The possibility of assessing the thickness of the hardened layer on the surface of AISI 321 metastable austenitic steel, subjected to frictional treatment with a sliding indenter under various normal loads, using the magnetic Barkhausen noise method and the eddy-current method is investigated. The production of hardened layers of different thicknesses is simulated by stepwise electrolytic etching. The results of the non-destructive methods were compared to those obtained by the microhardness method to determine the thickness of the hardened layer. It is shown that the thickness of the hardened layer can be assessed using the eddy-current method and the magnetic Barkhausen noise method. However, the eddy-current method is preferable. This is because, in addition to sensitivity to the ferromagnetic phase, it is also sensitive to the level of defectiveness of the γ-phase. At the same time, it is necessary to take into account in the test method that the thickness of the hardened layer determined by the non-destructive methods is less than that determined by the microhardness method.

The paper studies the structure, mechanical properties and wear resistance of a composite produced by self-propagating high-temperature synthesis (SHS) with an average chemical composition, wt%: 35.47 ± 1.5 Fe; 24.08 ± 1.4 Ti; 13.99 ± 0.5 Ni; 17.91 ± 0.4 B; 8.54 ± 0.5 C. Testing has revealed that the composite has wear resistance on a level with one of the Hardox 500 wear-resistant steels. The composite is characterized by a wide range of values of transverse bending strength Rbm30 from 200 to 800 MPa. Steel 40X shows a bending strength Rbm30 of 1590 MPa, and the values of this characteristic for the Hardox 500 steel range between 2970 and 3020 MPa. The composite has low impact strength values KCU = 0.02 MJ/m2, compared with KCU = 0.35 MJ/m2 for steel 40X and KCU = 1.59 MJ/m2 for Hardox 500. The Fe–Ni–Ti–C–B SHS composite should not be used for bending parts and those experiencing shock loads; however, it suits perfectly for protecting the surfaces of parts subject to intense abrasive wear.

This work investigates the effect of liquid carburizing at 780°C on the structure, chemical and phase composition, microhardness, and surface roughness of corrosion-resistant austenitic chromium-nickel steel. The depth of the carburized layer has been determined to be about 2 mm. The steel structure at a distance of 0.15 mm from the surface consists of carbon-saturated austenite γ C , α' martensite, and fine Cr 23 C 6 chromium carbides located along austenitic grain boundaries. No carbides are observed in the grain body. There are austenite γ C and chromium Cr 23 C 6 carbides in the structure at a depth from 0.15 to 2 mm. The number and the size of carbides decrease with distance from the steel surface. Carburizing increased the microhardness of the steel surface by a factor of four (from 200 to 800 HV0.025) and the roughness parameter Ra to 1.35 μm.

Based on the study of the interaction in the “indenter—steel” contact zone, the choice of process parameters of the frictional treatment with a sliding indenter, namely, indenter material, load, and process medium, was carried out and substantiated for the 12Cr18Ni10Ti austenitic steel. Scanning electron microscopy, energy-dispersive microanalysis, optical profilometry and microhardness measurement are used as methods of investigation. It has been discovered that the choice of the process parameters of frictional treatment with a sliding indenter must be carried out taking into account mass transfer of the steel onto the indenter surface. The combination of significant strain hardening and low surface roughness was employed as a criterion for stating the advantages of using a synthetic diamond indenter and a noncorrosive argon environment over using natural diamond (conventional diamond burnishing), WC–Co hard alloy, and dense boron nitride indenters in the presence of a lubricating and cooling liquid. In the case of a synthetic diamond indenter and a noncorrosive argon environment, microhardness increased from 220 to 590–685 HV0.025, with a surface roughness of Ra = 0.075–0.115 μm. In the other cases, microhardness increased to 515, 635, and 660 HV0.025, with a surface roughness of Ra = 0.060, 0.380, and 0.255 μm, respectively.

Aluminum matrix composites reinforced with ceramic particles are widely used in parts and components operating under sever friction and wear in the presence of abrasive particles. This work investigates the effect of the dispersion and the amount of B4C and SiC reinforcements ranging from 0 to 25 wt % in the initial powder mixture on the microstructure, micromechanical properties, and abrasive wear resistance of aluminum matrix composites. It is shown that B4C and SiC reinforcement particles contribute to the refinement of the aluminum matrix. Micromechanical properties determined by instrumented microindentation indicate that the hardness of the composites exceeds the hardness of sintered aluminum, and Al-25% SiC composite has the highest mechanical load resistance compared to other composites studied. Pin-on-plate wear tests of samples sliding against fixed electrocorundum grains revealed the greatest abrasive wear resistance of Al-25% SiC and Al-12.5% В4С-12.5% SiC composites, and the minimum resistance was observed for Al-25% B4C. These materials demonstrate adhesive and abrasive wear behavior with the formation of characteristic wear grooves and peeling pits.

Microhardness and electromagnetic characteristics of corrosion-resistant chromium-nickel (wt. %: 16.80 Cr; 8.44 Ni) austenitic steel subjected to electron beam plasma carburizing at temperatures of 350 and 500°C, frictional treatment with a sliding indenter and combined treatments, including frictional treatment and plasma carburizing have been investigated. It has been found that plasma carburizing increases the microhardness of the steel surface from 200 to 1100 HV0.025. The total hardening depth was 25 microns after carburizing at T = 350°C and 300 microns after carburizing at T = 500°C. Frictional treatment increases the microhardness of the steel to 600 HV0.025 with a total hardening depth of 500 microns. It has been shown that the diffusion-active layer with a dispersed structure formed during preliminary frictional treatment contributes to additional hardening of the steel (up to 1275 HV0.025) during subsequent low-temperature (350°C) carburizing. Combined treatment with carburizing at a temperature of 500 °C increases the microhardness of the steel to 820 HV0.025, and the total hardening depth is 500 microns for both combined treatments. It has also been found that plasma carburizing of the steel leads to a decrease in the eddy-current readings compared to the quenched steel and their growth compared to the steel subjected to frictional treatment, which can be used to develop quality control techniques for such treatments.

The study covered changes in the microstructure and physical -mechanical properties of AISI 321 corrosion -resistant steel after frictional treatment of the surface by a sliding semi -spherical indenter with varying loads on the indenter. The maximum load was found, for which the amount of the formed strain -induced martensite was the highest and did not change. It was shown that such frictional treatment formed a gradient structure whose maximum depth of the modified layer at the maximum indenter load of 400 N was about 450 mu m. Hardness, amounts of strain -induced martensite, and magnetic parameters depending on the normal indenter loading after frictional treatment were well aligned with each other.

Currently, to increase the hardness, strength and wear resistance of thermally non-hardenable austenitic chromium-nickel steels, such methods as frictional treatment with a sliding indenter and liquid carburizing have been used. However, along with an effective increase in mechanical characteristics, the application of these types of treatment may be accompanied by a decrease in the corrosion resistance of austenitic steels. Therefore, it is reasonable to study the influence of frictional treatment and liquid carburizing on the general corrosion resistance of Cr–Ni austenitic steels. In this work, the surface microhardness of the 12Cr18Ni10Ti and AISI 321 steels was determined using the recovered indentation method after electropolishing, mechanical grinding, frictional treatment, and liquid carburizing at a temperature of 780 °C. Using scanning electron microscopy and optical profilometry, the authors studied steel surfaces subjected to the specified types of treatment and determined their roughness. The corrosion resistance of steel was studied by testing for general corrosion using the gravimetric method. When testing for general corrosion, it was found that hardening (up to 710 HV 0.025) frictional treatment leads to an increase in the corrosion rate of the 12Cr18Ni10Ti austenitic steel compared to the electropolished state (from km=0.35 g/(m2·h) to km=0.53–0.54 g/(m2·h)). The corrosion rate of the ground steel is km=0.58 g/(m2∙h), while mechanical grinding does not provide a significant increase in the microhardness of the steel under study (from 220 to 240 HV 0.025). It is shown that the corrosion behavior of 12Cr18Ni10Ti steel subjected to various types of treatment is determined by the following factors: the presence/absence of strain-induced α'-martensite in the structure, the quality of the formed surface and, apparently, the dispersion of the formed structure. Liquid carburizing of the AISI 321 austenitic steel leads simultaneously to an increase in its microhardness to 890 HV 0.025 and a certain increase in corrosion resistance compared to fine mechanical grinding. This is related to the fact that carbon embedding atoms stabilize the electronic structure of iron (austenite and martensite), thereby increasing its corrosion resistance.

The features of the structure and phase composition of corrosion-resistant austenitic chromium–nickel steel (16.80 wt % Cr, 8.44 wt % Ni) subjected to carburizing in electron beam plasma at temperatures of 350 and 500°C, frictional treatment with a sliding indenter, and a combination of frictional treatment and plasma carburizing have been considered. It has been established that plasma carburizing results in the formation of a modified surface layer consisting of carbon-saturated austenite and carbides (Cr 23 C 6 , Fe 3 C); in this case, the formation of γ C -phase occurs only at a temperature of 350°C. The depth of a modified layer increases with an increase in the carburizing temperature. It has been shown that it is useful to perform combined frictional treatment and plasma carburizing at a carburizing temperature of 350°C, since in this case the deformation-induced structure formed as a result of frictional treatment is preserved, and the precipitated carbides remain highly dispersed. In this case, frictional treatment should provide the formation of the deepest possible diffusion-active layer with a dispersed structure.

The paper studies the polishing power of a tribochemically active abrasive material based on a solid solution of iron and aluminum oxides, as well as a solid solution of aluminum and iron oxides modified by zirconium oxide and yttrium oxide additives, and the tribotechnical properties of a lubricant doped with these abrasive materials. The modified Al2O3·Fe2O3·ZrO2·Y2O3 powders prove to have an essentially higher polishing power producing a considerably lower surface roughness than that of the unmodified Al2O3·Fe2O3 powder. By varying the content of the modifying oxides, one can change the tribochemical activity of the abrasive powder and select the best composition depending on the material to be polished. The addition of these abrasive powders is shown to have an essential effect on the tribotechnical properties of the lubricant for the wheel–rail contact. The laboratory testing of the lubricant compositions suggests their effective applicability to the wheel–rail contact.

Frictional treatment, as a method of surface plastic deformation, forms a gradient hardened layer. In the case of metastable steels, this hardening is due, among other things, to the formation of strain-induced α'-martensite. The most reliable information about the thickness of this hardened layer can be obtained by measuring the hardness on transverse sections. This paper compares strain distribution through the depth of the hardened layer, obtained from layer-by-layer phase analysis and finite element modeling, with the data of durametric studies for the AISI 321 metastable steel subjected to frictional treatment under various loads on the indenter. A satisfactory coincidence of the distributions of the α'-phase concentration and hardness through the depth is observed only for the specimen subjected to frictional treatment at a maximum load of 400 N on the indenter. At the other loads on the indenter, the thickness of the layer containing α'-martensite is lower than the thickness of the hardened layer estimated from the durametric studies. In contrast, it is shown that, for all the loads applied to the indenter during frictional treatment, the through-depth distributions of the calculated values of equivalent plastic strain obtained from finite element modeling agree satisfactorily with the experimental hardness values.

Structural and phase transformations occurring due to the supersaturation of austenite with interstitial atoms (carbon and/or nitrogen) are the key priority in the study of AISI 300 series austenitic steels. It is also very important to achieve a greater hardening depth by nitriding or carburizing. For this purpose, a method of salt bath carburizing at low temperature was proposed. The aim of this work is to perform a detailed analysis of structural-phase transformations and their effect on the properties of AISI 321 austenitic steel subjected to liquid carburizing at a temperature of 780?. Optical and scanning electron microscopy, optical profilometry, X-ray diffraction analysis, energy-dispersive microanalysis, electron backscatter diffraction analysis, instrumented microindentation and microhardness measurement are used as methods of investigation. It has been discovered that, along with carbon-rich (up to 0.46 wt% C) austenite, chromium carbide Cr23C6, cementite Fe3C, e-martensite, and alpha-martensite are formed in the surface layer of the carburized AISI 321 steel. Carbides are present both at the grain boundaries and within the austenite grains. Martensite formed in the carburized AISI 321 steel is induced by deformation, and the martensitic transformation path is gamma -> epsilon -> alpha ' (two-stage transformation). In its turn, plastic deformation occurs during cooling that follows carburizing, and this is a relaxation mechanism of high thermal stresses. Liquid carburizing of AISI 321 steel also multiplies the microhardness of the steel surface from 200 +/- 7 to 890 +/- 110 HV0.025, with the total hardening depth being about 500 mu m. The hardened layer is gradient and characterized by increased resistance to elastic-plastic deformation, this being important for increasing the contact endurance and wear resistance of the steel. It has also been found that, due to high carbon concentration, the corrosion resistance of the carburized steel does not deteriorate significantly.

AISI H13 tool steel is intended for making various tools and die-casting molds, which generally are of complex shapes. The application of selective laser melting (SLM) can significantly speed up their production, but it is accompanied by the appearance of various defects, such as high surface roughness, cracking, and reduced density. In particular, there is a fairly limited amount of data on the influence of SLM process parameters on the surface roughness of tool steels. The aim of this work is to study the possibility of improving the quality of AISI H13 steel by varying laser power and scanning speed during SLM. Optical profilometry and microscopy are used as methods of investigation, with statistical data analysis being carried out. It has been discovered that both surface roughness and porosity can be effectively influenced by varying the laser power and scanning speed during SLM. A direct relationship between surface roughness and porosity has been established, and this makes it possible to control effectively the quality of AISI H13 tool steel produced by selective laser melting. Steel of the highest quality with the lowest surface roughness and porosity has been obtained at a laser power of 250 W and a scanning speed of 350 mm/s. It has also been found that varying laser power and scanning speed does not prevent crack formation, and other technological solutions should be sought to eliminate cracking.

Previous studies have shown the possibility of eddy current monitoring of fatigue degradation during contact loading of austenitic AISI 321 steel. However, AISI 321 steel has insufficiently high contact endurance under cyclic impact loading conditions. Therefore, the application of physical methods for nondestructive testing of fatigue degradation of surface-hardened austenitic AISI 321 steel, which has an increased contact endurance, is of considerable interest. The aim of this work is to investigate the possibility of eddy current testing of fatigue degradation during contact loading of austenitic AISI 321 steel subjected to surface hardening frictional treatment. Mechanical tests for contact gigacycle fatigue were carried out according to the scheme of pulsating impact “plane–plane” contact with ultrasonic loading frequency. It is shown that eddy current monitoring of fatigue degradation during contact loading of surface-hardened AISI 321 steel is possible but has certain limitations due to nonmonotonic changes in the readings $$\alpha $$ of the eddy current device depending on the number of loading cycles. At the same time, it is possible to control the development of intensive destruction of the surface layer of steel that is observed under these loading conditions in the range of the number of cycles $$3 \times {{10}^{8}}~$$ – $$5 \times {{10}^{8}}$$ taking into account the ambiguous nature of the dependences of the eddy current readings on the number of loading cycles in the testing method. The testing can be carried out by measuring the readings of the eddy current device at the eddy-current transducer excitation frequencies $$f = 96- 124$$ kHz. In this case, we largely analyze surface layers in which fatigue degradation processes are intensively developing and affecting the physical characteristics of steel. The greatest influence on the value of $$\alpha $$ is exerted by plastic deformation and destruction of the steel surface.

The effect of the frictional treatment with a sliding indenter on the micromechanical properties of the austenitic corrosion-resistant chromium–nickel AISI 321 steel (16.80 wt % Cr, 8.44 wt % Ni) has been investigated. The instrumented microindentation results, which was performed on the surface of the steel and at different depths from the surface, has shown the exponential distribution of maximum hmax and permanent hp indentation depths, Martens hardness HM, indentation hardness at the maximum load HIT, elastic reverse deformation work of indentation We, total mechanical work of indentation Wt, elastic recovery Rе, ratio of indentation hardness to contact elastic modulus НIT/Е*, power ratio $${{H_{{{\text{IT}}}}^{3}} \mathord{\left/ {\vphantom {{H_{{{\text{IT}}}}^{3}} {{{E}^{{*2}}}}}} \right. \kern-0em} {{{E}^{{*2}}}}}$$ , and plasticity index δA over the depth of the hardened gradient layer. In this case, the HM, HIT, We, Rе, НIT/Е*, and $${{H_{{{\text{IT}}}}^{3}} \mathord{\left/ {\vphantom {{H_{{{\text{IT}}}}^{3}} {{{E}^{{*2}}}}}} \right. \kern-0em} {{{E}^{{*2}}}}}$$ values are the highest, whereas the hmax, hp, Wt, and δA values are the lowest for the steel surface. The E* contact elastic modulus of AISI 321 steel also increases after the frictional treatment. It is distributed nonmonotonously over the depth of the hardened layer. This can be explained by the formation of different dislocation structures on the steel surface and in the underlying layers. The indentation results have shown that the frictional treatment increases the resistance to mechanical action of both the steel surface and the hardened layer with a depth of to 500 µm.

Layered metal composites made of dissimilar metals and alloys occupy a special place among modern composite materials. In particular, their use is considered promising when high strength, fatigue resistance, and wear resistance are required. However, there are few data on the abrasive wear resistance of such composites, and further study is necessary. In this paper, an attempt is made to formulate some approaches to the development of wear-resistant laminated metal composites in order to promote more detailed research. For this purpose, the abrasive wear resistance at room (+25 °C) and cryogenic (−196 °C) temperatures of a layered metal composite consisting of low-alloy and maraging steels was studied. The composite was obtained by explosive welding. It is shown that the wear resistance of the composite is determined by the combined influence of a number of factors, namely the presence of interlayer boundaries, the structural state, hardness, and toughness of the steels. It is concluded that, for better wear resistance of a layered composite, the dissimilar layers must wear out evenly under existing environmental conditions.

The mechanical alloying method is widely used for production of powdered alloys. However, focused studies have shown that this method may also be used for deposition of coatings. Therefore, there is a need to summarize the results obtained and assess opportunities for creation of coatings by the mechanical alloying method in order to improve performance characteristics of different metal materials. This review presents the results of the reported works concerning the structure and properties of coatings deposited by means of mechanical alloying onto titanium and titanium-based alloys, carbon and alloyed steels, aluminum and aluminum-based alloys, copper, and nickel substrates. The composition, hardness, and thickness of the coatings are discussed, as well as defining features of their structure and their influence on the operating properties of materials. The impact of the main parameters of the mechanical alloying process on the coating characteristics and specific features of the mechanism of mechanical intermixing during mechanical alloying are analyzed.

The surfaces of parts made of austenitic chromium-nickel steels are subjected to heavy cyclically repeated contact loads, including impact loads, during operation. Therefore, the study of contact endurance and the development of methods for non-destructive testing of fatigue degradation of such steels is a relevant task. The aim of this work is to study the possibility of eddy-current testing of the fatigue degradation of the AISI 321 steel under contact loading. Mechanical testing for gigacycle contact fatigue has been conducted in accordance with the pulsing impact “plane-to-plane” contact scheme with an ultrasonic loading frequency. It has been shown that eddy-current testing of the fatigue degradation under contact loading of the AISI 321 steel is possible, but has certain limitations due to non-monotonic changes in the eddy-current device readings α depending on the number of loading cycles. Along with this, using the ascending branch it is possible to test the degree of failure of the surface layer, taking into account in the control technique the ambiguous character of the dependences of the eddy-current device readings on the number of loading cycles. The testing can be performed by measuring the eddy-current device readings at the excitation frequency of the eddy current probe f = 124 kHz. In this case, mainly surface layers are analyzed, where the processes of the fatigue degradation that affect the physical characteristics of the steel are developed intensively. The greatest influence on the value of α is exerted by the quantitative ratio of austenite to strain-induced martensite in the control zone.