The Kinetics of Hydrogen Absorption and Evolution on a Carbon-Manganese Steel Exposed to Acidified Solutions of Sodium Chloride

The use of steels stressed in tension, in environments that promote hydrogen pickup, can be limited by premature failure. To better understand the effect of hydrogen on steel behavior, an electrochemical investigation of the kinetics of corrosion-product hydrogen absorption by a carbon-manganese steel has been conducted. The data show, that the rate determining discharge step during corrosion-product hydrogen evolution is the charge-transfer stage (2H⁺ + 2e ⇄ 2H_ads). The specific rate constant for hydrogen absorption into the steel exposed to acidified sodium chloride has values in the range 11 to 15 sec⁻¹, over the chloride concentration range of 0.1 to 1M Cl⁻ in pH 2 solution. The above values for k_abs approximately twice that determined for pure iron at an equivalent corrosion rate.