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Information × Registration Number 0221U100305, 0118U000461 , R & D reports Title Determining of change of hydrogen effect mechanisms on strength and resistance to fracture of low-alloyed ferrite-pearlite steels depending on its concentration in metal popup.stage_title Head Dmytrakh Ihor M, Доктор технічних наук Registration Date 04-01-2021 Organization Physico-Mechanical Institute named after GV Karpenko of the National Academy of Sciences of Ukraine popup.description2  For the first time, the fact of a specific formal decrease in the yield strength of carbon steel in the presence of diffusible hydrogen of low concentration has been established. It is shown that the hydrogen charging-discharging of steel does not pass without a trace concerning its microstructure and even the short-term presence of diffusible hydrogen of low concentration in steel leads to irreversible changes in the structure of the material, which causes changes in its macroscopic mechanical behaviour. An ambiguous relationship between the fatigue crack growth rate and the initial bulk concentration of hydrogen in the metal under cyclic loading of low-alloy ferritic-pearlitic steel under different test conditions in hydrogen-containing environments was confirmed, i.e. a certain characteristic value of bulk hydrogen concentration was established at which the cyclic crack growth resistance increases. For the studied steel, this value retains its feature ("characteristic") regardless of the conditions of further testing of the material. A mathematical model of a dislocation crack in an elastic body as a potential trap for the accumulation of molecular hydrogen in the material has been developed. Analytical relations are obtained to calculate the volume of such a crack-trap, and the criterion for its start (transition from equilibrium to non-equilibrium state) is proposed. The comparative assessment of the strength characteristics of two modern nickel-cobalt alloys - polycrystalline with a cobalt content of 15% and monocrystalline with a cobalt content of 10% depending on the concentration of hydrogen in the range of 0 - 30 ppm was made. It is shown that according to the characteristics of short-term strength, the polycrystalline alloy is somewhat more resistant to hydrogen embrittlement, but the monocrystalline alloy shows significantly higher resistance to the propagation of fatigue cracks. Product Description popup.authors Ivasʹkevych Lyubomyr M Balytsʹkyy Oleksandr I Barna Roman A. Vovk Roman I. Dmytrakh Ihor M Leshchak Rostyslav L. Syrotyuk Andriy M Stashchuk Mykola Н. popup.nrat_date 2021-01-04 Close