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The main equations of the mathematical model are formulated, which allow

to estimate the influence of hydrogen and mechanical load on the plastic

deformation of metal. It is shown that hydrogen can increase or decrease the

dislocation rate depending on the conditions of hydrogen concentration,

temperature, and applied stress in iron. At low concentrations, hydrogen enhances

the movement of dislocations, thereby increasing the rate of plastic deformation.

On the basis of theoretical concepts known in the literature and

experimentally substantiated hypotheses, a new mathematical model of hydrogen-

induced crack growth in metals under the action of static load was built, taking

into account the mechanisms of hydrogen influence on metal deformation, and on

this basis, a method for estimating the residual length was developed. eternity of

structural elements in water.

It has been quantitatively established that for the values of the concentration

of pre-absorbed hydrogen, the durability of a plate with a crack is an order of

magnitude lower than for the concentration of hydrogen that gradually diffuses

from the top of the crack into the prefracture zone. This is due to the fact that the

gradual flooding of the prefracture zone first plasticizes it, thereby spitting out the

top of the crack, increasing its opening and retarding its propagation. The obtained

results indicate that plasticizing the material with hydrogen has a positive effect
on the durability of structural elements in hydrogen-containing environments.

All the theoretical developments of the thesis are brought to a specific
engineering methodology for predicting the safe operation of elements of thermal

power equipment, taking into account the action of the operating environment.
The developed models, methods, and software are used in the Karpenko

Physico-Mechanical Institute of the National Academy of Sciences of Ukraine

during the execution of the topics of the departmental order of the National

Academy of Sciences of Ukraine in the Department of Acoustic Methods and

Means of Technical Diagnostics III-7-20 (state registration number

0120U101792, 2020 - 2022) and NFDU competitive project No. 2020.02/0049

(state registration number 0120U104904, 2020 – 2022).

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