Influence Of Environmental Factors On Corrosion Behavior Of X90 Pipeline Steel In Simulated Soil Solution Of Shenyang

With the continuous development of China's economy,China's demand for oil and gas resources continues to rise.In recent years,China has continuously accelerated the construction of oil and gas pipelines and the development and application of high-grade pipeline steel.At present,large caliber,long distance and high pressure are the development trend of pipeline steel.Therefore,it is of great significance to carry out research on corrosion behavior of X90 oil and gas pipeline steel in Shenyang soil simulation solution.Taking X90 oil and gas pipeline steel as the research object,through the electrochemical experiment and slow strain rate tensile test test,combined with the scanning electron microscope observation analysis,the corrosion law of X90 pipeline steel in Shenyang soil simulated solution under different pH was studied.It shows that with the continuous increase of pH in the simulated soil solution,the electrochemical corrosion rate of X90 pipeline steel shows a trend of decreasing first and then increasing,and the corrosion current density is the lowest in the neutral environment with pH 7.When the pH is 3,the electrochemical corrosion rate is the fastest.The stress corrosion cracking mechanism is affected by the anode dissolution,resulting in greater sensitivity to stress corrosion;the use of AC impedance technology and polarization curve technology for X90 steel at different SO₄^2-concentrations The corrosion behavior was studied and the fracture morphology was observed by scanning electron microscope.The results show that the corrosion rate of X90 pipeline steel in simulated solutions of Shenyang soil with different concentrations of SO₄^2-shows a trend of decreasing first and then increasing with the increase of SO₄^2-concentration.The main influencing factor of SO₄^2-on the corrosion rate of X90 pipeline steel is the competitive adsorption of SO₄^2-and Cl^-.When the concentration of SO₄^2-is 10%,under the combined action of mechanical factors and electrochemical factors,X90 pipeline steel has high stress corrosion sensitivity;using AC impedance technology and dynamic potential polarization curve technology for X90 steel under different HCO₃^-concentrations The corrosion behavior of X90 pipeline steel was shown to show that the polarization curve of X90 pipeline steel in different concentrations of HCO₃^-in Shenyang soil simulated solution showed typical activation-passivation control.The main influencing factor of HCO₃^-on the corrosion rate of X90 pipeline steel was HCO₃^-The concentration affects the product film properties.X90 pipeline steel exhibits ductile fracture in simulated solutions with different HCO₃^-concentrations.When the HCO₃^-concentration is 7%,X90 pipeline steel has the highest stress corrosion sensitivity.