TY - JOUR A1 - Kempf, Andreas A1 - Kruse, Julius A1 - Madia, Mauro A1 - Hilgenberg, Kai T1 - Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion N2 - In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals. T2 - FATIGUE DESIGN 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - AlSi10Mg KW - Tensile properties KW - Fatigue properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544921 DO - https://doi.org/10.1016/j.prostr.2022.03.009 SN - 2452-3216 VL - 38 SP - 77 EP - 83 PB - Elsevier B.V. AN - OPUS4-54492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strauß, Lea A1 - Duarte, Larissa A1 - Kruse, Julius A1 - Madia, Mauro A1 - Löwisch, Günther T1 - An equivalent stress approach for predicting fatigue behavior of additively manufactured AlSi10Mg N2 - Laser-based powder bed fusion (PBF-LB) is an advanced additive manufacturing technique renowned for its precision and capability to fabricate complex metal components. However, the high thermal gradients and rapid cooling rates intrinsic to this process introduce significant process-induced effects, such as inhomogeneities, surface roughness, anisotropy, and residual stress, all of which critically influence the fatigue behavior of the produced parts. This study investigates the fatigue performance of AlSi10Mg samples produced by PBF-LB, examining the impact of varying surface conditions, geometries, and residual stress levels. Fatigue-life prediction models are formulated based on nominal stress amplitude, residual stress, form factor, crack-initiating inhomogeneity, and surface roughness, with smooth samples serving as a baseline reference. The study presents two empirical models for predicting fatigue life and fatigue strength using S–N curves and the Kitagawa–Takahashi diagram with the El Haddad approach, derived from comprehensive experimental data, including finite element modeling, fatigue-life measurements, surface roughness evaluations, and residual stress analysis. KW - AlSi10Mg KW - Kitagawa–Takahashi diagram KW - El Haddad KW - Equivalent stress KW - Fatigue-life prediction KW - PBF-LB/M PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625176 DO - https://doi.org/10.1007/s40964-025-00974-0 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-62517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kruse, Julius T1 - Anwendung der IBESS-Prozedur zur Berechnung der Schwingfestigkeit geschweißter bauteilähnlicher Proben mit künstlichen Defekten N2 - Im Rahmen eines Kooperationsprojekts mit der Schottel GmbH wurde eine bauteilnahe Probengeometrie entwickelt, mit der sich unter Verwendung einer einachsigen Prüfmaschine das Spannungstiefenprofil in dem unter überlagerter Biege- und Zugspannung beanspruchtem Querschnitt im Schweißnahtübergang des Bauteils reproduzieren ließ. Proben dieser Geometrie wurden vom Kooperationspartner im geschweißten bzw. geschweißten und spannungsarmgeglühten Zustand bereitgestellt. An der BAM wurden je Wärmebehandlungszustand mittels Senkerodieren zwei verschiedene künstliche Defektgeometrien im Schweißnahtübergang eingebracht. Anhand der Proben wurden experimentell für alle vier Probenzustände Wöhlerlinien für ein Spannungsverhältnis von R = 0,1 ermittelt. Zusätzlich wurde das u.a. an der BAM entwickelte IBESS-Verfahren angewandt, um die Wöhlerlinien analytisch zu bestimmen. Hierbei wurde eine sehr gute Übereinstimmung von Berechnung und Experiment erreicht, wobei die Berechnung zu einer leicht konservativen Lebensdauervorhersage führte. T2 - 56. DVM Tagung "Bruchmechanik und Bauteilsicherheit" CY - Kassel, Germany DA - 20.02.2024 KW - Bruchmechanik KW - Ermüdung KW - Schwingfestigkeit KW - Schweißverbindungen PY - 2024 AN - OPUS4-59781 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhu, Jiangchao A1 - Madia, Mauro A1 - Schurig, Michael A1 - Kruse, Julius A1 - Conrad, Fabian A1 - Schlums, Hartmut A1 - Kontermann, Christian A1 - Zerbst, Uwe T1 - On the use of representative specimens for the structural integrity assessment of safety-relevant rotating components N2 - Safety-relevant components, for which a failure in service could have catastrophic consequences, are usually designed for extremely low probability of failure and they are subjected to stringent part qualification procedures according to guidelines set by regulatory agencies. Manufacturers are often forced to perform tests on full scale or scaled components to ensure the structural integrity under defined loading conditions, which usually implies a huge experimental and financial effort. Therefore, companies try to develop new strategies such as digital twins, which allow to massively reduce costs, without compromising safety. This work presents a new quasi-static testing and assessment concept, the main idea of which is to replace, or at least reduce, the experimental testing on components by testing specimens representative of the component. Fracture mechanics specimens have been designed iteratively by numerical simulations to match the stress state at the crack-tip of the maximum permissible defect defined by regulatory agencies for the component. Potentially, the major benefit of the proposed approach is that the tests can be performed on conventional laboratory testing machines. The effectiveness of the methodology is demonstrated in case of the structural integrity assessment of a Ni-base superalloy aero-engine turbine disk at overspeed conditions. KW - Structural integrity KW - Turbine disk KW - Burst KW - Fracture mechanics KW - Representative specimens KW - Quasi-static testing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624208 DO - https://doi.org/10.1016/j.engfracmech.2024.110710 SN - 0013-7944 VL - 314 SP - 1 EP - 23 PB - Elsevier Ltd. AN - OPUS4-62420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhu, J. A1 - Madia, Mauro A1 - Schurig, M. A1 - Kruse, Julius A1 - Conrad, F. A1 - Schlums, H. A1 - Kontermann, C. A1 - Zerbst, Uwe T1 - Anwendung von repräsentativen Proben zur Bewertung der Strukturintegrität von sicherheitsrelevanten Komponenten N2 - Sicherheitsrelevante Bauteile, bei denen ein Versagen im Betrieb katastrophale Folgen haben könnte, sind in der Regel für eine sehr geringe Ausfallwahrscheinlichkeit ausgelegt und unterliegen strengen Qualifizierungsverfahren gemäß den von den Aufsichtsbehörden festgelegten Richtlinien. Die Hersteller sind oft gezwungen, Tests an realen oder skalierten Komponenten durchzuführen, um die Strukturintegrität unter definierten Belastungsbedingungen sicherzustellen, die in der Regel strenger sind als die im Betrieb zu erwartenden. Dies ist in der Regel mit einem enormen experimentellen und finanziellen Aufwand verbunden. Daher versuchen die Unternehmen, neue Strategien wie digitale Zwillinge zu entwickeln, mit denen die Kosten massiv gesenkt werden können, ohne die Sicherheit zu beeinträchtigen. In dieser Arbeit wird ein neues quasistatisches Prüf- und Bewertungskonzept vorgestellt, dessen Hauptidee darin besteht, die experimentelle Prüfung von Bauteilen durch die Prüfung von für das Bauteil repräsentativen Proben zu ersetzen oder zumindest zu reduzieren. Der größte Vorteil des vorgeschlagenen Konzepts besteht darin, dass die Versuche auf Laborprüfmaschinen durchgeführt werden können. Die Wirksamkeit der Methodik wird anhand der Bewertung der Strukturintegrität einer Turbinenscheibe aus einer Ni-Basis-Superlegierung für Flugzeugtriebwerke bei Überdrehzahl demonstriert. T2 - 57. Tagung des DVM-Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Köln, Germany DA - 18.02.2025 KW - Strukturintegrität KW - Bruchmechanik KW - Turbinenscheibe KW - Repräsentative Proben PY - 2025 DO - https://doi.org/10.48447/BR-2025-536 SP - 231 EP - 240 PB - DVM CY - Berlin AN - OPUS4-62602 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blasón Gonzalez, Sergio A1 - Werner, Tiago A1 - Kruse, Julius A1 - Gilli, Daniel A1 - Madia, Mauro T1 - Experimental procedure for the determination of intrinsic fatigue crack propagation threshold ΔKth,eff and characterization of FCGR curves on miniature steel specimens N2 - The largest percentage of component life under fatigue loading conditions is spent in the short crack regime and in the initial phase of long cracks. The use of Fracture Mechanics in the characterization of fatigue crack growth rate curves has proven to be a useful and adequate tool in the prediction of fatigue lifetimes as long as certain conditions are satisfied. All the above implies the need for a methodical and accurate procedure of assessment of the material response in order to achieve a reliable prediction of lifetime in components under safe conditions, based on the damage tolerance approach. It also highlights the need to analyse the response of increasingly reduced thicknesses, which, as time goes by, show greater differences with respect to those commonly studied and defined in standards and design guidelines, as well as to the experimental studies that can be found in the literature at present. Some examples of thin-walled components are turbine blades or certain additively manufactured parts where, additionally, variations in material properties can occur locally and should also be examined. T2 - 2nd International Symposium on Notch Mechanics (2nd ISNM) CY - Madrid, Spain DA - 03.09.2020 KW - miniature specimens; FCGR curves; intrinsic threshold PY - 2021 SP - 1 EP - 2 AN - OPUS4-55242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Werner, Tiago A1 - Blasón Gonzalez, Sergio A1 - Madia, Mauro A1 - Kruse, Julius A1 - Benedetti, Matteo T1 - Determination of fatigue crack propagation thresholds using small-scale specimens N2 - The damage tolerance approach is widely used in the design and estimation of inspection intervals of safety-relevant metallic components subject to fatigue loading. The approach relies on the knowledge of the fatigue crack propagation characteristics, wherein a relevant role is played by the fatigue crack propagation threshold. Nevertheless, the use of material data determined by testing on conventional specimens is not straightforward in the case of thin-walled components such as turbine blades or additively manufactured parts, in which the local variation of material properties in highly stressed regions must be considered. In these cases, the possibility of investigating the fatigue crack propagation properties on a limited portion of material is crucial. For this purpose, a new test procedure has been developed for small-scale specimens which allows the determination of the intrinsic fatigue crack propagation threshold and the near-threshold regime. The validity and limitations of the method are demonstrated on the high strength steel S960QL, along with a comparison with data determined by testing on conventional geometries. T2 - FATIGUE DESIGN 2021 CY - Online meeting DA - 17.11.2021 KW - Fatigue crack propagation threshold KW - Small-scale specimens KW - High strength steel KW - Crack-tip constraint KW - Damage tolerance PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544967 DO - https://doi.org/10.1016/j.prostr.2022.03.031 SN - 2452-3216 VL - 38 SP - 300 EP - 308 PB - Elsevier B.V. AN - OPUS4-54496 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Nina A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Investigation of the local strain behavior by digital image correlation and transverse tensile tests on welded differently microalloyed high strength structural steel N2 - Der Einsatz von hochfesten niedriglegierten Stählen (HSLA) ist in vielen Industriesektoren, wie dem allgemeinen Bauwesen, Offshore Strukturen, Mobilkranbau usw. unumgänglich geworden. Die steigende Nachfrage an Stählen mit einer hohen Festigkeit und gleichzeitig hervorragenden Zähigkeit stellt ein ökonomisches und ökologisches Potential dieser Stähle in Vordergrund. Aktuell gültige Normvorgaben (EN ISO 10025-6) geben den Stahlherstellern Vorgaben bezüglich der chemischen Zusammensetzung, um die geforderten mechanischen Eigenschaften erreichen zu können. Die Legierungsrouten variieren jedoch von Hersteller zu Hersteller. In Betracht der Schweißeignung dieser Stähle zeigt sich das Problem, dass diese bereits bei geringen Nb- und Ti-Mikrolegierungsunterschieden im Grundwerkstoff ein divergentes metallurgisches Verhalten in der Wärmeeinflusszone (WEZ) aufweisen. In diesem Vortrag werden die schweiß-metallurgischen Unterschiede zwischen verschieden mikrolegiertem hochfestem Feinkornbaustahl S690QL thematisiert. Zur Prüfung der Schweißnahtfestigkeit wurden mittels eines instrumentierten DIC (ARAMIS) Systems Querzugversuche an Schweiß-Querflachzugproben durchgeführt. T2 - AJP 2023 3rd International Conference on Advanced Joining Processes CY - Braga, Portugal DA - 19.10.2023 KW - WEZ-Erweichung KW - Hochfester Feinkornbaustahl KW - Digital Image Correlation KW - Querzugversuch KW - Mikrolegierungseinfluss PY - 2023 AN - OPUS4-58721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Giese, Marcel A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Local strain behaviour in cross weld tensile specimens of microalloyed high strength steels using digital image correlation N2 - This study specifically examines the role of the microalloying element titanium (Ti) in achieving the desired mechanical properties of quenched and tempered high-strength fine-grain structural steels, with a nominal yield strength of ≥ 690 MPa. Current specifications limit chemical composition only by defining upper thresholds, but even minor variations in Ti content can substantially alter mechanical properties. Consequently, accurate prediction of weldability and welded joint integrity becomes challenging, as variations in Ti lead to distinct microstructural characteristics, potentially causing undesirable softening or hardening effects in the heat-affected zone (HAZ). To address these complexities, two distinct titanium concentrations were systematically investigated for the first time using specially developed laboratory-cast alloys. Both alloying configurations were based on the standard S690QL grade, with consistent chemical composition and heat treatment parameters maintained across the samples. For the weldability analysis, three-layer welds were executed using gas metal arc welding (GMAW), allowing for the identification of critical microstructural zones within the HAZ that exhibit significant softening or hardening. The influence of the softened HAZ region on failure mechanisms was assessed through transverse tensile tests. Digital image correlation (DIC) was employed to capture local strain variations across different HAZ regions in situ. With a custom-developed mirror system, local strains in microstructural zones on both the top and bottom surfaces of the weld were recorded simultaneously. This setup enabled a detailed analysis of how weld seam geometry (e.g., V-groove configuration) influences strain gradients. Additionally, the investigation of localized deformation provided insights into how variations in Ti content within the HAZ affect global strain, fracture constriction, fracture location, and overall fracture behavior. T2 - MPA Seminar 2024 Materials Processes Applications CY - Stuttgart, Germany DA - 08.10.2024 KW - HAZ-Softening KW - Digital Image Correlation KW - Cross weld tensile test PY - 2024 AN - OPUS4-61488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro A1 - Purayil, Sruthi Krishna Kunji A1 - Kruse, Julius A1 - Madia, Mauro A1 - Nielsen, Sören T1 - Thermography-Assisted Mechanical Testing of Cold-Spray (AM) Repair N2 - Cold Spray Additive Manufacturing (CSAM) is a solid-state process that is being increasingly used for structural repairs in aerospace and energy sectors. It enables the deposition of dense material at low temperatures by accelerating metal particles to supersonic velocities, thereby reducing thermal distortion. However, the structural integrity of CSAM repairs—particularly at the interface between the deposited layer and the substrate—remains a critical concern. Various post-treatments and characterization methods have been explored to optimize performance. While X-ray Computed Tomography (XCT) is effective for sub-surface inspection, it cannot be applied in situ during mechanical testing. Digital Image Correlation (DIC), a surface-based method, also lacks sub-surface sensitivity. To address this, Infrared Thermography (IRT) was employed alongside DIC during the tensile and fatigue testing of aluminum CSAM-repaired specimens. A cooled IRT camera operating at 200 FPS captured thermal data, with lock-in processing subsequently applied in post-processing. IRT successfully detected early interfacial damage and enabled the tracking of crack propagation, which was later confirmed through fracture surface analysis. This extended abstract presents findings from fatigue tests using IRT. T2 - 18th International Workshop on Advanced Infrared Technology and Applications (AITA 2025) CY - Kobe, Japan DA - 15.09.2025 KW - Thermography KW - Thermografie KW - Thermal stress analysis KW - Cold spray KW - Damage detection PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642299 DO - https://doi.org/10.3390/proceedings2025129018 VL - 129 IS - 1 SP - 1 EP - 5 PB - MDPI CY - Basel AN - OPUS4-64229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blasón Gonzalez, Sergio A1 - Werner, Tiago A1 - Kruse, Julius A1 - Madia, Mauro A1 - Miarka, P. A1 - Seitl, S. A1 - Benedetti, M. T1 - Determination of fatigue crack growth in the near-threshold regime using small-scale specimens N2 - A complete description of the experimental procedure for characterizing the intrinsic fatigue crack propagation threshold (ΔKth,eff) as well as the fatigue crack growth rate (FCGR) in the near-threshold regime using small-scale specimens is presented. A comparative study is carried out on the high strength steel S960QL considering different single edge notch bend (SENB) specimen geometries. On one hand, the reference dimensions of 6 mm thickness (B) and 19 mm width (W) are analysed and referred to as conventional specimens. On the other hand, small-scale specimens with B = 3 mm and W = 4 and 6 mm are also considered. Several loading configurations (3-, 4- and 8-point bending) are used and a load ratio R = 0.8 is applied to avoid crack closure effects. The direct current potential drop (DCPD) technique is used to monitor the crack length. The reduced dimensions of the small-scale specimens imply the necessity of implementing a modified testing procedure compared to the recommendations of current standards for the generation of FCGR data. The results show a good agreement between tests conducted on different specimen sizes, which opens new perspectives in the use of small-scale specimens for characterizing the fatigue crack growth properties in metallic materials. Recommendations and limitations of the procedure are provided and discussed. KW - Fatigue crack growth KW - Small-scale specimens KW - Intrinsic fatigue propagation threshold KW - Near-threshold regime KW - High-strength steel KW - Alternative test procedure PY - 2022 DO - https://doi.org/10.1016/j.tafmec.2021.103224 SN - 0167-8442 VL - 118 SP - 1 EP - 12 PB - Elsevier CY - Amsterdam AN - OPUS4-54209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blasón Gonzalez, Sergio A1 - Werner, Tiago A1 - Kruse, Julius A1 - Gilli, D. A1 - Madia, Mauro T1 - Procedimiento experimental para la determinación del valor ΔK umbral intrínseco y caracterización de velocidad de propagación de grietas en fatiga en probetas de acero N2 - Se presenta una guía completa del procedimiento experimental para la determinación del valor umbral ΔKth intrínseco y caracterización de curvas FCGR sobre el acero de alta resistencia S960QL empleando probetas de pequeña escala. El análisis se realiza comparando probetas SENB de diferentes geometrías, distinguiendo entre “convencionales” y “miniatura”. Las primeras con espesor (B) de 6 mm y anchura (W) de 19, y las segundas con B = 3 y dos valores distintos de W, 4 y 6 mm. A fin de identificar el valor umbral ΔKth intrínseco, la relación de cargas (R) aplicada en todos los ensayos fue 0,8. La técnica de caída de potencial (DCPD) se utilizó para la monitorización del tamaño de grieta a lo largo de los ensayos. La evaluación de los resultados experimentales confirma la equiparación de resultados entre las distintas geometrías y configuraciones de ensayo practicadas, así como la viabilidad de emplear probetas de pequeña escala en la determinación del valor umbral ΔKth intrínseco. Esto abre nuevas perspectivas en lo relativo al empleo de probetas de reducidas dimensiones en la caracterización de materiales a fatiga. A su vez, permite ofrecer una serie de recomendaciones para reproducir con éxito ensayos semejantes utilizando probetas de pequeñas dimensiones de acero y otros materiales metálicos. T2 - XXXVII Congreso del Grupo Español de Fractura CY - Online meeting DA - 07.06.2021 KW - Probetas miniatura KW - Determinación Kth intrínseco KW - Curvas FCGR KW - Acero alta resistencia KW - Recomendaciones procedimiento de ensayo PY - 2021 AN - OPUS4-55244 LA - spa AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Kadoke, Daniel A1 - Kruse, Julius T1 - Effect of Ti microalloying on the local strain behavior of cross-weld tensile samples determined by digital image correlation N2 - High-strength low-alloyed (HSLA) steels with yield strength / proof stress ≥ 600 MPa are the basis of modern light-weight steel constructions. Indeed, the economic and ecological benefits strongly depend on their processability in terms of welding. In this context, the use of highly productive welding processes and suitable welding consumables is of vital interest and requires a fundamental understanding of the microstructural changes in the HSLA steel and especially the heat-affected zone (HAZ) of the welded joint. Microalloying elements, such as Ti or Nb, are essential to achieve the desired mechanical properties. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the HAZ that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using cross-weld tensile specimens. Digital image correlation (DIC) was used for in-situ monitoring of the development and accumulation of the local strains in different HAZ regions during tensile testing. Using a specially designed mirror system, the local strains of the microstructure zones on the top and bottom of the weld were recorded simultaneously. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the reduction in area, the fracture position, and the overall fracture behavior. KW - High-strength structural steel KW - Microalloying influences KW - HAZ-softening KW - Digital Image Correlation KW - Constraint effect KW - Thermodynamic simulation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643558 DO - https://doi.org/10.1007/s40194-025-02185-1 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-64355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Han, Ying A1 - Kruse, Julius A1 - Rosalie, Julian A1 - Radners, J. A1 - von Hartrott, P. A1 - Skrotzki, Birgit T1 - Influence of mean stress and overaging on fatigue life of aluminum alloy EN AW-2618A N2 - Fatigue tests were performed on the forged aluminum alloy EN AW-2618A in the T61 state. Different stress ratios (R = -1, R = 0.1) were selected to study the influence of mean stress on fatigue life. Two overaged states (10 h/230 ◦C, 1000 h/230 ◦C) were also tested to investigate the influence of overaging on fatigue life. Transmission electron microscopy (TEM) was used to characterize the precipitates (S-phase), which are mainly responsible for the strength of the alloy. A fractographic analysis was also performed to determine the failure mode. Overaging reduces the fatigue life compared to the T61 state. The longer the aging time, the lower the fatigue resistance. The reason is the decrease in (yield) strength, which correlates with the radius of the S-phase: the precipitate radius increases by a factor of approximately two for the overaged states compared to the initial state. The analysis of the fracture surfaces showed crack initiation occurs predominantly on the outer surface and is associated with the primary phases. KW - Aluminum alloys KW - Aging KW - Fatigue KW - Microstructure KW - Electron microscopy KW - S-Phase PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583708 DO - https://doi.org/10.1016/j.msea.2023.145660 SN - 0921-5093 VL - 886 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-58370 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -