2017 Volume 58 Issue 2 Pages 211-217
The corrosion behavior and the amount of absorbed hydrogen in steel were investigated in neutral and alkaline solutions with pH values ranging from 8.3 to 12.4. The amount of absorbed hydrogen into steel during immersion in the solutions was evaluated by thermal desorption analysis. In the alkaline solution of pH 12.4, the steel maintained a noble potential in a passive state, and almost no hydrogen absorption into the steel was detected. However, as the pH moved towards a more neutral pH, the corrosion potential shifted in the less noble direction, and the amount of hydrogen absorbed increased dramatically. These results indicate that the steel surface became more active in the neutral solutions, and the hydrogen evolution reaction, one of the cathodic reactions of steel corrosion, was enhanced close to the neutral pH with decreasing corrosion potential in the less noble direction. The change of the surface state from passive to active with decreasing pH accelerated the anodic dissolution of steel and made the corrosion potential less noble, resulting in the enhancement of hydrogen evolution and absorption reactions on the steel.