In the production of critical parts for various machines and mechanisms, expensive structural steels are used alloyed with chromium, nickel, molybdenum, and vanadium. In practice, the wear resistance of parts, especially under severe operating conditions, may be insufficient due to uneven microstructure and the content of retained austenite. Therefore, increasing the operational stability of various products made of alloy steels is an important task. The purpose of this work is to investigate the effect of isothermal hardening from the intermediate (γ+α)-area and the duration of deep cryogenic treatment on the structure formation and frictional wear resistance of 38CrNi3MoV steel. The isothermal hardening promotes the formation of the required multiphase microstructure of 38CrNi3MoV steel. The influence of the duration of deep cryogenic treatment on the microhardness, amount of retained austenite, fine structure parameters, and friction wear of 38CrNi3MoV steel are established. Complex heat treatment of 38CrNi3MoV steel, according to the proposed mode, makes it possible to achieve a significant decomposition of retained austenite to martensite, which leads to an increase in frictional wear resistance of ~58%.

The purpose of this work is developing of the statistical model of hydrogen diffusion in the crystal lattice of BCC metals with an estimate of the contribution of quantum effects and deviations from the Arrhenius equation. The values of the statistical model calculations of H diffusion coefficients in Fe, V, Nb and Ta are in good agreement with the experimental data. The statistical model can also explain deviations from the Arrhenius equation at temperatures 300-500 K in Fe and Nb. The downward deviation of the diffusion coefficient at 300K can be explained by the fact that the statistical model does not consider the tunneling effect at temperatures below 300K. It was suggested that thermally activated fast tunnelling transition of hydrogen atoms through the potential barrier at temperatures below 500 K provides an almost free movement of H atoms in the α-Fe and V. Using the statistical model allows for the prediction of the diffusion coefficient for H in BCC metals at intermediate temperatures.