为了研究3Cr钢在不同CO2、H2S腐蚀介质中耐蚀性,对3Cr钢分别在1 MPa CO2、0.3 MPa H2S及1 MPa CO2+0.3 MPa H2S腐蚀环境中的腐蚀速率和电化学性能进行测试,同时采用SEM、EDS和XRD等手段对上述三种腐蚀环境中的腐蚀产物进行分析对比.结果表明,3Cr钢在1 MPa CO2环境下腐蚀速率最大,通过对腐蚀产物进行分析,发现其表面未形成连续分布且具有致密性腐蚀产物保护膜是其腐蚀速率高的主要原因.电化学测试发现3Cr钢EIS阻抗在1 MPa CO2中呈现单容抗弧,而在0.3 MPa H2S和1 MPa CO2+0.3 MPa H2S环境中呈现双容抗弧,进一步印证了其在1 MPa CO2环境中耐蚀性较差的结果.

The work aims to observe the corrosion characteristics of sulfate reducing bacteria （SRB） / saturated CO 2 anti-microbial corrosion pipe and to explore the effect of SRB on CO 2 corrosion. Through the bacterial culture experiment in the constant temperature 40℃ biochemical incubator， the 15-day growth curve of planktonic SRB in the environment with and without saturated CO 2 was obtained by using the method of blood plate counting. The effects of SRB， saturated CO 2 and SRB+ saturated CO 2 （three different environments） on the corrosion rate were obtained by immersion corrosion test in a constant temperature 40 ℃ biochemical incubator. The surface morphologies after corrosion in three different environments were analyzed by scanning electron microscope （SEM）. The composition and phase composition of corrosion products in three different environments were analyzed by energy dispersive spectroscopy （EDS） and X-ray diffractometer （XRD）. The corrosion electrochemical tests were carried out in a 40℃ water bath to study the effects of three different environments on the corrosion of microbial corrosion pipes. The results of bacterial culture in the presence and absence of saturated CO 2 showed that CO 2 could be used as a delayed carbon source for the growth of SRB and provide energy for the secondary growth of SRB. The results of corrosion immersion test showed that the corrosion rate was the highest in saturated CO 2 environment， the second in SRB environment and the lowest in SRB+ saturated CO 2 environment. The results of SEM analysis showed that the corrosion product film formed in CO 2 environment showed serious cracking phenomenon， and the corrosion was the most serious; many bacteria gathered together in SRB environment and adhered to EPS to form a similar network biofilm， which was more and relatively continuous than in the SRB+ saturated CO 2 environment. The results of EDS analysis showed that in the environment containing SRB， the sulfur element detected in the environment was higher than that in the aseptic environment due to the reduction of sulfate to H 2 S after the corrosion reaction of SRB， the reaction of H 2 S with Fe 2+ to form FeS and the contact of a little FeS with air to form simple substance S. The results of XRD analysis showed that in saturated CO 2 environment， the corrosion products were mainly in FeCO 3 ， Fe 2 O 3 and Fe 3 O 4 ; in the SRB environment， and the corrosion products were mainly in FeS， FePS 3 ， Fe 3 O 4 ， Fe 2 O 3 and simple substance S， in the SRB + saturated CO 2 environment， and only Fe diffraction peaks were detected. The electrochemical test results show that in the three environments， the slope of cathodic Tafel is larger than that of anode Tafel， and the corrosion is controlled by cathodic reaction. The whole corrosion process is affected by CO 2 corrosion， normal bacterial growth and metabolism， and the film is easy to crack and fall off. After immersion for 15 days， the polarization resistance shows the law of R p（SRB） ＞Rp （SRB+saturated CO2） ＞Rp （CO2） corrosion and SRB corrosion influence each other. In SRB+ saturated CO 2 environment， the formation of the biofilm improves the adhesion of the corrosion product film， reduces the corrosive ions passing through the film， and slows down the corrosion， so the existence of SRB can obviously inhibit the CO 2 corrosion of the microbial corrosion pipe.

通过浸泡腐蚀实验与高温高压电化学测试,研究了 J55钢在1.0 MPa CO2、0.3 MPa H2S及1.0 MPaCO2+0.3 MPa H2S气体组分下的腐蚀特征,并采用XRD、SEM和EDS分析腐蚀产物膜组成与形貌.结果显示,溶液中气体组分为H2S及CO2+H2S下的腐蚀速率相近,其表面产物为FeS.在只含H2S气体时,J55钢的表面FeS产物膜致密;而在CO2氛围下J55钢的腐蚀速率最高,其产物为疏松、覆盖率较低的FeCO3.高温高压原位电化学测试显示,不含腐蚀气体时溶液介质对J55钢的腐蚀表现为阴极控制;加入H2S使腐蚀转为阳极控制,腐蚀电位明显升高;而CO2的加入能强化阴极控制效果,同时降低腐蚀电位;溶液中CO2与H2S共存时,CO2使FeS的成膜电位增加.EIS图显示,J55钢在不含腐蚀性气体时极化电阻最大,仅含CO2时极化电阻最小,仅含H2S时出现高频容抗弧与低频容抗弧两个时间常数.

针对N80钢油套管在CO2/H2S共存环境中的腐蚀问题,利用失重法与电化学测试方法作对比分析,并利用扫描电子显微镜以及X射线衍射仪对浸泡腐蚀试验后的N80钢试样进行研究.结果显示,浸泡腐蚀试验结果与电化学测试结果一致,在单独CO2环境中,N80钢的自腐蚀电流与平均腐蚀速率最大,腐蚀最严重;在单独H2S环境中,N80钢试样腐蚀速率最小,自腐蚀电流最小;在PCO2/PH2 S=1:0.3时,主要以H2S腐蚀为主,但在表面发生局部产物膜剥落,此时的腐蚀速率高于纯H2S条件下的腐蚀速率.研究表明,在单独CO2环境中,腐蚀以阴极反应过程控制为主;在单独H2S环境中,腐蚀以阳极反应过程控制为主;在PCO2/PH2 S=1:0.3时,腐蚀以阴极反应过程控制为主.

针对Φ88.9 mm×6.45 mm L80-13Cr油管穿孔现象,采用宏观分析、化学成分分析、金相分析、力学性能测试及扫描电子显微镜、能谱仪等手段,对规格为Φ88.9 mm×6.45 mm的L80-13Cr马氏体不锈钢油管发生穿孔的原因进行了分析.结果表明:该油管材质的化学成分、显微组织及力学性能等未见异常,但内壁存在严重的均匀腐蚀以及孔蚀,腐蚀形貌呈苔地状,腐蚀产物及腐蚀坑内填充物主要为Fe3O4、FeOOH、FeCr2O4及CrOOH.因此穿孔的发生主要是由于油管内壁的水中存在溶解氧,导致油管发生了严重的均匀腐蚀及孔蚀,孔蚀处壁厚减少,导致油管穿孔.

为了研究影响Q245R钢硫化物应力腐蚀开裂的主要原因,通过拉伸试验、宏观形貌观察、显微组织分析、能谱分析等手段研究其断口及表面处的腐蚀产物,并分析其腐蚀机理.结果表明:Q245R钢在H2S环境中发生开裂的类型主要是SSC,开裂的主要原因是其存在明显的带状组织,氢原子在带状组织的两种组织界面处与硫化物夹杂处聚集,产生氢压,形成微裂纹,致使最终开裂.Q245R钢断口符合应力腐蚀开裂断口特征且存在明显的带状组织二次裂纹,在二次裂纹的间隙中存在FeS晶体.

燃煤锅炉水冷壁管发生腐蚀会影响锅炉的使用寿命,缩短其使用周期从而影响经济效益,甚至影响锅炉的安全使用.为分析其发生腐蚀的原因,利用能谱和X射线衍射等技术对20#钢锅炉水冷壁管的腐蚀特征进行分析,研究腐蚀机理及类型,并提出相关防护与控制措施.研究结果表明:燃料煤中的硫元素、氯元素以及硫酸盐是管道外壁腐蚀的主要因素,此外,管道外壁的高温氧化也会促进其发生腐蚀.1号试样的腐蚀速率为0.1925mm/a,2号试样的腐蚀速率为0.3150mm/a.