Effect Of Nano-oxide Addition On Corrosion Performance Of X80 Pipeline Steel

With the gradual growth of oil and gas resources’ s consumption, and the increase of oil and gas pipeline storage transportation engineering. The requirements on the properties of oil and gas pipelines is extremely harsh because of the complexity of the working environment that the oil and gas pipelines are faced with. Pipeline corrosion damage is one of the pipeline steel major safety problems, once happened, economic loss caused is immeasurable. This paper chose X80 pipeline steel as the research object, research the effect of nanometer oxide on corrosin resistance in rolling state pipeline steel and welding heat affected zone the most weak link organize elaboration of pipeline steel, the mainly research results of this article include:Observe the morphology and distribution of inclusions in steel by scanning electron microscopy(sem) and metallographic microscope.Obtained by contrast, added MgO and CaO can decrease the average size of the inclusions in the pipeline steel effectively. The average size of inclusions in steel is in 0.9-1.5 μm range that add mass fraction is 0.02% and 0.05% of nano oxide experiment, to induce the acicular ferrite is better; mass fraction is 0.01% of nano oxide experiment, to induce the acicular ferrite is not significant. Compare all group of experimental steel through microstructure observation after corrosion, The rolling experiment of steel and the corresponding welding heat affected zone grain size is the most small that add the mass fraction of 0.02% nano MgO style; Add amount was 0.02% and 0.05% of nano oxide make organization ferrite content increase.Test the ac impedance spectroscopy and potentiodynamic polarization curve of each groups experiment steel in neutral and acidic NaCl solution. Experimental results show nano oxide as the second phase particles to join makes material corrosion performance degradation in neutral solution, nanoscale MgO style and CaO make little differerce with material impedance, the electrochemical corrosion performance is slightly lower, pitting potential decreased, pitting sensitivity improvement; Corrosion performance promotion of nano oxide effect on material in acidic solution, nano MgO style and CaO made material have certain improve corrosion resistance, pitting potential rise, pitting sensitivity decreases.Through the salt spray test of steel corrosion resistance tests. Contrast experiment results show that adding nanometer oxide in varying degrees of salt fog corrosion resistance of pipeline steel. Add nano MgO style sample corrosion resistance is superior to add the same content of nanometer CaO sample, add 0.02% rolling and welding heat affected zone of nanometer MgO style sample resistance to salt fog corrosion effect is best.