Citation

Wan H, Song D, Liu Z, Du C, Li X. Jinshu Xuebao/Acta Metallurgica Sinica 2017; 53(5): 575-582.

Copyright

(Copyright © 2017)

DOI

10.11900/0412.1961.2016.00500

PMID

unavailable

Abstract

The rapid development of energy, electricity, and transportation industries has created a market for steel pipes; however, buried steel pipelines near high-voltage transmission lines and electrified railways often experience alternating current (AC) corrosion at the damaged coating of pipelines; such phenomenon is mostly due to the resistance between the capacitance and inductance coupling, especially for long-distance pipelines in parallel operation. AC corrosion can cause pipeline corrosion perforation and stress corrosion cracking (SCC) in some cases, which has been a vital threat to the pipeline safety. In this work, the influence of AC on corrosion behavior of X80 pipeline steel was investigated in NS4 nearneutral solution by data acquisition technique, electrochemical test, immersion tests and surface analysis techniques.

RESULTS show that with the increasing of AC density, corrosion morphology changed from uniform corrosion to localized corrosion with many pits. Under the full AC interference, X80 steel occurred cathodic and anodic polarization which resulted in iron dissolution and hydrogen precipitation. The negative half wave AC would lead to hydrogen evolution and hydrogen induced anodic dissolution, the pits in X80 steel surface present sharp. However, under disturbance of positive half-wave AC, only anodic dissolution occurred and the pitting appeared spill shape and smoothly. Under various AC waveform interference, the corrosion products of X80 steel surface were different. Under full AC wave and positive halfwave interference, the corrosion products were loose, had have no a-FeOOH and occurred cracks; however, under negative half- wave AC interference, the corrosion products were denser and contained aFeOOH which has protective effect on substrates.

Keywords: Pipeline transportation

Language: zh

Keywords

Data acquisition; Pipeline corrosion; Pipelines; Steel corrosion; Steel pipe; Corrosive effects; Underground corrosion; Corrosion resistant coatings; Stress corrosion cracking; Electric impedance measurement; Hydrogen; Localized corrosion; Dissolution; Surface analysis; Morphology; Capacitance