This paper is devoted to the development of hydrogen-containing, environmentally safe, fire-resistant, and corrosion-protected lubricant cooling liquids (LCLs) from vegetable oils with improved sanitary and hygienic parameters for the machining of parts and equipment made from high-strength steels for application during the interoperation period in turbine halls. The use of plant raw materials as ecologically and fire-safe LCLs increased the efficiency of LCLs when evaluating drilling steel in terms of the dependence of the stability of the cutting tool on the drilling speed. Chips formed from LCLs during turning had a compact, cylindrical appearance, and the addition of both water and coolant during turning significantly changed the morphology of the cutting particles. Using water and LCL intensified the physical and chemical destruction processes. After the use of water and LCL, the concentration of hydrogen in the cutting products of 38KHN3MFA steel increased, which indicated its participation in facilitating the destruction during machining. In the chips formed when using LCL, the amount of hydrogen increased by 2.25 times compared to the chips obtained with the dry treatment, while with coolants, it increased by 2.6 times, indicating the intense flow of decomposition products of LCL through diffusion processes in the cutting zone. Hydrogen reduces the energy costs for the destruction of structural and phase components and promotes their dispersion. The creation of 2D and 3D images allowed for a more detailed approach to the study of the influence of LCL on surface treatments.

Changes in the properties of 38KhN3MFA steel, from which the rotor shaft is made, were investigated by comparing the hardness of the shaft surface and hydrogen concentration in the chips and analyzing changes in the morphology of the chips under the influence of various factors. The microstructures obtained from the surface of the rotor shaft samples are presented, and histograms reflecting the parameters of the structural components are constructed. An abbreviated diagram of the “life cycle” of the turbine rotor shaft is given. It was found that, during long-term operation (up to 250 thousand hours), the hardness of the rotor shaft surface decreases from 290 HB to 250 HB. It was recorded that, in the microstructure of the shaft during 250 thousand hours of operation, the amount of cementite decreased from 87% to 62%, and the proportion of free ferrite increased from 5% to 20%. The average values of ferrite microhardness decreased from 1.9 GPa to 1.5 GPa. An increase in the content of alloying elements in carbides was recorded: Cr and V—by 1.15–1.6 times; and Mo—by 2.2–2.8 times. With the help of the developed program (using computer vision methods), changes in their microrelief were detected to study photos of chips.

In this study, modern nitrogen steels used for the manufacture of rings for Honda engines (70CC, 90CC, CRF70F, XL70, XR70, C70, CT70, ATC70, CL70) as well as other transport tribotechnical units was investigated. Due to the present ecological situation in the world, new environmentally friendly lubricating fluids for nitrogen steels’ tribotechnical units and surface treatments have been proposed. The results of tribotechnical tests are presented in the form of diagrams, graphs and step polynomials obtained by mathematically describing the changes in wear intensity when the load changes for different lubricating fluids. Friction pairs were compared with ShellHF-E 46 (synthetic lubricating fluid), ShellHF-R (biological origin) and lubricating and cooling liquids with 1%, 3% and 5% vegetable oil concentrations. In tribocoupling it was found that hydrogen diffuses into the metal because the tribodestruction of lubricating coolants plays an active role in the destruction of friction surfaces.

This paper briefly describes the conceptual direction of the application of computer vision (CV) methods that involve controlling the morphology of hydrogenated wear particles (WPs). During long-term operation, in the surface and subsurface layers of the materials of parts in the tribo-joint, changes in the micromechanisms of fracture occur, which change the morphology of WPs. It has been shown that the developed computer program (CP) can be used to monitor the fractography of the surface of wear particles, and, accordingly, it is possible to control changes in the surface morphology. Therefore, it is possible to predict the operational stability and durability of the tribo-joint. A conceptual scheme for determining the performance of a tribotechnical assembly depending on the determined parameters of WPs is presented. The modes marked on it, including normal operation, transient, run-in, and catastrophic failure, can be evaluated by robotics approaches.

Rotor shafts are the most heavily loaded and accident-prone parts of powerful turbine generators, which are cooled using hydrogen. To eliminate damage sustained during operations, repair work was carried out, including the removal of defective parts, surfacing, and turning. This study tested the machinability of the rotor shaft using prototypes made from 38KhN3MFA steel. A section of the shaft was degraded due to prolonged operation (250 thousand hours), and compared to the central part, a decrease in the average grain size from 21.57 μm to 12.72 μm and an increase in the amount of hydrogen absorbed during operation from 2.27 to 7.54 ppm were observed. With the frequency of dry turning increasing from 200 to 315 RPM, the chips changed their form from mostly rectangular with linear dimensions of 10 to 20 mm to large spiral rings with a diameter of 15 to 20 mm and a length of more than 50 mm. Cracks of 1 to 4 mm in length were found in most chip particles at both rotational speeds. Increasing the rotational speed from 200 to 315 and up to 500 RPM led to the formation of an oxide film on the surface of the specimens, as evidenced by the appearance of oxygen during local analyses of the elemental content on the chip surface. The saturation of specimens by hydrogen gas led to the formation of finer chips compared to the non-hydrated material, and the roughness of the machined surface increased at hydrogen contents of 6 and 8 ppm. In both dry and coolant cutting operations, surface roughness reflects the degradation of the rotor shaft or experimental prototypes due to hydrogenation, which can be used to diagnose the condition of the rotor after long-term operation.

Rotor equipment material samples with varying degrees of degradation during long-term operation are characterized by lower (up to 17%) corrosion and hydrogen resistance compared to the initial state. The scheme of redistribution of carbides in structural components in the initial state and after long-term operation is presented. The schemes of the turning rotor shaft are visualized, while taking the microstructure features into account. During long-term service, the properties of steels are affected by changes in the parameters of structural components caused by the action of a hydrogen-containing environment. Based on the experimental data, the regression equation and approximation probability R² value describing the change in the electrochemical parameters of 38KhN3MFA rotor steel samples after 200, 225, 250, and 350 thousand hours of operation were obtained. During machining, an increase in hydrogen content was recorded in the chips, especially from degraded areas of the rotor shaft (up to 7.94 ppm), while in undegraded zones, it ranged from 2.1 to 4.4 ppm. A higher hydrogen concentration was correlated with increased surface roughness. The use of LCLs improved surface quality by 1.5 times compared to LCL_p. Dispersion caused by degradation contributed to hydrogen accumulation and changed the nature of material destruction. After repair, the rotors demonstrated stable operation for over 25 thousand hours, with no reappearance of critical defects observed during scheduled inspections.