Investigation into the effect of dissimilar metal coupling, potential, and processing on the mode and distribution of galvanic corrosion attack on 5086 aluminum alloy in synthetic seawater.
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Authors
Locke, John Sinclair
Subjects
dissimilar metal coupling
galvanic corrosion
50 86 aluminum alloy
galvanic corrosion
50 86 aluminum alloy
Advisors
Perkins, J.
Date of Issue
1977-09
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The galvanic corrosion behavior of 5086 aluminum alloy in three tempers (H116, H117, H32) when coupled with three more noble metals (1040 steel, 60/40 naval brass, Ti-150A
titanium) and immersed in aerated synthetic seawater has been characterized. In so doing, use was made of potentiodynamic polarization techniques, galvanic current density monitoring for twenty- four hours, and optical and scanning electron microscopic observations. The results obtained through the use of these techniques are presented and discussed. Galvanic corrosion of 5086 Al when coupled to the dissimilar metals was found to be independent of temper and to decrease in the order (of coupled metals) Ti-150A > 60/40 naval brass > 1040 steel. The effect of dissimilar metal coupling was found to be reduced by the formation on the anode and cathode of insulating corrosion product structures; this also caused an increased domination of the attack by localized corrosion modes. The effect of edges and crevices in concentrating attack and the correlation
between distribution of corrosion product and metal dissolution is discussed.
Type
Thesis