CORROSION AND HYDROGEN ABSORPTION PREVENTIONBY X5CrNi 18.10 STEEL CORROSION IN AQUEOUS SALTMEDIUM WITH SRB

摘要

The corrosion and hydrogen absorption (HA) by stainless austenitic X5CrNi 18.10 steel in corrosionrnprocesses in standardized microbiological Postgate B medium with sulphate reducing bacteria (SRB)rnare studied. The SRB develop rapidly in anaerobic situations, covering steel with insoluble FeS andrndepolarizing the cathodes of local corrosion cells on the steel surface by involving Had in their metabolismrnfor catalytic interaction with sulphate ions.rnThe main metabolite of SRB - H2S acts as a strong stimulator of HA by steel surface layer. H2Srnconcentration in corrosion medium, its pH, Eh and bacterial titre were tested. In this work the HA byrncorroded steel was studied with the aid of stepwise anodic dissolution technique. This permits thernhydrogen content in steel to be obtained as a function of depth in the metal.rnA large quantity of Had is absorbed by steel subsurface layer. The integral hydrogen content of 25 μ mrnsubsurface layer of steel runs to 30 p.p.m. after corrosion 170 h in specified above medium. Thernexperimental evidence points to the fact that existence of H2 traps in the subsurface steel layer preventsrnthe deeper penetration of H diffusing into the steel.rnIt is found that the hydrogen content of steel is proportional to the corrosion rate K and quantity ofrnbacterial cells N in the corrosion medium. The HA of the steel subsurface layers was less in specimens,rncorroded in aqueous salt medium, containing special organic compounds with inhibiting corrosion andrnHA efficiency.