磁场对X80管线钢在沈阳草甸土中腐蚀行为的影响

Effect of Magnetic Field on Corrosion of X80 Pipeline Steel in Meadow Soil at Shenyang Area

采用失重法并结合XRD,SEM和EDS等手段,研究了磁场对X80管线钢在沈阳草甸土中腐蚀行为的影响规律。结果表明:磁场的存在促进了X80管线钢在沈阳土壤中的腐蚀;与无磁场相比,外加磁场下X80钢电极表面腐蚀产物出现了疏松多孔型的FeO(OH),导致产物膜保护性减弱;随着磁场强度的增大,腐蚀产物中Fe_3O_4含量降低,FeO(OH)含量增多,产物膜保护性逐渐减弱,X80钢腐蚀速率逐渐增加,但增大的幅度逐渐减小。磁场强度增大到一定程度会抑制完整产物膜的形成,当磁场达到20 m T时,X80钢年平均腐蚀速率达到73.799μm/a,产物膜完整性差,出现了明显的裂纹,腐蚀现象最为严重,这是由于磁场能够使单个氧化物晶粒沿择优取向生长的缘故。

The influence of magnetic field on the corrosion of X80 pipeline steel in meadow soil at Shenyang area was investigated by means of mass loss method, X-ray diffractometer （XRD）, scanning electron microscope （SEM）, and energy dispersive spectrometer （EDS）. The results indicated that the magnetic field accelerated the corrosion rate of X80 pipeline steel in the soil. In contrast to the circum- stance without magnetic field, porous FeO（OH） emerged on the X80 steel electrode surface under mag- netic field which weakened the protectiveness of the formed scales. With the increase of the magnetic field strength, Fe30, content decreased and FeO（OH） content increased in the corrosion products, which led to the increase of the corrosion rate of X80 steel. However, the increment of the corrosion rate slowed down during the process. As the magnetic field intensity increases to a certain extent, the formation of an integrated corrosion product may be suppressed. As the magnetic field intensity reached to 20 mT, the in- tegrity of the formed scale became poor with cracks, thereby the corrosion rate of X80 steel increased to 73.799 pm/a. These phenomena may be ascribed to that the magnetic field facilitates the preferred orient- ed growth of oxide grains.