Hydrogen permeation and corrosion behaviour of high strength steel 35CrMo under cyclic wet–dry conditions

Abstract

Hydrogen permeation behaviours of high strength steel 35CrMo under different cyclic wet–dry conditions have been investigated by using Devanathan–Stachurski's technique. Four electrolytes were used: distilled water, seawater, seawater containing 1500 ppm H₂ S and seawater containing 0 · 03 mol L^{2 1} SO₂. The corrosion weight loss of 35CrMo in the wet–dry cycles was measured simultaneously. The experimental results show that hydrogen can be detected at the surface opposite to the corroding side of the specimen during wet–dry cycles and the permeation current density during a wet–dry cycle showed a maximum during the drying process. The hydrogen permeation was obviously promoted by Cl² ions, H₂ S and SO₂. The hydrogen permeation in the real marine atmosphere has also been investigated. There is a clear correlation between the amount of hydrogen permeated and the corrosion weight losses. Results show the importance of hydrogen permeation that merits further investigation.

Keywords:

• ATMOSPHERIC CORROSION
• WET&NDASH
• DRY CYCLE
• HYDROGEN PERMEATION CURRENT
• CORROSION WEIGHT LOSS