# 材料期刊网

During the past decades, more buried oil or gas pipeline failures have been attributed to alternating current (AC) interference, and finally, those corrosion failures were investigated and the AC current density was identified as the critical influence parameter. There is general agreement on AC current density as a chief factor in determining metal wastage condition or assessing the AC corrosion risk for any type of soil in the presence of AC corrosion. Different degrees of AC corrosion may occurr if long distance pipelines pass through different kinds of soil environments, however, the effect of soil ions on pipeline steel without cathodic protection is still not well understood. Therefore, it is imperative to study the AC corrosion behaviors of pipeline steel in different soil environments. In the AC corrosion simulation experiment, by investigating the AC corrosion behaviors of X70 steel in 4 kinds of environmental media, the corrosion rates (Kd) were obtained, whose order was $Kd (NaCl)$>$Kd Na2SO4)$>$Kd (CaCl2)$>$Kd (MgCl2)$. SEM, EDS and XRD were used to characterize and analyse the microscope morphologies, elements and phase compositions of the corrosion product films surfaces/cross-sections. Under the same AC current density, the reasons of differences of X70 steel's corrosion rate in different media were discussed. The presence of corrosive ions SO42- and Cl- would accelerate the corrosion rate, Na+ would not affect the formation of corrosion product film in NaCl and Na2SO4 solution media, however, the presence of Ca2+ and Mg2+ were helpful to form protective corrosion product films in MgCl2 and CaCl2 solution media.

[1]

• 下载量()
• 访问量()

• 您的评分：
• 1
0%
• 2
0%
• 3
0%
• 4
0%
• 5
0%