直流电作用下X70钢在近中性土壤中应力腐蚀行为研究  

Stress Corrosion Behavior of X70 Steel in an Artificial Near-neutral Soil Solution Under Direct Current

作　　者：吴宇航 陈旭[1] 王首德 刘畅[2] 刘杰[1] WU Yuhang;CHEN Xu;WANG Shoude;LIU Chang;LIU Jie(College of Petroleum Engineering,Liaoning Petrochemical University,Fushun 113001,China;China National Petroleum Corporation Daqing Refining&Chemical Company,Daqing 163411,China)

机构地区：[1]辽宁石油化工大学石油天然气工程学院,抚顺113001 [2]中国石油天然气股份有限公司大庆炼化分公司,大庆163411

出　　处：《中国腐蚀与防护学报》2025年第2期489-496,共8页Journal of Chinese Society For Corrosion and Protection

基　　金：教育部“春晖”国际合作计划项目,辽宁省教育厅面上项目(LJKZ0416);辽宁省教育厅项目(LJ212410148059)。

摘　　要：采用极化曲线、电化学阻抗谱技术和慢应变速率拉伸方法,研究了直流电(DC)作用下X70钢在近中性土壤模拟溶液中的应力腐蚀敏感性。通过对断口表面形貌观察,分析了不同DC下X70钢的开裂机制。结果表明:随着DC密度增加,X70钢阳极极化程度增加,表面生成的氧化膜具有一定的保护作用。当DC密度不大于0.5 mA/cm^(2)时,腐蚀速率随DC密度增加而降低。DC密度增加至1 mA/cm^(2)时,腐蚀产物膜不能阻止阳极溶解,腐蚀速率急剧增大。无DC时,X70钢开裂机制为氢致开裂。DC和应力协同作用下,DC导致裂纹尖端持续发生阳极溶解。随DC密度增加,X70钢在近中性土壤模拟溶液中的开裂机制由氢致开裂转变为阳极溶解。With the development of urban construction,it is inevitable that high voltage direct current transmission projects and buried oil and gas pipelines often share the proximity of public space corridors.Therefore,the potential danger of corrosion and damage to the adjacent buried oil and gas pipelines due to current leakage of transmission lines is becoming more and more prominent.In this paper,the stress corrosion sensitivity of X70 steel in a simulated solution of near-neutral soil under direct current(DC)was studied by means of electrochemical polarization curve,electrochemical impedance spectroscopy and slow strain rate tensile method.The results showed that the anode polarization of X70 steel increased with the increase in DC density.When the DC density was less than 0.5 mA/cm^(2),the corrosion rate decreased with the increase in DC density.When the DC density increased to 1 mA/cm^(2),the corrosion product film could not prevent the anodic dissolution and the corrosion rate increased sharply.In the absence of DC, the cracking mechanism of X70 steel was hydrogen induced cracking. Under the synergistic effect of DC and stress, DC led to continuous anodic dissolution at the crack tip. With the increase in DC density,the cracking mechanism of X70 steel in the simulated solution of near-neutral pH changed from hydrogen induced cracking to anodic dissolution.

关 键 词：X70钢 近中性溶液 直流电流 应力腐蚀 开裂机制 

分 类 号：TG147[一般工业技术—材料科学与工程]