摘要
目的 探究磁场(Magnetic Field, MF)和硫酸盐还原菌(Sulfate reducing bacteria, SRB)对X80钢应力腐蚀开裂行为的影响。方法 将X80钢拉伸试样浸泡在接种SRB的培养基中分别1、4、7、10、14 d以形成生物膜,随后分别在无磁场和100 mT垂直磁场的环境下进行慢应变速率拉伸试验,并利用扫描电子显微镜进行断口形貌观察。结果 慢应变速率拉伸数据表明,试样在SRB溶液中的断裂应变和结合能大幅减小;磁场单独作用于无菌溶液中表现出更弱的应力腐蚀趋势而施加磁场在接种SRB溶液中变为增强趋势。表征分析也观察到SRB组试件主断口主要由解理性台阶组成,侧表面出现多条裂纹;磁场单独作用于无菌溶液中试件主断口有大量韧窝,侧表面平整、无裂纹;同等天数下SRB+MF组试件的脆性断裂加重,主断口解理性台阶更多更深且侧表面裂纹较SRB组也更深。结论 在无菌环境下,MF阻碍了腐蚀性离子迁移到电极表面,从而抑制腐蚀过程。而在有菌环境下,磁场使SRB在X80钢表面的黏附情况发生改变,使试件表面的生物膜分布更为聚集,导致局部浓度差进而加速了点蚀。X80钢试件在MF、SRB、应力三者协同作用下的腐蚀速率显著增加。
The stress corrosion cracking(SCC)behavior of X80 pipeline steel buried in sea mud is often influenced by magnetic fields and sulfate reducing bacteria(SRB).By immersion experiments,electrochemical experiments,and characterization analysis,the influence of stresses and magnetic fields on the film formation law and the corrosion mechanism of SRB was studied,and the effects of SRB and magnetic fields on stress corrosion cracking of X80 steel under different stresses were further explored,providing a theoretical basis for pipeline protection in complex environments.The research results indicate that in a sterile environment,after applying a magnetic field,the Lorentz force enhances the transport process of substances in the solution,leading to the accumulation of nutrients in the solution on the steel surface,thereby hindering the corrosion of corrosive ions on the electrode surface.The magnetic field gradient force can attract particles such as oxygen and ferric chloride to the outside of the defect,and attract hydroxyl ions to the inside of the defect to form an oxide film with iron,thereby weakening the corrosion inside the defect and reducing the sensitivity of the metal to SCC.MF hinders the migration of corrosive ions to the electrode surface,thereby inhibiting the corrosion process.In a bacterial environment,the magnetic field changes the adhesion of SRB on the surface of X80 steel,making the distribution of the biofilm on the surface of the specimen more uneven,which leads to galvanic corrosion,where the biofilm is covered by the anode and surrounded by the cathode.With the densification of the biofilm,a complete biofilm prevents oxygen and corrosive anions(Cl-)from coming into contact with the steel surface,but leads to a local oxygen deficient environment on the steel surface,accelerating the cathodic depolarization process of SRB.Under the combined action of stress and SRB,pitting corrosion pits appear on the specimens.SRB significantly enhances the SCC sensitivity of X80 pipeline steel in simulated sea mud solution.The SCC sensitivity in SRB inoculation solution is several times higher than that in sterile solution,reaching 42%.The role of SRB in assisting pitting corrosion and promoting hydrogen infiltration into steel accelerates the initiation and propagation of cracks.SCC crack initiation usually starts within the pit.Once the crack is formed,magnetic field forces will also be generated inside the crack under the action of an external magnetic field.The magnetic field provides a carrier for the extracellular electron transfer process of SRB by attracting paramagnetic Fe3O4,thereby accelerating corrosion and causing the expansion of pitting corrosion pits.The expanded pitting will be subject to the action of the magnetic field and SRB again.In this cycle,SRB and the magnetic field will intensify the stress corrosion of steel.The corrosion rate of X80 steel specimens significantly increases under the synergistic effect of the three factors.
作者
申雨欣
王丹
郭大成
谢飞
王雨欣
SHEN Yuxin;WANG Dan;GUO Dacheng;XIE Fei;WANG Yuxin(School of Petroleum and Natural Gas Engineering,Liaoning Petrochemical University,Liaoning Fushun 113001,China;PetroChina Planning&Engineering Institute,Beijing 100000,China)
出处
《表面技术》
北大核心
2025年第14期37-47,共11页
Surface Technology
基金
国家自然科学基金(52402428)。
关键词
磁场
硫酸盐还原菌
X80钢
应力腐蚀开裂
生物
magnetic field
sulfate reducing bacteria
X80 steel
stress corrosion cracking
organism
