Abstract
Environmental factors affecting hydrogen absorption into steels have been investigated by hydrogen permeation tests under atmospheric exposure and simulated environmental conditions. Hydrogen absorption into steels under atmospheric exposure depended upon time in day, seasons and exposure locations. It was confirmed that main environmental factors deciding hydrogen absorption were temperature, humidity and salt concentration by simulated environmental tests. The hydrogen absorption into steels was caused by the hydrolysis accelerated by the combination of Fe3+ ion and Cl- ion in water film on the steel surface. Fe3+ ion which was supplied during corrosion, increased by temperature, humidity and salt on the steels. On the other hand, Cl- concentrated in water film at the lower humidity. The opposite reliability on humidity between the corrosion rate and the Cl- concentration, resulted in the highest hydrogen absorption value in the specific relative humidity range, 50-60%.
