交直流杂散电流与应力耦合作用下高强钢管线腐蚀与涂层剥离的非稳态电化学理论与分析方法研究

With the increase of operating pressure and the interference of alternating current/direct current (AC/DC) stray current, the operating environment of buried high-strength steel pipeline is becoming more complex, which proposes new requirement for safety running and corrosion protection of buried high-strength steel pipeline. In this project, high-strength steel (X70, X80, X100) pipelines without coating, asphalt-coated steel pipeline and three-layer polyethylene-coated(3PE) steel pipeline are objects researched. For the cathodic disbonding and coating defects where the problem of the disbonded coating caused by stray current flowing and the point of layers under corrosion with corrosions on defects resulted fom the disbonded coating, based on the electrochemical theory, the multidisciplinary cross research thought and the oretical analysis and experimental research, besides, the integration of material science, mechanics, electromagnetism and fusion, chemical, metal corrosion, thermodynamics and other multi-disciplinary theory, by adopting multi-physics coupling numerical method, advanced electrochemical measurement technique and surface characterisation technique, the non-steady-state electrochemical process of disbonded coating and corrosion of high-strength steel beneath coupling effect of stress and AC/DC stray current are studied, finally, the corrosion mechanism and release properties, disbonded coating mechanism and release properties of high-strength steel are revealled fully. Its research contents mainly include: the propagation characteristics and propagation law of AC/DC stray current in buried high-strength steel pipeline beneath stress; the non-steady-state electrochemical process and mechanism of disbonded coating for high-strength steel pipeline under coupling effect of stress and AC/DC stray current; the non-steady-state electrochemical process and mechanism of corrosion of high-strength steel pipeline under coupling effect of stress and AC/DC stray current; the establishment of dynamic mathematical model and the research on electrochemical behavior of high-strength steel pipeline beneath the interaction between disbonded coating and corrosion, while the pipeline suffered coupling effect of stress and AC/DC stray current; corrosion law and properties experiment of high-strength steel pipeline under coupling effect of stress and AC/DC stray current, the establishment of corrosion rate mathematical mode and the research on evaluation method of corrosive hazardous of high-strength steel pipeline under coupling effect of stress and AC/DC stray current. Through this study, the essential characteristics and electrochemical protection technology for corrosion beneath coupling effect of mechanical and electrochemical are revealed by establishing the electrochemical basic theory and method of analyzing corrosion of high-strength steel pipeline under coupling effect of stress and AC/DC stray current.

随着输送压力的不断提高以及各种交直流杂散电流的侵扰，埋地高强钢管线的运行环境更趋复杂，给埋地高强钢管线的安全运行与腐蚀防护提出了新的要求。项目以X70、X80、X100高强钢管线和涂覆石油沥青、三层PE的埋地钢质管道为研究对象，针对应力与交直流杂散电流耦合作用下高强钢管线的腐蚀与涂层剥离新问题，以电化学理论为基础，并融合材料学、力学、电磁学、化学、金属腐蚀学、热力学等多学科理论，在理论分析与实验研究基础上，通过采用多物理场数值计算方法以及先进的电化学测试与表面分析技术，系统研究应力作用下交直流杂散电流在埋地高强钢管线内的传播特性与传播规律，研究交直流杂散电流与应力耦合作用下埋地高强钢管线的腐蚀机理与腐蚀特性以及涂层剥离机理与剥离特性，并建立相应的危害性评价技术与方法，形成系统开展交直流杂散电流与应力耦合作用下高强钢管线腐蚀与涂层剥离研究的电化学基础理论与方法。

随着高强管线钢被广泛应用于高压力埋地油气输送管道，研究和探索应力作用下高强管线钢的腐蚀问题，成为高强管线钢腐蚀研究的一个新问题。而人们对于交直流混流杂散电流干扰作用下埋地金属管道产生腐蚀危害的研究尚处于空白，对其腐蚀机理、腐蚀行为以及电化学防护技术缺乏清楚的认识，急需开展这方面的研究。同时，管道由于运行压力所承受的应力对涂层的作用会更加强烈，这种应力作用下涂层产生剥离的机理和行为以及对腐蚀的影响规律，是值得进一步研究和澄清的，也是高强钢管线推广过程中必需面对的一个新问题。进一步，应力与交直流杂散电流以及与交直流混流杂散电流耦合作用下高强钢管线的涂层剥离与腐蚀问题也将是埋地高强钢管线研究的一个新课题和新领域，对解决高强钢管线的腐蚀防护问题至关重要。.项目以X70、X80、X100高强钢管线和涂覆石油沥青、三层PE的埋地钢质管道为研究对象，针对应力与交直流杂散电流耦合作用下高强钢管线的腐蚀与涂层剥离新问题，以电化学理论为基础，并融合材料学、力学、电磁学、化学、金属腐蚀学、热力学等多学科理论，在理论分析与实验研究基础上，通过采用多物理场数值计算方法以及先进的电化学测试与表面分析技术，系统研究了杂散电流在埋地管线钢附近土壤域及涂层破损点处传播规律，分析了交流杂散电流及直流杂散电流作用下管线钢涂层剥离规律及金属腐蚀行为规律、交直流杂散电流耦合作用下管线钢腐蚀行为规律，提出了交流杂散电流与应力耦合作用下X70/X80钢在不同土壤模拟溶液中的腐蚀规律以及直流杂散电流与应力耦合作用下X80钢三层PE涂层线缺陷处的剥离机理及金属腐蚀行为研究，并对高强管线钢在土壤模拟溶液中的阴极保护基本参数进行了研究，最终提出了应力作用下油气管道用高强钢直流杂散电流腐蚀评价方法以及腐蚀控制方法。.交直流杂散电流与应力耦合作用下高强钢管线腐蚀与涂层剥离的非稳态电化学问题是影响高强钢管道安全运行的关键科学问题之一，本项目系统研究了应力作用下交直流杂散电流在埋地高强钢管线内的传播特性与传播规律以及交直流杂散电流与应力耦合作用下埋地高强钢管线的腐蚀机理与腐蚀特性以及涂层剥离机理与剥离特性，并建立相应的危害性评价技术与方法，形成系统开展交直流杂散电流与应力耦合作用下高强钢管线腐蚀与涂层剥离研究的电化学基础理论与方法，填补了国内外在杂散电流与应力耦合作用下高强钢管线腐蚀防护方面的理论空白。