Effect Of External Potential And Temperature On The Corrosion Behavior Of Film-Formed X80 Pipeline Steel In SRB

Sulfate-reducing bacteria(SRB)are the main microorganisms that induce corrosion.Especially in the petroleum industry,microbial corrosion is a key factor affecting the pipeline system.The harmfulness of metal microbial corrosion(MIC)has attracted more and more attention and attention.X80 pipeline steel has good comprehensive performance and is widely used in oil and gas and pipeline transportation systems.Microorganisms adhere to metal surfaces by metabolism to form biofilms,which play a major role in the corrosion of metals.Therefore,it is of great practical significance to study the electrochemical corrosion behavior of X80 high strength pipeline steel under biofilm.In this paper,X80 pipeline steel is taken as the research object,and the soil of Dagang is collected by Dagang Soil Center Station of National Material Soil Environmental Corrosion Test Station,and SRB extraction is carried out to determine the amount of bacteria contained in the soil.The purification culture and growth pattern of SRB were studied,and the SRB morphology was observed by microscope.The results show that SRB in Dagang soil belongs to Gram-negative bacteria.Divided into viscous growth phase,logarithmic growth phase,stable growth phase,decay and residual period in a growth cycle.Scanning electron microscopy was used to observe the surface morphology of X80 high-strength pipeline steel in Dagang soil simulation solution.Combined with EDS analysis of surface element composition,and possible compounds,the film formation morphology and film formation characteristics at different stages are clarified.The results show: After immersion for 5 days in X80 pipeline steel,the surface biofilm is evenly covered.At this time,the microbial activity is the strongest,and the formed biofilm has the greatest influence on corrosion.With the prolongation of time,the surface biofilm has local shedding phenomenon.Using AC impedance testing and potentiodynamic polarization testing,the surface corrosion morphology was observed by metallographic microscope.The electrochemical corrosion behavior of X80 pipeline steel in Dagang soil simulated solution was studied under the action of biofilm and external potential.The electrochemical corrosion mechanism of X80 steel under the action of biofilm and external potential is clarified.Research indicates: Under the action of the external potential,the biofilm activity is reduced,but it still promotes corrosion,in the aseptic solution,the applied potential can better inhibit the corrosion of X80 steel.The AC impedance test and the potentiodynamic polarization test were used,and the surface corrosion morphology was observed by a metallographic microscope,the electrochemical corrosion behavior of X80 pipeline steel in Dagang soil simulated solution under the action of biofilm and temperature was studied.The electrochemical corrosion mechanism of X80 steel under the action of biofilm and temperature is clarified.