在役环境磁场对L360管线钢及焊接接头腐蚀行为的影响

Effect of Magnetic Field on Corrosion Behavior of L360 Pipeline Steel and Welded Joints in 3.5%NaCl Solution

为明确磁场对L360输油管道腐蚀行为的影响,通过电化学测试及腐蚀形貌观察等手段,研究了L360管线钢母材及其焊接接头在不同强度磁场作用下3.5%NaCl溶液中的腐蚀行为。结果表明:随着磁场强度的增大,L360管线钢母材及其焊接接头的电荷转移电阻先增大后减小,腐蚀电流密度先减小后增大,较低强度磁场(60 mT)抑制了腐蚀,而较高强度磁场(120 mT)加速了腐蚀。相同磁场强度下,焊接接头腐蚀速率大于母材。机理分析表明:磁场作用力诱导金属离子吸附于电极界面,形成腐蚀产物膜阻碍腐蚀进行;高强度磁场作用下,Lorentz力能够破坏腐蚀产物膜,加速离子扩散,进而加速金属腐蚀。

To clarify the influence of magnetic fields on the corrosion behavior of oil pipelines of L360 steel in service,the corrosion behavior of L360 pipeline steel and its welded joints in 3.5%NaCl solution by applied magnetic field of various intensities was studied via electrochemical tests and corrosion morphology characterization.The results indicate that as the magnetic field intensity increases,the charge transfer resistance of L360 pipeline steel and its welded joints initially increases and then decreases,while the corrosion current density initially decreases and then increases.Corrosion is inhibited by a lower intensity magnetic field(60 mT),while it is accelerated by a higher intensity magnetic field(120 mT).Moreover,by the same applied magnetic field intensity,the corrosion rate of the welded joints is higher than that of the base metal.It is proposed that the existed gradient magnetic field force may be favor the adsorption of metal ions at the electrode interface,resulting in the formation of a corrosion product film that hinders the corrosion process.Under the influence of a high-intensity magnetic field,the Lorentz force can disrupt the corrosion product film,accelerating ion diffusion and subsequently accelerating the corrosion of the steel.