Effect of <scp>AC</scp> current on corrosion behavior of cathodically protected Q235 steel

Tang, Dezhi; Du, Yanxia; Lu, Minxu; Jiang, Zi‐Tao; Wang, J. J.

doi:10.1002/maco.201307234

Cited by 41 publications

(15 citation statements)

References 14 publications

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“…It has been acknowledged [ 29 ] that DC potential is closely related to the quantity of electrons on the electrode surface. Thus, the shifting direction of the DC potential is decided by the relative magnitude of anodic and cathodic current densities of the electrode.…”

Section: Discussionmentioning

confidence: 99%

Combined Effect of Alternating Current Interference and Cathodic Protection on Pitting Corrosion and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Environment

Wang

Cheng

et al. 2018

Materials

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Influence of alternating current (AC) on pitting corrosion and stress corrosion cracking (SCC) behavior of X70 pipeline steel in the near-neutral pH environment under cathodic protection (CP) was investigated. Both corrosion and SCC are inhibited by −0.775 VSCE CP without AC interference. With the superimposition of AC current (1–10 mA/cm2), the direct current (DC) potential shifts negatively under the CP of −0.775 VSCE and the cathodic DC current decreases and shifts to the anodic direction. Under the CP potential of −0.95 VSCE and −1.2 VSCE, the applied AC current promotes the cathodic reaction and leads to the positive shift of DC potential and increase of cathodic current. Local anodic dissolution occurs attributing to the generated anodic current transients in the positive half-cycle of the AC current, resulting in the initiation of corrosion pits (0.6–2 μm in diameter). AC enhances the SCC susceptibility of X70 steel under −0.775 VSCE CP, attributing to the promotion of anodic dissolution and hydrogen evolution. Even an AC current as low as 1 mA/cm2 can enhance the SCC susceptibility.

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Section: Discussionmentioning

confidence: 99%

Combined Effect of Alternating Current Interference and Cathodic Protection on Pitting Corrosion and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Environment

Wang

Cheng

et al. 2018

Materials

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“…Due to the limitation of various factors, more and more pipelines are parallel to or cross high-voltage transmission lines or electrified railways in recent years. The AC stray current caused by high-voltage transmission lines or electrified railways can induce serious corrosion in buried pipelines (Kim et al 2004;Fu and Cheng 2010;Büchler 2012;Xu et al 2012;Tang et al 2013), especially when buried pipelines are parallel to high-voltage transmission lines or electrified railways over long distances. Even with the application of cathodic protection (CP), when the pipeline coating contains microscopic defects or surface damage, corrosion of pipelines could also be very serious from the influence of AC stray current (Gummow 1999;Kajiyama and Nakamura 1999;Ibrahim et al 2007;Büchler and Schöneich 2009;Ormellese et al 2011;Fu and Cheng 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of alternating current interference on corrosion of X60 pipeline steel

et al. 2015

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With rapid economic development in China, demand for energy and transportation is growing. Due to the limitations of factors such as terrain and traffic, a large number of buried oil and gas pipelines are parallel to highvoltage transmission lines and electrified railways over long distances. Alternating current (AC) corrosion of pipelines is very serious in such cases. In this work, laboratory experiments were carried out with an electrochemical method in a simulated soil solution at various AC current densities from 0 to 200 A/m 2 and AC frequencies from 10 to 200 Hz. Experimental results indicated that with an increase in the AC current density, the corrosion potential of an X60 steel electrode shifted negatively, the anodic current density increased significantly, and the corrosion rate increased. Moreover, with an increase in the AC frequency, the corrosion potential of the X60 electrode shifted positively and the anodic current density decreased, which led to a decrease in the corrosion rate. Furthermore, the morphology of X60 electrodes indicated that uniform corrosion occurred at a low AC current density; while corrosion pits were found on the X60 electrode surface at a high AC current density, and deep corrosion pits seriously damaged the pipelines and might lead to leakage.

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“…However, few mechanisms have been proposed for the influence of AC on the CP potential. Du et al [ 4 , 32 ] suggested that the shifting direction of the CP potential might depend on the varying slopes of the three parts of the cathodic polarization curve, i.e., the activation control stage with low slope, the oxygen diffusion control stage with high slope, and the mixed control stage with low slope. This theory was limited to diffusion-controlled systems, and neglects the effect of anodic reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Unfortunately, many different results have been obtained and the mechanism of AC corrosion under CP has not reached a consensus so far. Du et al [ 4 ] proved that AC corrosion can be controlled by the increase of CP current when the AC current density is below 300 A/m 2 . Similarly, Cheng et al [ 5 , 6 ] illustrated that only when the CP potential is sufficiently negative, will the steel be under a complete cathodic protection even when the AC current density is up to 400 A/m 2 .…”

Section: Introductionmentioning

confidence: 99%

Effect of Alternating Current on the Cathodic Protection and Interface Structure of X80 Steel

Wang

et al. 2017

Materials

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This study employs potential-monitoring techniques, cyclic voltammetry tests, alternating current (AC) voltammetry methods, and surface characterization to investigate the AC corrosion of cathodically protected X80 pipeline steel. In a non-passive neutral solution at pH 7.2, a sufficiently negative potential completely protects steel at an AC current density of 100 A/m2. In an alkaline solution at pH 9.6, more serious AC corrosion occurs at more negative cathodic protection (CP) potential, whereas without CP the steel suffers negligible corrosion. In addition, the interface capacitance increases with AC amplitude. Based on these results, the AC corrosion mechanisms that function under various conditions are analyzed and described.

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Effect of AC current on corrosion behavior of cathodically protected Q235 steel

Cited by 41 publications

References 14 publications

Combined Effect of Alternating Current Interference and Cathodic Protection on Pitting Corrosion and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Environment

Combined Effect of Alternating Current Interference and Cathodic Protection on Pitting Corrosion and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Environment

Effects of alternating current interference on corrosion of X60 pipeline steel

Effect of Alternating Current on the Cathodic Protection and Interface Structure of X80 Steel

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