显微组织对X70钢在含有硫酸盐还原菌的3.5%NaCl溶液中腐蚀行为的影响

发布时间：2019-01-27 19:24

【摘要】：通过空冷、水冷和炉冷3种热处理方法得到不同显微组织的X70钢。采用SEM和EDS分析了不同显微组织X70钢在含有硫酸盐还原菌(SRB)的3.5%(质量分数)Na Cl溶液中的腐蚀形貌和腐蚀产物成分。采用动电位极化和电化学阻抗谱技术研究不同显微组织X70钢的电化学行为。结果表明,X70钢的原始组织为铁素体+珠光体;空冷组织为粒状珠光体分布在铁素体晶界上;炉冷组织由片状珠光体和先共析铁素体组成;水冷组织主要由板条状马氏体和少量块状铁素体组成。各热处理条件下试样在有菌介质中浸泡初期表面覆盖一层致密的生物膜,对电极起到了保护作用。水冷和空冷试样表面生物膜在浸泡第8和10 d后破裂,而炉冷和原始试样表面的生物膜完整性则较好;在有SRB的3.5%Na Cl溶液中X70钢炉冷试样的耐蚀性最好,水冷试样的耐蚀性最差。
[Abstract]:X70 steel with different microstructure was obtained by air cooling, water cooling and furnace cooling. The corrosion morphology and corrosion product composition of X70 steel containing 3.5% (SRB) (mass fraction of) Na Cl) were analyzed by SEM and EDS. The electrochemical behavior of X70 steel with different microstructure was studied by potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the primary structure of X70 steel is ferrite pearlite, the air-cooled structure is granular pearlite on the grain boundary of ferrite, the furnace cold structure is composed of lamellar pearlite and proeutectoid ferrite. The water-cooled microstructure is mainly composed of lath martensite and a small amount of bulk ferrite. The sample is covered with a dense biofilm at the beginning of soaking in the medium of bacteria under various heat treatment conditions, which has a protective effect on the electrode. The biofilm on the surface of water-cooled and air-cooled samples was ruptured at the 8th and 10th day after soaking, but the biofilm integrity on the surface of the furnace cooling and the original sample was better. The corrosion resistance of X70 steel in 3.5%Na Cl solution with SRB is the best and the corrosion resistance of water-cooled sample is the worst.
【作者单位】：辽宁石油化工大学石油天然气工程学院;
【基金】：国家自然科学基金(51201009) 辽宁省自然科学基金(2013020078)~~
【分类号】：TG178

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