X65MS钢在饱和H2S/CO2环境下的腐蚀产物研究

利用高温高压反应釜模拟酸性油气输送环境，研究X65MS管线钢在饱和H₂S/CO₂环境下的腐蚀行为.采用加速腐蚀实验法评测不同浸泡周期下的平均腐蚀速率.借助X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)和电子探针(EPMA)等测试技术，分析了不同实验周期下氧化产物膜层的物相组成、表面形貌和截面形貌.结果表明，根据平均腐蚀速率随时间变化曲线的走势与氧化膜层的结构特征，腐蚀过程分为三个阶段.腐蚀过程以H₂S腐蚀为主，氧化产物主要为硫铁化合物(Fe_○xS_○y).随着浸泡时间的增加，铁元素比例减小，富S相比例增大，腐蚀产物膜层厚度增加，结构由疏松逐渐变为均匀、致密，腐蚀产物顺序为马基诺矿(Mackinawite)→过渡相陨硫铁(Troilite)→磁黄铁矿(Pyrrhotite)，稳定的磁黄铁矿对X65MS管线钢基体的耐蚀性起到保护作用.

Corrosion Products of X65MS Steel Under Saturated H2S/CO2 Environment

The corrosion behavior of a X65MS pipeline steel in saturated H₂S/CO₂ environment is studied by simulating oil and gas delivery environment with high temperature and high pressure reactor. The corrosion rate under different immersion time periods is measured by the mass loss method， and the phase composition and morphology of corrosion products are analyzed by means of X-ray diffraction (XRD)， scanning electron microscope (SEM)， energy disperse spectroscopy (EDS) and electron probe microanalysis (EPMA)， respectively. The results show that the corrosion rate can be divided into three stages， i.e. the initial corrosion rate decreases rapidly， then changes slowly and finally flattens out. The corrosion process is mainly controlled by H₂S corrosion， and the products are dominated by ferrosulfur compound (Fe_○xS_○y). With the increase of immersion time， the proportion of iron decreases， the proportion of sulfur-rich phase increases， the film thickness of corrosion products increases， and the structure changes from loose to uniform and compact gradually. The corrosion products are mackinawite→troilite→pyrrhotite， and the stable pyrrhotite has a protective effect on the corrosion resistance of X65MS pipeline steel matrix.