油气集输用碳钢管材耐蚀性能与机理分析

Analyses of corrosion resistance performance and mechanism of carbon steel pipes used for oil and gas pipelines

某油田管道材质多为20无缝钢管,现场应用发现,对于不同厂商生产的20无缝钢管,其耐蚀性能差异明显。因此,通过试验研究其耐蚀性能差异,以便为管材的优选提供理论依据。对两个不同厂商生产的20无缝钢管进行了电化学腐蚀试验和单轴拉伸试验,借助微观表征技术(SEM、EDS、XRD),对比分析了两种钢材的耐蚀机理与性能。结果表明:20无缝钢管在原油水溶液中的腐蚀机理主要是以铁素体为阳极与以珠光体中的渗碳体为阴极构成的腐蚀微电池的阳极溶解型腐蚀过程;钢材的耐蚀性能差异主要是由其内部铁素体和珠光体含量高低引起的,铁素体含量高,其耐腐蚀性低;对钢材进行热处理后生成的组织对材料耐蚀性能的影响有限。

The pipeline material of an oilfield is mostly 20 seamless steel pipe.Field application has found that the corrosion resistance performance is significantly different for the 20 seamless steel pipes produced by different manufacturers.Therefore,the corrosion resistance difference was studied by tests to provide a theoretical basis for optimal selection of pipe material.The electrochemical corrosion test and uniaxial tensile test on 20 seamless steel pipes produced by two manufacturers were conducted,the corrosion resistance performance and mechanism of the two steel materials were compared and analyzed in terms of micro characterization techniques,i.e SEM,EDS and XRD.The results show that the corrosion mechanism of 20 seamless steel pipes in crude oil aqueous solution is mainly the anodic dissolution corrosion process of the corrosion micro cell composed of ferrite as anode and cementite in pearlite as cathode;the difference of corrosion resistance of the steel materials is mainly caused by the different contents of ferrite and pearlite in steel,and the ferrite content is high with low corrosion resistance;the microstructure generated after heat treatment of steel materials has limited influence on material corrosion resistance.