The influence of environment on the fatigue behavior of HF-80 HSLA steel
Ahn, Seung-Ho
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https://hdl.handle.net/2142/19408
Description
Title
The influence of environment on the fatigue behavior of HF-80 HSLA steel
Author(s)
Ahn, Seung-Ho
Issue Date
1990
Doctoral Committee Chair(s)
Lawrence, Frederick V., Jr
Department of Study
Materials Science and Engineering
Discipline
Metallurgical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
Single-pitted specimens of HF-80, a HSLA steel, were tested in laboratory air and in 1 M NaCl solution to study the influence of a corrosive environment on its fatigue life.
The growth of fatigue cracks and the partitioning of the fatigue life into fatigue crack initiation and fatigue crack propagation were studied by photographing the pit and the cracks developing on it periodically during testing. Non-propagating or dormant surface cracks were not observed in this study. Fractography using SEM showed the locations of fatigue crack initiation.
The mechanisms of corrosion fatigue were studied by performing tests in 1 M NaCl at different test frequencies. Corrosion pits proved to be crack initiation sites. Hydrogen embrittlement was found to be insignificant in the corrosion fatigue of HSLA steel in this study. The 1 M NaCl corrosive environment appeared to reduce the fatigue life of this material by a dissolution mechanism.
The effect of pit depth was studied by testing specimens having various pit depths. An effect of pit size was apparent. Fatigue life decreased with increasing pit depth. Pit depth, rather than the ratio of pit depth to pit diameter, influenced fatigue behavior. A non-damaging pit depth was found.
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