溶解氧对X70管线钢在高pH值溶液中的电化学行为和SCC敏感性的影响

Influence of Dissolved Oxygen on Electrochemical Behaviour and SCC Susceptibility of Pipeline Steel X70 in High pH Solution

采用动电位极化、恒电位极化曲线测试法研究了X70管线钢在0.5 mol/L Na2CO3+1 mol/L NaHCO3溶液中的电化学行为,分析了供氧状况和扫描速度等因素对极化曲线的影响。采用慢应变速率试验(SSRT)研究了X70管线钢在不同供氧状况的溶液中的应力腐蚀破裂(SCC)敏感性。结果表明,X70管线钢在通高纯氮气和不通气溶液中的动电位极化曲线形状相似,但是在通压缩空气的溶液中的动电位极化曲线出现三个零电流电位,分别位于活化区、活化-钝化过渡区和钝化区;不同供氧状况下SCC敏感电位范围不同。

The influence of oxygen concentration on the electrochemical behavior and stress corrosion cracking （SCC） susceptibility of pipeline steel X70 in 0.5 mol/L Na2 CO3＋1 mol/L NaHCO3 solution was investigated using potentiodynarnic polarization, potentiostatic polarization and slow strain rate testing （SSRT）. The influence of oxygen concentration and scan rate on the potentiodynamic polarization curves is analyzed. The potentiodynamic polarization curves in the solution deaerated by high purity nitrogen are sirnilar to those in the sealed non-aerated solution. There are three zero current potentials in the potentiodynamic polarization curve in the solution aerated by compressed air. The potential range of SCC susceptibility differs from each other in the different oxygen concentration solutions.