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| Corrosion & Environmental Degradation |
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| ·
A
metal with a protective oxide coat, such as aluminum, may exhibit stress
corrosion in a suitable ambient. The diagram shows the sequence of steps
associated with the corrosion process.
· Application of the stress causes localized failure of the protective oxide coating which permits contact between the metal and the electrolyte. Local pitting of the metal occurs at this site (2) and the pit continues to grow with time. · Stress corrosion occurs at the sharp base of the pit (3) and corrosion enhanced crack growth occurs. · When the crack has grown to the critical size for rapid crack propagation in the material at the applied stress level, mechanical rupture (4) causes material failure. |
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| From:
Guy and Hren,
"Elements of Physical Metallurgy," Addison Wesley (1974) |
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