Corrosion Behavior Of Super 13Cr Martensitic Stainless Steel In Stratum Water Environment Of Oil Field

With the exploitation of oil and gas fields facing the harsh environment,the corrosion of metal materials by the stratum water of oil and gas fields with high salinity cannot be ignored.Super 13Cr stainless steel is widely used in oil and gas fields due to its excellent corrosion resistance.However,in recent years,several super 13Cr stainless steel tubing failures have been reported.The excellent properties of super 13Cr stainless steel need to be obtained by heat treatment.In order to eliminate the residual stress produced during welding,heat treatment is usually required.Super 13Cr stainless steel will form different microstructure after different heat treatment process,which will affect its corrosion resistance.Therefore,this paper studied the corrosion behavior of super 13Cr stainless steel in oil field stratum water through SEM,XRD,TEM and other microscopic observation means,combined with electrochemical experiment and slow strain rate tensile experiment,and obtained the following main conclusions:（1）The microstructure of the samples quenched by oil and water was similar.Compared with water-quenched samples,oil-quenched samples have better plasticity,and the elongation and corrosion resistance of oil-quenched samples are improved greatly after tempering treatment.Therefore,oil is a suitable quenching medium for super 13Cr stainless steel.（2）After tempering,the microstructure of super 13Cr stainless steel became tempered martensite.The 620℃-tempered specimen was contained the reversed austenite.With the increase of tempering temperature,the elongation of material increased first and then decreased,and the tensile strength changed conversely.The elongation can be further improved by second tempering.（3）Super13Cr stainless steel with different heat treatments had passivation behavior in simulated oilfield stratum water solution,and the stress corrosion sensitivity was low.With the increase of tempering temperature,the corrosion resistance of samples increased first and then decreased,and the second tempering can improve the corrosion resistance.（4）Super 13Cr stainless steel with different heat treatments also had passivation behavior in the simulated oil field stratum water solution containing saturated CO₂,but the presence of CO₂ reduced the material corrosion resistance and improved the material stress corrosion sensitivity.The stress corrosion sensitivity of oil-quenched sample was the highest,and tempering treatment can reduce the stress corrosion sensitivity.