Mechanical Behavior of Nuclear Reactor Materials and Components III: In-situ Testing and Novel Techniques
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Assel Aitkaliyeva, University of Florida; Clarissa Yablinsky, Los Alamos National Laboratory; Osman Anderoglu, University of New Mexico; Eda Aydogan, Middle East Technical University; Kayla Yano, Pacific Northwest National Laboratory; Caleb Massey, Oak Ridge National Laboratory; Djamel Kaoumi, North Carolina State University
Thursday 8:30 AM
March 23, 2023
Room: 28D
Location: SDCC
Session Chair: Assel Aitkaliyeva, University of Florida; Kayla Yano, PNNL
8:30 AM Invited
Mechanical Martensites in Nuclear Steels: Janelle Wharry1; Patrick Warren1; Haozheng Qu1; Chao Yang1; Yangyang Zhao1; Keyou Mao2; 1Purdue University; 2Florida State University
The objective of this talk is to demonstrate the many and varied observations of mechanical martensites in nuclear steels, and their implications on mechanical behavior. Deformation-induced martensites form through diffusionless, solid-state phase transformations in both austenitic and ferritic steels. High stress and low temperature are thought to be necessary conditions for martensitic transformations, but we will show examples of mechanical martensites at room temperature and above, during both micromechanical loading and transgranular stress corrosion cracking (TGSCC). Nanoindentation of 304L and model Fe-P, Fe-N, and Fe-Mn alloys reveal the role of alloying on martensitic transformations. Subsequently, irradiation promotes or pins the extent of the transformation, depending on the defect type; experiments will be corroborated with molecular dynamics simulations. Finally, evidence of mechanical martensites in 304L during TGSCC propagation will be presented. Implications of mechanical martensites will be discussed in the context of mechanical integrity and longevity of nuclear reactor components.
9:00 AM
Evaluation of Size Effects in Small Scale Mechanical Testing Combining Multi-length Scale Models and Experiments: David Frazer1; Stephanie Pitts1; Brennan Harris1; Fei Teng1; Trishelle Copeland-Johnson1; Kaustubh Bawane1; Sebastian Lam2; Dewen Yushu1; Peter Hosemann2; Fabiola Cappia1; 1Idaho National Laboratory; 2UC Bereley
Small scale mechanical testing (SSMT) has an advantage in the nuclear mechanical testing community by reducing the volume of material tested. This reduction permits the testing of ion beam irradiated material and better utilization with reduced costs for neutron irradiated material. The main challenge with SSMT is the size effects, smaller is stronger phenomenon, make it difficult to relate the mechanical properties measured in the small test specimens to bulk values. In this work micro-tensile specimens of various sizes were manufactured with focused ion beam and femto-second laser techniques and coupled with crystal plasticity, through hybrid modeling approaches, to elucidate the transition from the size effect region to the bulk mechanical properties. These experiments were performed on tungsten, zirconium and irradiated zirconium to evaluate different crystal structures and defect densities in the material. The effect of temperature, above and below ambient, on the transition is being examined in BCC materials.
9:20 AM
Micromechanical Aspects of Deformation and Failure of Advanced Iron-Chromium-Aluminum Alloys: Ercan Cakmak1; Maxim Gussev1; Nedim Cinbiz2; Kevin Field3; Ke An1; 1Oak Ridge National Laboratory; 2Idaho National Laboratory; 3University of Michigan
Mechanical behavior of as-received (AR) and welded (W) Fe-13Cr-5Al with Nb or TiC additions was investigated using digital image correlation (DIC) and neutron diffraction in situ. Deformation-induced void microstructure was characterized by x-ray computed tomography to reveal the microscopic aspects of the failure. Neutron diffraction, DIC, and XCT data were analyzed together to reveal the microscopic aspects of the deformation. Although the high density of voids distributed along the gauge section of Nb-modified specimens, the brittle-like failure of W sample with cleavage was observed. On the other hand, TiC modification improved the ductility of AR and W samples, and failure occurred via completely ductile processes. Results indicated that ductile processes were operative for all samples, but type of modification determines the failure type either governed by the dislocation motion or toughness or both.
9:40 AM
The Influence of Nanoindentation Orientation on Deformation Mechanisms in Irradiated Fe – P and Fe – N: Patrick Warren1; Keyou Mao2; Janelle Wharry1; 1Purdue University; 2Florida State University
The objective of this study is twofold: first to evaluate differences in deformation mechanisms induced by Berkovich nanoindentation along different crystallographic directions, and second to contrast the deformation mechanisms in irradiated substitutional (Fe–P) and interstitial (Fe–N) binary alloys. Nanoindentation is a widely used method for evaluating hardening in ion irradiated layers. However, the geometry of the Berkovich nanoindentation tip produces anisotropic, orientation-specific plasticity. Moreover, the nature of the alloying elements (substitutional or interstitial solutes), will also influence the irradiated microstructures and consequently the deformation mechanisms. In this work, indents are made along the <001> and <011> crystallographic directions on [001] grains in irradiated and as-received Fe–P and Fe–N. Deformation mechanisms are discerned by transmission electron microscopy (TEM). In Fe–P, indent direction changes the deformation mechanism from cross slip to slip, whereas in Fe–N, stress-induced martensitic phase transformations occur but are pinned by irradiation-induced defects.
10:00 AM Break
10:20 AM Invited
Non-destructive Stress Evaluation in Nuclear Materials by Positron Annihilation Spectroscopy: Farida Selim1; Djamel Kaoumi2; 1Bowling Green State University; 2North Carolina State University
Understanding radiation damage and assessing the mechanical properties of structural materials are essential for developing high-strength materials with good radiation tolerance for the development of advanced nuclear reactors. Positron annihilation spectroscopy (PAS) was shown to be an effective tool in probing radiation damage on small length scale not accessible by most characterization techniques including HRTEM. Positron can also probe the microstructural changes associated with stress generation and the measured PAS parameters reflect the induced deformation due to tensile, fatigue, cold work, and bending. However not much work was done to employ PAS for assessing the mechanical properties. Here we will show that PAS is an effective sensitive nondestructive tool for assessing the mechanical strength of structural materials and the PAS defect parameters mimic the stress strain engineering curve. Examples will be given on stress measurements in steel alloys the prospect of advancing material strength evaluation by PAS will be discussed.
10:50 AM
Error in RUS Measurements Due to Geometric Uncertainties: Mathew Hayne1; Luke Beardslee1; Anna Buckthorpe1; Paul Geimer1; Timothy Ulrich II1; Tarik Saleh1; 1Los Alamos National Laboratory
Resonant ultrasound spectroscopy (RUS) is a powerful nondestructive evaluation (NDE) technique allowing for precise measurement of the elastic constants of a given material. Recently developed finite element (FERUS) techniques, which will be reviewed, allow for the determination of properties on samples with complex geometries. This contrasts with the simple and very computationally efficient set of functions determined by Visscher et al., which have been traditionally utilized, allowing for the general solution to be easily determined for simple geometries (right parallelepipeds, right cylinders, and spheres). This process assumes a certain level of geometric precision in the sample. In this study we determined the error associated with deviations from the ideal through the systematical evaluation of imperfect geometries using finite element (FERUS) techniques. An overview of the RUS technique along with how FERUS has allowed for elastic modulus measurement to be made on cladding material, in their final form, will be discussed.
11:10 AM
Optimizing Nuclear Cladding Mechanical Property Output for Hot-cell Testing: Benton Garrison1; Caleb Massey1; Maxim Gussev1; Nathan Capps1; Jason Harp1; 1Oak Ridge National Lab
Although the ring-pull test is the simplest methodology for testing the hoop tensile properties of cladding relevant geometries, significant artifacts complicate data interpretation. Using digital image correlation, several ring tensile specimen geometries of unirradiated Zircaloy-4 were tested to evaluate strain localizations and gradients across the gage sections as a function of sample orientation and gauge dimensions. It was found that ring tensile tests configured with the gage on the side of the mandrel produced severe strain gradients across the wall thickness. Furthermore, ring tensile tests with longer gage lengths produced severe strain localizations near the specimen shoulders for all orientations, while the gage center remained undeformed. It was found that a ring tensile test with 1.5 mm gage length with gage on top of the mandrel produced a uniform deformation across the entire gage length up to the UTS and did not produce strain gradients across the tube wall thickness.