The corrosion behavior of X80 pipeline steel in simulated Ku’erle soil solution was investigated by potentiodynamic polarization,electrochemical impedance spectroscopy (EIS) and mass loss measurement. The corrosion products and morphologies were observed by X-ray diffraction (XRD) and optical microscope (OM). The results showed that the longer the metal is in the solution,the higher the corrosion potential,and the thicker the corrosion products. However,the corrosion rate of weld joint decreases first and then increases. The corrosion rate of X80 steel and its weld joint slows down because of the protection from the corrosion product film of Fe3O4of inner layer. After 30 days in the solution,cracks show on the metal due to the shelling down of the corrosion product film,which is good for the invasion of Cl-. It accelerates the corrosion of certain part. The corrosion of weld joint part is more than other part of the steel in the exactly same solution environment. This is due to the fact that there are different structures on the same pipeline steel,leading to higher energy of lattice distortion and activity and lower corrosion resistance.
