Study of the Corrosion Behavior of 316L Stainless Steel under the Synergistic Effect of Cl- and HCO3-

Abstract

In order toinvestigatethe synergistic effectof Cl－ and HCO3－ onthecorrosion behavior of 316L stainlesssteel， the effectsof differentCl－ concentrations(0， 0.0300， 0.0515and 0.070 0 mol/L) andHCO3－concentrations (0.01， 0.03 and 0.05 mol/L) on the electrochemical corrosion behavior of 316L in groundwater environment simulation fluid in Liaohe Oilfield were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic polarization curve technology.Moreover， the corrosion morphology of the specimen was characterized using a metallographic microscope， and the product composition was determined using X-ray photoelectron spectroscopy (XPS).Results showed that as the Cl－ concentration increased， the capacitive arc diameter decreased，the dispersion index decreased，the pitting corrosion potential decreased，and the corrosion situation intensified.In comparisons， as the HCO3－ concentration increased， the diameter of the capacitive arc increased， the dispersion index increased， the pitting corrosion potential increased， and the corrosion of 316L slowed down.This was due to the fact that Clwould destroy the passivation film on the surface of 316L， and HCO3－ would react with the substrate to form a dense FeCO3 protective film.

Keywords

• 316l stainless steel|corrosive behavior|cl－|hco3－|synergistic effect