| LI Hai-kun,SUN Qian,ZHANG Xiao-ming,WU Shi-jie,HUANG Lin,XIE Tao.Local Corrosion Behavior around Artificial Groove Defect of X80 Pipeline Steel under the Tensile Stress[J],48(2):226-231 |
| Local Corrosion Behavior around Artificial Groove Defect of X80 Pipeline Steel under the Tensile Stress |
| Received:August 14, 2018 Revised:February 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.02.032 |
| KeyWord:groove defect stress concentration local corrosion localized electrochemistry corrosion rate |
| Author | Institution |
| LI Hai-kun |
1.China Petroleum Natural Gas Pipeline Research Institute Co., Ltd, Langfang , China |
| SUN Qian |
2.China University of Petroleum Beijing, Beijing , China |
| ZHANG Xiao-ming |
3.International Division of China Petroleum Pipeline Bureau Langfang , China |
| WU Shi-jie |
4.Shashi Steel Pipe Works, Sinopec Oilfield Equipment Corporation, Jingzhou , China |
| HUANG Lin |
1.China Petroleum Natural Gas Pipeline Research Institute Co., Ltd, Langfang , China |
| XIE Tao |
1.China Petroleum Natural Gas Pipeline Research Institute Co., Ltd, Langfang , China |
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| Abstract: |
| The work aims to evaluate the corrosion rate around the artificial groove defect of pipeline in soil under the tensile stress. The stress distribution around the long groove artificial defect of the X80 pipeline perpendicular to stress direction under 100% yield stress was analyzed by finite element. The electrochemical activity around the artificial defect of X80 pipeline steel samples after immersed in the pre-prepared Korla soil simulated solution for 40 days was measured with the Scanning Electrochemical Microscopy (SECM). The corrosion rate of the stress concentration area at the artificial defect ends and both sides of defects was calculated and estimated by the model of current field and the Faraday's law. The ends of long grooved prefabricated defects had stress concentration under external stress and local stress on both ends of defects reached 2~3.4 times of external stress on samples. In the soil simulation solution, the stress concentration area at ends of defects was anodic area, while the low stress area at both sides of defects was cathodic area. The stress concentration area at the end of prefabricated defects as anodic area could accelerate the corrosion and tended to appear pitting. Under tensile stress, the average corrosion and pitting rates of defect ends of X80 steel in Korla soil simulation solution are 0.12 mm/a and 0.9~1.7 mm/a respectively, being 1.25 and 9.4~17.7 times of natural corrosion rate. Therefore, the stress concentration area is easy to generate pitting. |
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