Corrosion Behavior of 20 Steel in a Solution Containing Hydrogen Sulfide and Hydrochloric Acid

Corrosion behavior of 20 steel was studied in a solution containing hydrogen sulfide and hydrochloric acid at 90 ℃. The results showed that FeS film formed firstly during the experiment when the solution contained hydrogen sulfide, then the film obstructed corrosion caused by hydrochloric acid. With increasing the hydrogen sulfide content, the resistance of corrosion product film and the charge transfer impedance decreased, indicating that the film density decreased and corrosion increased. In the solutions with relatively high concentrations of hydrochloric acid the film became loose and with the increase of content of the acid the density and the protection of the film declined and the corrosion rate increased.