L245NS伴生气管线腐蚀穿孔原因分析

通过对腐蚀穿孔L245NS伴生气管线进行腐蚀形貌、材质性能和腐蚀产物等分析,结合管线服役历程分析,对伴生气管线腐蚀穿孔原因进行了探讨。结果表明:L245NS伴生气管线腐蚀穿孔形貌呈孤立同心圆状,同时该失效管线材质性能符合GB/T 9711-2011标准对L245NS钢的要求。失效管线腐蚀产物主要成分为铁氧化物(Fe₃O₄和Fe₂O₃)、FeS_x等,且在腐蚀产物中培养出大量硫酸盐还原菌、铁细菌、腐生菌等细菌,同时腐蚀穿孔部位附近存在大量细菌和细菌代谢分泌的胞外聚合物。结合该管段其他部位腐蚀速率最高仅0.039 mm/a,且无明显局部腐蚀,管线穿孔形貌呈孤立同心圆形貌,故认为该L245NS管线主要发生细菌腐蚀穿孔。     

硫酸盐还原细菌和铁还原细菌混合生物膜对碳钢腐蚀的影响

使用电化学交流阻抗技术,研究了碳钢在硫酸盐还原细菌和铁还原细菌混合微生物培养基介质中的腐蚀行为。结果表明,混合微生物膜能够抑制碳钢的腐蚀,而硫酸盐还原细菌加速腐蚀。铁还原细菌作用下的铁磷酸盐化合物和绿锈生成可能是抑制腐蚀的主要因素。     

硫酸盐还原菌诱发腐蚀的研究热点

概述了硫酸盐还原菌诱发腐蚀及相关领域的研究现状,包括硫酸盐还原菌的生化、生态特性研究,并着重论述了硫酸盐还原菌诱发腐蚀产物 铁硫化物对腐蚀过程的影响。     

高矿化度油田卤水中pH值对20碳钢在硫酸盐还原菌作用下腐蚀行为的影响

目前对含硫酸盐还原菌(SRB)高矿化度下油气田卤水的腐蚀行为报道较少.采用挂片腐蚀试验和电化学试验法研究了20碳钢在含硫酸盐还原菌的不同pH值高矿化度油田卤水中的腐蚀规律,采用扫描电镜观察试样形貌.结果表明:20碳钢在pH值为5.5的含SRB腐蚀液中的腐蚀较pH值为7.5时严重,是不含SRB腐蚀液中的6倍多;pH值为7.5时,20碳钢表面微生物膜较厚,碳钢的腐蚀速率有所下降,致密的SRB生物膜的形成对溶液中Cl-的迁移起到了阻碍作用,碳钢的腐蚀得到了一定的抑制.     

硫酸盐还原菌的生长过程及其对D36钢海水腐蚀行为的影响

通过测定海水中硫酸盐还原菌(SRB)的生长曲线及其不同生长阶段的硫离子浓度、D36钢电极体系的氧化还原电位、自腐蚀电位、极化曲线和电化学阻抗谱,研究了硫酸盐还原菌对该体系钢电极腐蚀行为的影响。结果表明,海水中D36钢氧化还原电位和自腐蚀电位主要由体系中硫酸盐还原菌代谢产物硫离子的浓度所决定;体系的阳极和阴极反应速率均在硫酸盐还原菌增殖期增加,而且阳极反应速率衰亡期和残余期保持不变。     

硫酸盐还原菌对海泥中Q235钢腐蚀界面的影响

从钢基体与腐蚀产物界面的角度,深入研究了海泥中硫酸盐还原菌对Q235钢的腐蚀行为的影响.结果表明,最初的腐蚀产物为铁的(水合)氧化物,在硫酸盐还原菌代谢活动的影响下,腐蚀产物逐渐向贫硫,以及富硫的铁硫化物转化.后者的晶体缺陷较多且结构疏松,不能阻挡Fe2 的扩散和侵蚀性离子的渗入,导致腐蚀加速.微生物的代谢产物以及腐蚀产物的转变为点蚀的形成和扩展提供了条件,其点蚀的位置一般发生在晶界和珠光体区,并沿晶界或珠光体扩展.     

某注水海管腐蚀原因

采用组分含量测试、化学成分分析、X射线衍射分析、热重-质谱分析、红外光谱分析、气相色谱-质谱分析和硫酸盐还原菌检测等方法对某注水海管腐蚀的原因进行分析。结果表明：该注水海管中的有机组分主要以烃类为主,同时含有脂类、胺类、醇类、烯烃类等物质,无机组分主要为铁的氧化物、碳酸亚铁和砂石;管道中含有大量的硫酸盐还原菌,在硫酸盐还原菌的协助下,发生了垢下腐蚀,最终导致该注水海管发生腐蚀。     

减二线馏分油中炼厂常用钢材的动态冲刷腐蚀行为

为了更好地解决炼厂在流动条件下减二线馏分油对管路的腐蚀问题,研究了流动条件下Q235碳钢和Cr5Mo合金钢的耐环烷酸和硫冲刷腐蚀性能,并与炼厂常用钢材渗铝碳钢和304不锈钢进行比较。结果表明:Cr5Mo钢的腐蚀速率明显小于Q235钢的,酸值越大两者的腐蚀差别越明显(酸值>5 mg KOH/g);随着酸值和硫含量的增大,Q235钢腐蚀速率有明显增大的趋势; Cr5Mo钢的腐蚀速率随着酸值的增大基本保持不变,甚至有一定的下降;相比于Q235(腐蚀速率6.3 mm/a)和Cr5Mo钢(腐蚀速率1.5 mm/a),渗铝碳钢和304不锈钢表现出优异的耐冲刷腐蚀性能,渗铝碳钢腐蚀速率为0.2 mm/a,而304不锈钢几乎没有失重。     

油田污水中碳钢表面生物膜的生长监测与控制

金属表面硫酸盐还原菌微生物膜内的反应影响金属腐蚀的机理和速度,杀灭膜内微生物是控制微生物膜腐蚀金属的重要措施。采用丝束电极技术,研究了油田污水中生物膜在Q345碳钢表面的生长规律;通过投加3种杀菌剂来灭杀生物膜内细菌,并对其杀菌效果进行了比较,获得了杀菌剂对细菌的抑制周期及最低有效浓度。结果表明:油田污水中微生物首先在Q345碳钢表面大量附着、生长,至216 h时生长完整,至360 h时开始脱落;生物膜对Q345钢的腐蚀呈现不均匀性,微生物的存在可在局部范围内降低Q345碳钢表面的腐蚀电流密度,但有促进其腐蚀的倾向;杀菌剂HGY-B1的杀菌效果优于KD-24及LC-3,投添加量为300 mg/L时,对生物膜内细菌抑制周期可达8 d,最低杀菌浓度为40 mg/L。     

化学杀菌剂的筛选及评定

在实验室中，通过对加入杀菌剂的循环水的异养菌，铁细菌，硫酸盐还原菌静态杀菌实验，对各种杀菌剂进行试验评定，择优使用。筛选出杀菌率高；药效持续时间长且经济实用的杀菌剂。并且对加入杀菌剂后的工业循环冷却水系统中（动态）的异养菌，铁细菌，硫酸盐还原菌等进行了统计，结果表明：筛选出的杀菌剂是适合该公司循环冷却水系统要求的。     

Pitting initiation of 316L stainless steel in the media of sulfate-reducing and iron-oxidizing bacteria

Pitting corrosion behavior of stainless steel 316L in the presence of aerobic and anaerobic bacteria isolated from cooling water system in oil refinery was investigated using open circuit potential measurement, electrochemically impedance spectroscopy, scanning electron microscopy examinations, and energy dispersive spectrum analysis. The results show the corrosion potential (E _cor) and polarization resistance (R _p) decrease in the presence of sulfate-reducing bacteria (SRB), iron-oxidizing bacteria (IOB), and a combination of SRB and IOB, in comparison with those observed in the sterile medium for the same exposure time. The presence of SRB demonstrated higher corrosion rates than IOB. The combination of SRB and IOB created the highest corrosion rate. The metabolic activity of bacteria and the integrality and compactness of biofilm influenced the pitting corrosion process, increased the corrosion damage degree of the passive film, and accelerated the pitting corrosion. It is suggested that SRB and IOB in influencing the pitting corrosion of 316L SS is highlighted. The text was submitted by the authors in English.     

Effect of Sulfate-reducing Bacteria on Corrosion Behavior of Mild Steel in Sea Mud

Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria （SRB） on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis （EPMA）, transmission electron microscopy （TEM） combined with energy dispersive X-ray analysis （EDX） and electrochemical impedance spectroscopy （EIS）. The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric （oxyhydr） oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.     

S2O2-3对DP980高强钢在NaCl水溶液中的点蚀行为的影响

钢是一种冷轧双相高强度结构钢,成本低且具备良好的强度和塑性,在海工领域有巨大的潜在应用价值,但其在苛刻海水环境下的耐腐蚀性能,尤其是耐点蚀等局部腐蚀的能力有待深入研究.本文采用动电位极化法对DP980高强钢在含S₂O₃^2-离子的NaCl水溶液中的点蚀行为进行了研究,结果发现：在纯硫代硫酸钠水溶液中,DP980高强钢不发生点蚀;在不同质量分数的NaCl水溶液中,DP980高强钢发生点蚀,且随着Cl^-离子浓度的增大,DP980高强钢试样的耐点蚀性能下降明显;向NaCl溶液中加入浓度为0.001、0.01、0.1、1 mol/L的Na₂S₂O₃时,DP980高强钢试样的点蚀敏感性降低,点蚀受到明显抑制;随着Na₂S₂O₃浓度的升高,DP980高强钢的腐蚀主要以均匀腐蚀的形式发生;当试样浸泡在不同质量分数(0.1%、1%、10%)NaCl的1 mol/L Na₂S₂O₃溶液后,对试样表面腐蚀产物及腐蚀形貌进行扫描电镜观察及能谱分析,显示试样均发生均匀腐蚀,腐蚀产物为铁的硫化物,且未发现明显的点蚀.     

Characteristics of sulfide corrosion products on 316L stainless steel surfaces in the presence of sulfate-reducing bacteria

It has been found that microbial communities play a significant role in the corrosion process of steels exposed in aquatic and soil environments. Biomineralization influenced by microorganisms is believed to be responsible for the formation of corrosion products via complicated pathways of electron transfer between microbial cells and the metal. In this study, sulfide corrosion products were investigated for 316L stainless steel exposed to media with sulfate-reducing bacteria media for 7 weeks. The species of inorganic and organic sulfides in the passive film on the stainless steel were observed by epifluorescence microscope, environmental scanning electron microscope combined with energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The transformation from metal oxides to metal sulfides influenced by sulfate-reducing bacteria is emphasized in this paper.     

304不锈钢在盐湖卤水中的腐蚀行为

用腐蚀挂片试验方法研究了304不锈钢在盐湖卤水中暴露2a的腐蚀行为,井运用室内电化学试验方法研究了其电化学行为。结果表明：盐湖卤水浸泡2a后,304不锈钢腐蚀速率为0．0003mm／a,主要表现为点蚀,试样侧面加工缺陷处存在较深的点蚀坑;在卤水中浸泡768h后,304不锈钢表面钝化膜局部被破坏,出现点蚀孔。     

Localized corrosion behavior of 316L stainless steel in the presence of sulfate-reducing and iron-oxidizing bacteria

Localized corrosion behavior of 316L stainless steel was investigated in the presence of sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB) isolated from cooling water system using polarization measurement, scanning electron microscopy (SEM) examinations and energy dispersive spectrum (EDS) analysis. The results show the corrosion potential (E_corr) and breakdown potential (E_b) of SS decreased in turn with the presence of IOB, SRB and SRB + IOB, indicating decreased relative resistance to localized corrosion. E_corr in the sterile medium remained virtually unchanged with exposure time, indicating that localized attack did not occur. However, micrometer-scale pitting was observed on the SS surface in the presence of bacteria. The presence of SRB demonstrated higher corrosion rates than IOB. The combination of SRB and IOB yielded the highest corrosion rate. The presence and metabolic activities of bacteria on SS surface produce environments that can alter rates of partial reactions in corrosion processes and shift corrosion mechanisms. The most severe microbiologically induced corrosion takes place in aquatic solution where physiological groups of aerobic and anaerobic microorganisms interact.     

热网换热站不锈钢换热板点蚀的临界条件

热网二级换热站一般采用板式换热器,在其使役过程中不锈钢换热板一旦出现腐蚀穿孔,不但影响一次水水质,而且干扰换热器稳定运行,甚至影响居民供热,因此阐明换热板发生点蚀的临界条件对于科学设定水质控制标准和防止点蚀发生具有重要意义。为此,通过材料化学分析、XRD、SEM及电化学测试等方法对这一问题进行研究。结果表明:在65℃条件下,304不锈钢点蚀的临界Cl;浓度为125 mg/L,316L不锈钢点蚀的临界Cl;浓度为230 mg/L;不锈钢表面一旦形成垢层,表面会发生局部酸化,此时不锈钢更容易发生点蚀;运行过程中为了防止不锈钢换热板点蚀,不仅要严格控制循环水中Cl;浓度,还应防止换热板表面结垢或附着腐蚀产物。     

Role of ureolytic bacteria on corrosion behavior of fretted grade 880 mild steel rail

Corrosion due to toilet droppings has a pronounced effect on rails. In the present study, corrosion behavior of Mild Steel (Grade 880) was evaluated by bacterial spray chamber in presence of bacteria, and the impact of air bacteria on fretted steel was investigated. The production of ammonia and pH of medium in presence of microbes were monitored at regular intervals. The pH was observed to rise to a value of 9.6, with increase in estimated ammonia content to 6000 ppm. Conversion of FeOOH in bare steel to Fe₂O₃ and FeO as a result of corrosive attack by bacterial species revealed from XRD data. Bacterial contribution was significant in augmenting the rate of corrosion in fretted mild steel samples. SEM reveals the occurrence of pitting on fretted steel under bacterial spray chamber environment. The present study concludes by inferring that the presence of ureolytic bacteria enhances corrosion in fretted Mild steel (Grade 880).