Award Date

1-1-2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Ajit K. Roy

Number of Pages

179

Abstract

Austenitic nickel-base Alloy 617 has been tested under tensile loading at temperatures relevant to both the Nuclear Hydrogen Initiative and the Next Generation Nuclear Plant programs of the U.S. Department of Energy. Two important metallurgical phenomena, namely dynamic strain aging (DSA) and yield strength anomaly (YSA), have been identified based on the resultant data. DSA was characterized by reduced plastic strain and serrations in the engineering stress versus engineering strain diagrams. YSA was manifested by enhanced yield strength at relatively higher temperatures. A mechanistic understanding of DSA and YSA phenomena has been developed based on the estimation of dislocation density, activation energy, work-hardening index and precipitate morphology, where applicable. Stress-intensity-factor and crack-growth-rates of this alloy have been evaluated with and without the presence of an acidic solution at different temperatures using fracture-mechanics-based principles. Fractographic evaluations of all tested specimens have also been performed to characterize the extent and morphology of failures resulting from different modes of loaDing

Keywords

Alloy; Crack; Crack Propagation; Deformation; Dynamic Strain Aging; Fracture Toughness

Controlled Subject

Mechanical engineering; Materials science; Materials science

File Format

pdf

File Size

3932.16 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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