TY - CONF A1 - Schröpfer, Dirk T1 - Residual stress evaluation using the contour method of an additive manufactured high-strength steel solid cuboid N2 - Direct Energy Deposition with Arc (DED-Arc) enables the weight-optimized and near-net-shape manufacturing of complex structures. Lightweight construction principles allow a reduction of CO2 emissions by saving time, costs, and resources. Further optimisations can be achieved by using high-strength steel. This allows for a reduction in wall thickness and optimisation of weight. However, manufacturing intricate geometries using high-strength steels poses challenges in managing residual stresses (RS), which are essential for ensuring the structural integrity of welded components. High residual stresses can increase the risk of cold cracking, arising from the complex interactions between material properties, process conditions, and component design. Despite the availability of suitable filler metals, the lack of comprehensive knowledge and guidelines on residual stress formation limits the industrial application. Therefore, in the present study, the contour method (CM) was used to analyse the full field longitudinal residual stresses in an solid cuboid component (dimensions: 120 × 50 × 35 mm³) manufactured by DED-Arc. The CM enables the analysis of the two-dimensional map of residual stresses normal to a cutting plane using a finite element model. For this purpose, a solid cuboid component was welded fully automatically with a high-strength solid wire specially adapted for DED-Arc (yield strength > 790 MPa) onto conventionally manufactured substrates made of S690QL. The residual stresses from CM in the volume are compared with residual stress analyses using X-Ray diffraction on the surface. Additionally, comparative data from previous studies on hollow cuboid structures was included in order to identify similarities and differences in the resulting stress state, and to complement and validate the CM results. These results demonstrate the significant influence of the geometry on the residual stress profiles within the solid cuboid in relation to the open hollow. T2 - 4th International Conference on Advanced Joining Processes 2026 CY - Coimbra, Portugal DA - 16.10.2025 KW - Residual stress KW - Contour method KW - DED-Arc/M KW - High-strength steel KW - Filler metals KW - Neutron diffraction PY - 2025 AN - OPUS4-65209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graebner, Maraike A1 - Giese, Marcel A1 - Lorenz, Svenja A1 - Treutler, Kai A1 - Schröpfer, Dirk A1 - Wesling, Volker A1 - Kannengießer, Thomas T1 - Wear resistance of modified NiMoCrSi claddings in relation to the resulting surface machinability via ultrasonic-assisted milling N2 - In the field of plastics processing, extruder screws are subjected to significant wear stresses. The extruder screw is the main wear component in those production machines and is usually coated with intermetallic wear protection alloys composed of Ni-based alloys, specifically Colmonoy C56 PTA (NiMoCrSi). There is a growing demand for providing an economic machinability of these alloys to achieve defined contours with a sufficient surface integrity. Recent investigations exhibit promising results applying ultrasonic milling for such hard-to-cut materials. The Colmonoy C56 is modified by various alloying additions Ti, Nb, Mo, Hf, and Al, and then cladded on a steel S355 via Plasma Transferred Arc process. The effect of alloying additions on the microstructure is analyzed regarding their resistance to abrasive and adhesive wear. With Miller test ASTM G75 the influence of alloying elements on resistance to abrasive wear for two abrasive materials is investigated (high-grade corundum F220 and quartz powder). The wear loss is not increased for additions of Nb and Ti compared to the base material C56. Modifications with Hf or Al reduces the resistance to abrasive wear and significantly increases material loss. The extruder screw is also subject to adhesive wear, which can be quantified by means of the pin-roll test. It is demonstrated that the addition of Hf, for example, contributes to a reduction in wear loss. Aim of the investigations is to find suitable modifications for the wear claddings of C56 for a sufficient machineability, without compemising the wear resistant. The machinability is considerably affected by the alloy additions, and is determined using ultrasonic-assisted milling. The addition of hafnium reduces machinability, i.e. significantly increases cutting forces. The incorporation of Nb exhibits a significant reduction of cutting forces, and results in reduced tool wear and an enhanced of surface integrity (roughness, density of defects, residual stresses). KW - Colmonoy C56 KW - PTA welding KW - Adhesive wear KW - Abrasive wear KW - Ultrasonic-assisted milling process KW - Surface integrity KW - Service life and efficiency KW - Substitution of critical raw materials PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651530 DO - https://doi.org/10.1016/j.wear.2025.205830 SN - 0043-1648 VL - 571 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-65153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schaupp, Thomas A1 - Rhode, Michael A1 - Yahyaoui, Hamza A1 - Kannengießer, Thomas ED - Lippold, J. ED - Böllinghaus, Thomas ED - Norrish, J. ED - Scotti, A. T1 - Hydrogen-assisted cracking in GMA welding of high-strength structural steels using the modified spray arc process N2 - High-strength structural steels are used in machine, steel, and crane construction with yield strength up to 960 MPa. However, welding of these steels requires profound knowledge of three factors in terms of avoidance of hydrogen-assisted cracking (HAC): the interaction of microstructure, local stress/strain, and local hydrogen concentration. In addition to the three main factors, the used arc process is also important for the performance of the welded joint. In the past, the conventional transitional arc process (Conv. A) was mainly used for welding of high-strength steel grades. In the past decade, the so-called modified spray arc process (Mod. SA) has been increasingly used for welding production. This modified process enables reduced seam opening angles with increased deposition rates compared with the Conv. A. Economic benefits of using this arc type are a reduction of necessary weld beads and required filler material. In the present study, the susceptibility to HAC in the heat-affected zone (HAZ) of the high-strength structural steel S960QL was investigated with the externally loaded implant test. For that purpose, both Conv. A and Mod. SA were used with same heat input at different deposition rates. Both conducted test series showed same embrittlement index “EI” of 0.21 at diffusible hydrogen concentrations of 1.3 to 1.6 ml/100 g of arc weld metal. The fracture occurred in the HAZ or in the weld metal (WM). However, the test series withMod. SA showed a significant extension of the time to failure of several hours compared with tests carried out with Conv. A. KW - High-strength steel KW - GMA welding KW - Diffusible hydrogen KW - Implant test KW - Fractography PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515330 DO - https://doi.org/10.1007/s40194-020-00978-0 SN - 1878-6669 SN - 0043-2288 VL - 64 IS - 12 SP - 1997 EP - 2009 PB - Springer CY - Berlin Heidelberg AN - OPUS4-51533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madia, Mauro A1 - Baer, Wolfram A1 - Wagener, Rainer A1 - Kiyak, Yusuf T1 - Betriebsfestigkeit und Bruchverhalten von bainitischen Schmiedestählen N2 - Die neue Generation von bainitischen Schmiedestählen bietet auf der einen Seite ein erhebliches Festigkeitspotenzial, das es im Sinne des Leichtbaus auch für zyklisch belastete Sicherheitsbauteile zu heben gilt. Auf der anderen Seite geht mit dieser Festigkeitssteigerung im Vergleich zu Vergütungsstählen ein Verlust an Duktilität und Zähigkeit einher. Am Beispiel des Demonstratorbauteils Achsschenkel ging das Forschungsvorhaben der Frage nach, wie ein Freigabeprozess zu gestalten ist, damit das Festigkeitspotenzial der neuen Stähle zuverlässig ausgenutzt werden kann. Als Ergebnis wird eine Vorgehensweise dargestellt, die den Eigenschaften der neuen Generation von Schmiedestählen Rechnung trägt, um den sicheren Betrieb der Komponenten zu gewährleisten. KW - Bainitischer Schmiedestahl KW - Bruchmechanik KW - Sicherheit KW - Betriebsfestigkeit KW - Bauteilauslegung PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594296 SN - 2366-5106 SP - 50 EP - 54 PB - Industrieverband Massivumformung e. V CY - Hagen AN - OPUS4-59429 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baer, Wolfram A1 - Breidung, Marc A1 - Kiyak, Yusuf A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Küppers, M. 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 - FEM KW - Bauteilbewertung KW - Fail-safe KW - Analytisches Modell PY - 2022 DO - https://doi.org/10.48447/Br-2022-BB VL - 254 SP - 1 EP - 11 PB - DVM CY - Berlin AN - OPUS4-54406 LA - deu 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 - 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 - 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 - 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 - 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 - 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 - Kromm, Arne T1 - Effect of a High-Performance Modified Spray Arc MAG Process on Load-Oriented Repair of Old Steel Structures N2 - Steel structures erected in the late 19th and early 20th centuries still constitute a substantial part of today’s technical infrastructure. A significant proportion of bridge and engineering structures have been in service for more than 80 or even 100 years and are subjected to continuously increasing traffic volumes, axle loads, and dynamic actions. In view of these rising service demands, load-oriented and structurally adequate repair strategies are essential to ensure long-term structural integrity while preserving the existing building stock in a sustainable manner. As historical steel constructions were predominantly designed for riveted or bolted joints, the subsequent implementation of welded repair or strengthening measures represents a particular challenge. In addition to the specific material characteristics of old mild steels, welding-induced residual stresses and microstructural alterations must be carefully considered, as they can significantly affect load-bearing capacity and the overall structure performance. Consequently, repair concepts must not only restore geometry but also be adapted to the actual stress conditions and service requirements of the structure. Against this background, the present study investigates MAG welding trials on mixed joints between old and modern structural steels. The groove opening angle was systematically varied between 50° and 30° in order to analyse the influence of joint geometry on weld metal volume, heat input, and the resulting residual stress state. Furthermore, advanced high-performance arc processes, such as a modified spray arc mode, were applied to enable controlled and reduced heat input. The objective is to minimise welding-induced residual stresses through process and joint design optimisation, thereby providing a technically sound and load-oriented repair strategy for existing old steel structures suitable for long-term service. T2 - IIW Intermediate Meeting, Commission II-E CY - Bangkok, Thailand DA - 16.03.2026 KW - Historic mild steel KW - Weldability KW - High strength steel PY - 2026 AN - OPUS4-65745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kaiser, Sebastian T1 - Schweißen an druckführenden Wasserstoff-Ferngasleitungen im Betrieb – Ein Überblick über aktuelle FuE-Ergebnisse N2 - Grüner Wasserstoff wird als zukünftiger Energieträger eine wichtige Rolle bei der Dekarbonisierung der Energieversorgung spielen. Der Transport über große Entfernungen wird mittels eines Wasserstoff-Fernleitungsnetzes erfolgen. Ein solches Netz erfordert regelmäßig Schweißarbeiten zu Reparatur-, Wartungs- oder Erweiterungszwecken. Im Erdgasnetz ist das Schweißen im laufenden Betrieb gängige Praxis, da eine Außerbetriebnahme der Leitung technisch und wirtschaftlich sehr schwierig ist. Wasserstoff kann jedoch in den Rohrleitungsstahl eindringen, insbesondere bei erhöhten Temperaturen. Dies könnte zu einer Degradation der Materialeigenschaften oder sogar zu einem Versagen führen, bedingt durch die bekannten Effekte der wasserstoffinduzierten Versprödung und der wasserstoffunterstützten Rissbildung. Im Forschungsprojekt H2-SuD wird dies gezielt untersucht. Hierfür werden unter anderem Druckgasbeladung, Schweißversuche an vereinfachten Ersatzgeometrien und an realitätsnahen Demonstratoren, sowie numerische Simulation auf Basis gewonnener experimenteller Daten eingesetzt. T2 - Sitzung DIN NA 092-00-05 GA CY - Berlin, Germany DA - 24.03.2026 KW - Pipeline KW - Schweißen KW - Wasserstoff KW - Ferngasleitung PY - 2026 AN - OPUS4-65744 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Avila Calderon, Luis Alexander T1 - On the role of the manufacturing-induced cell structure in laser-powder-bed-fused stainless steel 316L during cyclic plastic deformation N2 - The room temperature cyclic plastic deformation behavior of stainless steel 316L produced by laser powder bed fusion and heat treated to two microstructural conditions was investigated in strain-controlled incremental-step-test low-cycle fatigue experiments. The heat treatments were performed at 450 °C for 4 h and at 900 °C for 1 h. The lower temperature heat treatment retains the cell structure present in the as-built material. The higher temperature heat treatment leads to disappearance of the cell structure and a decreased proof strength. Both investigated heat treatment conditions exhibited cyclic softening. In the condition heat treated at 900 °C for 1 h, the ability of the cell structure to act as barrier against plastic deformation when cyclically strained is degraded, which is reflected in the reduction of the cyclic yield strength. In that same condition, the cyclic softening was less pronounced. The presence or absence of the manufacturing-induced cell structure seems to determine the slip mode. When present, the microstructural evidence points to a planar slip behavior. After heat treatment at 900 °C for 1 h, which led to its dissolution, microstructural investigations revealed a wavy slip behavior, which has been also reported for the conventionally manufactured 316L counterpart [1]. In this case, the formation of low-energy dislocation structures acts as softening agent. T2 - Additive Manufacturing 2026 CY - Kassel, Germany DA - 25.03.2026 KW - AGIL KW - Additive Fertigung KW - Low-Cycle-Fatigue KW - 316L KW - Mikrostruktur PY - 2026 AN - OPUS4-65746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübner, Martin T1 - (K)ein explosives Thema? - Schweißen an und auf zukünftigen Wasserstoffpipelines im Betrieb unter Druckgasfluss N2 - Das Schweißen an druckführenden Leitungen im Betrieb ist beim Erdgas-Fernleitungsnetz Stand der Technik, beispielsweise beim Setzen von Abgängen durch „Hot-Tapping“. Diese Technik wird auch beim zukünftigen Wasserstoff-Kernnetz eine bedeutende Rolle spielen. Verfahrensbedingt ist daher eine bestimmte Wasserstoffaufnahme während des Schweißens unvermeidbar. Aus diesem Grund werden derzeit in mehreren Forschungsprojekten wie umfassende Erkenntnisse zum Schweißen an Rohrleitungen unter Druckwasserstoff gewonnen. Die grundsätzliche Übertragbarkeit des „Hot-Tapping“ auf zukünftige Wasserstoff-Rohrleitungen wurde bereits bestätigt (u. a. DNV-Projekt und HyTap). Allerdings besteht allein das zukünftige Wasserstoff-Kernnetz in Deutschland aus einer Vielzahl von Bestands- und Neuwerkstoffen mit unterschiedlichen Festigkeiten, Durchmessern und Wandstärken. Für diese ist eine umfassende Betrachtung notwendig. In diesem Bereich leistet das Projekt H2-SuD wesentliche Beiträge, insbesondere zur Frage der Anpassung der Mindestwandstärke für sicheres Schweißen. Hierzu bieten die Demonstratoren eine ideale Grundlage zum Screening vieler Schweißparameter-Werkstoff-Kombinationen. Eine erhöhte Wasserstoffkonzentration beim Schweißen wurde experimentell belegt (DNV-Projekt und H2-SuD), allerdings im allgemein nicht als kritisch erachteten Bereich. Zudem wurde eine Wasserstoffversprödung der Schweißnaht während des Schweißens an druckwasserstoffführenden Demonstratoren bisher nicht beobachtet. Dies liegt u.a. an den mechanischen Eigenschaften der Rohrleitungswerkstoffe (gute Dehnfähigkeit, auch im geschweißten Zustand). T2 - Vortragsreihe des Bezirksverbandes Berlin des Deutschen Verbandes für Schweißen und verwandte Verfahren (DVS) e.V. CY - Berlin, Germany DA - 25.03.2026 KW - Wasserstoff KW - Rohrleitung KW - Schweißen KW - Demonstrator KW - Bauteilprüfung PY - 2026 AN - OPUS4-65774 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Praktikable Prüfung der Wasserstoffverteilung in Mehrlagenschweißungen in Anlehnung an die DIN EN ISO 3690 N2 - Das Forschungsvorhaben adressiert eine zentrale Lücke und damit einhergehende Einschränkung für geschweißte hochfeste Werkstoffe in der aktuellen Normung: Die DIN EN ISO 3690 erlaubt ausschließlich die Bestimmung des diffusiblen Wasserstoffs in einlagigen Prüfraupen und bildet damit die realen Bedingungen in mehrlagigen Schweißnähten hochfester Stähle nicht ab. Durch das mehrfache wiederholte Aufwärmen wird die eingebrachte Wasserstoffkonzentration deutlich unter die konservativen, einlagigen Prüfraupen bereits während des Schweißens abgesenkt. Hierzu fehlt jedoch eine einfache, experimentelle Methoden, um die tatsächliche lokale lagenabhängige bzw. globale Wasserstoffverteilung quantifizieren zu können. Das Vorhaben entwickelt daher erstmals eine Versuchsmethodik, der reale Diffusions- und Entgasungsbedingungen von Mehrlagenschweißungen experimentell reproduziert. Dadurch werden die Nachteile der ISO 3690 (einlagige Prüfraupe, konservative Bewertung) aufgehoben und mit dem Hauptvorteil (robuste, einfache Handhabung) kombiniert. Durch gezielte Variation von Wärmeführung, Zwischenlagentemperaturen und Wasserstoffangebot werden lokale und globale Wasserstoffverteilungen quantifiziert. Ergänzt durch ein numerisches Diffusionsmodell entsteht ein skalierbares Bewertungswerkzeug, das die experimentellen Daten generalisiert und auf reale Schweißnähte überträgt. Die Ergebnisse ermöglichen: (1) eine realitätsnahe Bewertung verbleibender Wasserstoffgehalte, Kaltrisssicherheit, damit die (2) die mögliche Ausweitung der HD Klassifizierung hochfester Schweißzusätze, und (3) die Beurteilung der Effektivität und Notwendigkeit von Wärmenachbehandlungs-maßnahmen (wie „Wasserstoffarmglühen“). T2 - Sitzung des NA 092-00-05 GA Gemeinschaftsarbeitsausschuss NAS/NMP: Zerstörende Prüfung von Schweißverbindungen (DVS AG Q 4/Q 4.1) CY - Berlin, Germany DA - 24.03.2026 KW - Schweißen KW - Wasserstoff KW - ISO 3690 KW - Prüfung KW - Mehrlagennaht PY - 2026 AN - OPUS4-65784 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hartwig, Peter T1 - Sichere Wasserstoffnetze ModuH2Pipe N2 - Modulare Testplattform für den sicheren Transport von Wasserstoff in neuen und vorhandenen Gasverteilnetzen Die BAM schafft mit der modularen Testplattform ModuH2Pipe erstmals in Europa eine Testinfrastruktur, welche die Betrachtung sicherheitstechnischer Fragestellungen im Realmaßstab und zugleich unter kritischen Bedingungen erlaubt, die sich im Zusammenhang mit Wasserstoff-und Wasserstoff-Erdgas-Pipelines stellen. Ziel ist, Gasnetzbetreibern u. a. ein Dienstleistungsangebot zur Verfügung zu stellen, welches die umfassende Beantwortung dieser und weiterer sicherheitstechnischer Fragestellungen ermöglicht. Die Testplattform ModuH2Pipe wird auf dem BAM Testgelände Technische Sicherheit (BAM TTS) stehen und integriert zwei Module, die für die experimentelle Untersuchung von Pipelinesegmenten, -komponenten (Dichtungen, Ventile etc.) und Polymerkomponenten im Originalmaßstab ausgelegt sind. Aber auch digitale Aspekte für Wasserstoffnetze können betrachtet werden. T2 - 1. Fachtagung für Anlagen- und Prozesstechnik CY - Berlin, Germany DA - 24.03.2026 KW - Wasserstoff KW - ModuH2Pipe KW - Testplattform KW - Realmaßstab KW - Wasserstoffkernnetz PY - 2026 AN - OPUS4-65765 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -