To solve a number of technological issues, it is advisable to use mathematical modeling, which will allow us to obtain the dependences of the influence of the technological parameters of chemical and thermal treatment processes on forming the depth of the diffusion layers of steels and alloys. The paper presents mathematical modeling of diffusion processes based on the existing chemical and thermal treatment of steel parts. Mathematical modeling is considered on the example of 38Cr2MoAl steel after gas nitriding. The gas nitriding technology was carried out at different temperatures for a duration of 20, 50, and 80 h in the SSHAM-12.12/7 electric furnace. When modeling the diffusion processes of surface hardening of parts in general, providing a specifically given distribution of nitrogen concentration over the diffusion layer’s depth from the product’s surface was solved. The model of the diffusion stage is used under the following assumptions: The diffusion coefficient of the saturating element primarily depends on temperature changes; the metal surface is instantly saturated to equilibrium concentrations with the saturating atmosphere; the surface layer and the entire product are heated unevenly, that is, the product temperature is a function of time and coordinates. Having satisfied the limit, initial, and boundary conditions, the temperature distribution equations over the diffusion layer’s depth were obtained. The final determination of the temperature was solved by an iterative method. Mathematical modeling allowed us to get functional dependencies for calculating the temperature distribution over the depth of the layer and studying the influence of various factors on the body’s temperature state of the body.

The study of the influence of laser hardening conditions on the change in properties of steels

Modeling of the ion nitriding process allows solving many problems of operations management, forecasting of results and development of new treatment regimes, which is an urgent issue today. The goal of the paper was modeling of the case depth and surface hardness of 38Cr2MoAl А steel during ion nitriding. The experimental data showed that the case depth varies from 20 to 620 µm in the ion nitriding temperature range of 500-560 °С and duration of 1-12 hours, with the surface hardness varying from 8 to 12 GPa. The mathematical models in the form of quadratic polynomials, describing the dependence of the nitrided case depth and surface hardness on the temperature and duration of thermochemical treatment were obtained. The graph-analytical description of variations in the nitrided case depth and surface hardness depending on variations in temperature and duration of treatment, which allows determining the specific conditions of ion nitriding 38Cr2MoAl steel is constructed.

The choice of the optimal temperature and time parameters of gas nitriding of steel

The conditions for the formation of nanostructures in the surface layer of steels with different carbon content, which determine the required temperature (500-1500 K) and the rate of their growth (more than 10 ⁷ K/s). Zones of formation of nanostructures depending on the heat flux density on the time of action of ionizing radiation are determined. It is shown that it is necessary to take into account the rate of temperature rise and the probability of thermoelastic failure due to the action of temperature stresses. So, with the low speed temperature rise formed micro and submicrostructure that has been confirmed experimentally. It is shown that the use of steels with nanostructured layers will significantly increase the microhardness of the steel surface, which means that the wear resistance of the drone engine parts will increase, and therefore there will be no need to use expensive materials. This will significantly increase the life of unmanned aerial vehicles.

The relevant problem is searching for up-to-date methods to improve tools and machine parts’ performance due to the hardening of surface layers. This article shows that, after the magnetic-pulse treatment of bearing steel Cr15, its surface microhardness was increased by 40–50% compared to baseline. In this case, the depth of the hardened layer was 0.08–0.1 mm. The magnetic-pulse processing of hard alloys reduces the coefficient of microhardness variation from 0.13 to 0.06. A decrease in the coefficient of variation of wear resistance from 0.48 to 0.27 indicates the increased stability of physical and mechanical properties. The nitriding of alloy steels was accelerated 10-fold that of traditional gas upon receipt of the hardened layer depth of 0.3–0.5 mm. As a result, the surface hardness was increased to 12.7 GPa. Boriding in the nano-dispersed powder was accelerated 2–3-fold compared to existing technologies while ensuring surface hardness up to 21–23 GPa with a boride layer thickness of up to 0.073 mm. Experimental data showed that the cutting tool equipped with inserts from WC92Co8 and WC79TiC15 has a resistance relative to the untreated WC92Co8 higher by 183% and WC85TiC6Co9—than 200%. Depending on alloy steel, nitriding allowed us to raise wear resistance by 120–177%, boriding—by 180–340%, and magneto-pulse treatment—by more than 183–200%.