Mechanism Of Hydrogen Induced Cracking Of Marine Steel In Marine Atmospheric Environment

Hydrogen induced cracking and hydrogen embrittlement have long been recognized as a serious problem for the petroleum and petrochemical industries, but researches on hydrogen permeation of steel are mostly in solutions, while less in atmospheric environment, especially less research about steel in service in atmospheric environment.In this work, electrochemistry method and slow strain rate test (SSRT) were used to investigate the effect of marine atmospheric environment on hydrogen permeation of steels and the effect on susceptivity of SCC, especially while the environment contained H2S/SO2. The results shows hydrogen can permeate through steel not only in lab simulate environment but also in real marine environment. And the susceptivity of SCC increased with increasing the concentration of H2S/SO2. The SEM photography also showed the susceptivity of SCC increased with increasing the concentration of H2S/SO2. The corrosion weight loss experiment showed there was clearly linear ship between corrosion weight loss and the amount of hydrogen permeated. According this linear ship, we developed a corrosion monitor to measure corrosion weight loss by measuring hydrogen permeation current, the outside results were consistent with the lab results well.In this work, we studied the hydrogen permeation current under load condition. The results showed the hydrogen permeation current increased very slightly under elastic deformation; and the hydrogen permeation current decreased sharply with the onset of plastic deformation, and then reached a certain balanced value. Under elastic deformation, the reason of the increasing of hydrogen permeation is lattice expansion. And the reason of the decreasing of hydrogen permeation curretn is the formation of lattice defects formed by plastic deformation.