X70管线钢在含CO2库尔勒土壤模拟溶液中的腐蚀行为

CORROSION BEHAVIOR OF X70 PIPELINE STEEL IN SIMULATED KU'ERLE SOIL SOLUTION WITH CO_2

采用动电位扫描、交流阻抗电化学方法和慢应变速率拉伸实验(SSRT)研究了CO_2对X70管线钢在库尔勒七壤模拟溶液中应力腐蚀开裂(SCC)行为的影响,并利用扫描电镜分析了不同CO_2分压下的断面形貌.结果表明:CO_2能够与腐蚀膜FeCO_3反应,生成可溶性Fe的络合物Fe(CO_3)_2^(2-),加速X70管线钢腐蚀;CO_2与H_2O形成H_2CO_3和HCO_3^-,为阴极反应提供H^+.X70管线钢在含CO_2溶液中的SCC机理为氢脆-阳极溶解协同机理,且随CO_2分压的增加,氢脆作用增大.

The effect of CO2 on the stress corrosion cracking （SCC） behavior of X70 pipeline steel in simulated Ku＇erle soil solution was investigated by polarization curve, EIS and slow strain rate testing （SSRT）. The morphologies of fracture surface of X70 pipeline steel in the solution with the different partial pressures of CO2 were analyzed by SEM. The results show that the dissolved CO2 reacted with the corrosion product of FeCO3 and a dissolved complex （Fe（CO3）2^2-） is formed. The cathodic regime representing evolution of hydrogen is also affected by the presence of dissolved CO2. The SCC of X70 pipeline steel in dissolved CO2 solution follows the mechanism of hydrogen-facilitated dissolution. As the increase of the pressure of CO2 in the solution, the effect of hydrogen induced cracking is enhanced.