Research on the Kinetics of CO_2 Corrosion on N80 Steel

The CO2 corrosion kinetics of N80 steel was researched by using high temperature and high pressure corrosion test,corrosion product film analysis and electrochemical measurement technology.The results show that,as time went on,corrosion rate showed exponential decline law.The two stages for the formation of corrosion product film including nucleation and crystal grain growth were observed,which were respectively controlled by the cathodic process and anodic process.The composition of corrosion product could be stable after the 6th day by the EDS analysis,then the Warburg impedance was found from EIS.It was speculated from the polarization curves that the diffusion of Fe2+ was hindered by the product film,which resulted in grains growth and made the corrosion products more dense.Therefore,the corrosion resistance increased and the corrosion current density drastically reduced.