Effect of Environmental Factors on Hydrogen Absorption into Steel Sheet under a Wet-dry Cyclic Corrosion Condition

Abstract

The effects of temperature and chloride deposition on hydrogen absorption into steel were evaluated during wet/dry cyclic corrosion using a temperature-compensated hydrogen absorption monitoring system based on the electrochemical hydrogen permeation method. Hydrogen absorption into steel was detected through the measurement of hydrogen permeation currents during the wet periods under the wet/dry cyclic corrosion. The enhancement of hydrogen absorption was mainly caused by the changes in the solution chemistry during the wetting and drying periods, with a decrease in pH due to the hydrolysis reaction of Fe³⁺ at high Cl^- concentration. Hydrogen absorption into steel increased with increasing temperature and chloride deposition. The reasons for the increment of hydrogen absorption are considered that enhancement of the hydrogen evolution reaction with temperature and that the corrosion potential shifted to less noble by increase in the electrolyte thickness with increasing chloride deposition. Based on these results, the amount of absorbed hydrogen map effected by these factors under atmospheric corrosion environment was described.