Fatigue in Materials: Fundamentals, Multiscale Characterizations and Computational Modeling: Advanced Experimental Characterization of Microstructurally Driven Fatigue Behavior
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Computational Materials Science and Engineering Committee, TMS: Integrated Computational Materials Engineering Committee, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Additive Manufacturing Committee
Program Organizers: J.C. Stinville, University of Illinois Urbana-Champaign; Garrett Pataky, Clemson University; Ashley Spear, University of Utah; Antonios Kontsos, Drexel University; Brian Wisner, Ohio University; Orion Kafka, National Institute Of Standards And Technology
Tuesday 8:00 AM
March 21, 2023
Room: Sapphire H
Location: Hilton
Session Chair: Garrett Pataky, Clemson University
8:00 AM Invited
Characterising Fatigue Crack Tip Deformation States in Nickel Base Superalloys: Slip Character, Strain Accumulation and Oxidation Effects: Philippa Reed1; Andrew Hamilton2; 1University of Southampton; 2University of Southhampton
The process or plastic zone at a crack tip controls the rate of crack advance, but the combination of factors that control this are wide ranging. We can use markers or fiduciaries associated with the microstructure itself to help us assess the evolution of stress and strain responses. These can include SEM-DIC approaches, EBSD analysis and X-ray CT analysis. We can also assess the degree of slip planarity and the role of oxidation in both accelerating and decelerating crack advance. A clearer micromechanical view of the features affecting the crack tip deformation processes is now available to us, and the full field nature of these approaches allows a much richer evaluation of the fatigue propagation processes. Taken together with 3D evaluations via X-ray CT approaches we can decipher the effects of deformation and local micromechanics both ahead of the crack tip and in its wake on fatigue growth.
8:30 AM Invited
Monitoring of Fatigue Evolution by In-Situ Measurement Methods and Micromagnetic Analysis: Ramin Hajavifard1; Lukas Lücker1; Julian Rozo Vasquez1; Yashar Sarafraz1; Simon Strodick1; Nikolas Baak1; Frank Walther1; 1TU Dortmund University
This paper focusses on the monitoring of production processes and material evolution under fatigue loading by non-destructive measurement methods, e.g. micromagnetic Barkhausen noise and eddy current. These very versatile and flexible techniques offer time-efficient possibility for the inspection of surface integrity of components. Approaches for a robust in-situ evaluation of surface integrity induced by manufacture, as well as the development of models for fatigue damage evolution, especially for materials with regard to high-performance and long-term sustainability, are presented. Different mechanisms are considered, e.g. production-induced formation of white etching layers (WEL), fatigue-induced relaxation of residual stresses and microstructural damage of component edge zone under fatigue loading. The mechanism-based consideration of influencing variables and cause-effect relationships is of decisive importance, since the effect interference represents a central challenge in identification of robust correlations for industrial applications.
8:50 AM
Fatigue Damage Evolution in Duplex Steel Investigated by µLaue Diffraction Using a 3D Energy-dispersive Detector: Carolin Leidigkeit1; Ullrich Pietsch2; Hans-Jürgen Christ1; 1Universität Siegen - Institut für Werkstofftechnik; 2Universität Siegen - Festkörperphysik
The microstructural changes (e.g., dislocation arrangement) inside a metallic material caused by cyclic plastic strain are usually monitored by time-consuming and destructive methods as long as no fatigue crack has been formed. The present work shows an alternative approach using white X-ray radiation and a 3D energy-dispersive detector allowing for non-destructive real structure analysis of specimen by a single-shot experiment. The method is demonstrated by experiment obtained on a duplex steel (AISI 318LN), which consists of two phases (ferrite and austenite) strongly differing in slip behavior. We present that we are able to address single grains of the polycrystalline material and to investigate different types of dislocation arrangements. The received results are interpreted on the basis of the corresponding investigations on nickel and α-brass showing pure wavy and pure planar dislocation glide, respectively.
9:10 AM
Build Orientation and Stress Ratio Effects on the Fatigue Crack Growth Properties of Laser Powder Bed Fused Ti-6Al-4V: Mikyle Paul1; Shuai Shao1; Nima Shamsaei1; 1Auburn University
While additive manufacturing enables the production of parts with complex geometries, anisotropy within the material may be induced during the fusion process, resulting in a directionally ordered microstructure. This directionality, if not removed by post-process heat treatments, could lead to differences in the mechanical behavior depending on the loading direction. Therefore, in this study, the fatigue crack growth properties of Ti-6Al-4V manufactured using laser powder bed fusion were investigated. Three build orientations, i.e., vertical, horizontal, and diagonal, were fabricated, stress relieved, and machined to standard compact tension specimens using wire electric discharge machining. Specimens were tested on servo-hydraulic load frames at three different stress ratios to capture the effects of mean stresses and crack closure on the fatigue crack growth behavior for different build orientations. Results indicated less dependence on build orientation in the threshold region as stress ratio was increased. Paris regions remained similar for all test conditions.
9:30 AM Break
9:50 AM
High-throughput Characterization of Small Crack Growth Behavior in Ti-6-4: Michelle Harr1; Bradley Rucker2; Ayman Salem3; Adam Pilchak3; T. Broderick4; S.I. Rao3; 1Wright Patterson Air Force Laboratories; MRL Materials Resources LLC ; 2MRL Materials Resources LLC; 3Wright Patterson Air Force Laboratories; MRL Materials Resources LLC; 4Wright Patterson Air Force Laboratories
Short crack growth rates are highly stochastic, with short cracks propagating significantly faster than long cracks with similar stress intensities. This anomalous behavior is hypothesized to be related to the local microstructure, but there are no known mechanistic links. We seek to understand microstructural effects on short crack growth behavior in Ti-6Al-4V by developing and utilizing an automated, high throughput fatigue crack growth system. Towards this goal, we have (1) designed and validated a novel combined optical monitoring and bending fatigue system; (2) developed a motion detection-based crack measurement method; and (3) implemented this system to investigate the crystallographic orientation dependence of small crack growth in Ti-6Al-4V. Results comparing traditionally measured small crack data and data collected with the high-throughput, optical measurement system will be discussed toward the goal of investigating the effect of local microstructure on short crack growth rates in Ti-6Al-4V.
10:10 AM
High Resolution Microcrack Growth Analysis in Thermomechanical Fatigue Loading: Nicolas Leost1; Djamel Missoum-Benziane1; Laurent Cameriano2; François Comte2; Vincent Maurel1; 1Le Centre des Matériaux de MINES PARIS - PSL University; 2Safran Aircraft Engines
Combustion chambers of aircraft engines sustain low cycle fatigue in presence of severe thermomechanical gradient. This paper develops an original testing procedure representative of chambers environment using a coplanar biaxial fatigue facility. Thermomechanical fatigue conditions were obtained by temperature cycling thanks to an induction heating device and by prescribing displacements to a cross shaped specimen. Full field analysis of temperature, strain and damage are obtained by infrared thermography (IRT), digital image correlation (DIC) and machine learning (ML) respectively. High temperature displacements acquisition was enabled by a recently developed laser engraved speckle patterns convenient for temperature above 900 °C. On this experimental basis, thermomechanical gradient effect has been investigated by modifying the inductor geometry and location. Finally, finite element analysis (FEA) validated by temperature and strain measurements enables to validate the mechanical behaviour of the tested alloy and to propose microcrack growth rate model accounting for severe gradients in anisothermal fatigue.
10:30 AM
Ultrasonic Fatigue Investigations for High and Very-High Cycle Fatigue Applications of A356 Cast Aluminum Alloys: Hayden Furcolo1; Anthony Spangenberger1; Qigui Wang2; Diana Lados1; 1Worcester Polytechnic Institute; 2General Motors
Ultrasonic fatigue (USF) testing has the potential to be used for rapid material evaluation in the high and very-high cycle fatigue regimes (105-1010 cycles) by decreasing operational cost and particularly test time. However, materials may exhibit frequency sensitivities, producing discrepancies between fatigue lifetimes measured at conventional and ultrasonic frequencies. Cast aluminum alloy A356Sr-T6 was used to assess these differences and understand if similar underlying physical phenomena are operative. Fatigue testing (R=-1) was conducted at 20 Hz (servo-hydraulic machine) and 20 kHz (USF machine) such that lifetime data are available for both methods in the 105-107 range. Post-test fractographic studies reveal initiating defect size/location and early growth mechanisms for both frequency conditions. Complementary computed tomography scans were conducted to measure pore size/location distributions and make comparisons with fractographic data. The results are presented and discussed in the context of the applicability of USF to the design and qualification of safety-critical components.