4-42502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Steffens, B. R. A1 - Böllinghaus, Thomas A1 - Shoales, G. A. A1 - Rhode, Michael ED - Somerday, B. P. ED - Sofronis, P. T1 - Hydrogen dependent material properties of UHSS for aerospace applications N2 - Quantitative investigations of hydrogen dependent properties of aircraft landing gear materials have only scarcely been carried out in the past. They are essential for respective component life time assessments. To better understand the behavior of these landing gear materials in a hydrogen rich environment, specimens were charged in the condition as delivered with known concentrations of hydrogen and then mechanically tested to evaluate the degradation effects. The present contribution is focused on evaluating the hydrogen concentration dependent material properties and the respective fracture topographies of the two investigated steels, and then continued by the comparison of the results with other previously investigated martensitic steels in order to better understand the thresholds for these materials to maintain structural integrity. T2 - International Hydrogen Conference 2016 CY - Jackson Lake Lodge, Moran, WY, USA DA - 11.09.2016 KW - Material properties KW - Hydrogen assisted cracking KW - Degradation KW - Aerospace materials KW - Ultra high strength steels PY - 2017 SN - 978-0-7918-6138-7 DO - https://doi.org/10.1115/1.861387_ch12 SP - 123 EP - 131 PB - ASME CY - New York, USA AN - OPUS4-42504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czeskleba, Denis A1 - Rhode, Michael A1 - Wandtke, Karsten A1 - Irfan, Muhammad Dary A1 - Kannengiesser, Thomas T1 - Hydrogen diffusion in thick-walled S690 saw joints: part 1—experimental determination of microstructure-dependent diffusion coefficients N2 - High-strength low-alloyed steel S690 is widely used in heavy-duty applications, such as structural components, mobile cranes, and industrial plant construction, owing to their high strength and weldability. However, thick-plate submerged arc welding (SAW) can introduce elevated hydrogen levels and residual stresses that promote time-delayed hydrogen-assisted cold cracking (HACC). Accurate, microstructure-specific diffusion data are scarce, limiting predictive HACC assessments. This study presents an experimental determination of hydrogen diffusion coefficients (DH) in two S690 variants: thermomechanically rolled (S690MC) and quenched and tempered (S690Q). Multi-layer SAW welds were produced from 30 mm thick plate material at three heat input levels, and diffusion membranes were extracted from weld metal (WM), heat-affected zone (HAZ), and base material (BM). Hydrogen permeation tests, conducted in accordance with DIN En ISO 17081, yielded flux curves normalized in time from which DH was derived using the inflection-point method. At room temperature, DH values ranged from 6 × 10−5 mm2/s to 9 × 10−5 mm2/s across all regions and heat inputs, with no significant difference between S690MC and S690Q. Weld metal exhibited marginally lower DH, attributed to enhanced hydrogen trapping, while base material measurements showed greater variability. These microstructure-resolved diffusion coefficients add quantitative data for modern S690 SAW welds and provide internally consistent input parameters for the numerical simulations presented in part 2. The results support improved parameterization for subsequent assessments of HACC risk through the optimization of welding parameters. KW - Hydrogen assisted cracking KW - Submerged arc welding KW - Diffusion KW - Electrochemical permeation KW - Microstructure PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655711 DO - https://doi.org/10.1007/s40194-026-02400-7 SN - 0043-2288 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-65571 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czeskleba, Denis A1 - Rhode, Michael A1 - Wandtke, Karsten A1 - Irfan, Muhammad Dary A1 - Kannengiesser, Thomas T1 - Hydrogen diffusion in thick-walled S690 SAW joints: part 2 – predictive modeling of heat input and microstructure influence N2 - High-strength low-alloy (HSLA) steels such as S690 are widely employed in thick-walled welded structures, where hydrogen-assisted cold cracking (HACC) remains a persistent concern. While microstructure-specific hydrogen diffusion coefficients (DH) for weld metal (WM), heat-affected zone (HAZ), and base material (BM) were experimentally established in Part 1 of this study, their quantitative influence on hydrogen accumulation and effusion has not yet been fully clarified. This work presents a transient, spatially resolved numerical model for simulating hydrogen transport in multi-pass submerged arc welds. The model integrates experimentally determined DH values with realistic thermal cycles and temperature-dependent boundary conditions. Developed in Python, the simulation tool is purpose-built for hydrogen diffusion in welded joints. It offers a focused, transparent alternative. It offers a focused, transparent alternative to general-purpose finite element platforms. Parametric analyses demonstrate that, although the diffusion coefficients vary by up to 50%, their impact on overall hydrogen retention is minor. In contrast, plate thickness, bead geometry, cooling time (t₈/₅), and interpass temperature exert a dominant influence on hydrogen distribution. Despite clear microstructural differences between the thermomechanically rolled (S690MC) and quenched and tempered (S690Q) variants, including opposite HAZ hardness responses (softening in S690MC, hardening in S690Q) in the (pen)ultimate weld bead, the simulations confirm that their diffusion behavior and hydrogen solubility are closely aligned. Consequently, differences in DH and solubility exert only a minor influence on hydrogen retention compared to thermal exposure and joint geometry. These findings support the interchangeable use of both steel grades in terms of HACC risk due to hydrogen diffusion kinetics under comparable welding conditions. KW - Hydrogen assisted cracking KW - Numerical simulation KW - Diffusion KW - Submerged arc welding PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655721 DO - https://doi.org/10.1007/s40194-026-02395-1 SN - 0043-2288 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-65572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -