Study On The Influence Of The Coupling Of AC Stray Current And Srb On The Corrosion Behavior Of X80 Steel Under Stripped Coating

Both AC stray current and SRB can cause serious corrosion to buried pipelines,especially when the coating was damaged or peeled off.Once the buried oil and gas pipeline is corroded,perforated and leaked,it will have an immeasurable impact on manpower,financial resources,and the environment.Therefore,it is of great value and significance to carry out the research on the influence of the coupling effect of AC stray current and SRB on the corrosion behavior of X80 steel.Electrochemical methods,macroscopic corrosion product morphology observation,surface analysis techniques,and weight loss experiments were used to study the effect of SRB and AC stray current on the corrosion behavior and corrosion laws of X80pipeline steel under the stripped coating.The main conclusions are as follows:、（1）The corrosion rate of X80 steel in the soil simulated solution under the interference of different AC stray current densities first decreases and then increases with the increase of immersion time.If the immersion time is the same,the corrosion rate of X80 steel increases with the increase of AC stray current density.When X80 steel is not interfered by AC in the soil simulation solution,it is mainly uniformly corroded,and when it is disturbed by stray current,it is mainly localized.（2）During the growth and reproduction of SRB,SO₄^2-is reduced,and H⁺in the soil simulation solution is consumed,which causes the p H of the solution to rise.The open circuit potential of X80 steel in aseptic and bacteria-containing environments is basically the same with time,and the corrosion tendency is greater in the simulated soil solution containing SRB,which means that SRB promotes the corrosion of X80 steel in the simulated soil solution.effect.In addition,when the soil simulation solution contains SRB,the cathodic reaction is the depolarization reaction of phosphide and sulfide,and the anode is the dissolution of Fe.（3）When the AC stray current density is less than 100 A/m²,it has little effect on the growth of SRB in the soil simulation solution.When the AC stray current density is increased to 200 A/m²,300 A/m²,the growth period of SRB is significantly reduced,and the larger the current density,the shorter the growth period of SRB.Meanwhile,At the same time,the AC stray current promotes the desorption of biofilm on the surface of the sample and promotes the corrosion of X80 steel.The metabolites of SRB are mainly sulfides when the surface of X80steel is not subject to AC interference or when the AC interference is weak.When subjected to strong AC interference,its metabolites are mainly phosphides.The active biofilm inhibits the corrosion of X80 steel,and the metabolites of SRB promote the corrosion of X80 steel.In general,the presence of SRB promotes the corrosion of X80 steel under the peeling coating.