西南石油大学学报(自然科学版) ›› 2009, Vol. 31 ›› Issue (5): 171-174.DOI: 10.3863/j.issn.1674-5086.2009.05.038

• 石油机械工程及其它 • Previous Articles     Next Articles

MICROSTRUCTURE AND SEAWATER CORROSION TO WELDING JOINT OF X70 PIPELINE STEEL

FAN Zhou1a LIU Jian-yi1b LI Shi-lun1b ZHANG Tian-jiang2   

  1. 1.Southwest Petroleum University：a.School of Materials Science and Engineering，b.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation，Chengdu Sichuan 610500，China；2.Offshore Oil Engineering Company Ltd.，CNOOC，Tanggu Tianjin 300452，China
  • Received:1900-01-01 Revised:1900-01-01 Online:2009-10-20 Published:2009-10-20

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Abstract: The welding joint of X70 pipeline steel under certain practical welding process is studied.The microstructure of welding base metal，welding seam and HAZ of X70 pipeline steel are analyzed with microscope and elec-chemistry，the polarization curves and corrosion rate of different welding joint zones are tested in order to study the corrosion resistance property.The results show that the microstructure of different zones of welding joint is uneven，and there are obvious difference in corrosion rate and electrochemical behavior，corrosion potential and rate of different zones of welding joint change during the process of corrosion，and couple corrosion is formed between HAZ and welding base metal，at the same time，welding joint mainly exists spot corrosion.

Key words: X70 pipeline steel, welding joint, microstructure, seawater corrosion, spot corrosion

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