Effect of Hydrodynamic Conditions on the Corrosion Mechanism of HSLA X100 Steel by EIS and EN Analysis

In this research work, the influence of the electrolyte hydrodynamic conditions on the corrosion mechanism of the high-strength low-alloy (HSLA) X100 steel used in the petroleum transportation pipelines was analyzed. A Rotary Cylinder Electrode (RCE) was used to simulate the hydrodynamic conditions (1000 and 5000 rpm). Mechanical, microstructural and elemental characterization tests were performed on X100 steel, and the electrochemical impedance spectroscopy (EIS) technique was used to analyze the corrosion mechanism, while the morphology of the corrosion process on the corroded surfaces was obtained by scanning electronic microscopy (SEM). It was found that the increasing rotation rate (υ rot) generates a fully developed flow regime where the system was dominated by a mass transfer process and increases the kinetics of chemical and electrochemical reactions so there is an increase in the corrosion rate (CR). On the other hand, the adsorption of corrosion product films that limits the charge transfer process depended on the magnitude of the shear stress that can generate wear and roughness, as well as a greater number of anodic sites, leaving the metal exposure to the corrosive medium.