Effects of temperature and applied strain on corrosion of X80 pipeline steel in chloride solutions

In this work, corrosion of X80 pipeline steel was investigated in 3.5 wt-% NaCl solutions with two different dissolved oxygen (DO) concentrations by electrochemical measurements and surface analysis techniques. The effects of temperature and applied strain on the steel corrosion were determined. Results show that an elevated temperature increases the corrosion activity of the steel and its corrosion reaction kinetics, which is mainly realised by the anodic reaction, rather than cathodic reaction. At a high DO concentration (i.e. 7 mg L-1) in the solution, the corrosion is diffusion-controlled. When the DO concentration is reduced to 3 mg L-1, it becomes mixed controlled. The applied strain, although increasing the thermodynamic activity of the steel, does not obviously affect the corrosion of the steel due to the generation of corrosion scales, primarily gamma-FeOOH, which provides somewhat protection to the steel and offsets the increased corrosion activity.