Holovei S. Influence of iron sulfides on corrosion and hydrogenation of carbon steels and hydrogen sulfide corrosion cracking

Thesis for the candidate degree of Technical sciences by speciality 05.17.14 Chemical Resistance of Materials and Corrosion Protection. – Karpenko Physico-Mechanical Institute, National Academy of Sciences of Ukraine, Lviv, 2018. The thesis of establishment of the relationship between the rate of oxidation-reduction reactions and steels hydrogenation of different structures in the presence of iron sulfide on the surface in chloride-acetate hydrogen sulfide media and determination of their resistance to hydrogen sulfide corrosion cracking is devoted. It is shown by method of cyclic voltammetry in sulfide-containing media on inert glassgraphite electrode that the process oxidation runs pass with the release of sulfur with inhibited next chemical reaction. At the same time, the process reduction runs according to the reaction of discharge of polysulfide ions with their preliminary adsorbtion. The known scheme of the influence of hydrogen sulfide on increasing the rate of corrosion and hydrogenation of steels by reactions of formation of iron sulfides at various concentrations that determine the rate of the reaction of recombination of hydrogen atoms is supplemented. 0.8% C steel with the structures of sorbite and troosite and 0.45% C steel with ferrito - perlite and sorbite structures have the greatest resistance to hydrogen sulfide corrosion cracking. However, steels with sorbite structures are most suitable for using in hydrogen sulfide media taking into account the influence of hydrogenation and localization of corrosion. Keywords: Armko iron, 0.8% C steel, 0.45% C steel, hydrogen sulfide, iron sulfides, overvoltage, corrosion, hydrogenation, corrosion cracking.