动态载荷下高强管线钢硫酸盐还原菌腐蚀机理研究

Corrosion failure is one of the major threats to safe services of pipelines. Many investigations in the field and laboratory have verified that microorganisms participate in and significantly affect the crack initiation and propagation of pipeline steels. The synergistic effects of sulfate-reducing bacteria (SRB) and static stresses on corrosion of X80 steel in soil environment were discovered in our previous researches. However, mechanisms and regularities of SRB induced corrosion of pipeline steels under dynamic loads still remain unclear. In the project, SRB induced corrosion of high strength pipeline steels under dynamic loads is investigated systematically in typical soil solutions via slow strain rate tensile tests, dynamic tensile tests and corrosion fatigue tests. Electrochemical measurement, XRD, XPS, SEM and TEM are synthetically applied into the studies. The initiation and propagation of pits and micro-cracks of pipeline steel under the actions of SRB physiological activity and dynamic loads will be clearly illuminated. There is an attempt to establish the relationship between the electrochemical activity and the initiation of pits and micro-cracks under the actions of SRB physiological activity and dynamic loads. The mechanism of stress corrosion cracking and corrosion fatigue of pipeline steel under microbiological corrosion will be discussed in this project. The results of the project will provide the guidance for the selection and revision of cathodic protection potential for pipeline steel in practice, and provide the technical support and theoretical basis for safety evaluation of crack initiation and propagation of high strength pipeline steels under the combined actions of SRB and dynamic loads in soils.

管线腐蚀失效是管线安全运行的重要威胁，现场调查和实验研究都表明土壤微生物参与并显著影响了管线钢的腐蚀及裂纹萌生和扩展过程。前期研究已发现了静载荷和硫酸盐还原菌(SRB)在管线钢腐蚀过程中的协同作用，但对动态载荷条件下管线钢SRB腐蚀的规律和机理尚不清楚。本项目拟在典型土壤溶液中，通过慢应变速率拉伸、动态拉伸和腐蚀疲劳等实验方法，利用电化学测试、XRD、XPS、SEM和TEM等测试技术，系统地开展动态载荷条件下高强管线钢SRB腐蚀研究，阐明SRB生理活动和动载荷作用下管线钢点蚀和微裂纹的萌生及扩展规律，建立SRB生理活动和动载荷作用下管线钢电化学活性与点蚀/微裂纹萌生的关系，揭示SRB生理活动对管线钢应力腐蚀开裂和腐蚀疲劳的影响及其机理。本项目的研究成果可为实际管线阴极保护参数的选择和修正提供指导，为建立土壤中动态载荷和SRB共同作用下高强管线安全评价提供理论及技术支持。

前期研究表明静载荷和硫酸盐还原菌(SRB)在管线钢腐蚀过程中的协同作用，但对动态载荷条件下管线钢SRB腐蚀的规律和机理尚不清楚。本项目通过理论计算、慢应变速率拉伸(SSRT)和动态拉伸等方法系统地开展动态载荷条件下高强管线钢SRB腐蚀研究，给出了管线钢微生物腐蚀开裂的热力学解释，说明了动态拉伸过程中管线钢微生物腐蚀过程中的力学-化学效应，提出了阴极保护参数优化建议。此外，在项目资助下开展了剥离涂层下微生物腐蚀开裂的研究，阐述了微生物代谢产物对管线钢微生物腐蚀行为的影响。本项目的研究成果可为实际管线阴极保护参数的选择和修正提供指导，为建立土壤中动态载荷和SRB共同作用下高强管线安全评价提供理论及技术支持。