RESEARCH OF PROCESSES OF HYDROGENATION OF CARBON STEEL OF DIFFERENT STRUCTURES IN HYDROGEN SULPHIDE ENVIRONMENTS

Abstract

The effect of applied static loads, structure, and carbon content in steels on their hydrogenation was investigated in the paper. The content of absorbed hydrogen was determined by the method of vacuum extraction at temperatures of 200, 400, 600 and 800 °С for 720 hours, after corrosion in the NACE solution. It was shown that the hydrogenation of 0.8% C steel in the number of structures: pearlite, sorbite, troostite and martensite increased. The ferrite-pearlite structure of 0.45% C steel was the most intensively hydrogenation (19.4 ppm), sorbitic, troostitic and martensitic - less by 30...50%. The main contribution to the absorbed hydrogen was made by diffusive-mobile hydrogen. Its share in the total amount of absorbed reached~65...74% for pearlitic, 50...54% sorbitic, 64...78% troostitic and ~67% martensitic U8 steel structure. For steel 45, it is ~61...72% for ferrite-pearlitic, ~74...79% sorbitic, ~61...75% troostitic, and ~52...85% martensitic. The absorbed hydrogen content of 0.8 % C steel with sorbitic, trostitic, and martensitic structures at temperatures of 400, 600, and 800 ºС increased, while that of steel 45, on the contrary, decreased. This indicated the greater strength of the hydrogen-metal bond in 0.8 % C steel. Therefore, the structure of steels affects the sorption of hydrogen more than the carbon content. Applied static loads  = 300 MPa increased the content of hydrogen absorbed by steels by ~9...15%. On 0.8% C steel, this manifests itself more significantly - СН/С0Н= 1.3...1.8. As the imbalance of the structure increased, the resistance of steels to corrosion cracking under static loads decreased. This was determined by the dispersity of the structure and the morphology of sulfide films, which are formed during the corrosion of steels in the NACE solution. Therefore, static loads most contributed to the hydrogenation of 0.8 % C steel with a troostite structure, and 0.45% C - troostite and martensitе.