SCM3 steel (TS: 123kg/mm2) was immersed in the acetic buffer solution saturated with hydrogen sulfide gas of different partial pressure, and its hydrogen content was measured with a modified electrochemical technique.
The hydrogen content was found to increase with partial pressure of hydrogen sulfide and to reach to 10ppm, which is about 140 fold compared with that in the absence of hydrogen sulfide. Also the mechanism of hydrogen evolution reaction was presumed from the usual polarization curve and the relationship between hydrogen content and electrode potential to be Volmer-Horiuti reactions in which the latter was the rate-determing. Hydrogen sulfide caused a significant shift of corrosion potential to less nobel, which means a sharp increase in hydrogen content.
