L450钢在不同温度模拟土壤溶液中最大阴极保护电位
Research on the maximum cathodic protection potential of L450 steel in simulated soil solution at different temperatures
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- 引用格式:
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程猛猛,廖臻,马晓凤,陶文金,马愉,刘乐乐,翁祥,王银强,吴明浩,王晨,吕祥鸿.L450钢在不同温度模拟土壤溶液中最大阴极保护电位[J].天然气与石油,2023,41(1):104-112.doi:10.3969/j.issn.1006-5539.2023.01.014
CHENG Mengmeng, LIAO Zhen, MA Xiaofeng, TAO Wenjin, MA Yu, LIU Lele, WENG Xiang, WANG Yinqian.Research on the maximum cathodic protection potential of L450 steel in simulated soil solution at different temperatures[J].Natural Gas and Oil,2023,41(1):104-112.doi:10.3969/j.issn.1006-5539.2023.01.014
- DOI:
- 10.3969/j.issn.1006-5539.2023.01.014
- 作者:
- 程猛猛1 廖臻1 马晓凤2 陶文金1 马愉1 刘乐乐2 翁祥1 王银强1 吴明浩1 王晨2 吕祥鸿
CHENG Mengmeng1, LIAO Zhen1, MA Xiaofeng2, TAO Wenjin1, MA Yu1, LIU Lele2, WENG Xiang1, WANG Yinqian
- 作者单位:
- 1. 中国石油新疆油田油气储运分公司, 新疆 克拉玛依 831100; 2. 西安石油大学材料科学与工程学院, 陕西 西安 710065
1. Oil-Gas Storage and Transportation Company, PetroChina Xinjiang Oilfield, Karamay, Xinjiang, 831100, China; 2. School of Materials Science and Engineering, Xi’an Shiyou University, Xi’an, Shaanxi, 710065, China
- 关键词:
- 慢应变速率拉伸测试;最大阴极保护电位;断面收缩率;恒电位极化
Slow Strain Rate Test; Maximum cathodic protection potential; Reduction of area; Potentiometric polarization
- 摘要:
为深入研究稠油高温管道的阴极保护规律,明确温度对最大阴极保护电位的影响,采用恒电位极化结合慢应变速率拉伸测试(Slow Strain Rate Test),分析了L450钢在不同温度模拟土壤溶液中的最大阴极保护电位。采用扫描电镜观测慢应变速率拉伸测试试样的断面形貌,用X射线衍射分析试样表面沉积层组分。结果表明:在温度从20 ℃上升到60 ℃的过程中,施加相同阴极保护电位时,温度越高,氢含量和氢扩散速率越高,阴极析氢反应增强,更易导致氢脆现象发生；随着温度升高,断面收缩率损失系数越大,L450钢氢脆敏感性增强,最大阴极保护电位负向移动,从-1 200 mV(CSE)降低到-1 400 mV(CSE)；增大施加阴极保护电位,拉伸断口形貌从典型韧性断裂向脆性断裂特征转变；而当温度升高至80 ℃时,溶液中Ca2+离子与Mg2+离子在L450钢表面形成沉积层,降低了氢扩散速率,因此L450钢试样断面收缩率损失系数较小,断口为明显的韧性断口形貌,不具有明显氢损伤敏感性,此时,L450钢的最大阴极保护电位不应超过-1 500 mV(CSE)。研究结果可用于评价管道运行环境的阴极保护准则，特别是高温运行管道的阴极保护准则。
In order to study the cathodic protection principle of high temperature heavy oil pipeline in more depth and clarify the influence of temperature on the maximum protection potential, the maximum protection potential of L450 steel in simulated soil solution at different temperatures was analyzed by constant potential polarization combined with slow strain rate test. The cross section morphology of the sample was observed by scanning electron microscope, and the composition of the deposition layer on the sample surface was analyzed by X-ray diffraction. The results show that when the temperature rises from 20 ℃ to 60 ℃ and the same cathodic potential is applied, the higher the temperature, the higher the hydrogen content and hydrogen diffusion rate, the stronger the cathode hydrogen evolution reaction, which is more likely to cause hydrogen embrittlement. With the increase in temperature, the reduction of area increases and the L450 steel is more susceptible to the hydrogen embrittlement, while the maximum cathodic protection potential shift negatively, from -1 200 mV (CSE) to -1 400 mV (CSE). The morphology of the tensile fracture changes from a typical ductile fracture to a brittle fracture as negative shift of the negative potential is applied. When the temperature rises to 80 ℃, a deposition layer of Ca2+ and Mg2+ ions formed on the surface of L450 steel, resulting in a reduction in the diffusion of hydrogen. Therefore, the reduction of area of L450 steel sample is small, and the resulted fracture is an obvious ductile fracture morphology, without exhibiting any obvious hydrogen damage sensitivity. In conclusion, the maximum protective potential of L450 steel should not exceed -1 500 mV (CSE). The result can be used for the evaluation of cathodic protection code of pipeline operation conditions.
