温度与SRB协同作用下X70钢在海泥模拟溶液中应力腐蚀行为研究

研究了温度对硫酸盐还原菌(SRB)活性的影响,并采用慢应变速率拉伸实验研究了不同温度下X70钢在含SRB的海泥模拟溶液中应力腐蚀行为及其开裂机理。结果表明,SRB在海泥模拟溶液中生存温度范围为20～40℃,且随温度增加,SRB活性增加,数量增大。X70钢表面生物膜保护性与SRB活性和数量密切相关。20℃时,由于SRB数量最少,X70钢在含SRB海泥中应力腐蚀开裂(SCC)敏感性最小;30℃时,X70钢表面的生物膜与基体金属构成大阴极小阳极面积比的腐蚀原电池,耐蚀性最低,此时SCC机理为阳极溶解和氢致开裂共同作用下的混合断裂;40℃时SRB活性最好,X70钢表面形成较为完整生物膜,耐蚀性最好,但SCC敏感性最高,其开裂机理为氢致开裂。     

硫酸盐还原菌对A3钢电化学腐蚀行为的影响

采用交流阻抗技术和动电位扫描法测Tafel曲线技术 对A3钢在含不同浓度硫酸盐还原菌介质中且未除氧条件下的电化学特性进行了研究，并采用SEM观察试样表面的腐蚀状况.结果表明：硫酸盐还原茵可以促进A3钢的阴极去极化和阳极极化，Ecorr降低；不同菌液浓度中的A3钢的交流阻抗谱图均呈单容抗弧特征，极化电阻Rp随菌液浓度增大而增大. SRB对腐蚀的影响作用与生成的生物膜的致密程 度有关.     

海泥中硫酸盐还原菌对碳钢腐蚀行为的影响

利用交流阻抗测试技术、扫描电镜及表面能谱、失重 法、微生物分析等方法，在室内模拟条件下研究了海泥中硫酸盐还原菌对碳钢腐蚀的影响，及在含和不含硫酸盐还原菌的海泥构成的宏电池腐蚀中碳钢的腐蚀行为.180天的试验结果表明，在有菌泥中碳钢的自然腐蚀速度均大于在灭菌泥中，两者相差35倍.说明海泥中硫酸盐还原菌增大了碳钢的腐蚀速率.在有菌和灭菌海泥构成宏电池时，有菌海泥中碳钢作为阳极，腐蚀速率比自然腐蚀状态下有所增大，加速率为119%.而在灭菌海泥中碳钢作为阴极，腐蚀速率比自然腐蚀状态下有所减小.     

16Mn钢在海泥中的氢渗透行为研究

采用改进的devnathan-stachurski双电解池技术研究了16Mn钢在含硫酸盐还原菌（sulfate reducing bacteria,简称SRB）海泥和灭菌海泥中的氢渗透行为.结果表明：海泥中活性SRB的存在能促进16Mn钢的氢渗透,即使在SRB的残余阶段,16Mn钢在含SRB海泥中的氢渗透电流密度也比在灭菌海泥中的氢渗透电流密度要高;在实际海洋工程应用中,16Mn钢在含SRB海泥中的氢渗透电流密度大约是在不含SRB海泥中的3倍~4倍.     

温度对三种Cr钢腐蚀行为的影响

利用高温高压釜模拟油田高CO_2分压和高矿化度的生产环境进行腐蚀试验,测定在不同温度条件下1Cr、3Cr和13Cr钢的腐蚀速率,利用扫描电镜(SEM)、X射线衍射仪(XRD)等手段分析了腐蚀产物形貌和成分。结果表明:1Cr、3Cr钢的腐蚀速率随温度升高先增大后减小,二者的腐蚀速率均在80℃达到最大值,分别为7.515mm/a和4.339mm/a;13Cr钢的腐蚀速率在温度低于110℃时随温度的升高缓慢增大,在温度高于110℃时腐蚀速率迅速增大;1Cr、3Cr油管钢在试验温度范围内均出现局部腐蚀,13Cr油管钢在整个试验的温度区间表现出优秀的耐蚀性。     

SRB对X70管线钢在近中性pH溶液中腐蚀行为的影响

采用电化学阻抗、动电位极化及微观观察法,对比了有、无硫酸盐还原菌(SRB)的情况下X70管线钢在近中性p H溶液(NS4)中的腐蚀行为,研究了SRB生长周期对X70钢腐蚀行为的影响。结果表明:X70钢在无菌溶液中腐蚀速率随时间增加呈单一增大的趋势。SRB在NS4溶液中的生长周期分为对数繁殖期(1~3 d),稳定生长期(4~7 d)和衰亡期(7~14 d)3个阶段。SRB对X70钢在NS4溶液中腐蚀速率的影响与其在溶液中生长规律有关:当SRB处于对数繁殖期和稳定期时,X70钢表面覆盖一层致密的生物膜,对钢起到了保护作用,此时X70钢的腐蚀速率比无菌条件下低;当SRB进入衰亡期,X70钢腐蚀的程度比无菌介质中严重,钢表面腐蚀产物逐渐增多,生物膜出现破裂,腐蚀速率增大。     

地面集输管道在CO2/H2S/O2体系下的腐蚀行为研究

目的 研究集输管道常用钢材在CO2/H2S/O2体系下的腐蚀行为,为新疆油田集输管道的腐蚀防控提供指导依据.方法 基于新疆油田重油热采现场工况,以L245NS钢为试材,316L钢为对照,采用高温高压釜试验,研究CO2/H2S/O2体系下温度和H2S含量对L245NS钢和316L不锈钢的腐蚀影响规律,并结合SEM/EDS+XPS+3D显微镜等手段对典型工况下的腐蚀产物进行测试分析.结果 在CO2/H2S/O2共存体系中,L245NS钢的腐蚀速率随温度的升高,呈先增大、后减小的趋势;而随H2S含量的升高,呈先减小、后增大的趋势.316L钢的腐蚀速率随温度的升高,呈先增大后减小的趋势;随H2S含量的升高,呈一直增大的趋势.L245NS钢腐蚀产物呈针状、菱状、颗粒状多种形态,而316L钢腐蚀产物较少.在CO2/H2S/O2共存体系中,L245NS钢的腐蚀产物主要包含FeS、FeS2、单质S、FeCO3、Fe(OH)3、FeOOH、Fe3O4、Fe2O3、Na2SO4等物质.结论 L245NS钢在CO2/H2S/O2体系(22PCO H S/P<200)下的腐蚀行为主要由H2S主导,生成的FeS分布在产物底层.O2具有促进腐蚀进程的三方面作用:与H2S发生交互作用生成了单质S;作为去极化剂参与阴极反应;作为强氧化剂氧化FeS、FeCO3,反应生成单质S、FeS2、Fe2O3、Fe3O4、FeO(OH)等物质.     

二氧化碳对X60钢微生物腐蚀行为影响

利用失重法和扫描电镜研究了CO₂与嗜热SRB共存条件下X60钢在海底污泥和污水中的腐蚀行为.结果表明:CO₂饱和条件下,随着温度的升高,污泥和污水中腐蚀速率均增加,且含SRB的污泥和污水中X60钢的腐蚀速率均大于不含SRB的腐蚀速率,SEM观察表明,X60钢遭受的破坏以点蚀为主;随着CO₂分压的增大,X60钢的腐蚀速率增大,且污泥中腐蚀速率大于污水中腐蚀速率.     

硫酸盐还原菌对海底土中锌腐蚀的影响

利用微生物分析、交流阻抗测试技术、扫描电镜及表面能谱等方法，在室内模拟条件下研究了海底土中硫酸盐还原菌对锌腐蚀的影响，以及在以接菌及灭菌的海底土构成的宏电池腐蚀中锌的腐蚀行为。180d的试验结果表明：海底土中硫酸盐还原菌增强锌的腐蚀，锌在接菌泥中的平均腐蚀速率及点蚀深度均大于在灭菌泥中的平均腐蚀速率及点饰深度，平均腐蚀速率相差7．0倍，点蚀速率相差15．0倍以上。在接菌和灭菌海底土构成宏电池时，接菌海底土中锌作为阳极，腐蚀速率比自然腐蚀状态下有所增大，加速率为12．7％，而在灭菌海底土中锌作为阴极，腐蚀速率比自然腐蚀状态下有所减小。     

天然气集输管道微生物腐蚀规律及腐蚀速率模型

为了研究硫酸盐还原菌(SRB)对天然气集输管道腐蚀行为的影响,通过浸泡试验,研究了常压和高压条件下不同SRB含量时5种钢材的腐蚀速率及其耐SRB腐蚀性能。依据试验结果建立了微生物腐蚀速率预测模型,并利用PIPSIM软件模拟管道温度和压力变化对模型进行了修正。结果表明：在常压和高压环境中,钢材的腐蚀速率均随着SRB含量的增加而增大,其中N80钢的耐SRB腐蚀能力最强;根据预测模型计算的腐蚀速率与实际腐蚀速率存在0.06～0.07 mm/a的误差,修正后的模型能够更好地预测管道微生物腐蚀速率。     

Effect of different offshore seabed sediment on steel corrosion

A series of simulation experiments on corrosion behaviour of carbon steel (A₃ Steel) and low alloy steel (16Mn steel) in marine atmosphere (MA), seawater (SW) and seabed sediment (SBS) including rough sea sand, fine sea sand and seabed mud were carried out indoors for a year or so by means of individually hanging plates (IHP) and electrically connected hanging plates (ECHP). Results showed that the corrosion rates of A₃ and 16Mn steel in marine environment were in the order: MA > SW > SBS by the IHP method, MA > SBS > SW by the ECHP method. The corrosion rates of steels in the water/sediment interface were directly proportional to the grain size of the SBS by the ECHP method, but those of steels in the water/sediment interface did not vary with the grain size of SBS by the IHP method. The corrosion rate of low alloy steel was a little higher than that of carbon steel. The corrosion in seabed sediment was mainly determined by the macrogalvanic cell (oxygen concentration difference cell) between steel plates in different sediment and depth.     

Corrosion failure of marine steel in sea‐mud containing sulfate reducing bacteria

The corrosion failure behavior of marine steel is affected by stress, which exists in offshore structures at sea‐mud region. The sulfate reducing bacteria (SRB) in the sea‐mud made the steel more sensitive to stress corrosion cracking (SCC) and weaken the corrosion fatigue endurance. In this paper, a kind of natural sea‐mud containing SRB was collected. Both SCC tests by slow strain rate technique and corrosion fatigue tests were performed on a kind of selected steel in sea‐mud with and without SRB at corrosion and cathodic potentials. After this, the electrochemical response of static and cyclic stress of the specimen with and without cracks in sea‐mud was analyzed in order to explain the failure mechanism. Hydrogen permeation tests were also performed in the sea‐mud at corrosion and cathodic potentials. It is concluded that the effect of SRB on environment sensitive fracture maybe explained as the consequences of the acceleration of SRB on corrosion rate and hydrogen entry into the metal.     

The hydrogen permeation investigation of API X56 steel in sea mud

It was found that the corrosion rate of steel in the sea mud with sulfate‐reducing bacteria (SRB) could be as high as 10 times of that in the sea mud without SRB. And the hydrogen permeation reaction would occur when metals were corroded. So it is necessary to investigate the effect of living SRB on hydrogen permeation in the sea mud. Cathodic potential was often added to metals in order to protect them. But hydrogen permeation could be affected by the cathodic potential. So it is also necessary to study the effect of cathodic potential on hydrogen permeation. In this paper, the hydrogen permeation actions of API X56 steel in the sea mud with and without SRB at corrosion and cathodic potential were studied with an improved Devanathan‐Stachurski's electrolytic cell. Experimental results showed that during the growth of SRB, the current density curve of hydrogen permeation was accordant with the growth curve of SRB. But the hydrogen permeation current density of API X56 steel hardly changed in the sterilized sea mud. Compared with the hydrogen permeation current density of API X56 steel in the sterilized sea mud, the hydrogen permeation of API X56 steel in the sea mud could be accelerated by living SRB. Experimental results also showed that the hydrogen permeation current density increased rapidly when the cathodic potential was added to the three‐electrode system of the cathodic cell, and then the hydrogen permeation current density could obtain a stable value slowly. So the cathodic potential added to the cathodic cell could accelerate hydrogen permeation.     

镀锌层破损汽车钢板在含NaCl溶液和泥浆中的腐蚀行为与EIS研究

采用镀锌层破损面积不同的热镀锌汽车钢板试样,在含相同3.5%Cl-浓度的鹰潭泥浆和NaCl水溶液中进行了浸泡和浸没腐蚀实验,研究了镀锌板、基板和镀锌层不同程度破损试样在两种介质中的腐蚀规律.结果表明:完整镀锌层的腐蚀速率高于基板;镀锌层破损试样的腐蚀失重随镀锌层破损面积的增加而增大;在泥浆中的腐蚀速率比在溶液中大,且腐蚀速率随时间的变化不同.EIS分析结果表明,镀锌层破损试样的锌层在两种介质中的电荷转移电阻都比基材小得多,镀锌层的腐蚀对腐蚀失重结果起主要贡献.泥浆溶氧高和pH值低是造成镀锌层破损试样在两种介质中腐蚀行为明显不同的主要因素.     

Corrosion of mild steel in different granularity seabed sediment saturated with seawater

In order to investigate the corrosion of pipeline materials in Seabed Sediment (SBS) environment, weight‐loss and electrochemical measurements in saturated sand and mud cells with seawater were performed for a simulation. The used electrochemical measurements included linear polarization resistance (LPR) and potentiodynamic scanning measurement. It was showed that the corrosion rate of mild steel in the present condition was lower than the corrosion rate of other marine environment corrosion zones of it; that the granularity of SBS could affect the corrosion behavior greatly; that with increasing grain size of SBS, the corrosion rate increased. Integrated over the results of the weight loss and polarization curves, the oxygen diffusion (oxygen as a depolarizant agent) mechanism was proposed and discussed.     

氯离子含量对黄壤土中碳钢腐蚀行为的影响

利用极化曲线技术、电化学阻抗测试技术等方法,研究了氯离子含量对黄壤土中碳钢腐蚀行为的影响。实验结果表明,氯离子对黄壤土中碳钢腐蚀影响显著。碳钢的腐蚀速率随土壤中氯离子含量的增加而增加,当氯离子的质量百分含量增加到0.90%时,腐蚀速率达到最大,然后腐蚀速率随着氯离子含量增加有所减小。碳钢在低氯含量土壤中阻抗谱表现为单容抗弧,在高氯含量土壤中为双容抗弧。     

Al-Zn-In-Si牺牲阳极在模拟海水及海泥环境中的电化学性能

目的 分析A13型Al-Zn-In-Si牺牲阳极在海水、海泥中的电化学性能.方法 采用恒电流极化进行4 d的加速实验,使用电化学阻抗谱(EIS)分析电化学腐蚀过程,通过扫描电子显微镜(SEM)、能谱分析(EDS)及三维超景深显微镜观察分析腐蚀形貌及表面化学成分,对比研究了Al-Zn-In-Si牺牲阳极在模拟海水和海泥环境下的腐蚀形貌、电化学性能.结果 在模拟海水和海泥环境中,尽管Al-Zn-In-Si牺牲阳极都满足DNVGL-RP-B401的要求,但在海泥环境中,其电化学效率仅为65.97％,远低于海水环境中的89.43％.牺牲阳极在海水环境中发生均匀腐蚀,而在海泥环境中却呈现严重的不均匀腐蚀现象,表面腐蚀坑为疏松多孔蜂窝状.结论 在海泥环境下,Al-Zn-In-Si牺牲阳极的腐蚀产物扩散困难,局部呈现腐蚀坑,自腐蚀速率高,导致电化学效率降低.溶解过程中,由于组织脱落,自身消耗增加,电化学容量降低,从而导致阳极在模拟海泥环境中的电化学性能低于海水环境,并揭示了阳极在模拟海水、海泥环境中的腐蚀机理.     

Cl-对汽车镀锌板在泥浆中腐蚀行为的影响

用浸泡试验、电化学阻抗技术和扫描电镜(SEM)研究比较了汽车镀锌板及基板在不同Cl~-含量鹰潭泥浆中的腐蚀行为。结果表明:在实验介质条件下,镀锌板和IF钢(无间隙原子钢,有时也称超低碳钢)基板均发生了明显的腐蚀,镀锌板的腐蚀速率普遍高于基板;泥浆中的Cl~-含量对腐蚀行为有较大影响,镀锌板在5%Cl~-的泥浆中腐蚀速率最大,基板在1%Cl~-泥浆中腐蚀速率最大;腐蚀产物的致密性影响其保护性能,Cl~-通过影响泥浆中的溶氧量和腐蚀产物的保护性综合影响金属在泥浆中的腐蚀行为;腐蚀电位和电化学阻抗测量的分析结果与实际腐蚀速率具有很好的对应性,反映了腐蚀随时间变化的电极表面特性。     

Combined erosion and corrosion of thermal sprayed WC and CrC coatings

This paper presents investigations of the combined effect of erosion and corrosion on one stainless steel and four different thermal sprayed coatings with carbide particles in a metal matrix. The materials were exposed to flowing synthetic sea water containing sand. Pure erosion, electrochemical corrosion and total material loss were determined at different sand concentrations. The effect of exposure time was also studied. The results show that erosion is the dominating process at high sand concentrations while corrosion is important at lower concentrations. The relative importance depends on the material. The corrosion resistance of the metal matrix has great influence on the total material loss rate. For the coating with lowest corrosion resistance there seems to be a synergistic effect between the mechanical and electrochemical processes.     

湿度对土壤中微生物腐蚀作用的影响

研究了不同湿度,不同接菌条件的同一土壤对钢的腐蚀作用。其结果是随着土壤湿度从6.5％上升到25％,土壤电阻,氧化还原电位,好气菌量递减,硫酸盐还原菌递增。钢的腐蚀失重随湿度提高而下降,接近饱和点(22％)后腐蚀率变化很小,腐蚀率变化临界点在湿度为18～20％之间。蚀坑深度在湿度为12～15％时最大,低于10％时次之,超过20％时最低。湿度在6.5～20％下是局部腐蚀,超过20％为均匀腐蚀。低湿度(6.5～16％)下,菌生长旺盛的比加杀菌剂抑制菌生长的土壤中,钢腐蚀失重高40～123％。文中对不同湿度土壤中钢的腐蚀原因进行了讨论。