The study examined the influence of ion-plasma nitriding on the structure, mechanical, and tribological properties of high-speed steels AISI M2 and AISI M41. A comprehensive study was conducted on the changes in phase composition, microhardness, and wear resistance of the obtained modified layers. It was established that the optimal approach was the formation of high-nitrogen martensite without excessive nitrides, which ensured improved mechanical properties of the steels. The dependence of the nitrided layer depth and its microhardness on nitriding temperature and duration was investigated. It was found that at a temperature of 480–520 °C and a processing duration of up to 1 h, a hardened layer with a depth of 25–40 μm was formed, exhibiting increased wear resistance and microhardness of up to 10–12 GPa. The analysis of structural transformations confirmed the presence of ε and γ’ phases, which contributed to increased strength and reduced friction coefficient. The obtained results can be used to improve the technological processes of heat treatment for high-speed steels used in the production of cutting tools. The proposed nitriding parameters contribute to extending the service life of steel components, which is relevant for the mechanical engineering and metallurgical industries.

From the great variety of methods to improve the efficiency of cutting tools, it is necessary to highlight the methods of applying wear-resistant coatings, which in recent years are increasingly used. Applying wear-resistant coatings on the cutting tool can significantly increase its efficiency and intensify machining modes. Mechanisms of strengthening the wear-resistant coating for materials have been analyzed under the impact of technological parameters of coating condensation process on its structure parameters and mechanical properties, formation of single and multi-element coatings based on titanium nitrides, aluminum, and silicon, the transformation of coating properties by obtaining complex coatings, and principles formation of complex coatings designed for different cutting tools. The influence of the coating on the mechanical properties of high-speed steel is shown. In the magnetron sputtering coatings on P6M5 steel samples, the microhardness of the coatings is TiN – 20–24 GPa, AlN – up to 16 GPa, TiAlN – up to 35 GPa, AlTiN – up to 32 GPa, TiAlSiN – 32–37 GPa, including while the microhardness of the substrate of steel P6M5 – 6–9 GPa. The microhardness of TiAlN and TiAlSiN coatings applied on an instrumental basis is 1,5 – 1,9 times higher than the microhardness of TiN, AlN coatings. It was found that the wear intensity of P6M5 steel without coating is 6 times higher than with AlTiN, TiAlN, and TiAlSiN coating, 3 times higher than with TiN and AlN coating. The coated tool is characterized by increased reliability and higher stability and allows the processing process with higher cutting modes.

One of the urgent problems in reciprocating machinery is ensuring the functional properties of direct-flow valves. Coatings of these parts should increase energy efficiency, reduce compressed gas temperature, and increase compressor performance. In this article, the effect of nitrocarburizing in pastes on increasing the performance and resource of such valves was studied. The primary research methods were metallographic and electron-metallographic research of the surface layer structure of steel 60Si2Cr. Comparison with similar characteristics obtained for stainless steel 09Cr15Ni8Al was also performed. As a result, it was determined that nitrocarburizing of carbon spring steel 60Si2Cr leads to a greater depth of the diffusion layer than nitrocarburizing of alloyed chromium-nickel steel 09Cr15Ni8Al. Simultaneously, the diffusion layers of both types of steel are almost the same. Simultaneously, the increase in the endurance limit of 60Si2Cr steel during nitrocarburizing is about 1.3 times compared to untreated material. Finally, the predictive maintenance showed that the evaluated lifetime of nitrocarburized valves increases by 5.7 times compared with untreated valves.

One of the methods for increasing the complexity of chromium steel properties of martensitic class AISI 420 is the use of an optimal heat treatment mode. The steel of martensitic class AISI 420 has high resistance in atmospheric conditions (except for the sea atmosphere), in the river, and tap water. It is widely used in power engineering, in cracking units with a long service life at temperatures up to 500 °C, for furnace parts. Additionally, it is used in the following fields: the production of turbine blades, working in conditions of high temperatures and parts of increased plasticity, subject to shock loads, for products exposed to atmospheric precipitation, solutions of organic salts and other slightly aggressive environments; production of fasteners; production of parts for compressor machines operating with inert gas; production of parts operating at low temperatures in corrosive environments; production of parts for aviation purposes. It is shown that the optimal mode of heat treatment for a maximum hardness of 40 HRC is quenching at a temperature of 980 °C with cooling in oil and tempering at a temperature of 200 °C with air cooling. With an increase in the tempering temperature from 200 °C to 450–500°C, the impact strength does not change much. Tempering at higher temperatures leads to the intense weakening of the steel. Simultaneously, a decrease in the impact strength is observed, the minimum value is reached at a tempering temperature of 550 °C. With an increase in the tempering temperature to 700 °C, the impact toughness increases, but the steel’s hardness sharply decreases at such temperatures. Keywords: hardening, tempering, hardness, toughness, mechanical properties, chromium carbide.