Corrosion Mechanism of Low Alloy Steel in NaCl Solution with CO2 and H2S

Abstract

The corrosion mechanism of low alloy steel is studied in NaCl solution containing CO2 and H2S. The study is carried out using accelerated corrosion and electrochemical measurements. Scanning electron microscopy (SEM) is applied to reflect the microstructure and corrosion morphology, and the compositions are analyzed using energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Results show the FeS and FeCO3 are observed when corrosion immersion time is at 24h and 48h, an inner layer is relatively thin and a wavy outer layer is seen on the metal surface. From 96h to 288h, the pattern of FeCO3 is not appeared, the thickness of outer layer and inner layer increase gradually, the corrosion products films are more uniform and dense. The experiments prove that the properties of corrosion product film seriously influence on corrosion resistance of low alloy steel.