| YAN Ling-yun,HU Nan-nan,JIA Yi-zheng.Corrosion Behaviour of X80 Pipeline Steel in Near-neutral pH Solution[J],45(3):52-57 |
| Corrosion Behaviour of X80 Pipeline Steel in Near-neutral pH Solution |
| Received:December 01, 2015 Revised:March 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.03.009 |
| KeyWord:X80 pipeline steel, near-neutral pH solution, corrosion, stress corrosion cracking, crack initiation, slow strain rate tensile |
| Author | Institution |
| YAN Ling-yun |
Department of Mechanical Engineering, Sichuan College of Architectural Technology, Deyang , China |
| HU Nan-nan |
Department of Materials Engineering, Sichuan College of Architectural Technology, Deyang , China |
| JIA Yi-zheng |
Department of Mechanical Engineering, Sichuan College of Architectural Technology, Deyang , China |
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| Abstract: |
| Objective To study corrosion and stress corrosion crack initiation behaviour of X80 pipeline steel in near-neutral pH solution. Methods In this paper, electrochemical measurement and immersion test were conducted to research corrosion behavior of X80 pipeline steel in near-neutral pH solution. Slow strain rate tensile tests were also conducted to research stress corrosion crack initiation behavior of X80 pipeline steel in near-neutral pH solution at open circuit potential (OCP) and applied potential. Results There was just active and no passive region in polarization curve of X80 pipeline steel in near-neutral pH solution. The OCP was measured to be about -750 mVSCE. No oxidation film was formed in the surface of X80 pipeline steel after immersed 195 days, but pits were observed. At OCP, a lot of secondary stress corrosion cracks were found in the surface of X80 pipeline steel. At applied anodic potential of -500 mVSCE, hardly secondary stress corrosion cracks were found in the surface of X80 pipeline steel. At applied cathode potential of -850 mVSCE, a few secondary stress corrosion cracks were found in the surface of X80 pipeline steel, but the number of secondary stress corrosion cracks increased as applied cathode potential negative shifted to -1300 mVSCE. Conclusion Uniform corrosion occurs of X80 pipeline steel in near-neutral pH solution, but pits form in the surface because inclusions disbonded. At OCP, the sensitivity of stress corrosion crack initiation of X80 pipeline steel are strongest in near-neutral pH solution. Stress corrosion crack initiation is inhibited by applied cathode potential, but the sensitivity of stress corrosion crack initiation increases as applied cathode potential negative shifted. At applied anodic potential, the sensitivity of stress corrosion crack initiation is weak because of uniform corrosion. |
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