Research On The Erosion-corrosion Behavior Of P110 Steel In Liquid-solid Two-phase Flow

The P110 steel is a kind of senior product of oil casing pipe,which exhibits excellent mechanical properties.The casing pipe exposed to the multiphase flow underground will be subjected to erosion-corrosion damage,especially in the two-phase flow with particles.The damage is more serious and will greatly shorten the life of casing.However,up to now few researches have been focused on the erosion-corrosion behavior of P110 steel.Therefore,it is of great technological interest to investigate the erosion-corrosion behavior of P110 steel in the liquid-solid two-phase,and more attention should be paid to its application for developing new materials and surface modification technology.The erosion-corrosion behavior of P110 steel in the liquid-solid two-phase was studied in this paper.The study focused on some main factors of erosion-corrosion process such as particle size,flow rate, time,NaCl solution and sand content.A erosion-corrosion mimic device installed electrochemical corrosion testing device under different circumstances was used.The effect of factors on erosion-corrosion behavior of P110 was studied by weight loss rate,linear polarization resistance,polarization cuives and electrochemical impedance spectroscopy.Also, the corrosion surface topographic was observed by optical microscopy and scanning electron microscopy,and the erosion-corrosion mechanism was analyzed in conclusion.The results showed that the electrochemical corrosion process exerted a major role in erosion-corrosion process,and the pure mechanical erosion accounted for the secondary factors.The particle size,flow rate, time,NaCl solution and sand content showed great influence on erosion-corrosion behavior of P110 steel.In a certain range, erosion-corrosion rate increased with flow velocity,sand particle size and NaCl concentration.As the time increased,the erosion-corrosion rate increased firstly and then decreased.There existed a "critical velocity",which the value was 4m/s.When the flow rate lower than the"critical velocity"the amount of erosion rate decreased slightly,after that the condition was quite the reverse.When the sand content attained to 3%,the erosion-corrosion rate arrived at a maximum,then the erosion-corrosion rate decreased for the"shielding effect".