TY - CONF A1 - Kröll, Mirco T1 - Tribological performance of polymer compounds in gaseous hydrogen N2 - In this study, friction and wear of conventional and alternative high performance polymer compounds, typically used for components of compressors, were investigated in gaseous hydrogen and nitrogen up to 80 bar of gas pressure. The compounds used were a commercial PEEK matrix with 10 wt.% each of PTFE, graphite, and short carbon fibres, a PPS matrix with 10 wt.% each of PTFE and graphite, and an experimental PA12 matrix with PTFE chemically coupled with an oleyl alcohol. Due to the cylindrical shape of the polymer samples, the contact area and pressure change if wear occurs. Therefore, experimental results of pre-screening tests have been used as input for FEM and an analytical model to determine the decreasing contact pressure over time. Afterwards, the outcome of the models was used to determine the duration of the experiments to reach typical contact pressures of seals in hydrogen compressors. T2 - ASMET TriboCorrosion International Conference 2025 CY - Vienna, Austria DA - 23.10.2025 KW - Hydrogen KW - Polymer KW - Tribometer KW - Comparability KW - Harmonisation KW - Oil-coupled compounds KW - Coefficient of Friction KW - Wear KW - FAIR data KW - Standardisation KW - Tribology KW - Database KW - i-TRIBOMAT PY - 2025 AN - OPUS4-64473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Comparison of the sliding behavior of several polymers in gaseous and liquid hydrogen N2 - The development of hydrogen technologies entails high safety requirements in distribution and dispensing infrastructure. Therefore, it is necessary to pursue research on material compatibility in hydrogen, especially for critical parts with tribological issues. The focus of this study is to evaluate the influence of hydrogen on a wider range of commercially available polymer materials. Thereby, the friction and wear behavior of different grades of TPE, POM, PA66, PA12, PPA, PEEK, PPS, PTFE, PAI, PI and PBI were investigated against a rotating steel disk (AISI 304). Filled and unfilled polymers from different suppliers were evaluated at room temperature in air, vacuum and hydrogen gas (H2) as well as in liquid hydrogen at - 253°C (LH2). The sliding behavior of the polymer materials is discussed by means of surface analyses, whereby special attention is paid to the formation of a transfer film. According to the results at ambient temperature, the effect of hydrogen environment on the tribological behavior of neat polymers may be related to lack of moisture, but also to saturated hydrocarbons in gaseous hydrogen. In liquid hydrogen, the best tribological performances were achieved with neat PA polymers as well as PPS and PI composites. KW - Polymers KW - Composites KW - Sliding wear KW - Hydrogen KW - Cryogenic temperature PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597123 DO - https://doi.org/10.2474/trol.18.217 SN - 1881-2198 VL - 18 IS - 5 SP - 217 EP - 231 PB - Japanese Society of Tribologists AN - OPUS4-59712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Comparison of the sliding behaviour of several polymers in hydrogen N2 - The work presented here deals with the friction and wear behaviour of polymer materials in hydrogen. Commercially available grades of PEEK, PA, PPA, PAI, PI and PBI were investigated at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -253°C (LH2). T2 - 7th World Tribology Congress, WTC 2022 CY - Lyon, France DA - 10.07.2022 KW - Friction KW - Wear KW - Polymers KW - Hydrogen KW - Cryogenic PY - 2021 SP - 1 AN - OPUS4-62089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Influence of counterface and environment on the tribological behaviour of polymer materials N2 - This paper focuses on the influence of the counterface materials on the sliding behaviour of polymer materials in hydrogen. Polyimide (PI), polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE) materials were investigated against hardened 52100 martensitic bearing steel and 304 austenitic stainless steel with similar roughness (Ra = 0.2 μm). Results indicate that the friction and wear of PI and PEEK materials depend on the counterface material. This effect wasn’t observed for PTFE composites. While the tribological performance of polyimide is better against 52100 in hydrogen, improved sliding behaviour of PEEK materials is observed with 304 counterface, particularly at higher sliding speed. Surface analyses of the transfer film reveal that the influence of the counterface is primarily related to the chemical nature of the steel for PI and to the thermal conductivity of the disc for PEEK materials. KW - Friction KW - Wear KW - Polymers KW - Hydrogen Transfer Film PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515483 DO - https://doi.org/10.1016/j.polymertesting.2020.106912 VL - 93 SP - 106912 PB - Elsevier Ltd. AN - OPUS4-51548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Influence of the counterface on the sliding behavior of polymer materials in hydrogen N2 - This presentation deals with the influence of the counterface materials on the sliding behaviour of some polymer materials in hydrogen. Polyimide (PI), polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE) materials were investigated against hardened 52100 martensitic bearing steel and 304 austenitic stainless steel with similar roughness (Ra = 0.2 μm). Results indicate that the friction and wear of PI and PEEK materials depend on the counterface material. This effect wasn’t observed for PTFE composites. While the tribological performance of polyimide is better against 52100 in hydrogen, improved sliding behaviour of PEEK materials is observed with 304 counterface, particularly at higher sliding speed. Surface analyses of the transfer film reveal that the influence of the counterface is primarily related to the chemical nature of the steel for PI and to the thermal conductivity of the disc for PEEK materials. T2 - Hydrogenius & I2CNER Tribology Symposium CY - Online meeting DA - 29.01.2021 KW - Polymers KW - Hydrogen KW - Counterface KW - Friction KW - Wear PY - 2021 AN - OPUS4-52093 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Polymer materials in hydrogen N2 - This presentation provides an overview of the applications and challenges related to polymer materials in hydrogen. The effects of hydrogen on polymers are described and test methods to evaluate the interactions between polymers and hydrogen are presented along with case studies. T2 - Masterstudiengang Wasserstofftechnologien DIU CY - Online meeting DA - 25.08.2023 KW - Hydrogen KW - Polymers PY - 2023 AN - OPUS4-61964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Tribology of polymeric materials in gaseous and liquid hydrogen N2 - This presentation gives an overview of the tribological behaviour of polymeric materials in gaseous and luquid hydrogen. T2 - HYDROGENIUS-BAM Joint Hydrogen Symposium CY - Online meeting DA - 06.07.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-53701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Benchmarking of polymer materials for tribological applications in hydrogen N2 - The focus of this study is to evaluate of hydrogen on the friction and wear behavior of a wide range of polymer materials. Thereby, the tribological performance of filled and unfilled polymers from different suppliers were compared at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -253°C (LH2). T2 - 62. Tribologie-Fachtagung der Gesellschaft für Tribologie e. V. CY - Online meeting DA - 27.09.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-53700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cano Murillo, Natalia T1 - Effect of high-pressure hydrogen environment on the physical and mechanical properties of different kinds of carbon black filled elastomers. N2 - As the transition towards the usage of renewable energy is getting urgent, the fluctuations of clean energy production require efficient storage alternatives. Hydrogen offers not only the possibility of energy storage but also, acts as an energy carrier. It is then important to study the effect of highly pressurized hydrogen atmosphere on the materials destinated for its storage and transport, in order to assure the reliable performance of the sealing materials containing hydrogen. In this study, a set of carbon black (CB) filled rubbers comprising hydrogenated acrylonitrile butadiene rubber (HNBR), acrylonitrile butadiene rubber (NBR) and ethylene propylene diene monomer rubber (EPDM) was tested under high pressure hydrogen atmosphere (1000 bar) and at different temperature conditions: 120°C for HNBR, room temperature and 85°C for NBR and EPDM. The influence of hydrogen on the materials properties was measured after 7 days of exposure under hydrogen and evaluated again after 48h. Density and volume change, as well as hardness, tensile tests, compression set, dynamic mechanical measurements and infrared spectroscopy evaluations were conducted to estimate the impact of high-pressure hydrogen on the rubber grades. Our study reveals, an effect on the physical and mechanical properties, possibly related to small changes in the matrix-filler interaction after the hydrogen exposure. All materials, however, show a trend to recover most of their properties 48h after hydrogen exposure. T2 - RubberCon 2023 CY - Edinburgh, Scotland DA - 09.05.2023 KW - Elastomers KW - Hydrogen exposure KW - Mechanical properties PY - 2023 AN - OPUS4-62007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Comparison of the sliding behaviour of several polymers in hydrogen N2 - The work presented here deals with the friction and wear behaviour of polymer materials in hydrogen. Commercially available grades of PEEK, PA, PPA, PAI, PI and PBI were investigated at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at - 253°C (LH2). T2 - 7th World Tribology Congress, WTC 2022 CY - Lyon, France DA - 10.07.2022 KW - Friction KW - Wear KW - Polymers KW - Hydrogen KW - Cryogenic PY - 2022 AN - OPUS4-62087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denora, Isabella A1 - Clute, Clara A1 - Murillo, Natalia Cano A1 - Theiler, Geraldine A1 - Balasooriya, Winoj A1 - Kaiser, Andreas A1 - Fasching, Michael A1 - Schwarz, Thomas A1 - Marano, Claudia T1 - A study on the mechanical behaviour of carbon black and Struktosil-filled NBR compounds for hydrogen applications N2 - This study investigates the effect of the addition of a 2D filler (Struktosil) to a carbon black-filled acrylonitrile butadiene rubber, developed for seals in hydrogen applications. Several characterization methods have been adopted. The addition of Struktosil increases the stiffness of the material up to a strain of about 100%, to a lesser extent in presence of a plasticizer. The dissipative response of the material is increased by Struktosil addition and decreased in presence of the plasticizer. Concerning fracture behaviour, the crack initiation and Rapid Gas Decompression (RGD) resistance were not affected by the addition of Struktosil but decreased in presence of plasticizer. Furthermore, the addition of Struktosil had a positive effect on crack propagation resistance. The effects of pressurized hydrogen exposure on physical-mechanical properties were also evaluated and correlated with the results. A correlation between fracture toughness and RGD resistance has been also attempted. KW - Acrylonitrile Butadiene rubber KW - Fracture mechanics KW - 2D filler KW - High-pressure hydrogen KW - Rapid gas decompression PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648285 DO - https://doi.org/10.1016/j.ijhydene.2025.03.122 SN - 0360-3199 VL - 118 SP - 407 EP - 416 PB - Elsevier Ltd. AN - OPUS4-64828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Cano Murillo, Natalia A1 - Sawae, Y. A1 - Shinmori, H. A1 - Hashimoto, H. A1 - Aoyagi, A. A1 - Dobbelaar, E. T1 - Towards sustainable and hydrogen compatible sealing materials N2 - Materialien auf PTFE-Basis werden in der Regel als Kolbenringe in Hochdruck- und/oder kryogenem Wasserstoff verwendet. In diesem Projekt werden neu formulierte und nachhaltigere Polymerwerkstoffe mit herkömmlichen Materialien verglichen. Auf Grundlage der tribologischen Ergebnisse werden vielversprechende Kandidaten zusammen mit Reibungsmechanismen sowohl bei Hochdruck- als auch bei Niedrigtemperatur-Wasserstoff vorgeschlagen. T2 - 66. GfT Tribologie-Fachtagung 2025 CY - Wernigerode, Germany DA - 29.09.2025 KW - Wasserstoff KW - Reibung KW - Verschleiß KW - Kolbenring KW - Dynamische Dichtung PY - 2025 VL - 09 SP - 1 EP - 4 AN - OPUS4-64314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - An overview of tribology in gaseous Hydrogen N2 - In this presentation, an overview in gaseous hydrogen is given along with examples related to metal, coatings, polymers and rubbers materials. T2 - International Seminar, Hydrogen & Materials 2024 CY - Espoo, Finland DA - 06.06.2024 KW - Hydrogen KW - Friction KW - Wear KW - Materials PY - 2024 AN - OPUS4-61408 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Halder, Karabi A1 - Balasooriya, Winoj T1 - Effect of high-pressure hydrogen environment on the physical and mechanical properties of elastomers N2 - This paper deals with the exposure of HBNR rubbers to high pressure hydrogen (100 MPa) at 120 °C for 7 and 21 days under static conditions followed by characterization of their physical and mechanical properties. T2 - EHEC European Hydrogen Energy Conference 2022 CY - Madrid, Spain DA - 18.05.2022 KW - Rubbers KW - Hydrogen KW - Characterization PY - 2022 SP - 1 EP - 2 AN - OPUS4-62085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Effect of hydrogen pressure on the fretting behavior of elastomers N2 - In this study, the fretting behavior of several elastomer materials against 316L were evaluated in air and hydrogen environment up to 10 MPa. Furthermore, aging experiments were conducted for 7 days under static conditions in 100 MPa hydrogen and the physical and mechanical properties of the rubber materials were examined before and after hydrogen exposure. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After aging experiment, the friction response of HNBR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip. T2 - 4th Int. Conf. on Polymer Tribology, PolyTrib 2022 CY - Stockholm, Sweden DA - 05.12.2022 KW - Hydrogen KW - Fretting KW - Elastomers PY - 2022 AN - OPUS4-62006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Toward sustainable and hydrogen compatible sealing materials N2 - As sealing components, polymeric materials are used in a wide range of applications e.g. as O-rings and piston rings in high-pressure and/or cryogenic hydrogen. For these extreme demanding application, PTFE or PPS based materials are often used as high-performance polymer matrix. This project aims to provide a safe and sustainable sealing solutions for hydrogen applications. New materials with improved sustainability were investigated and compared with conventional grades. Tests were performed in hydrogen over a wide range of temperature and pressure (0.1 MPa to 40 MPa, and 100°C down to -150°C) at Kyushu University and BAM using a pin-on-disk apparatus in a continuous sliding motion. Polymer samples ran against 316L disk at 0.5 m/s and 3 MPa contact pressure. Based on the tribological results and surface analyses, promising candidates are suggested along with friction mechanisms in both high-pressure and low temperature hydrogen. T2 - STLE Meeting CY - Atlanta, Georgia, USA DA - 18.05.2025 KW - Hydrogen KW - Friction KW - Wear KW - Piston ring KW - Reciprocating seals PY - 2025 AN - OPUS4-63809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Benchmarking of polymer materials for tribological applications in hydrogen N2 - The focus of this study is to evaluate the influence of hydrogen on the friction and wear behavior of a wide range of polymer materials. Thereby, the tribological performance of filled und unfilled polymers from different suppliers were compared at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -235°C (LH2). T2 - 23rd International Conference on Wear of Materials CY - Online meeting DA - 26.04.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-52651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - Comparative evaluation of the sliding performance of polymers materials in gaseous and liquid hydrogen N2 - The focus of this study is to evaluate the influence of hydrogen on the friction and wear behavior of a wide range of commercially available polymer materials. Thereby, Filled and unfilled polymers from different suppliers were evaluated at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at - 253°C (LH2). T2 - 2023 Hydrogenius & I2CNER Tribology Symposium CY - Fukuoka, Japan DA - 03.02.2023 KW - Hydrogen KW - Tribology KW - Cryogenic KW - LH2 KW - Polymers PY - 2023 AN - OPUS4-61961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - On the assessment of dynamic fracture toughness of ferritic ductile cast iron using the master curve concept N2 - An established and validated method to determine and assess dynamic fracture toughness values of ferritic ductile cast iron (DCI) in the ductile-to-brittle transition regime is currently not available. Although the ASME-Code, Sect. III, Div. 3, WC-2330 explicitly requires safety assessment considerations for dynamic loading, sufficiently substantial information on the procedure is not given. Therefore, the applicability of the probabilistic Master Curve (MC) concept according to ASTM E1921 to DCI is being investigated in the joint German research project MCGUSS conducted by BAM Berlin and MPA Stuttgart. Using a tailored manufacturing specification, a DCI material of grade GJS-400 has been casted to provide a test material which is very homogeneous but typical for heavy-sections. The experimental test program covers test specimens of various geometries and sizes (Tensile, Charpy-V, Pellini, SE(B)10, SE(B)25, SE(B)140, DC(T)9, C(T)25 and C(T)50). In total about 500 specimens will be tested to investigate and validate the Master Curve concept and its background for DCI (e.g. size effects, weakest-link, Weibull distribution, microstructure-property correlation). While the whole project has not yet concluded, several work packages have already been completed. This presentation is focused on dynamic large-scale fracture mechanics test series using SE(B)140 specimens and instrumented Charpy impact testing using ISO-V specimens. T2 - European Conference on Fracture 2024 CY - Zagreb, Croatia DA - 26.08.2024 KW - Dynamic fracture toughness KW - Ductile cast iron KW - Master curve concept PY - 2024 AN - OPUS4-61452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - Recent Results on the Investigation of the Master Curve Concept for Ferritic Ductile Cast Iron N2 - Within the current framework for safety assessment of ferritic ductile cast iron (DCI) containers for transport as well as interim and final storage of radioactive materials, the IAEA guidelines SSG 26 apply fracture mechanics principles. Crack initiation in either, stable or unstable modes is generally forbidden. Additionally, for DCI, the ASME-Code, Sect. III, Div. 3, WC-2330, explicitly requires a safety proof regarding dynamic loading conditions. Nevertheless, corresponding information given in the ASME Code does not seem to be sufficient to appropriately perform a dynamic fracture mechanics safety assessment for DCI. To address and improve this status of the dynamic brittle fracture safety assessment framework for DCI, the application of the fracture mechanics master curve (MC) concept to DCI is being investigated in an ongoing joint research project (acronym MCGUSS) between BAM Berlin and MPA Stuttgart. For ferritic DCI, the MCGUSS project addresses the currently lacking systematic review of applicability and potential modifications to the assumptions and the procedure according to ASTM E1921. The aim is to establish a methodology to determine and assess dynamic fracture toughness values of DCI in the ductile-to-brittle transition regime using small samples extracted from a component. The research approach and the planned investigations were outlined in more detail earlier. This paper is focused on the discussion of recent experimental results to establish the dynamic fracture mechanics toughness data base and its MC analyses. MCGUSS fracture mechanics test setups and the dynamic fracture toughness data base achieved at the time of abstract submission is discussed (covering 128 specimens). Current application limits of ASTM E1921 MC to DCI are discussed, and planned investigations to further investigate and modify the MC procedure for DCI are outlined. T2 - ASTM 23rd International ASTM/ESIS Symposium on Fatigue and Fracture Mechanics CY - Atlanta, GA, USA DA - 12.11.2025 KW - Dynamic fracture toughness KW - Ductile cast iron KW - Safety assessment KW - Master curve KW - Statistics PY - 2025 AN - OPUS4-64746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzwarth, Marcel A1 - Baer, Wolfram T1 - Investigation of the Master Curve Concept for Ferritic Ductile Cast Iron N2 - The current framework for safety assessment of ferritic ductile cast iron (DCI) containers for transport and storage of radioactive materials applies fracture mechanics principles. As established by the IAEA safety standard SSG 26, prevention of crack initiation is the governing criterion and no reliance in design should be placed on any predicted ductile tearing resistance. Similarly, the ASME-Code, Sect. III, Div. 3 explicitly deals with DCI and requires a safety proof for dynamic loading conditions. However, information given in the guidelines does not seem to be sufficient to appropriately perform such dynamic fracture mechanics safety assessments. The ongoing German research project MCGUSS is tailored to tackle this status. In MCGUSS, the application potential of the probabilistic fracture mechanics master curve (MC) concept according to ASTM E1921 is being systematically investigated and potential modifications specific for dynamic brittle fracture of DCI will be identified. While MCGUSS covers testing of a high number of SE(B)- and C(T)-type specimens, this poster focuses on preliminary C(T) results. The obtained data was statistically analyzed, and current results of MC analyses are discussed. Special emphasis of MCGUSS is on using optical and scanning electron microscopy to link microstructural damage and failure processes to the fracture toughness data gained. A fracture mechanism called "specimen size-dependent arrest of local brittle fractures before global brittle failure by weakest link" is proposed to describe the established dynamic toughness data. Concerning the MC concept, it was shown that the ASTM E1921 procedure cannot simply be adopted to dynamic DCI toughness data on a one-to-one basis. Material specific modifications are being investigated and the DCI dynamic fracture toughness data base is to be expanded. T2 - MPA Conference 2025 CY - Stuttgart, Germany DA - 06.10.2025 KW - Dynamic fracture toughness KW - Ductile cast iron KW - Safety assessment KW - Master curve KW - Statistics PY - 2025 AN - OPUS4-64367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Kiyak, Yusuf A1 - Breidung, Marc A1 - Baer, Wolfram A1 - Küppers, M. ED - Madia, Mauro T1 - Stiffness/constraint effects in analytical flaw assessment - A technical note N2 - Using the case study of a fail-safe design criterion for a steering knuckle of a commercial vehicle, the effect of stiffness/constraint on the crack driving force in the component is discussed. The problem arises when assessment procedures such as R6, BS 7910 or SINTAP/FITNET are applied in conjunction with substitute geometries for determining the model parameters K-factor and limit load (or a substitute for the latter), as it is common practice. In the example, the conservatism was so pronounced that this procedure was in fact unusable. A way out could be the finite element-based determination of the model parameters and their use in the analytical framework. This procedure is useful and effective if the finite element-based calculations are used in parameter sensitivity analyses. KW - Fail-safe design KW - Fracture resistance KW - Fracture assessment KW - Stiffness KW - Constraint PY - 2022 DO - https://doi.org/10.1016/j.engfracmech.2022.108728 SN - 0013-7944 IS - 273 SP - 1 EP - 15 PB - Elsevier Science CY - Kidlington AN - OPUS4-55544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - Was Sie schon immer über Chunky-Graphit wissen w(s)ollten, aber bisher nicht zu fragen wagten N2 - Duktile Gusseisenwerkstoffe mit Kugelgraphit (GJS) haben ein erhebliches technisches Potenzial und sind von wirtschaftlicher Bedeutung. Nicht zuletzt daher ist es ökonomisch sinnvoll, gesellschaftlich nachhaltig und wissenschaftlich interessant, ihren Herstellungsprozess zu optimieren. Eine maßgebliche Rolle kommt hierbei der Vermeidung von Qualitätsabweichungen in Form von Gefügefehlern zu. Dieser Beitrag befasst sich mit der – leider vielfach nicht richtig oder zu wenig verstandenen, aber insbesondere bei kostenintensi-ven dickwandigen Gussteilen relevanten - Graphitentartung Chunky-Graphit (CG). Die metallurgischen Ursachen von CG werden noch immer kontrovers diskutiert. Eine allgemein akzeptierte Theorie zur Bildung und dem Wachstumsmechanismus von CG existiert nicht, in der Gießereipraxis wird gleichwohl eine Fülle spezifischer technologischer Abhilfemaßnahmen praktiziert [1]. Der Schwerpunkt dieses Beitrages liegt jedoch nicht auf der metallurgischen Seite, sondern auf der Beschrei-bung der spezifischen Morphologie von CG (Bild 1), dessen Detektion im Werkstoff bzw. Bauteil sowie den Auswirkungen von CG auf die Werkstoffeigenschaften. Detailliert werden Möglichkeiten und Grenzen zer-störungsfreier und zerstörender Untersuchungsverfahren zur Identifikation und Quantifizierung von CG aufgezeigt. Ausgehend von der charakteristischen Morphologie von CG wird dessen Einfluss auf das Ver-formungs- und Bruchverhalten von GJS behandelt. Beispielhaft werden dabei die Eigenschaften Festigkeit, Verformbarkeit, das Risswachstumsverhalten und die Bruchzähigkeit diskutiert und Schlussfolgerungen für die Bewertung von mit CG behafteten GJS-Bauteilen abgeleitet. T2 - Ledebur-Kolloquium 2023 CY - Freiberg, Germany DA - 26.10.2023 KW - Gusseisen mit Kugelgraphit GJS KW - Chunky-Graphit KW - Graphitentartung KW - Duktiles Gusseisen PY - 2023 AN - OPUS4-58636 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - Investigation of the Master Curve Concept for Ferritic Ductile Cast Iron (DCI) N2 - Based on state-of-the-art research and regulations, the application of the fracture mechanics master curve (MC) concept to ferritic ductile cast iron (DCI) is being investigated in a recently started German joint research project between BAM Berlin and MPA Stuttgart. This paper outlines the research approach and the planned investigations and provides first results. According to the IAEA guidelines SSG 26, the safety assessment of DCI containers for transport as well as interim and final storage of radioactive materials is based on the fracture mechanics criterion of general crack initiation exclusion. Within this context, the focus of the current research project is on the further development of brittle fracture safety assessment methods under dynamic loading conditions. Within fracture mechanics safety assessments for steels in nuclear technology, the probabilistic MC concept according to ASTM E1921 is currently used for quasi-static loading conditions as a supplement to the established deterministic ASME reference curve concept. The MC concept allows for an effective statistical consideration of the scatter of the material toughness in the transition regime. Furthermore, the MC can also be used for elevated loading rates as they occur in accident or crash scenarios. However, for DCI, a systematic review of potential modifications to the MC assumptions and procedure according to ASTM E1921 and an associated validation are still lacking. Therefore, a corresponding methodology shall be established to determine and assess dynamic fracture toughness values of DCI in the ductile-to-brittle transition regime, using samples extracted from a component. For the experimental program, a DCI material was produced as it is generally used for transport and storage containers. A basic mechanical-technological material characterization consisting of tensile, Charpy, and Pellini tests is planned. A comprehensive fracture mechanics test program was compiled covering dynamic testing of DC(T)9, C(T)25, C(T)50, SE(B)10, SE(B)25, and SE(B)140 specimens. Moreover, numerical analyses of different specimen geometries and test setups are planned to investigate the influences of stress triaxiality and loading rate. Throughout the experimental program, the microstructure-property relationship will be investigated based on quantitative metallographic and fractographic analyses. Finally, different MC assessment strategies will be considered, and modifications will be made if necessary. T2 - PATRAM22 Conference CY - Juans-les-Pins, France DA - 11.06.2023 KW - Dynamic Fracture Toughness KW - Ductile Cast Iron KW - Master Curve Method PY - 2023 AN - OPUS4-57766 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - Aspekte der analytischen bruchmechanischen Bauteilbewertung N2 - Am Beispiel eines abgesetzten zylindrischen Bauteils (Achsschenkel) werden Probleme der analytischen bruchmechanischen Bauteilbewertung diskutiert. Als Basis-philosophie wird ein Fail Safe-Kriterium (kontrolliertes Versagen) angesetzt. Die Forderung ist, dass sich der Achsschenkel, bevor er bricht, in einem Ausmaß plastisch verformen kann, bei dem der Fahrer bemerkt, dass mit seinem Fahrzeug etwas nicht in Ordnung ist. Um das zu gewährleisten, muss der Werkstoff einen bestimmten Riss-widerstand aufweisen. Dazu werden im hier vorgestellten ersten Teil des Projektes mittels FEM Rissspitzenbeanspruchungen in Abhängigkeit von der Auslenkung des Zylinders und angenommener Rissgrößen ermittelt. Diese finden als Zielgrößen in der weiteren Analyse Anwendung. Da eine einfach umzusetzende Lösung angestrebt wird, werden zusätzlich analytische Rechnungen an Ersatzgeometrien (halbunendliche Platte und Vollzylinder), aber mit den realen Spannungen am Bauteil durchgeführt. Es zeigt sich, dass die Ergebnisse wegen des Steifigkeitsunterschieds zwischen Bauteil und Ersatzgeometrie unvertretbar konservativ sind. Alternativ wird ein hybrides Konzept vorgestellt, für das die Modellparameter mittels FEM bestimmt werden. Es liefert sehr genaue Ergebnisse. Im Rahmen der analytischen Rechenvorschrift können die Lösungen auf andere Werkstoffe übertragen werden, ohne dass zusätzliche FEM-Analysen notwendig sind. T2 - 54. Tagung des DVM-Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Online meeting DA - 22.02.2022 KW - Bauteilbewertung KW - Fail-safe KW - Analytisches Modell KW - FEM PY - 2022 AN - OPUS4-54408 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzwarth, Marcel A1 - Baer, Wolfram A1 - Mayer, Uwe A1 - Weihe, Stephan T1 - Investigation of the Master Curve Concept for Ferritic Ductile Cast Iron N2 - Within fracture mechanics safety assessment for steels in nuclear technology, the probabilistic master curve (MC) concept according to ASTM E1921 is currently used for quasi-static loading conditions as a supplement to the established deterministic ASME reference curve concept. However, for ductile cast iron (DCI), a systematic review of potential modifications to the assumptions and the procedure according to ASTM E1921 and an associated validation are still lacking. For this reason, the application of the fracture mechanics MC concept to ferritic ductile cast iron is being investigated in a recently started joint research project between MPA Stuttgart and BAM Berlin. According to the IAEA guidelines SSG 26, the safety assessment of DCI containers for transport as well as storage of radioactive materials is based on the fracture mechanics criterion of general crack initiation exclusion. Within this context, the focus of the current research project is on the further development of brittle fracture safety assessment methods. Therefore, a methodology shall be established to determine and assess dynamic fracture toughness values of DCI in the ductile-to-brittle transition regime, using samples extracted from a component. For the experimental program, a DCI material will be produced as it is generally used for transport and storage containers. A basic mechanical-technological material characterization consisting of tensile, Charpy and Pellini tests is planned and a comprehensive fracture mechanics test program was compiled covering dynamic testing of DC(T)9, C(T)25, C(T)50, SE(B)10, SE(B)25, and SE(B)140 specimens. Numerical analyses of different specimen geometries and test setups are planned to investigate the influences of stress triaxiality and loading rate. Throughout the experimental program, the microstructure-property relationship will be investigated based on quantitative metallographic and fractographic analyses. Finally, different MC assessment strategies will be considered and modifications will be made if necessary. T2 - 21st International Symposium ASTM/ESIS Symposium on Fatigue and Fracture Mechanics CY - Washington, DC, USA DA - 08.11.2023 KW - Ductile Cast Iron KW - Dynamic Fracture Toughness KW - Cleavage Fracture KW - Master Curve Concept PY - 2023 SP - 1 EP - 5 PB - ASTM International CY - West Conshohocken, PA AN - OPUS4-59064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzwarth, Marcel A1 - Baer, Wolfram A1 - Mayer, Uwe A1 - Weihe, Stefan T1 - Master Curve-Auswertungen und Untersuchung des Größeneffekts für c(t)-proben - Aktuelle Erkenntnisse zur Untersuchung des Master Curve Konzepts für ferritisches Gusseisen mit Kugelgraphit bei dynamischer Beanspruchung N2 - Ausgehend vom Stand des Regelwerkes und der Forschung wird in einem BMUV-Verbundprojekt zwischen der MPA Stuttgart und der BAM Berlin die Anwendung des Master Curve (MC)-Konzepts auf ferritisches Gusseisen mit Kugelgraphit (DCI) untersucht. Ziel des Verbundprojekts ist die Anwendbarkeit des MC-Konzepts näher zu untersuchen und ggf. Modifikationen vorzunehmen, um eine Bewertungsmethode für die dynamische Bruchzähigkeit von DCI im Übergangsbereich zu erarbeiten. Auf den Jahrestagungen 2023 und 2024 des DVM-AK Bruchmechanik und Bauteilsicherheit wurden bereits der Forschungsansatz sowie erste Ergebnisse des Projekts MCGUSS präsentiert. Der Beitrag für die diesjährige Tagung soll nun MC-Auswertungen und den Größeneffekt für C(T)-Proben aus DCI diskutieren. T2 - 57. Tagung des DVM-Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Köln, Germany DA - 18.02.2025 KW - Versuche KW - Master Curve KW - Bruchmechanik KW - Dynamische Beanspruchung KW - Gusseisen mit Kugelgraphit PY - 2025 DO - https://doi.org/10.48447/BR-2025-495 SP - 123 EP - 129 PB - DVM-Verlag CY - Berlin AN - OPUS4-62555 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzwarth, Marcel A1 - Mayer, Uwe A1 - Baer, Wolfram T1 - Investigating the Applicability of the Master Curve Concept for Ductile Cast Iron – Early Results for 2 Different Test Temperatures N2 - Based on the state-of-the-art research and regulations, the application of the fracture mechanics master curve (MC) concept to ferritic ductile cast iron (DCI) is being investigated in a joint research project between MPA Stuttgart and BAM Berlin. This paper outlines the research approach, the planned investigations and first results of the experimental program. T2 - 8th SEDS Workshop: Safety of Extended Dry Storage CY - Garching, Germany DA - 15.05.2024 KW - Dynamic fracture KW - Brittle fracture KW - Ductile cast iron KW - Master Curve PY - 2024 SP - 1 EP - 4 AN - OPUS4-60013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram T1 - Statistische Auswertung der SE(B)-Bruchzähigkeitsdatenbasis und Untersuchungen zum Bruchmechanismus - Neue Ergebnisse zur Untersuchung des Master Curve Konzepts für ferritisches Gusseisen mit Kugelgraphit bei dynamischer Beanspruchung (Projekt MCGUSS) N2 - Die Zielstellung des laufenden Kooperationsprojektes MCGUSS zwischen der BAM Berlin und der MPA Stuttgart ist es, das probabilistische Master Curve (MC)-Konzept hinsichtlich seiner Übertragbarkeit auf ferritisches Gusseisen mit Kugelgraphit (DCI) zu untersuchen. Über Teilergebnisse der Arbeiten wurde bereits auf den Jahrestagungen 2023 bis 2025 des DVM-AK Bruchmechanik und Bauteilsicherheit berichtet. Der vorliegende Beitrag hat zwei Schwerpunkte. Zum einen wurde die Datenbasis der dynamischen Bruchzähigkeit für SE(B)-Proben der Dicken 10 mm, 25 mm und 140 mm auf insgesamt 101 Versuche bei Temperaturen von -40 °C bis -140 °C erweitert, statistisch ausgewertet sowie MC-Analysen unterzogen. Die Ergebnisse zeigen, dass die Daten sich zwar mit einer Weibullverteilung gut beschreiben lassen, die MC-Methode nach ASTM E1921 jedoch nicht ohne Weiteres anwendbar ist, sondern Modifikationen erforderlich sind. Des Weiteren werden neue Ergebnisse zum werkstoffspezifischen Bruchmechanismus bei dynamischer Belastung im unteren Übergangsbereich der Zähigkeit diskutiert. Die fraktographische Datenbank wurde durch REM-Analysen weiterer Bruchflächen von SE(B)25-Proben bei -40 °C, -60 °C und -80 °C ergänzt. Die Ergebnisse unterstreichen die prägende Rolle, die Rissarrestereignissen im Verlauf des dynamischen Sprödbruchversagens bei DCI zukommt. Der in MCGUSS zur Erklärung eines gegenüber Stahl inversen Probengrößeneinflusses vorgeschlagene Mechanismus „Specimen size-dependent arrest of local brittle fractures before global brittle failure by weakest link“ wird dadurch weiter unterstützt. T2 - DVM-Jahrestagung 2026 des Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Stuttgart, Germany DA - 24.02.2026 KW - Dynamic fracture toughness KW - Ductile cast iron KW - Safety assessment KW - Master curve KW - Statistics PY - 2026 AN - OPUS4-65593 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram A1 - Ohm, Katrin A1 - Holzwarth, Marcel T1 - Statistische Auswertung der SE(B)-Bruchzähigkeitsdatenbasis und Untersuchungen zum Bruchmechanismus – neue Ergebnisse zur Untersuchung des Master Curve Konzepts für ferritisches Gusseisen mit Kugelgraphit bei dynamischer Beanspruchung (Projekt MCGUSS) N2 - Die Zielstellung des laufenden Kooperationsprojektes MCGUSS zwischen der BAM Berlin und der MPA Stuttgart ist es, das probabilistische Master Curve (MC)-Konzept hinsichtlich seiner Übertragbarkeit auf ferritisches Gusseisen mit Kugelgraphit (DCI) zu untersuchen. Über Teilergebnisse der Arbeiten wurde bereits auf den Jahrestagungen 2023 bis 2025 des DVM-AK Bruchmechanik und Bauteilsicherheit berichtet. Der vorliegende Beitrag hat zwei Schwerpunkte. Zum einen wurde die Datenbasis der dynamischen Bruchzähigkeit für SE(B)-Proben der Dicken 10 mm, 25 mm und 140 mm auf insgesamt 101 Versuche bei Temperaturen von -40 °C bis -140 °C erweitert, statistisch ausgewertet sowie MC-Analysen unterzogen. Die Ergebnisse zeigen, dass die Daten sich zwar mit einer Weibullverteilung gut beschreiben lassen, die MC-Methode nach ASTM E1921 jedoch nicht ohne Weiteres anwendbar ist, sondern Modifikationen erforderlich sind. Des Weiteren werden neue Ergebnisse zum werkstoffspezifischen Bruchmechanismus bei dynamischer Belastung im unteren Übergangsbereich der Zähigkeit diskutiert. Die fraktographische Datenbank wurde durch REM-Analysen weiterer Bruchflächen von SE(B)25-Proben bei -40 °C, -60 °C und -80 °C ergänzt. Die Ergebnisse unterstreichen die prägende Rolle, die Rissarrestereignissen im Verlauf des dynamischen Sprödbruchversagens bei DCI zukommt. Der in MCGUSS zur Erklärung eines gegenüber Stahl inversen Probengrößeneinflusses vorgeschlagene Mechanismus „Specimen size-dependent arrest of local brittle fractures before global brittle failure by weakest link“ wird dadurch weiter unterstützt. T2 - DVM-Jahrestagung 2026 des Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Stuttgart, Germany DA - 24.02.2026 KW - Statistics KW - Dynamic fracture toughness KW - Ductile cast iron KW - Master curve KW - Safety assessment PY - 2026 SP - 1 EP - 12 PB - DVM-Verlag CY - Berlin AN - OPUS4-65591 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peters, Stefan A1 - Kunkel, Benny A1 - Cakir, Cafer Tufan A1 - Kabelitz, Anke A1 - Witte, Steffen A1 - Bernstein, Thomas A1 - Bartling, Stephan A1 - Radtke, Martin A1 - Emmerling, Franziska A1 - Abdel-Mageed, Ali Mohamed A1 - Wohlrab, Sebastian A1 - de Oliveira Guilherme Buzanich, Ana T1 - Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy N2 - A novel setup for dispersive X-ray absorption spectroscopy (XAS) with simultaneous resolution of space, time and energy for in situ characterization of solid materials is demonstrated. KW - Dispersive XAS KW - Catalysis KW - In situ KW - Structure analysis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584924 DO - https://doi.org/10.1039/d3cc03277a SN - 1359-7345 SP - 1 EP - 4 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kittner, Maria A1 - Coesfeld, Bianca A1 - Schlau, Sven A1 - Werischak, Thomas A1 - Altmann, Korinna A1 - Kalbe, Ute T1 - Simultaneous sampling for microplastics and environmental contaminants from artificial turf: development of a new integrated microplastics eluate lysimeter N2 - To get a better understanding of potentially harmful contaminant emissions from soils or materials into the environment, politics demand practical and holistic sampling concepts for environmental samples such as leachates containing polycyclic aromatic hydrocarbons (PAH) or heavy metals, and hazardous particulate matter like microplastics (MP). Of particular concern are MP emissions from artificial turf sports pitches. So far, there has been only very limited data on MP mass emissions from artificial turf potentially posing a risk to the groundwater and no sampling device that allowed simultaneous sampling for dissolved and particulate contaminants. In this study, a novel integrative microplastics eluate lysimeter was developed to determine contaminant emissions from three artificial turf systems at different ageing states (fabric-new, artificially aged, real-time aged). For the accelerated ageing, all environmental simulation parameters were based on Central German conditions and simulated outdoor stress during the turf service lifespan of 15 years. MP masses from eluates were analysed using thermal extraction desorption-gas chromatography/mass spectrometry, PAH concentrations using gas chromatography/mass spectrometry and heavy metals using inductively coupled plasma-optical emission spectroscopy. Results showed that no PAH or heavy metal concentrations from the seepage water were above German legal limits for alternative granular construction materials considering soil and groundwater protection. Furthermore, it was found that only minimal MP emissions were released from new turf systems into the seepage water (< 1 mg/m2). Ageing of the artificial turf increased MP formation, especially from rubber infill and grass fibres, which are then carried into the seepage water. The highest total MP emissions over a simulated turf lifespan of 15 years were detected in two real-time aged turf systems ranging from 136.4–252.5 mg/m2. Considerably less total MP emissions were detected in accelerated aged artificial turf systems, one of which contained a synthetic rubber infill (5.4–8.0 mg/m2) and one without rubber infill (0.2–5.3 mg/m2). In summary, it was demonstrated that the newly developed MEL generated reliable and reproducible data and has thus proven itself as an integrated, straightforward and automated sampling device for simultaneous monitoring of particulate and dissolved pollutant emissions from simple soil matrices. KW - Lysimeter KW - Microplastics KW - Artificial turf KW - Thermal extraction desorption-gas chromatography/mass spectrometry KW - TED-GC/MS KW - Polycyclic aromatic hydrocarbons KW - PAH KW - Heavy metals KW - Soil samples PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645301 DO - https://doi.org/10.1186/s12302-025-01235-1 SN - 2190-4715 VL - 37 IS - 1 SP - 1 EP - 15 PB - Springer Open AN - OPUS4-64530 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 - TY - CONF A1 - Madia, Mauro T1 - Ermittlung von Kitagawa-Takahashi Diagrammen auf der Basis der Schwingbruchmechanik N2 - Das Kitagawa-Takahashi Diagramm ist ein unverzichtbares Werkszeug zur Auslegung von Bauteilen aus fehlerbehafteten Werkstoffen. Zur Beschreibung des Diagramms werden im Allgemeinen die Modelle nach Kitagawa-Takahashi, El Haddad oder Chapetti verwendet, die sich aber im technisch relevanten Bereich zum Teil deutlich voneinander unterscheiden. Daher ist eine experimentelle Absicherung dieses Bereichs zwingend erforderlich. Im Rahmen dieser Arbeit wurden verschiedene Methoden zur experimentellen Absicherung miteinander verglichen, mit dem Ziel eine einfache und schnelle experimentelle Absicherung des KT-Diagramms zu ermöglichen. Die neue experimentelle Methode hat sich als nützliches Werkzeug zur Validierung von KT-Diagrammen erwiesen. Durch die Erzeugung von Kerben mittels eines Gravierlasers und die Durchführung der Versuche mit Potentialmessung kann das KT-Diagramm eines Werkstoffes schnell und mit wenig Aufwand validiert werden. T2 - 58. Tagung des Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Stuttgart, Germany DA - 24.02.2026 KW - Schwingbruchmechanik KW - Ermüdungsfestigkeit KW - Kitagawa-Takahashi Diagramm KW - Gleichstrom-Potentialsonde PY - 2026 AN - OPUS4-65645 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro T1 - Ermittlung des intrinsischen Schwellenwerts und dessen Validierung als Werkstoffparameter N2 - Zuverlässige Rissfortschrittsdaten sind notwendig für die sichere Bewertung zyklisch beanspruchter Bauteile. Diese werden häufig im Schwellenwertbereich betrieben, daher ist die genaue experimentelle Ermittlung der Schwellenwerte gegen Rissausbreitung wichtig, um die Unsicherheit der Lebensdauerprognose zu minimieren. Viele Faktoren können die experimentellen Ergebnisse beeinflussen, u.a. die Versuchsparameter und die Umgebungsbedingungen. Diese Arbeit zeigt, dass der intrinsische Schwellenwert von der experimentellen Verfahren und von der Umgebung unabhängig ist. Daraus kann man schließen, dass der intrinsische Schwellenwert als Werkstoffparameter betrachtet werden kann. T2 - Workshop Schwellenwert CY - Munich, Germany DA - 26.02.2026 KW - Schwingbruchmechanik KW - Schwellenwert KW - Rissfortschritt KW - Umgebungseffekte PY - 2026 AN - OPUS4-65646 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Chunliang A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Phase-field simulation of the dendrite fragmentation by electromagnetic stirring in AA5754 aluminum alloy laser beam welding N2 - A phase-field model including magnetic field induced dendrite fragmentation was established and applied to the cases with different initial crystal nuclear positions for AA5754 aluminum alloy electromagnetic laser beam welding. Compare the calculated results that include dendrite fragmentation caused by the thermal electromagnetic Lorentz force with the results that consider only the thermal electromagnetic Lorentz force, without fragmentation, at the characteristic time instants. Both in the early and late stages, the small fragmentation at the dendrite tip promotes the number of higher-order branches and their growth, especially in the direction perpendicular to the solidification. The later stage fragmentation has the possibility of breaking one grain into several, which verifies the possibility of grain refinement caused by dendrite fragmentation. The fracture surface caused by fragmentation also makes more solid-liquid interfaces and their growth. In addition, the cases with different initial nuclear positions were compared. The grain growth in the low-temperature zone can be inhibited by the equiaxed grains' fragmentation at the high-temperature area (179.8 μm² and 14.7 % start at the center, 115.4 μm² and 9.4 % start at the high-temperature corner, 134.3 μm² and 10.9 % start at the low-temperature corner), which is another kind of grain refinement by the dendrite fragmentation. This kind of inhibition effect on grain growth in the low-temperature region will be enhanced with the increasing time interval between the two crystal nuclei’ appearance (179.8 μm² and 14.7 % when virtual grains appear at t = 4.3803 s and t = 4.3803 s, 134.3 μm² and 10.9 % at t = 4.0977 s and t = 3.9564 s, and 115.4 μm² and 9.4 % at t = 3.8151 s and t = 3.5325 s). KW - Laser beam welding KW - Electromagnetic KW - Aluminum alloys KW - Phase field method KW - Equiaxed grain KW - Dendrite fragmentation PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656610 DO - https://doi.org/10.1016/j.cwe.2025.100014 SN - 3117-4159 VL - 35 IS - 1 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-65661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Kising, Pascal A1 - Yang, Fan A1 - Rethmeier, Michael T1 - Prediction of weld pool and keyhole geometries in high-power laser beam welding through a physics-informed generative artificial intelligence approach N2 - The weld pool and keyhole geometries are critical characteristics in evaluating the stability of the high-power laser beam welding (LBW) process and determining the resultant weld quality. However, obtaining these data through experimental or numerical methods remains challenging due to the difficulties in experimental measurements and the high computational demands of numerical modelling. This paper presents a physics-informed generative approach for predicting weld pool and keyhole geometries in the LBW process. With the help of a well experimentally validated numerical model considering the underlying physics in the LBW, the geometries of the weld pool and keyhole under various welding conditions are calculated, serving as the dataset of the generative model. A conditional variational autoencoder model is employed to generate realistic 2D weld pool and keyhole geometries from the welding parameters. We utilize a β-variational autoencoder model with the evidence lower bound loss function and include Kullback–Leibler divergence annealing to better optimize model performance and stability during training. The generated results show a good agreement with the ground truth from the numerical simulation. The proposed approach exhibits the potential of physics-informed generative models for a rapid and accurate prediction of the weld pool geometries across a diverse range of process parameters, offering a computationally efficient alternative to full numerical simulations for process optimization and control in laser beam welding processes. KW - Laser beam welding KW - Generative artificial intelligence KW - Machine learning KW - Numerical simulation KW - Weld pool KW - Keyhole dynamics PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656621 DO - https://doi.org/10.2351/7.0001862 SN - 1042-346X VL - 38 IS - 1 SP - 1 EP - 8 PB - Laser Institute of America AN - OPUS4-65662 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ekici, Nilsah A1 - Sobol, Oded T1 - SHIMMER Database for Hydrogen Integration in European Gas Grids N2 - The integration of hydrogen into existing natural gas infrastructure is an important pathway for achieving the European Union’s climate neutrality goals. However, hydrogen blending in gas networks raises technical challenges related to material compatibility, operational safety, and the lack of harmonized assessment methodologies across Europe. These challenges are addressed within the Safe Hydrogen Injection Modelling and Management for European Gas Network Resilience (SHIMMER) project, funded by the Clean Hydrogen Partnership under the Horizon Europe programme. A key outcome of the project is the development of an openly accessible database designed to support the assessment of hydrogen readiness in European gas networks and to facilitate knowledge sharing. The database compiles infrastructure data provided by project partners, including several European transmission and distribution system operators. It contains detailed information on gas network components such as pipelines, valves, fittings, gaskets, and compressors. In addition, a new category has been introduced focusing on the hydrogen compatibility of gas grid components and materials. This section provides structured information linking infrastructure components with material types and their hydrogen compatibility, enabling more systematic evaluation of hydrogen injection scenarios. By organizing heterogeneous datasets into a harmonized and user-friendly structure, the SHIMMER database supports research, best-practice development, and the safe integration of hydrogen into existing European gas infrastructure. T2 - EHEC 2026 CY - Seville, Spain DA - 11.03.2026 KW - Database KW - Gas Grid KW - Hydrogen KW - Low-carbon KW - Pipeline Steel PY - 2026 AN - OPUS4-65683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Engelking, Lorenz A1 - Eissel, A. A1 - Madia, Mauro A1 - Schröpfer, Dirk A1 - Treutler, K. A1 - Kruse, Julius A1 - Kannengießer, Thomas A1 - Wesling, V. T1 - Influence of ultrasonic-assisted milling on surface integrity of additively manufactured components using MSG processes N2 - Additive manufacturing (AM) is increasingly used for producing complex metallic components. Subsequent machining is essential to achieve final geometries and surface conditions. The resulting surface integrity, particularly the near-surface residual stress state, plays a crucial role in component performance and fatigue life. This study investigates the potential of ultrasonic-assisted milling (USAM), a hybrid machining process, to improve surface integrity and machinability compared to conventional milling (CM). Three materials were investigated, two difficult-to-cut materials CoCr26Ni9Mo5W and FeNi36 and a low-alloy steel S355J2C. The CoCr26Ni9Mo5W and FeNi36 were additively manufactured via Directed Energy Deposition (DED)-Arc and then machined with varying cutting speeds and feed rates within a Design of Experiments. USAM exhibited enhanced machinability and surface integrity, particularly at low cutting speeds, by reducing cutting forces up to 40% and shifting near-surface residual stresses from tensile to compressive. For S355J2C, USAM reduced cutting forces by approximately 45% and induced near-surface compressive residual stresses up to approximately −700 MPa. Rotating bending tests (DIN50100) show that USAM increases the technical fatigue limit from 307 MPa (CM) to 341 MPa (USAM), i.e., by ∼11%. These findings highlight the advantages of ultrasonic assistance in post-AM machining, offering enhanced fatigue performance and surface quality for various metallic materials. T2 - 4th International Conference on Advanced Joining Processes 2025 CY - Coimbra, Portugal DA - 16.10.2025 KW - Ultrasonic-assisted milling KW - Residual stress KW - Surface integrity PY - 2026 DO - https://doi.org/10.1177/14644207261416395 SP - 1 EP - 12 PB - Sage Journals AN - OPUS4-65682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharf-Wildenhain, R. A1 - Engelking, Lorenz A1 - Hälsig, A. A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Hensel, J. T1 - Influence of build‑up height on residual stresses in additive repair and modification using DED‑Arc with high‑strength filler metals N2 - Directed energy deposition (DED)-Arc is suitable for the hybrid additive manufacturing, modification and repair of large metal components with high deposition rates. Residual stresses and distortion are of central importance when characterizing the manufactured components and the sensitive transition area between additive manufactured (AM) component and semifinished product. Residual stresses caused by the thermal cycles during the manufacturing process can impair the mechanical properties of the manufactured parts and can lead to component failure, especially for high-strength steels. Therefore, understanding and controlling residual stresses, when combining different base and feedstock materials, is critical to improve the quality and efficiency of the hybrid DED-Arc process. This article deals with the influence of the build-up height on the residual stress distribution of additively manufactured components with a selected base and feedstock material from commercial high-strength steels. Using a robot-assisted DED-system and a controlled short arc, AM welding experiments were carried out with close to the application parameters at working temperature (200 °C) and heat input (650 kJ/m). Five hybrid AM specimens (AM wall on upright structural steel plate) were produced using a one bead per layer strategy and selected AM-wall heights between 15 and 300 mm. The influence of the AM build height on the longitudinal residual stress in the whole hybrid AM specimen (in welding direction) was analyzed and discussed. All experiments exhibit comparable stress distributions in the area of the substrate plate up to the heat-affected zone (HAZ) and the transition zone, regardless of the building height. The height significantly influences the residual stress distribution of the deposited AM-component. Tensile residual stresses with a maximum range between 300and 400 MPa were always found in the last approx. 18 component layers (upper 40 mm). This is due to restraint of the shrinking of the top layers by the layers below. The lower layers show homogeneous residual stress distributions characterized by low compressive stresses due to the process-related tempering during the deposition of each layer on top of each other. As a result, the significant difference between the various AM build-up heights of the hybrid AM specimens is the extent (or height) of this tempered zone with low compressive stresses. These correlations contribute to the understanding of residual stress development with increasing structure height or ratio of component heights of substrate semi-finished product and AM component in hybrid additive manufacturing. T2 - 78th IIW Annual Assembly and International Conference CY - Genoa, Italy DA - 22.06.2025 KW - DED-Arc KW - Residual stress KW - Heat control PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656793 DO - https://doi.org/10.1007/s40194-026-02417-y SN - 1878-6669 SP - 1 EP - 12 PB - Spriner AN - OPUS4-65679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - Kaplan, Alexander A1 - Rethmeier, Michael T1 - Digitalisation and Carbon Footprint Evaluation of Gas Metal Arc Welding and Wire-Arc Directed Energy Deposition N2 - This paper showcases how a holistic approach to digitalisation enables data-driven welding applications, exemplarily for a gas metal arc welding (GMAW) laboratory. The workflow integrates advanced process monitoring, synchronised multi-sensor data acquisition and tools for data analytics. A welding domain-specific data exchange format weldx is presented that unifies and aggregates the data sets acquired during process monitoring with final component quality metrics, supporting reuse, traceability, and reproducibility. Two case studies illustrate the approach. First, GMAW parameters are adaptively adjusted according to local seam geometry to compensate joint-preparation deviations from nominal values typical for large-scale steel fabrication. Second, the seamless data aggregation along the welding production chain enables an automatic life-cycle assessment (LCA), quantifying the environmental impacts of additive manufacturing with DED Arc/M and attributing the dominant contributors to the carbon footprint. Collectively, the results indicate that a fully integrated experimental set-up together with standardised data structures and scalable analytics can couple monitoring, control, and sustainability, thereby realising the potential of digitalisation for high-quality and environmentally informed welding production. KW - Digitalisation KW - Arc welding KW - DED-arc KW - Life Cycle Assessment PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656812 DO - https://doi.org/10.1088/1757-899X/1342/1/012067 SN - 1757-8981 VL - 1342 IS - 1 SP - 1 EP - 15 PB - IOP Publishing AN - OPUS4-65681 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo T1 - Low-Cycle Fatigue Behavior of Laser Powder Bed Fused Inconel 718 at Room and High Temperature N2 - The nickel-base superalloy Inconel 718 (IN718) is one of the most commonly used Ni-based superalloys for high temperature structural applications for its remarkable strength, as well as creep, fatigue, and corrosion resistance up to 650 °C. While IN718 has traditionally been employed as cast or wrought material, it is difficult to machine because of its high strength and toughness. The additive manufacturing of IN718 components made by metal AM has thus gained extensive attention to produce expensive near-net shaped components of high-temperature alloys such as IN718, for it saves material and costs in processing and machining steps. Among all metal additive manufacturing (AM) technologies, laser powder bed fusion (PBF-LB/M) is the most widespread, IN718 being one of the most common alloys produced with it. However, high cooling rates associated to the PBF-LB/M process, hinders the primary strengthening phases γ’’ and γ’ to form, as these cooling rates induce a dislocation cellular substructure, at which walls primary Laves phases bind segregating Nb, Ti and Mo. Many of the therefore needed heat-treatment strategies can then promote Laves-phase transformation into the stable δ phase along the cell and grain boundaries. Laves and δ phases, as well as grain-boundary primary carbides may have adverse effects on mechanical properties. The mostly needle-shaped δ phase was namely found to have a detrimental effect on creep rupture life while no direct effect on LCF fatigue life was evident. In this work room- and high-temperature (650 °C) low-cycle fatigue behavior of PBF-LB/M IN718 is investigated in the four-step heat-treated state and compared to wrought IN718. The microstructure of both materials is characterized across length scales via microscopy methods. The fatigue life at room temperature of the PBF-LB/M IN718 material is slightly lower than that for the wrought material, which is reversed at 650 °C. The cyclic stress response for both materials is marked by cyclic softening that is more pronounced at higher test temperatures. Multiple secondary cracks form at high strain amplitudes, at both room and high temperatures. High testing temperatures enhance specially crack formation at the transitions of regions between elongated grains and columns of stacked grains with ripple patterns in the PBF-LB/M material. Additional to this behavior, pronounced crack branching and deflection indicate that the cracks are controlled by sharp micromechanical gradients. T2 - EUROMAT 2025 CY - Granada, Spain DA - 14.09.2025 KW - Additive manufacturing KW - Low-cycle fatigue KW - Microstructural characterization KW - Ni-base superalloy PY - 2025 AN - OPUS4-64354 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Witte, Julien A1 - Treutler, Kai A1 - Schroepfer, Dirk A1 - Kannengiesser, Thomas A1 - Wesling, Volker T1 - Influence of microstructure on the machinability and surface integrity of additively manufactured iron aluminides N2 - The increasing global focus on energy and resource efficiency has stimulated a growing interest in additive manufacturing. AM offers economic advantages and enables an efficient use of materials. However, AM components often require subsequent mechanical post-processing, such as machining (e.g., milling), to achieve the final contours or surfaces. This is a particular challenge due to the heterogeneous and anisotropic nature of AM structures, which affect machining and the resulting component properties. High-performance materials such as iron aluminide represent a promising alternative to conventional high-temperature materials with a significant economic advantage. However, the strength and hardness properties, which are advantageous for applications in highly stressed lightweight components, pose a challenge for economical machining in addition to the AM microstructure properties. The difficult-to-cut material causes accelerated tool wear and insufficient surface quality. This study shows that crack-free additive manufacturing of the three-component system of iron-nickel-aluminum is possible, and advantages in terms of machinability compared to FeAl-AM components are achieved. The more homogeneous microstructure leads to a reduction in cutting forces, with positive effects on the machinability and optimized surface integrity. Ultrasonic assisted milling (USAM) offers great potential to address the major challenges posed by difficult-to-cut materials and additively manufactured weld structures. Therefore, this study focuses on assessing the transferability of previous positive results by USAM to the selected iron aluminide alloys. The machinability of the aluminides is analyzed by varying significant influencing variables in finish milling experiments and evaluated in terms of the loads on the tool and the resulting surface integrity. KW - Iron aluminide KW - Additive manufacturing KW - Machinability KW - Surface integrity KW - Ultrasonic-assisted milling process PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656993 DO - https://doi.org/10.1007/s40194-026-02382-6 SN - 0043-2288 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-65699 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - R&D insights into sustainable additive manufacturing for high-temperature applications (HTA) N2 - Im Rahmen des AM Forums Berlin 2026 wird durch diesen Vortrag ein Einblick in FuE-Aktivitäten der BAM auf dem Gebiet der additiven Fertigung für Hochtemperaturanwendungen gegeben. Es werden dabei insbesondere Aspekte der nachhaltigen Verwendung von Pulverausgangswerkstoff und der Einfluss von Sauerstoff im Pulverwerkstoff auf die Degradation resultierender mechanischer Eigenschaften von Probekörpern beleuchtet. Die präsentierten Arbeiten sind im Rahmen des Pro FIT Projektes HTA2.0 entstanden. T2 - 10. AM Forum 2026 CY - Berlin, Germany DA - 10.03.2026 KW - Additive Manufacturing KW - Sustainability KW - Powder recycling KW - Powder degradation PY - 2026 AN - OPUS4-65725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Determination, Assessment and Quantification of Hydrogen in Multi-pass / Multi-layer Weld Joints by Adapted ISO 3690 Samples - DEAQuade - N2 - High-strength, low-alloy (HSLA) structural steels, such as S690 and higher grades, are used in numerous applications, enabling sustainable, lightweight structural construction. However, the welded joints of these steels can be susceptible to hydrogen-assisted cold cracking (HACC), especially in the hardened weld metal (WM) or heat-affected zone (HAZ). HACC in high-strength welds basically involves a critical combination of local, mutually dependent parameters consisting of: (1) a crack-critical microstructure; (2) sufficiently high mechanical stress; and (3) a diffusible hydrogen concentration (HD). In this context, thick-walled steel weld joints typically involve multi-layer welding with several passes. This leads to an effective, empirically known reduction in the global HD in the weld seam. This reduction is due to the repeated reheating of subsequently welded beads or layers, which reduces the local HD in the individual weld beads or layers. However, this has not yet been adequately quantified or described. Bead-on-plate tests, such as ISO 3690, cannot correctly reproduce the local HD distribution in individual welding passes (and thus, the global HD in the entire seam). Therefore, these tests lead to an extremely conservative evaluation of hydrogen ingress and the potential for "self-reduction" of HD due to increased interpass temperature during multi-layer welding, which has not yet been adequately addressed in the literature. Ideally, the local HD in each pass and the global (average) HD of the multi-layer weld would be known immediately after welding. For this reason, the study proposes an approach to address the local, track-, and layer-dependent, as well as global, hardness (HD) of multi-layer welds via a modified ISO 3690 test. To this end, representative welding parameter combinations for selected practical welding processes (e.g., SAW, GMAW, or SMAW) will be carried out as conventional bead-on-plate samples. These samples will be systematically extended by an increasing number of welding passes. Several sample series with an increasing number of beads or layers will be examined. Additionally, the initial HD is varied by methods such as targeted shielding gas variation (e.g., addition of hydrogen in GMAW) or moistened flux/coating (e.g., SAW/SMAW). Based on experimental data (temperature field measurements during welding and determination of temperature-dependent HD coefficients), a numerical hydrogen diffusion model is created. This model calculates the local HD (in the beads) and the HD across the weld cross-section. Additional variation calculations represent heat transfer conditions that were not recorded experimentally and their influence on HD distribution. Finally, we investigate the potential use of the modified ISO 3690 multi-layer geometry for application cases such as (1) predicting the effectiveness and necessity of hydrogen removal heat treatment procedures for given welding parameter sets and (2) extending the HD classification definition (e.g., allowing HD10 use for HSLA steels with RP0.2 > 690 MPa instead of HD5). Finally, an international round robin should be initiated once the concept has been successfully confirmed and verified. T2 - IIW Intermediate Meeting, Com. II-A CY - Bangkok, Thailand DA - 17.03.2026 KW - Hydrogen assisted cracking KW - Multi-pass welding KW - Diffusion KW - Cold cracking test PY - 2026 AN - OPUS4-65716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schaupp, Thomas A1 - Schröder, Nina A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas T1 - Hydrogen-assisted cracking in GMA welding of high-strength structural steel - A new look into this issue at narrow groove N2 - Modern arc processes, such as the modified spray arc (Mod. SA), have been developed for gas metal arc welding of high-strength structural steels with which even narrow weld seams can be welded. High-strength joints are subjected to increasingly stringent requirements in terms of welding processing and the resulting component performance. In the present work, this challenge is to be met by clarifying the influences on hydrogen-assisted cracking (HAC) in a high-strength structural steel S960QL. Adapted samples analogous to the self-restraint TEKKEN test are used and analyzed with respect to crack formation, microstructure, diffusible hydrogen concentration and residual stresses. The variation of the seam opening angle of the test seams is between 30° and 60°. To prevent HAC, the effectiveness of a dehydrogenation heat treatment (DHT) from the welding heat is investigated. As a result, the weld metals produced at reduced weld opening angle show slightly higher hydrogen concentrations on average. In addition, increased micro- as well as macro-crack formation can be observed on these weld metal samples. On all samples without DHT, cracks in the root notch occur due to HAC, which can be prevented by DHT immediately after welding. KW - High-strength structural steel KW - Gas metal arc welding KW - Diffusible hydrogen KW - Hydrogen-assisted cracking KW - TEKKEN KW - Residual stresses KW - Weld metal cracking PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527260 DO - https://doi.org/10.3390/met11060904 VL - 11 IS - 6 SP - 1 EP - 18 PB - MDPI CY - Basel AN - OPUS4-52726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Engelking, Lorenz A1 - Madia, Mauro A1 - Schröpfer, Dirk A1 - Kruse, Julius A1 - Saliwan Neumann, Romeo A1 - Kannengießer, Thomas T1 - Influence of Ultrasonic-Assisted Milling on Surface Integrity and Fatigue Strength of a Low Alloy Steel N2 - The milling process significantly influences the surface integrity of metallic components through machining induced near surface residual stresses. Modern hybrid machining processes, such as ultrasonic-assisted milling (USAM), offer the potential to induce beneficial near-surface compressive residual stresses compared to the near-surface tensile residual stresses typically resulting from conventional milling (CM). This study investigates the effects of USAM compared to CM on the near-surface residual stress state and fatigue performance of a S355J2C low-alloy steel. Milling experiments and subsequent rotating bending tests revealed that USAM significantly reduces cutting force by approximately 45% and induces near-surface compressive re sidual stresses as low as −733MPa. This leads to a significant improvement in fatigue strength estimated in approximately 34% compared to polished specimens and 11% compared to the CM. These findings highlight the potential of USAM to enhance the fatigue performance of components made of steel. KW - Fatigue strength KW - Residual stress KW - Surface integrity KW - Surface roughness KW - Ultrasonic-assisted milling PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657358 DO - https://doi.org/10.1111/ffe.70259 SP - 1 EP - 11 PB - Wiley AN - OPUS4-65735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Suarez Ocano, Patricia T1 - Effect of the powder composition on the microstructure and mechanical properties of 316L stainless steel fabricated by laser powder bed fusion N2 - Additive manufacturing (AM) has seen rapid growth in recent decades, with Laser Powder Bed Fusion (PBF-LB/M) emerging as the leading technique for producing high-density, geometrically complex metal parts. Austenitic stainless steel 316L is one of the most studied alloys for PBF-LB/M due to its excellent strength, ductility, and corrosion resistance [1]. The microstructure formed during PBF-LB/M processing can improve certain mechanical properties compared to conventionally manufactured 316L [2]. However, the current 316L standards allow broad ranges for key alloying elements, particularly Cr and Ni. While such variations have little effect on conventionally produced alloys, emerging evidence shows that they can markedly alter the microstructure and mechanical properties in PBF-LB/316L—even within specification limits [3]. This study investigates through microstructural and thermodynamical assessment, how two powders of nominally standard 316L composition (Alloys A and B) respond to identical PBF-LB/M processing parameters. Despite identical printing conditions, Alloy A exhibited twice the grain size and five times higher low-angle grain boundary (LAGB) density compared to Alloy B . Conversely, Alloy B showed a significantly higher density of Σ3 twin boundaries, nearly absent in Alloy A. These microstructural differences are attributed primarily to variations in Cr and Ni content in the liquid, which may influence icosahedral short-range ordering (ISRO) mechanism [4]. ISRO potentially facilitates twin boundary formation, ultimately refining grain structure [5]. This work highlights the critical impact of compositional control on final part microstructures and consequent mechanical properties and emphasizes the need to reassess compositional tolerances for AM-specific applications. T2 - 5th Symposium on Materials and Additive Manufacturing (Additive 2026) CY - Kassel, Germany DA - 24.03.2026 KW - Additive manufacturing KW - 316L stainless steel KW - Chemical composition KW - Lcosahedral short-range ordering mechanism KW - Grain size PY - 2026 AN - OPUS4-65738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, J. A1 - Schmidt, J. A1 - Bhadeliya, A. A1 - Rehmer, B. A1 - Olbricht, J. A1 - Jokisch, T. A1 - Biegler, M. A1 - Rethmeier, M. T1 - Investigation on seam quality and fatigue crack propagation in electron beam welded additive manufactured Inconel 939 N2 - Laser powder bed fusion of metals (PBF-LB/M) offers great potential for the production of new and spare parts for stationary gas turbines made of nickel superalloys such as Inconel 939 (IN939). In order to enable integration into existing assemblies and overcome design limitations, the additive manufacturing process chain must be expanded by suitable joining techniques. This study compares the electron beam welding of cast IN939 sheets and sheets produced additively using PBF-LB/M. The investigation focuses on the achievable seam quality with regard to geometric irregularities and internal defects in the form of liquation cracks on the microscale in the heat-affected zone. The evaluation of the welded samples shows no differences in the formation of the seam shape between the additively manufactured material and the cast material. For both materials, the highest quality category for beam-welded seams according to DIN EN ISO 13,919–1 was achieved at high welding speeds of 20 mm/s. Regardless of the manufacturing method, both materials show an increase in crack formation with increasing welding speed. However, due to its microstructure, the PBF-LB/M material exhibits significantly fewer microcracks overall. Final crack propagation tests on welded PBF-LB/M samples that were treated using HIP also show stable crack growth without sudden failure, which opens up potential for practical application. KW - Electron beam welding KW - Inconel 939 KW - PBF-LB/M KW - Liquation cracking KW - Fatigue crack propagation PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657015 DO - https://doi.org/10.1016/j.jajp.2026.100389 SN - 2666-3309 VL - 13 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-65701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -