From an economic point of view, transport and storage of hydrogen in a gaseous state is an important part of hydrogen energy. But the problem is that even a very low hydrogen concentrations (~0.0001 mass %) can cause degradation of the structure and properties of structural steels and welded joints, with significantly increasing their susceptibility to brittle fracture.
Our analytical equipment were upgraded and appropriate research methodologies were improved to achieve a recent scientific and technological level of hydrogen behavior experimental studies in HSLA steel welds.
The behavior of hydrogen in welded joints, as well as methods for estimation of a hydrogen concentration in the welds, and especially hydrogen distribution in the welded joints were analyzed. For calculating the parameters of energy traps on the basis of experimental data a code was developed. Taking into account the effect of energy traps and using the finite element method the computer simulations of hydrogen diffusion in HSLA steel welds since the beginning of crystallization of the weld until cooling to the room temperature were carried out. The influence of the trap parameters was analyzed for hydrogen redistribution between diffusible and residual hydrogen.
By the computer calculations it was analyzed the differences of the behavior of edge dislocation pile-up in hydrogen-charged and hydrogen-free metals. It was shown that the presence of diffusible hydrogen in the metal significantly effects on the edge dislocation pile-up properties, with reducing the repulsive force between similar dislocations (so-called effect of hydrogen-enhanced localized plasticity). А relationship between stress fracture of a grain and its size were obtained basing on proposed mathematical model for hydrogen-charged metal.
Keywords: hydrogen energy, high-strength low-alloy structural steel, welded joints, brittle fracture, diffusible and residual hydrogen, energy traps, computer simulation, hydrogen-enhanced localized plasticity