TY - CONF A1 - Agudo Jácome, Leonardo A1 - Nolze, Gert A1 - Roohbakhshan, Farshad A1 - Fedelich, Bernard A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit T1 - Cyclic operation performance of 9-12% Cr ferritic-martensitic steels part 2: Microstructural evolution during cyclic loading and its representation in a physically-based micromechanical model N2 - The current competitive situation on electricity markets forces conventional power plants into cyclic operation regimes with frequent load shifts and starts/shutdowns. In the present work, the cyclic mechanical behavior of ferritic-martensitic 9-12 % Cr steels under isothermal and thermomechanical loading was investigated for the example of grade P92 material. A continuous softening was observed under all loading conditions. The introduction of hold periods to the applied cycles reduced material lifetime, with most prominent effects at technologically relevant small strain levels. The microstructural characterization reveals a coarsening of the original “martensitic” lath-type microstructure to a structure with polygonal subgrains and reduced dislocation density. The microstructural data forms the input for a physically-based modelling approach. T2 - 45. MPA-Seminar CY - Leinfelden-Echterdingen, Germany DA - 01.10.2019 KW - Tempered Martensite Ferritic Steels KW - P92 KW - TEM KW - EBSD KW - Micromechanical model PY - 2019 SP - 80 EP - 85 PB - MPA (Materialprüfungsanstalt Universität Stuttgart) CY - Stuttgart AN - OPUS4-50052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Avila Calderon, Luis Alexander A1 - Schriever, Sina A1 - Hang, Y. A1 - Olbricht, Jürgen A1 - Portella, P. D. A1 - Skrotzki, Birgit T1 - Creep reference data of single-crystal Ni-based superalloy CMSX-6 N2 - The article presents creep data for the single-crystal, [001]-oriented nickel-based superalloy CMSX-6, tested at a temperature of 980 °C under initial stresses ranging from 140 MPa to 230 MPa. The constant-load creep experiments were performed in accordance with DIN EN ISO 204:2019–4 standard within an ISO 17025 accredited laboratory. A total of 12 datasets are included, each of which includes the percentage creep extension as a function of time. The data series and associated metadata were systematically documented using a data schema specifically developed for creep data of single-crystal Ni-based superalloys. This dataset serves multiple purposes: it can be used to compare with one's own creep test results on similar materials, to verify testing setups (e.g., by replicating tests on the same or comparable materials), to calibrate and validate creep models, and to support alloy development efforts. KW - NFDI MatWerk KW - Referenzdaten KW - Kriechen KW - CMSX-6 KW - Digitalisierung PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654056 DO - https://doi.org/10.1016/j.dib.2025.112436 VL - 65 SP - 1 EP - 11 PB - Elsevier AN - OPUS4-65405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bayerlein, Bernd A1 - Hanke, T. A1 - Muth, Thilo A1 - Riedel, Jens A1 - Schilling, Markus A1 - Schweizer, C. A1 - Skrotzki, Birgit A1 - Todor, A. A1 - Moreno Torres, Benjami A1 - Unger, Jörg F. A1 - Völker, Christoph A1 - Olbricht, Jürgen T1 - A Perspective on Digital Knowledge Representation in Materials Science and Engineering N2 - The amount of data generated worldwide is constantly increasing. These data come from a wide variety of sources and systems, are processed differently, have a multitude of formats, and are stored in an untraceable and unstructured manner, predominantly in natural language in data silos. This problem can be equally applied to the heterogeneous research data from materials science and engineering. In this domain, ways and solutions are increasingly being generated to smartly link material data together with their contextual information in a uniform and well-structured manner on platforms, thus making them discoverable, retrievable, and reusable for research and industry. Ontologies play a key role in this context. They enable the sustainable representation of expert knowledge and the semantically structured filling of databases with computer-processable data triples. In this perspective article, we present the project initiative Materials-open-Laboratory (Mat-o-Lab) that aims to provide a collaborative environment for domain experts to digitize their research results and processes and make them fit for data-driven materials research and development. The overarching challenge is to generate connection points to further link data from other domains to harness the promised potential of big materials data and harvest new knowledge. KW - Data infrastructures KW - Digital representations KW - Digital workflows KW - Knowledge graphs KW - Materials informatics KW - Ontologies KW - Vocabulary providers PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546729 DO - https://doi.org/10.1002/adem.202101176 SN - 1438-1656 SP - 1 EP - 14 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-54672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Fedelich, Bernard A1 - Jokisch, T. A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - Fatigue and fracture in dual-material specimens of nickel-based alloys fabricated by hybrid additive manufacturing N2 - The integration of additive manufacturing with traditional processes, termed hybrid additive manufacturing, has expanded its application domain, particularly in the repair of gas turbine blade tips. However, process-related defects in additively manufactured materials, interface formation, and material property mismatches in dual-material structures can significantly impact the fatigue performance of components. This investigation examines the low cycle fatigue and fatigue crack growth behaviors in dual-material specimens of nickel-based alloys, specifically the additively manufactured STAL15 and the cast alloy 247DS, at elevated temperatures. Low cycle fatigue experiments were conducted at temperatures of 950 °C and 1000 °C under a range of strain levels (0.3%–0.8%) and fatigue crack growth tests were conducted at 950 °C with stress ratios of 0.1 and −1. Fractographic and microscopic analyses were performed to comprehend fatigue crack initiation and crack growth mechanisms in the dual-material structure. The results consistently indicated crack initiation and fatigue fracture in the additively manufactured STAL15 material. Notably, fatigue crack growth retardation was observed near the interface when the crack extended from the additively manufactured STAL15 material to the perpendicularly positioned interface. This study highlights the importance of considering yield strength mismatch, as well as the potential effects of residual stresses and grain structure differences, in the interpretation of fatigue crack growth behavior at the interface. KW - Hybrid additive manufacturing KW - Dual-material nickel-based alloys KW - High-temperature fatigue crack growth KW - Low cycle fatigue PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609340 DO - https://doi.org/10.1016/j.jmrt.2024.08.211 SN - 2238-7854 VL - 32 SP - 3737 EP - 3749 PB - Elsevier B.V. AN - OPUS4-60934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Fedelich, Bernard A1 - Jokisch, T. A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - Fatigue crack growth behavior of Alloy 247DS brazed joints at high temperatures N2 - Gas turbine components made of nickel-based alloys can be repaired through diffusion brazing. However, process-induced imperfections, defects within the brazing zone, and material property mismatches between the braze alloy and base material may facilitate crack initiation and propagation, ultimately leading to early component failure. To gain insight into the crack growth mechanism and quantitatively characterize fatigue crack growth behavior within brazing zones, fatigue crack growth (FCG) experiments were conducted on brazed joint specimens of nickel-based alloy Alloy 247DS at a temperature of 950 ◦C and a stress ratio R = 0.1. The FCG tests were complemented by fractographic and microstructural analyses, to elucidate the relationship between crack growth mechanisms and the microstructure of the brazed joint. The results demonstrate stable crack propagation within the brazing zone and the nickel-based braze alloy. The latter contains brittle eutectic boride phases and intermetallic phases that reduce the resistance to crack propagation compared to the parent material. This study demonstrates the applicability of standard FCG experimental procedures to fusion zones, thereby enabling a preliminary understanding of crack growth behavior in brazing zones. KW - Diffusion brazing KW - High-temperature fatigue crack growth KW - Nickel-based alloys KW - Alloy 247DS PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615250 DO - https://doi.org/10.1016/j.msea.2024.147488 SN - 0921-5093 VL - 918 SP - 1 EP - 15 PB - Elsevier B.V. AN - OPUS4-61525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Fedelich, Bernard A1 - Jokisch, Torsten A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - High Temperature Fatigue Crack Growth in Nickel-Based Alloys Refurbished by Additive Manufacturing N2 - Hybrid additive manufacturing plays a crucial role in the restoration of gas turbine blades, where, e.g., the damaged blade tip is reconstructed by the additive manufacturing process on the existing blade made of a parent nickel-based alloy. However, inherent process-related defects in additively manufactured material, along with the interface created between the additively manufactured and the cast base material, impact the fatigue crack growth behavior in bi-material components. This study investigates the fatigue crack growth behavior in bi-material specimens of nickel-based alloys, specifically, additively manufactured STAL15 and cast alloy 247DS. The tests were conducted at 950 °C with stress ratios of 0.1 and −1. Metallographic and fractographic investigations were carried out to understand crack growth mechanisms. The results revealed significant retardation in crack growth at the interface. This study highlights the potential contributions of residual stresses and microstructural differences to the observed crack growth retardation phenomenon, along with the conclusion from an earlier study on the effect of yield strength mismatch on crack growth behavior at a perpendicular interface in bi-material specimens. T2 - Superalloys 2024 Conference CY - Champion, Pennsylvania, USA DA - 08.09.2024 KW - Fatigue crack growth KW - Bi-material structure KW - Additive manufacturing KW - Nickel-based alloys PY - 2024 SN - 978-3-031-63937-1 DO - https://doi.org/10.1007/978-3-031-63937-1_92 SN - 2367-1181 SN - 2367-1696 VL - 15th SP - 994 EP - 1001 PB - Springer CY - Cham AN - OPUS4-60907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Fedelich, Bernard A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit A1 - Jokisch, T. ED - Zimmermann, M. T1 - Rissfortschrittsuntersuchungen an gefügten Nickelbasiswerkstoffen bei hoher Temperatur N2 - In nickelbasierten Superlegierungen, die für Gasturbinenschaufeln verwendet werden, sind bei hohen Betriebstemperaturen und -belastungen Kriechschäden, Ermüdung, Korrosion und Oxi-dation zu beobachten. Die betroffenen Turbinenschaufeln müssen ersetzt oder repariert werden, um Effizienzverluste und ein eventuelles Bauteilversagen zu vermeiden. In letzter Zeit wurden additive Fertigungs- und Lötverfahren für die Reparatur und das Fügen von Nickelbasiswerk-stoffen entwickelt, um die Einschränkungen der traditionellen Reparaturverfahren zu überwinden. Für eine auslegungsrelevante Bewertung des Risswachstumsverhaltens in den Fügezonen, die durch diese neuen Technologien erzeugt werden, sind Rissfortschrittsuntersuchungen erfor-derlich. Entsprechende Untersuchungen an gefügten Proben werden in diesem Beitrag vorge-stellt. Die Rissfortschrittsversuche werden an gefügten SEN-Proben (Single Edge Notch) bei einem Spannungsverhältnis von 0,1 und einer Temperatur von 950 °C durchgeführt. Das Riss-wachstum wird mit der DCPD-Methode (Direct Current Potential Drop) überwacht, und die ge-messenen Potenzialsignale werden anhand der optisch vermessenen Risslänge und einer Finite-Elemente-Analyse kalibriert. Der Spannungsintensitätsfaktor (SIF) für die gefügte SEN-Geometrie wird mit Hilfe von Finite-Elemente-Analysen berechnet. Auf diese Weise können Rissfortschrittskurven aus den experimentellen Daten abgeleitet werden. T2 - Tagung „Werkstoffprüfung 2022“ CY - Dresden, Germany DA - 27.10.2022 KW - Lötverbindung KW - Rissfortschritt KW - SEN-Probe KW - Gefügte Nickelbasislegierungen PY - 2022 SN - 978-3-88355-430-3 VL - 2022 SP - 67 EP - 72 AN - OPUS4-57090 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bhadeliya, Ashok A1 - Rehmer, Birgit A1 - Skrotzki, Birgit A1 - Jokisch, Torsten A1 - Olbricht, Jürgen A1 - Fedelich, Bernard T1 - Fatigue crack growth in nickel-based alloy 247DS with side-brazed pre-sintered preform N2 - Pre-sintered preform (PSP) brazing is employed in the repair of gas turbine components made of nickel-based alloys, including restoring the surface and dimensions of turbine blades and vanes. This study investigates the fatigue crack growth (FCG) behavior of Alloy 247DS specimens with side-brazed PSP material, mimicking a typical sandwich structure formed during such repairs. FCG tests were conducted at an elevated temperature of 950 °C and a stress ratio (R) of 0.1 on specimens with PSP layer thicknesses of 1.5 mm, 2 mm, 3 mm, and 4.5 mm to assess the influence of PSP thickness on fatigue crack growth behavior. Fractographic and metallographic analyses were performed to elucidate the underlying crack growth mechanisms and the microstructural characteristics of both materials. The results revealed that a crack consistently initiated in the PSP material, originating from the starter notch, particularly at the specimen corner during the pre-cracking phase. Additionally, crack propagation in the PSP material consistently advanced ahead of the crack in the Alloy 247DS. This crack growth behavior is attributed to the difference in elastic properties and microstructural differences between the PSP and base material. Metallographic analysis revealed the presence of porosity and brittle precipitates within the PSP material, which led to faster intergranular crack growth. Conversely, Alloy 247DS exhibited transgranular crack growth, contributing to the observed crack propagation behavior. This study demonstrates the applicability of standard FCG testing methods and an approach to characterize the FCG behavior in sandwich specimens, where crack growth occurs simultaneously in both materials, providing a preliminary understanding of crack growth behavior in Alloy 247DS with side-brazed PSP. KW - High-temperature fatigue crack growth (FCG) KW - Nickel-based alloys KW - Alloy 247DS KW - Pre-Sintered Preform (PSP) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629783 DO - https://doi.org/10.1016/j.ijfatigue.2025.108961 VL - 197 SP - 1 EP - 13 PB - Elsevier BV AN - OPUS4-62978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bismarck, Marck A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - Size effects in miniature specimen creep testing of P91 N2 - The use of miniaturized specimen geometries in mechanical testing allows extracting the sample material directly from critical components of power plants like e.g. headers and pipes. In this way, both the impacts of the manufacture of the component (including all shaping and tempering influences) and of the complex aging/loading/oxidation conditions during Service can be analyzed and representative mechanical properties are obtained. In the present study, example results of a comparative creep and creep rupture study on P91 tempered martensite ferritic Steel, involving Standard and miniature specimens that were all taken from one batch of material, are presented. Cylindrical creep specimens with a minimum gauge length diameter of 3 mm were used, representing the smallest recommended test geometry of ISO 204. The test results of miniature specimens exhibit all characteristic creep features of tempered martensite ferritic steels, and analysis of the stress and temperature dependence of creep results in values that correspond well to literature data for P91. However, direct comparison with large scale specimen data reveals small but systematic variations in minimum creep rates, elongations at fracture and times to rupture. In our contribution, these differences are discussed in the light of literature findings on specimen size influences in other heat resistant alloys. Size effects need to be considered for a correct interpretation of results from miniature specimen creep tests. T2 - 3rd International ECCC Conference CY - Rom, Italy DA - 05.05.2014 KW - Material PY - 2017 SN - 978-88-7484-510-1 SP - 430 EP - 435 PB - Tipography Inail CY - Milan AN - OPUS4-41239 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Yue A1 - Schilling, Markus A1 - von Hartrott, P. A1 - Beygi Nasrabadi, Hossein A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - Ontopanel: A Tool for Domain Experts Facilitating Visual Ontology Development and Mapping for FAIR Data Sharing in Materials Testing N2 - In recent years, the design and development of materials are strongly interconnected with the development of digital technologies. In this respect, efficient data management is the building block of material digitization and, in the field of materials science and engineering (MSE), effective solutions for data standardization and sharing of different digital resources are needed. Therefore, ontologies are applied that represent a map of MSE concepts and relationships between them. Among different ontology development approaches, graphical editing based on standard conceptual modeling languages is increasingly used due to its intuitiveness and simplicity. This approach is also adopted by the Materials-open-Laboratory project (Mat-o-Lab), which aims to develop domain ontologies and method graphs in accordance with testing standards in the field of MSE. To suit the actual demands of domain experts in the project, Ontopanel was created as a plugin for the popular open-source graphical editor diagrams.net to enable graphical ontology editing. It includes a set of pipeline tools to foster ontology development in diagrams.net, comprising imports and reusage of ontologies, converting diagrams to Web Ontology Language (OWL), verifying diagrams using OWL rules, and mapping data. It reduces learning costs by eliminating the need for domain experts to switch between various tools. Brinell hardness testing is chosen in this study as a use case to demonstrate the utilization of Ontopanel. KW - Materials Testing KW - Ontology KW - Visual ontology development KW - Data mapping KW - FAIR PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560339 DO - https://doi.org/10.1007/s40192-022-00279-y SP - 1 EP - 12 PB - Springer AN - OPUS4-56033 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -