The Corrosion Resistance Of Super13Cr Stainless Steel In The Environment Of Oil And Gas Fields

This paper studied the influences of different temperature, different CO₂partial pressureand different Cl"concentartion in the gas-liquid two-phase environment on the corrosion ofsuper13Cr stainless steel by means of the autoclave testing and modern analytic methods, suchas SEM, EDS and XPS technologies. The corrosion-resistance differences of the mateiral in thegas-liquid two-phase environment were also discussed. Moreover, the electrochemicalproperties of passive film on the surface of super13Cr stainless steel were investigated byusing the electrochemical testing method.The results showed that the average corrosion rate of super13Cr stainless steel in thegas-liquid two-phase environment increased firstly and then dccrcascd with the temperatureincreasing. The average corrosion rate reached a maximum of0.0164inm/a at130℃in liquidphase and0.0665mm/a at150℃in gas phase respectively. The super13Cr stainless steel hasgood corrosion resistance. In gas phase environment, the mateiral’s surface easily adsorbedwater film, which generated differential concentration corrosion in the interface of water/liquid，eventually leading to the localized corrosion. CI" concentration in the water iflm greatlyexacerbated the corrosion of water film, and the action of gravity of water iflm exacerbated thewater-line corrosion which caused the corrosion rate in the gas phase greater than in the liquidphase. In the gas-liquid two-pha.se environment, the uneven coverage of corrosion products onthe surface of the mateiral resulted that the pitting corrosion rate is greater than the uniformcorrosion rate. The occurrence of corrosion could be resisted by the Cr irch components on thesurface of super13Cr stainless steel, and the Cr element existed in the form of Cr203on thesurface passivation film. The composition of passive film on the surface super13Cr stainlesssteel suffers the effect of temperature and environment slight.The passive iflm electrochemical test findings showed that compared to the surfaceself-passive film, the passive film of super13Cr formed atfer corroded in high temperatureenvironment has a higher corrosion potential, lower corrosion current density, but passiveregion is less obvious, which show that the corrosion resistance before iflm formation of super 13Cr film is better than no-film formation; and the corrosion resistance of passive film formedin110℃is better than in130℃and I50℃. The passive iflm on the surface of super13Crsigniifcantly improved the pitting resistance of mateirals.