注多元热流体环境下流速对N80钢腐蚀行为的影响研究  

Effect of Flow Rate on Corrosion Behavior of N80 Steel in a Multivariate Thermal Fluid Environment

作　　者：陈宇凡 林学强[1] 孙建波[1] 孙冲[1] 徐学旭 逄波 陈慧 CHEN Yufan;LIN Xueqiang;SUN Jianbo;SUN Chong;XU Xuexu;PANG Bo;CHEN Hui(China University of Petroleum(East China),Shandong Qingdao 266580,China;Shenzhen Polytechnic University,Guangdong Shenzhen 518055,China)

机构地区：[1]中国石油大学(华东),山东青岛266580 [2]深圳职业技术学院,广东深圳518055

出　　处：《表面技术》2024年第10期124-133,共10页Surface Technology

基　　金：国家自然科学基金青年基金项目(51701240);中国石油大学(华东)校自主创新项目(17CX02023A)。

摘　　要：目的研究不同流速条件下N80钢在注多元热流体环境中的腐蚀特征,探究流速变化对N80钢腐蚀行为的影响规律及机理。方法利用自制高温高压多相流冲刷腐蚀环路装置模拟不同流速(0、0.5、1.0、2.0m/s)的注多元热流体环境,采用失重法计算不同流速下N80钢的平均腐蚀速率,并同时进行原位电化学测试。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同流速条件下N80钢腐蚀后的腐蚀产物物相组成和表面微观形貌进行分析。结果N80钢在注多元热流体环境中的平均腐蚀速率随着流速增加而增大。流速增加影响O_(2)的扩散传质过程、近表面离子分布和壁面剪切力的大小,使腐蚀产物膜特征发生变化。0m/s时,腐蚀产物主要由FeCO_(3)和少量Fe_(2)O_(3)组成,为单层膜结构,腐蚀形态为均匀腐蚀。0.5~2.0m/s范围内,腐蚀产物种类增加,主要由FeCO_(3)、Fe_(2)O_(3)和少量FeO(OH)组成,呈双层膜结构,同时N80钢表面腐蚀产物膜出现鼓泡,且随流速增加鼓泡数量增加,去除腐蚀产物膜后发现鼓泡下方存在局部腐蚀。原位电化学测试结果表明:随着流速增加,塔菲尔极化曲线的阳极斜率增大,阴极斜率减小。电化学阻抗谱测试结果表明,N80钢表面外层腐蚀产物膜电阻Rf1、电荷转移电阻Rct和扩散电阻W随流速增加而减小。结论流速增大加快了O_(2)的扩散传质过程,使得腐蚀电化学控制步骤由阴极氧扩散过程转变为阳极溶解过程,且试样表面保护性FeCO_(3)膜厚度减小,导致产物膜保护性降低。另外,Fe^(2+)更容易被氧化形成Fe^(3+),局部FeCO_(3)被氧化成为Fe_(2)O_(3),破坏了内层膜的完整性,导致局部腐蚀发生。In order to study the corrosion characteristics of N80 steel under different flow rate conditions in the environment of injecting multiple thermal fluids,and to explore the influence and mechanism of flow rate changes on the corrosion behavior of N80 steel,this article used a self-made high-temperature and high-pressure multiphase flow erosion corrosion loop device to simulate the environment of injecting multiple thermal fluids with different flow rates(0,0.5,1.0,2.0 m/s).The corrosion simulation experiment was conducted in a corrosion testing section,and the average corrosion rate of N80 steel at different flow rates was measured by the weightlessness method.At the same time,in-situ electrochemical testing was conducted under the same conditions in the electrochemical testing section.Scanning electron microscope(SEM)and diffraction of X-rays(XRD)were used to analyze the phase composition and surface morphology of corrosion products of N80 steel after corrosion at different flow rates.The results indicated that the average corrosion rate of N80 steel in the multi element hot fluid environment increased with the increase of flow rate.The flow rate affected the diffusion and mass transfer of O_(2),the distribution of near surface ions,and the magnitude of wall shear force,leading to changes in the characteristics of the corrosion product film and inducing varying degrees of corrosion of the substrate.At 0 m/s,the corrosion product was composed of FeCO_(3) and a small amount of Fe_(2)O_(3),which was a single-layer film structure,and the bond between it and the steel substrate was relatively tight,and the corrosion was uniform.Within the range of 0.5-2.0 m/s,the types of corrosion products increased,which mainly composed of FeCO_(3),Fe_(2)O_(3),and small amounts of FeO(OH).The film layer showed a double-layer structure.The outer layer was an iron oxide film,which was reddish brown in color and had weak binding force with the inner layer film,making it easy to be detached.The inner layer was similar to the product fi

关 键 词：N80钢 流体流速 CO_(2)-O_(2)共存 多元热流体 原位电化学测试 腐蚀行为 

分 类 号：TG174[金属学及工艺—金属表面处理]