Corrosion Behavior of X65 Pipeline Steel in Simulated Soil Solution in Northeast Sichuan

The corrosion behavior of X65 pipeline steel was studied by immersion corrosion test at 25 ℃ in simulated soil solution in Northeast Sichuan. The corrosion rate was determined by weight loss method. The morphology and composition of corrosion products were observed and analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that with the increase of immersion time, the corrosion products gradually evolved from a single flocculent product to a double-layer product film with a dense inner layer and a flocculent outer layer, and the corrosion morphology changed from uneven corrosion to uniform corrosion. The corrosion products were mainly composed of Fe₃O₄, Fe₂O₃, FeO(OH), and the corrosion rate showed a trend of increasing first and then decreasing.