【作者】 李挺；

【导师】 左禹；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 硕士

【摘要】 本文利用静态挂片失重法研究了含H2S/CO2模拟油田水溶液中温度、Cl-浓度及Ca2+浓度对L360管线钢点腐蚀的影响,并利用XRD, SEM, EDS,附着力,电化学等测试方法研究了腐蚀产物膜的特征,另外本文还用概率统计法分析了蚀点分布特征。主要结论如下：1、通过XRD测试发现,L360管线钢在含H2S/CO2模拟油田产出水环境中,溶液的温度、Cl-浓度、Ca2+浓度的改变对腐蚀产物成分没有明显影响,均为FeS,没有发现Fe与CO2反应。说明L360管线钢的腐蚀表现为H2S腐蚀。2、Cl-浓度对点腐蚀发生有明显影响。当Cl-浓度为15 g/L时,腐蚀试样发生明显点蚀；当Cl-浓度大于20g/L时,试样主要发生均匀腐蚀,随着Cl-浓度的增大,腐蚀产物膜中对金属基体具有良好保护性能的四方晶系FeS含量不断减少,同时腐蚀产物膜变得更加疏松,导致腐蚀产物膜保护作用下降,均匀腐蚀速率增大。3、Cl-浓度为15g/L时,温度对点腐蚀发生有明显的影响。在40-70℃范围内,L360管线钢发生了不同程度的点腐蚀,并且蚀点密度和深度随温度的升高而不断增大,并且在70℃时出现了严重的坑蚀；L360管线钢的均匀腐蚀速率随着溶液温度升高先增大后减小,在60℃达到了极大值；对不同温度下腐蚀产物膜的观察发现,当温度升高至70℃时,腐蚀产物的粒度比其他温度明显变小,因此在70℃下腐蚀产物膜变得更加致密。4、在60℃下,腐蚀速率随Ca2+浓度的增加而增大,当Ca2+浓度为8.5g/L时,表面腐蚀产物极易脱落。在此浓度下,管线钢不仅发生点腐蚀,而且有片状的局部腐蚀发生。5、在40-70℃下,管线钢的最大蚀孔深度均服从Gumbel第一类近似分布。在70℃下,用泊松分布计算出了蚀孔密度为1237-1791个/m2,置信范围宽度值为553个/m2。同时蚀孔深度分布服从正态分布。更多还原

【Abstract】 The effects of Cl-,Ca2+ concentration and temperature on pitting corrosion of L360 steel in H2S/CO2 environment were studied using methods of weight loss testing, electrochemical testing, XRD, SEM, EDS and adhesion testing. In addition, distribution characteristic of pits was analyzed. The main results are as follows:1. XRD tests showed that in H2S/CO2 environment, the temperature, Cl- consentraion and Ca2+ consentraion had no significant effect on corrosion scales. It illustrates that H2S corrosion is the main corrosion.2. Pitting corrosion occurred in 15g/L Cl- solution at constant temperature, and uniform corrosion happened when the Cl- concentration is higher than 20 g/L. As the temperature increases, corrosion products on the surface become looser and the protective property decreases.3. The results showed that pitting corrosion tends to be more serious with the increase of temperature (from 40℃to 70℃) in 15 g/L Cl-solution. Serious pitting corrosion occoured at 70℃. At first uniform corrosion rate increased, then decreased with the increaseing temperature. And corrosion rate reached the maximum at 60℃. SEM photos showed that particle size of the corrosion scale decreases and becomes more density when the temperature reached to 70℃.4. As the Ca2+ concentration increased, uniform corrosion becamed more serious. When the Ca2+ concentration reached to 8.5g/L, not only pitting corrosion occoured but also local corrosion appeared and the corrosion scale falls off easily.5. The measured maximum depth of pits follows the Gumbel first approximating function at 40-70℃. Pit density was calculated by poisson distribution and the density is 1237-1791a/m2 and the depth of pits obeys the normal distribution at 70℃.更多还原