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

The influence of oxygen concentration on the electrochemical behavior and stress corrosion cracking(SCC) susceptibility of pipeline steel X70 in 0.5 mol/L Na2CO3+1 mol/L NaHCO3 solution was investigated using potentiodynamic 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 similar 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.