Study on Corrosion Resistance of 316L and 2205 Stainless Steels in High CO2 Environment

In order to study the corrosion behavior of 316L and 2205 stainless steels and explore their application prospects in underwater production systems, the corrosion rate, electrochemical behavior and pitting corrosion resistance of 316L and 2205 stainless steels were analyzed and compared by using long period immersion test, cyclic polarization curve, potentiostatic polarization and electrochemical impedance spectroscopy (EIS) with the help of scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Results showed that the corrosion resistance of 2205 duplex stainless steel was better than that of 316L austenitic stainless steel in the simulated seawater environment with high CO2 content. Compared with 316L stainless steel, 2205 stainless steel had larger passive region, lower passive current density and larger passive film resistance. The high corrosion resistance of 2205 stainless steel was attributed to its higher pitting resistance equivalent (PREN) value and fewer inclusions, which enabled the passive film on the surface of 2205 stainless steel more stable and less prone to localized damage.