Study on Factors Affecting Low Cr Alloy Steels in a CO2 Corrosion System

With the superior resistance to CO₂ corrosion, low Cr alloy steels (containing Cr: 1%~5%wt) have been the extremely economical choice gradually instead of carbon and stainless steels in some oilfield applications. However, to clarify the resistance mechanism to CO₂ corrosion, the formation of protective corrosion product films should be studied deeply. Thereby, a large number of autoclave experiments for simulating the oilfield and relevant theoretical analyses have been processed in the temperature range 20~140°C, furthermore, primarily focusing on the factors affecting film formation, such as Cl^- concentration range 10~50 g/L, microstructure and Cr content in steels in this paper. And also, the surface morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (SEM and EDS) and X-Ray diffraction (XRD), respectively. In addition, the molecular dynamic (MD) was applied for assistance.