Effect of Relative Humidity on the Corrosion Kinetics of HSLA and Low Carbon Steels

The role of humidity on the corrosion kinetics of HSLA and mild steels was quantitatively investigated. The test was performed by coupling sheets of steel with copper inside a chamber where preset conditions of relative humidity (RH) and temperature were maintained. A power dependence of the corrosion current on the RH changes like I_corr≈B⋅(ΔRH)^X was found. The values of the constants were calculated for all of the steels, thus allowing a comparison of the corrosion rates of the HSLA steel with respect to the mild steel. All five of the HSLA steels examined were found to be more susceptible to corrosion in humid air than were the mild steels.