6-1-5　Cr Addition Effect on Corrosion Films of Alloy Steel Pipe formed in High Temperature and High Carbon Dioxide Environment

Abstract

We studied corrosion of alloy steel that is used in oil well pipe under high temperature and high CO₂ environment. Corrosion tests of the specimens with different quantity of Cr addition was carried out. Cross section and surface morphology of corrosion products were analyzed by SEM and EDX. The corrosion products were changed from crystal state to film state by Cr increase in the alloy. The crystal form corrosion products were FeCO₃, and EDX analysis showed that there were Cr concentration in the film corrosion product. The dense structured Cr compound was formed by increasing Cr content in the alloy, and the corrosion resistance was improved by the suppressed dissolution of Fe in the dense structure Cr compound.