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| EFFECTS OF SOLUTION ENVIRONMENTS ON CORROSION BEHAVIORS OF X70 STEELS UNDER SIMULATED DISBONDED COATING |
| CHEN Xu1;2; LI Xiaogang1; DU Cuiwei1; LIANG Ping1 |
1. School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083
2. College of Petroleum Engineering; Liaoning Shihua University; Fushun 113001 |
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Abstract A rectangle crevice assembly was used to study the crevice corrosion behaviors of X70 steels in Na2SO4 solutions under cathodic polarization condition. Effects of bulk solution concentration, pH, dissolved oxygen concentration on the electrochemical and chemical environments under the simulated disbanded coating were analyzed. It is shown that the higher bulk solution concentration was in favor of the cathodic current flowing into the crevice. However, the passivation film on the steel was attacked and corrosion occurred. The pH values of the solution under the disbonded coating with the alkaline bulk solution hardly changed while it changed rapidly with the acidic one and the steel at the opening was corroded. The available cathodic protection distance decreased with the dissolved oxygen being removed in bulk solution. The switching off of the applied potential led to the solution acidification and a free corrosion state of the X70 steel.
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Received: 04 July 2008
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Corresponding Authors:
CHEN Xu
E-mail: cx0402@yahoo.cn
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| [1] Chin D T, Sabde G M. Modeling transport process and current distribute in a cathodically protected crevice [J].Corrosion, 2000, 56(8): 783-793
[2] Song Y Q, Du C W, Li X G. Electrochemical corrosion behavior of carbon steel with bulk coating holidays [J]. J. Univ. Sci. Technol.Beijing （Miner. Metall. Mater.）, 2006, 13(2): 37-43
[3] Puiggali M, Rousserie S, Touzet M．Fatigue crack initiation on low-carbon steel pipes in a near-neurtral-pH environment under potential control conditions [J]. Corrosion, 2002,58(11): 961-970
[4] Sridhar N, Dunn D S, Seth M. Application of a general reactive transport model to predict environment under disbonded coating [J]. Corrosion, 2001, 57(7): 598-613
[5] Yan M C, Wang J Q， Ke W, et al. Effectiveness of cathodic protection under simulated disbonded coating on pipelines [J]. J. Chin.Soc. Corros. Prot., 2007, 27(5): 257-262
(闫茂成，王俭秋，柯伟等. 埋地管线剥离涂层覆盖下阴极保护的有效性 [J]. 中国腐蚀与防护学报, 2007, 27(5): 257-262)
[6] Li H L，Gao K W，Qiao L J，et al. Strength effect in stress corrosion cracking of high-strength steel in aqueous solution [J]. Corrosion, 2001, 57(4): 295-299
[7] Yan M C, Wang J Q, Han E H. Local environment under simulated disbonded coating on steel pipelines in soil solution [J]. Corros. Sci., 2008,50(5): 1331-1339
[8] Li Z F, Gan F X, Mao X H. A study on cathodic protection against crevice corrosion in dilute NaCl solutions [J].Corros. Sci., 2002, 44(4): 689-701
[9] Jack T R, Erno B, Krist K.Generation on near neutral pH and high pH SCC environments on buried pipelines [R]. Corrosion/2000, NACE International, Houston, TX, 2000: 211
[10] Song F M, Kirk D W, Graydon J W, et al. Steel corrosion under a disbonded coating with a holiday-Part 1: The model and validation [J]. Corrosion, 2002, 58(12): 1015-1024
[11] Chen W，King F，Vokes E．Characteristics of near-neutral-pH stress corrosion cracks in an X65 pipeline [J]. Corrosion, 2002, 58(3): 267-275
[12] Parkins R N，Blanchard W K，Delanty B S．Transgranular stress corrosion cracking of high-pressure pipelines in contact with solution of near neutral [J]. Corrosion, 1994, 50(5): 394-408
[13] Gu B, Luo J, Mao X．Hydrogen-facilitated anodic dissolution-type stress corrosion cracking of pipeline steels in near-neutral pH solution [J]. Corrosion, 1999, 55(1): 96-106
[14] Liu X, Yang W. The susceptible environmental conditions of stress corrosion cracking of gas pipelines [J]．Mater. Mech. Eng., 2002, 26(1): 5-11
(刘杏，杨武．天然气长输管线应力腐蚀破裂的敏感性条件 [J]．机械工程材料,2002, 26(1): 5-11)
[15] Cao C N. The Environment Corrosion of Materials in China [M]. Beijing: Chemical Industry Press, 2005
(曹楚南．中国材料的自然环境腐蚀 [M]．北京：化学工业出版社，2005)
[16] Song F M, Jones D A, Kirk D W. Modeling pipeline corrosion within a disc-shaped crevice for various cathodic protection at the holiday and the effect of crevice geometry [R]. Corrosion /2005, Paper no.05137
[17] Song F M, Jones D A, Kirk D W. Predicting corrosion and current flow within a disc crevice on coated steels [J]. Corrosion, 2005, 61(2): 145-152
[18] Gan F，Sun Z W，Sabde G，et al. Cathodic protection to mitigate external corrosion of underground steel pipe beneath disbonded coating [J]. Corrosion，1994，50(10): 804-816
[19] Yan M C, Weng Y J. High pH environment under coating on cathodic protection pipelines [J]. J. Chin. Soc. Corros. Prot.,2004, 24(2): 95-99
(闫茂成，翁永基. 阴极保护管线破损涂层下高pH环境形成规律 [J]. 中国腐蚀与防护学报，2004, 24(2): 95-99)
[20] Yan M C, Weng Y J. Effect of environmental solution on electrochemical behaviors related to SCC of pipe line steels [J]. J. Chin. Soc. Corros. Prot., 2005, 25(1): 34-38
(闫茂成，翁永基. 环境溶液对管道钢应力腐蚀过程电化学行为的影响 [J]. 中国腐蚀与防护学报，2005, 25(1): 34-38)
[21] Song F M, Sridhar N. Modeling pipeline crevice corrosion under a disbonded coating with or without cathodic protection under transient and steady state conditions [J]. Corros. Sci., 2008, 50(1): 70-83
[22] Cherry B W, Gould A N. Pitting corrosion of nominally protected land-based pipelines [J]. Mater. Perform., 1990, 29(8): 22-31
[23] Brousseau R, Qian S. Distribution of steady-state current underneath a disbanded coatings [J]. Corrosion, 1994, 50(12): 907-911
[24] Perdomo J J, Chabica M E, Song I. Chemical and electrochemical conditions on steel under disbonded coatings: the effect of previously corrosion surface and wet and dry cycles [J]. Corros. Sci., 2001, 43(3): 515-532 |
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