Page 7 - dysertaciyahembara

The paper formulates a new calculation model of hydrogen-induced crack

growth in metals under the action of static load, which is based on modern

physical and mechanical theories of their deformation and destruction. On this

basis, a method of assessing the residual durability of structural elements with

cracks was developed, taking into account the mechanisms of hydrogen influence

on metal deformation.

In particular, a mathematical model of hydrogen diffusion in a piecewise

heterogeneous body in a three-dimensional setting was constructed; an algorithm

and corresponding numerical programs were developed for calculating the

distribution of hydrogen concentration in the entire volume of three-dimensional

bodies, taking into account the effect of force and temperature factors. A

certificate of copyright registration for the work №107646 was obtained for the

developed program for calculating the concentration of hydrogen in volumetric

elements of structures under the action of force loads "DIFEUS 3D".

In the case of piecewise heterogeneous bodies on the border of the transition

between subregions of homogeneity, the hydrogen solubility function will have a

jump, which means that the hydrogen concentration function will also have a

jump, which follows from the condition of continuity of the hydrogen chemical

potential function throughout the region. For this purpose, instead of the hydrogen
concentration, the so-called hydrogen potential function, which is continuous

throughout the region, was introduced. This made it possible to also obtain an
analytical solution of the differential equation in partial derivatives of the 2nd

order. As a result, the dependences of hydrogen concentration on time along the
grain boundary, in the grain itself, and their total value in the iron bicrystal were

constructed.

Based on the obtained theoretical results, a characteristic value of hydrogen

concentration in low-carbon steel, which changes the mechanism of hydrogen's

influence on steel deformation, was established, which does not contradict the

experimental data known in the literature for this class of steels.

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