Award Date

1-1-2006

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Committee Member

Ajit K. Roy

Number of Pages

84

Abstract

The structural material to contain the target material, used in transmutation of spent nuclear fuel, may develop residual stress due to different forming processes. Nondestructive neutron diffraction (ND) and positron annihilation spectroscopy (PAS) techniques have been utilized to characterize residual stress in martensitic Alloys EP-823 and HT-9, subjected to cold-reduction, plastic deformation and welDing The ND measurements revealed tensile residual stresses on the top and bottom surfaces of the cold-worked specimens. The residual stress was enhanced in cylindrical specimens with increased plastic-deformation. Post-weld-thermal-treatment was beneficial to reduce internal stresses in welded specimens. The line-shape-parameters (S, W and T) obtained from the PAS spectrum were related to the residual stress developed in cold-worked and plastically deformed specimens. The dislocation density determined by transmission electron microscopy was enhanced at higher cold-reduction levels. Fractographic evaluations by scanning electron microscopy revealed ductile failures in cylindrical specimens.

Keywords

Characterization; Defects; Diffraction; Microscopy; Neutron; Residual; Stresses

Controlled Subject

Mechanical engineering

File Format

pdf

File Size

3563.52 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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