Corrosion Behavior of X80 and X70 Pipeline Steels in Beijing Soil Environment

摘要

The corrosion behavior of X80 and X70 pipeline steels in Beijing soil environment was investigated by burying test in nature field for one and two years,while using SEM and XRD analyze the micro-morphology and phase composition of corrosion products of X80 and X70 pipeline steels.The results show that general corrosion has occurred mainly on the X80 and X70 pipeline steels in Beijing soil,with the pitting corrosion.With the increase of burying time,the corrosion rate of X80 and X70 pipeline steels remain steady,and the pitting corrosion depth increases.The corrosion rate of X80 steel is lower than that of X70 steel,and the pitting corrosion degree of X70 steel is more than X80 steel.The corrosion product of X80 and X70 pipeline steels can not protect the substrate,because of its incomplete,loose and incompact,and was consisted of α-FeOOH,β-FeOOH,γ-FeOOH,γ-Fe2O3 and Fe2O3.X80 steel exhibits higher corrosion resistance than X70 steel.