Hydrogen permeation and corrosion behavior of high strength steel 35CrMo in cyclic wet-dry conditions

摘要

Hydrogen is generated by corrosion of metals exposed to acidic process streams or during the chemical cleaning of industrial equipment. A portion of such hydrogen can be absorbed into the metal leading to hydrogen damage. Therefore, the study of hydrogen permeation in metals and their alloys is important for the understanding, prediction and prevention of hydrogen embrittlement. Hydrogen permeation under cyclic wet-dry distilled water and seawater conditions were investigated for a high strength steel of 3SCrMo by using an electrochemical technique. This study shows that measurable hydrogen can be detected at the surface opposite to the corroding side of the specimen during wet-dry cycles. The measurement continued separately for seven distilled water wet-dry cycles and seventeen seawater wet-dry cycles. The hydrogen permeation current was measured during atmospheric corrosion reaction and the permeation current during a wet-dry cycle showed a maximum in the drying process. The hydrogen permeation current amplitude changed differently in cyclic wet-dry distilled water and seawater conditions. The corrosion weight loss of 35CrMo during the wet-dry cycles was also investigated. There is a clear correlation between the quantities of hydrogen permeated through iron sheet and corrosion weight loss. Results suggest the importance of hydrogen permeation that merits further investigation.