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University of Nevada, Las Vegas

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Las Vegas (Nev.)

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The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV), the Idaho State University (ISU), and the Los Alamos National Laboratory (LANL) is to evaluate the feasibility of determining residual stresses in cold-worked, plastically-deformed (bent), and welded materials using a nondestructive method based on positron annihilation spectroscopy (PAS). This technique uses γ-rays from a small MeV electron Linac to generate positrons inside the sample via pair production. This method is known to have capabilities of characterizing defects in thick specimens that could not be accomplished by conventional positron technique or other nondestructive methods. The data generated by the PAS method has been compared to those obtained by other methods such as neutron diffraction (ND), X-ray diffraction (for thin specimens), and ring-core (destructive-for thick specimens) techniques. During the initial phase of this task residual stresses induced in experimental heats of austenitic type 304L stainless steel, and martensitic Alloy EP-823 have been determined by X-ray diffraction (XRD), PAS and ring-core (RC) techniques. More recently, residual stress measurements have been performed on Alloy HT-9 subjected to cold deformation and welding using all four techniques. The current testing is focused on the evaluation of residual stresses in irradiated materials (welded/plasticallydeformed), and welded specimens, with and without post-weld-thermal-treatment (PWTT). Measurements of residual stresses in cold-worked and welded specimens of Alloys EP-823 and HT-9 are planned to be performed at the Atomic Energy of Canada Limited (AECL) by using the ND technique. Development of calibration curves using the PAS method are also being planned at ISU involving Alloy HT-9. Transmission electron microscopic (TEM) analyses are also being continued.


Austenitic stainless steel; Deformations (Mechanics); Martensitic stainless steel; Nuclear reactors — Materials — Testing; Plasticity; Strains and stresses

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Austenitic stainless steel; Martensitic stainless steel; Nuclear reactors--Materials--Testing


Materials Science and Engineering | Metallurgy | Nuclear Engineering | Oil, Gas, and Energy

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175 KB




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