TY - JOUR A1 - Drexler, A A1 - Konert, Florian A1 - Sobol, Oded A1 - Rhode, Michael A1 - Domitner, J A1 - Sommitsch, C A1 - Böllinghaus, Thomas T1 - Enhanced gaseous hydrogen solubility in ferritic and martensitic steels at low temperatures N2 - Metals that are exposed to high pressure hydrogen gas may undergo detrimental failure by embrittlement. Understanding the mechanisms and driving forces of hydrogen absorption on the surface of metals is crucial for avoiding hydrogen embrittlement. In this study, the effect of stress-enhanced gaseous hydrogen uptake in bulk metals is investigated in detail. For that purpose, a generalized form of Sievert's law is derived from thermodynamic potentials considering the effect of microstructural trapping sites and multiaxial stresses. This new equation is parametrized and verified using experimental data for carbon steels, which were charged under gaseous hydrogen atmosphere at pressures up to 1000 bar. The role of microstructural trapping sites on the parameter identification is critically discussed. KW - Hydrogen KW - Thermodynamic modelling KW - Pressure-dependent solubility KW - Steel KW - Trapping PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559307 DO - https://doi.org/10.1016/j.ijhydene.2022.09.109 SN - 0360-3199 VL - 47 IS - 93 SP - 39639 EP - 39653 PB - Elsevier Ltd. AN - OPUS4-55930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Campari, Alessandro A1 - Konert, Florian A1 - Sobol, Oded A1 - Alvaro, Antonio T1 - A comparison of vintage and modern X65 pipeline steel using hollow specimen technique for in-situ hydrogen testing N2 - The transition toward a hydrogen-based economy requires a widespread transport and distribution network, and repurposed natural gas pipelines are a viable option. An assessment of the hydrogen-induced degradation of pipeline steels is needed to inject H2 gas into the existing infrastructure safely. The conservative and standardized method consists of in-situ tensile tests in an autoclave filled with high-pressure hydrogen gas. A proposed alternative method involves using a hollow specimen as containment volume and applying the gas pressure in the inner cavity. This technique has lower costs and shorter test preparation time but is not standardized yet. This study aims to evaluate and compare the tensile properties of API 5L X65 pipeline steel in two states: vintage and modern. The influence of the surface roughness is investigated through parallel tests with drilled and reamed specimens. Hydrogen tests are compared with reference tests in an inert environment. A significant hydrogen-induced decrease in tensile properties is observed, and no significant difference between vintage and modern X65 can be drawn. The reduction in tensile properties is more significant in specimens with higher inner surface roughness. The evaluation of surface conditions appears crucial when assessing the HE susceptibility of hydrogen transport and storage equipment. KW - Hydrogen embrittlement KW - Hollow specimen technique KW - Pipeline steel KW - SSRT PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603013 DO - https://doi.org/10.1016/j.engfailanal.2024.108530 VL - 163 SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-60301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzke, Jonathan A1 - Konert, Florian A1 - Poka, Konstantin A1 - Merz, Benjamin A1 - Sobol, Oded A1 - Böllinghaus, Thomas T1 - Comparison of hydrogen effects on additively manufactured and conventional austenitic steels N2 - Hydrogen and its derivatives are promising energy carriers for future renewable energy supplies. Austenitic stainless steels, such as AISI 316L, are commonly used in hydrogen transportation systems. While often thought to be resistant to hydrogen embrittlement, studies have shown that 316L is susceptible under certain conditions. As demand for hydrogen applications grows, additive manufacturing (AM) technologies offer design flexibility and customisation benefits. However, data on AM parts behaviour in hydrogen environments is lacking. This study investigates the influence of hydrogen on mechanical properties using slow strain rate testing (SSRT) on conventional AISI 304L, 316L and AM 316L specimens. The results indicate a greater effect of hydrogen on 304L compared to 316L, with AM 316L showing increased susceptibility. However, the ductility of AM 316L remains comparable to conventional 316L due to its initial ductility. The study provides insights into the performance of conventional and AM austenitic stainless steels in gaseous hydrogen environments. KW - Slow strain rate testing KW - Hollow specimen KW - Hydrogen embrittlement KW - Additive manufacturing KW - Austenitic steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615919 DO - https://doi.org/10.1016/j.engfailanal.2024.109042 SN - 1350-6307 VL - 167 SP - 1 PB - Elsevier B.V. AN - OPUS4-61591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grimault de Freitas, Tomás A1 - Konert, Florian A1 - Nietzke, Jonathan A1 - Krzysch, Zephanja A1 - Böllinghaus, Thomas A1 - Michler, Thorsten A1 - Wackermann, Ken A1 - Oesterlin, Heiner A1 - Tlili, Mohamed A1 - Ruchti, Peter A1 - Beitelschmidt, Denise A1 - Elsen-Humberg, Stephan A1 - Koenigs, Timo A1 - Systermans, Thomas A1 - Sobol, Oded T1 - Tensile testing in high-pressure gaseous hydrogen using the hollow specimen method N2 - Metallic materials, predominantly steels, are the most common structural materials in the various components along the hydrogen supply chain. Ensuring their sustainable and safe use in hydrogen technologies is a key factor in the ramp-up of the hydrogen economy. This requires extensive materials qualification, however, most of the accepted; and standardized test methods for determining the influence of gaseous hydrogen on metallic materials describe complex and costly procedures that are only available to a very limited extent worldwide. The hollow specimen technique is a simple, rapid, and economical method designed to overcome the limitations of the current methods for the qualification of metallic materials under high-pressure hydrogen gas. However, this technique is not yet standardized. The TransHyDE-H2Hohlzug project is presented in this article, along with the main steps required to optimize the hollow specimen technique. This includes closing knowledge gaps related to the specimen geometry, surface quality, and gas purity in dedicated working packages, thus contributing to a comprehensive standardization of the technique for tests in high-pressure hydrogen gas. KW - High-pressure Gaseous Hydrogen KW - Hydrogen Embrittlement KW - Tensile Testing KW - Hollow Specimen Technique PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610557 DO - https://doi.org/10.1557/s43577-024-00776-9 VL - 49 SP - 1 EP - 9 PB - Springer Nature AN - OPUS4-61055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Konert, Florian A1 - Nietzke, Jonathan A1 - Grimault de Freitas, Tomás A1 - Rhode, Michael A1 - Sobol, Oded A1 - Böllinghaus, Thomas T1 - Investigation of resistance to gaseous hydrogen of a longitudinal weld seam in a X65 pipeline using the hollow specimen technique N2 - The constantly increasing demand for renewable energy sources leads to the necessity of transporting large amounts of hydrogen. Since pipelines enable a cost-effective way for the distribution of gaseous hydrogen, the interaction of hydrogen and the pipeline materials must be carefully investigated as hydrogen can cause a degradation of the mechanical properties under certain conditions. Especially welds, which are assumed to be more susceptible to the degradation enhanced by hydrogen, are of great interest. The aim of this study is to investigate the effect of gaseous hydrogen on the mechanical properties of an X65 pipeline, and the longitudinal submerged arc welding (SAW) welded joint. The tests are conducted using the hollow specimen technique on two types of specimens: one extracted from the base material (BM) and the other extracted as a cross-weld (CW) specimen consisting of BM and weld seam. The specimens are charged in situ under a pressure of 60 bar and tested using slow strain rate (SSR) tensile tests with a nominal strain rate of 10−5 s−1. The properties obtained of specimens tested in hydrogen atmosphere are compared to the properties of comparable specimen in inert argon atmosphere as a reference. The performed tests showed a decrease of the reduction of area (RA) from 72% in inert atmosphere to 52% in hydrogen atmosphere for the CW specimen and a decrease from 73% in inert atmosphere to 51% for the BM. Metallographic analyses showed the crack initiation between fine-grained heat-affected zone (FGHAZ) and BM for the specimens tested in hydrogen atmosphere as well as for the reference specimens. This leads to the conclusion that the location of the crack initiation does not change due to the presence of gaseous hydrogen. KW - Hydrogen KW - Hollow specimen technique KW - Pipeline KW - SSRT KW - Hydrogen embrittlement KW - Cross-weld specimen PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624658 DO - https://doi.org/10.1007/s40194-025-01953-3 SN - 0043-2288 SN - 1878-6669 VL - 69 IS - 3 SP - 861 EP - 870 PB - Springer CY - Berlin AN - OPUS4-62465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grimault de Freitas, Tomás T1 - Hollow Specimen Method for Tests in High-Pressure Hydrogen Gas: The Role of Strain-Rate and Surface Quality N2 - The hollow specimen technique is a simple and economical technique that has the potential to make materials qualification with pressurised gaseous hydrogen widely accessible to academia and industry. This contribution focuses on the results obtained from assessing the influence of the specimen production and its response to hydrogen effects. Depending on the production method, different roughness and residual stresses can be expected on the inner hole surface of the specimens. This is relevant because an increase in stress concentration sites, e.g. notches, has been found to be associated with increased severity of hydrogen effects. The presence of strain-induced martensite caused by mechanical stress may also be detrimental and accelerate the embrittlement. To assess this influence, the inner hole of the hollow specimens was manufactured in two different ways: 1) only drilling; 2) EDM followed by honing. A representative steel widely used in hydrogen technologies was assessed, X5CrNi18-10 (AISI 304). Roughness measurements, and electron back-scatter diffraction (EBSD) analysis have been performed previous to mechanical testing to infer on the effect of the different production methods on the surface of the inner hole. Next, the specimens were mechanically tested via slow strain rate tensile tests in argon and in hydrogen, both at 150 bar and room temperature. Here, a strain-rate sensibility analysis was performed to investigate the influence of strain-rate on hydrogen degradation. T2 - International Conference on Hydrogen Safety 2025 CY - Seoul, South Korea DA - 22.09.2025 KW - Tensile Testing KW - Hollow Specimen Technique KW - High-Pressure Hydrogen Gas KW - Hydrogen Embrittlement KW - Surface Condition KW - Strain Rate PY - 2025 AN - OPUS4-64286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grimault de Freitas, Tomás T1 - Hollow Specimen Method for Tests in High-Pressure Hydrogen Gas: The TransHyDE - H2HohlZug Project N2 - As the world moves towards a decarbonised economy, the demand for sustainable and low-carbon alternatives is growing rapidly. Hydrogen has an important role to play in this transition, but in order to make the most of hydrogen as an energy carrier, a comprehensive understanding of its impact on the integrity of structural materials is necessary. Metallic materials, mainly steels, are the most commonly used structural materials in various components throughout the hydrogen supply chain. Ensuring their sustainable and safe use in hydrogen technologies is a crucial factor in the development of the hydrogen economy. This is particularly important since hydrogen can promote crack formation and ultimately lead to premature failure in these materials when combined with mechanical load. This process is commonly known as Hydrogen Embrittlement and can occur in almost all the steels used for the hydrogen technologies. Extensive materials qualification is required for the rapid implementation of hydrogen technologies, however, most accepted, and standardised test methods for determining the effect of gaseous hydrogen on metallic materials describe complex and costly procedures that are only available to a very limited extent worldwide. The hollow specimen technique is a simple and economical method that has the potential to overcome the limitations of the current methods and complement them for qualifying metallic materials under high-pressure hydrogen gas. Unlike the conventional autoclave technique, this method requires significantly lower amounts of hydrogen, resulting in fewer safety measures and no need for complex equipment or a specialised laboratory. The technique's low investment and testing costs, simple operation, and shorter testing time make it an optimal for widespread use around the world, thereby increasing the output of results. Initial studies have demonstrated the feasibility of assessing hydrogen effects in metallic materials using the hollow specimen technique. This led to the establishment of an ISO committee to standardise the method. However, there are open questions that currently prevent the technique from being standardised for hydrogen testing. These open questions relate to specimen geometry, inner hole surface and gas quality and are being addressed in the H2HohlZug project, of which the overall aim is to systematically close the gaps towards a standard. This contribution presents the structure and milestones of the project, followed by initial results. T2 - TransHyDE Vollversammlung 2025 CY - Leipzig, Germany DA - 26.11.2025 KW - Hydrogen KW - Hydrogen Embrittlement KW - Hollow Specimen Technique KW - High-Pressure Gaseous Hydrogen KW - TransHyDE KW - H2HohlZug KW - Standardisation PY - 2025 AN - OPUS4-64938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Konert, Florian T1 - Evaluation of hydrogen effect on hardened and annealed 100Cr6 steel N2 - The use of hydrogen demands high safety requirements, since hydrogen can be absorbed by metallic materials and may cause hydrogen embrittlement (HE) under certain conditions. Slow strain rate (SSR) tensile testing is a widespread method to quantify the hydrogen-induced ductility loss of alloys. Here, the hollow specimen technique was used to evaluate the effect of 150 bar hydrogen on the tensile properties of solution annealed and hardened 100Cr6 steel, which is a common material for bearing systems. This technique reduces the required amount of hydrogen and minimizes the duration and costs of the tests performed compared to in-situ tensile tests in autoclaves. T2 - EPRI Workshop on Hydrogen Embrittlement 2024 CY - Oxford, UK DA - 23.06.2024 KW - Hydrogen KW - Hydrogen Embrittlement KW - Hollow Specimen Technique KW - 100Cr6 PY - 2024 AN - OPUS4-60476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nietzke, Jonathan T1 - Influence of strain rate on the effect of hydrogen in pre-charged 316L stainless steel: A comparison of conventional and hollow specimen testing N2 - The growing demand for hydrogen requires an expansion of testing capabilities to assess the performance of metallic materials under hydrogen exposure. Considering only gaseous atmospheres, there is a variety of in-situ and ex-situ methods used to investigate the material behavior while or after exposed to hydrogen, respectively. Among these methods, a more conservative one is the in-situ testing at slow strain rates (SSRT) using conventional tensile specimens. While results obtained by a conservative procedure may be more applicable in many cases than those of ex-situ experiments, the tests are quite demanding, leading to limited testing capacities and high costs, especially for very slow strain rates. A possible solution that can enable in-situ testing at relatively low cost is the hollow specimen technique which gained increasing interest in the last decade. The main reasons are the minimal volume of hydrogen required and the elimination of a high-pressure hydrogen autoclave leading to significantly lower costs and enabling more laboratories worldwide to perform these tests. However, interpreting results from hollow specimens, especially when compared to conventional ones, remains a significant challenge. To address this, an experimental study was conducted using conventional and hollow specimens, both uncharged and pre-charged. Pre-charging was achieved using pure hydrogen (5.0, i.e. 99.999 %) at 100 bar and 300 °C for around 21 days. In order to obtain suitable reference specimens, other specimens were stored in argon at 100 bar and 300 °C for the same period of time. The tests were performed at various strain rates, down to 1E-6 1/s. While these ex-situ experiments are not directly comparable to in-situ tests with both types of specimens, they do provide some insights into the differences between the results of hollow and conventional specimens. Therefore, the elongation at fracture and reduction of area (RA) were compared, among other aspects. In addition, fractographical analyses were carried out using SEM images. Elongation at fracture was not significantly affected by hydrogen in conventional specimens, but it was slightly reduced in hollow specimens. RA, on the other hand, was lower for tests with hydrogen in both types of specimens across all strain rates. Moreover, the strain rate did not appear to influence hydrogen embrittlement in conventional specimens whereas in hollow specimens, tests conducted at higher strain rates (1E-4 1/s) showed a greater impact of hydrogen on elongation at fracture than those at lower strain rates (1E-6 1/s), which is contrary to the typical expectation. These findings suggest that the influence of hydrogen differs between conventional and hollow specimens, possibly due to factors such as surface roughness and differing stress states. However, further experiments are needed to fully understand these differences, including in-situ experiments to understand potential differences in hydrogen absorption between the two specimen types. T2 - EPRI Workshop on Hydrogen Embrittlement CY - Oxford, England, United Kingdom DA - 23.06.2024 KW - Stainless steel KW - Hollow specimen KW - Pre-charging KW - Hydrogen PY - 2024 AN - OPUS4-60494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shikomba, Nikanor A1 - Böllinghaus, Thomas A1 - Konert, Florian A1 - Sobol, Oded A1 - Blasón Gonzalez, Sergio A1 - Ohijeagbon, Idehai Olayemi A1 - Krafft, Eike A1 - Staudt, Thorsten T1 - Resistance of welded low-alloyed pressure vessel and pipeline steels in gaseous hydrogen N2 - Green hydrogen has become an essential energy carrier to achieve a climate-neutral economy. The production, storage, transport and usage of green hydrogen require safe and sustainable facilities and systems. The present contribution provides a procedure guideline to investigate the compatibility of steel welds for pressurised gaseous hydrogen applications under quasi-static mechanical loads, utilising the slow strain rate test and hollow specimen technique. Exemplarily, a weld of the low-alloyed steel P355NL1 was investigated and compared to an X65 weld. The results indicate that the base metal exhibits a higher ductility than the weld metal for both steels. Generally, hydrogen-exposed specimens exhibited a reduced strain, as compared to reference specimens. The hydrogen degradation, evaluated by the hydrogen embrittlement index, was more pronounced in the weld metal compared to the base P355NL1 material, whereas the X65 exhibited a larger hydrogen degradation of the base material than in the weld metal. Fractographic analysis of the test specimens revealed that hydrogen causes a transition from ductile to brittle features. Generally, the results of this study indicate a mild but significant degradation of the mechanical properties in terms of the ductility of the welds in the respective pressurised hydrogen atmosphere. KW - Hydrogen-assisted cracking KW - Welded joint KW - Slow strain rate test KW - Hollow Specimen KW - Structural steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634138 DO - https://doi.org/10.1007/s40194-025-02074-7 SN - 0043-2288 SP - 1 EP - 15 PB - Springer CY - Berlin AN - OPUS4-63413 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -