Nanoindentation study of corrosion-induced grain boundary degradation in a pipeline steel

Date
2018-03-01
Authors
Bastawros, Ashraf
Yavas, Denizhan
Mishra, Pratyush
Shrotriya, Pranav
Alshehri, Abdullah
Shrotriya, Pranav
Hebert, Kurt
Bastawros, Ashraf
Hebert, Kurt R
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Altmetrics
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Aerospace Engineering
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Mechanical Engineering
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Abstract

High-strength low-alloy steels used for oil and gas pipelines are vulnerable to intergranular stress corrosion cracking in moderately alkaline soils. The mechanism of corrosion-induced embrittlement under such conditions is not yet understood. Nanoindentation was used to detect localized degradation of mechanical properties near internal grain boundaries of X-70 steel undergoing intergranular corrosion at active dissolution potentials at pH 8.2. The measurements identified a one-micron thick mechanically-degraded layer with 25% reduced hardness near corroded grain boundaries. It is suggested that the corrosion process may introduce an active softening agent, possibly non-equilibrium lattice vacancies generated by oxidation.

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<p>This is a manuscript of an article published as Yavas, Denizhan, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, and Ashraf F. Bastawros. "Nanoindentation study of corrosion-induced grain boundary degradation in a pipeline steel." <em>Electrochemistry Communications</em> 88 (2018): 88-92. doi: <a href="http://dx.doi.org/10.1016/j.elecom.2018.02.001" target="_blank">10.1016/j.elecom.2018.02.001</a>. Posted with permission.</p>
Keywords
Intergranular corrosion, Dissolution-induced degradation, Stress corrosion cracking, Grain boundary softening, Nanoindentation
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