Plasma Hardening Research Articles

TRIBOLOGICAL AND CORROSION PROPERTIES OF 45 AND 65G STEELS USED IN AGRICULTURAL MACHINERY AFTER ELECTROLYTIC-PLASMA HARDENING

The article examines the effect of electrolytic plasma hardening on the wear resistance and corrosion resistance of steels 45 and 65G, which are used in the production of agricultural machinery components. The presented results demonstrate the improvement of the surface properties of steel through the application of electrolytic plasma hardening. This technology provides rapid heating and cooling, which contributes to the formation of a fine-grained and hardened surface layer, as evidenced by microstructural studies conducted using an optical metallographic microscope. Tribological tests showed an improvement in wear resistance after electrolytic plasma hardening: the wear volume for steel 45 was 3,03×10-4 mm³, and for steel 65G it was 6,17×10-5 mm³, which is 7 and 4,5 times less than the wear volume for the initial samples, respectively. The analysis of polarization curves showed that the corrosion current density decreased compared to the initial sample. For steel samples 45 and 65G after three cycles of electrolytic plasma hardening, the corrosion current densities were 6,87×10^-6 A/cm² and 1,61×10^-7 A/cm², respectively. Additionally, a shift in the corrosion potential towards more positive values was noted, indicating an increase in corrosion resistance. The results of the study demonstrate significant improvements in the tribological and corrosion properties of steels 45 and 65G after electrolytic plasma hardening, providing valuable data for industrial applications.

APPLICATION OF ELECTROLYTIC PLASMA HARDENING FOR IMPROVING THE PROPERTIES OF MACHINE PARTS MADE OF STEEL 45

This study examined the effect of electrolytic plasma hardening (EPH) on the properties of 45-grade steel, which can serve as an alternative to traditional heat treatment methods used before the release of finished products. The results of the experiments showed that the mechanical and operational properties of 45-grade steel significantly improved after the application of EPH. Steel 45, widely used in mechanical engineering and agricultural machinery production due to its strength characteristics and durability, demonstrated a significant increase in performance after treatment. It was observed that the properties of 45- grade steel improved considerably after applying electrolytic plasma hardening methods, with the hardness of the samples increasing by 3.1-3.62 times, and wear resistance improving by 7 times. Moreover, the study highlighted the economic efficiency of the proposed treatment method, showing that the introduction of EPH can lead to a significant reduction in material costs, extended product life, and improved environmental performance by reducing energy consumption and emissions. The use of a non-toxic 20% sodium carbonate solution in EPH contributed to the uniform distribution of electric current in the cell and allowed for achieving optimal cooling rates of the sample.

Влияние параметров плазменного упрочнения на качество поверхностного слоя тяжелонагруженных изделий

There has been studied the effect of the hardening current, the distance between the nozzle and the hardened surface of the product, the flow rate of the plasma-forming gas, the dependence of the cooling rate during plasma hardening on the speed of the plasma torch movement (treatment speed), and the diameter of the nozzle. Based on the theory of thermal processes, the cooling rates have been calculated for various values of the current strength. It has been shown that the ratings characterizing the significance of the main technological parameters of the plasma hardening mode for the depth and width of the hardened zone are practically the same. While the effect of the current strength on the dimensions (depth and width) of the plasma hardening zone significantly exceeds the effect of the other parameters of the hardening mode. This indicates that the arc current is the main controlled parameter of the plasma hardening process. There has been shown the possibility of regulating the mechanical properties of the hardened surface of the solid-rolled railway wheel rim depending on the required level of mechanical characteristics by means of controlling the speed of the wheelset.

The impact of technological parameters of electrolytic-plasma treatment on the changes in the mechano-tribological properties of steel 45

<p>This article presents the results of research on the effects of electrolyte plasma hardening on the structure, phase composition, tribological, and mechanical properties of medium-carbon structural steel 45, which is widely used in the manufacturing of tools and machine parts. Hardening experiments were conducted using an electrolyte plasma hardening setup with electrolytes varying in sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>) concentration in distilled water (15%, 20%, and 25%). With a consistent heating duration of 4 s during quenching, significant phase changes in the steel's microstructure were observed, enhancing hardness and wear resistance. The transformation of the initial structure of steel 45, which consists of ferrite and pearlite into martensite on the surface of the samples, led to an increase in microhardness up to 506–690 HV<sub>01</sub>. This value is 2.5–3.5 times higher compared to the untreated sample, and the thickness of the hardened layer reached up to 3.2 mm. Additionally, wear volume measurements showed that after electrolyte plasma hardening, the wear resistance of the samples increased by 1.3–1.5 times (2.01 × 10<sup>−4</sup>, 2.26 × 10<sup>−4</sup> m<sup>3</sup>). The obtained results on the changes in microstructure and mechano-tribological properties of steel 45 confirm the potential of electrolyte plasma hardening technology for improving operational characteristics and extending the service life of heavily loaded and critical machine parts.</p>

Исследование влияния плазменной закалки на процессы упрочнения тяжелонагруженных деталей почворежущих машин

The influence of plasma hardening on the processes of hardening of heavily loaded and, therefore, high-wear parts of the working bodies of soil-cutting machines has been studied. It is shown that during surface plasma hardening of a plow share made of 65G structural steel, a gradient-layered (mixed) structure is formed in a hardened zone 0.8 mm thick, consisting of a finely dispersed mixture of fine-grained austenite decomposition products with varying microhardness in the range of 760-395 HV. It has been established that the formation of a finely dispersed configuration and the features of its formation after surface plasma treatment are explained by ultra-high heating and cooling rates, which are unattainable with traditional heat treatment methods. During plasma treatment of parts, metastable structures with high strength and wear resistance are formed. The result of hardening the plow share by plasma hardening in the form of a modified layer with a finely dispersed configuration is obtained, an increase in the wear resistance of the plow share is observed compared to serial parts subjected to traditional heat treatment and a significant reduction in the cost of the hardening process due to the use of an economical, sufficiently productive surface plasma hardening technology

Changes in structure, hardness and crack resistance of plasma-strengthened steel 65G

The present paper describes the research of structure, hardness and crack resistance indicators before and after plasma treatment of 65G steel of a ploughshare part. As a result of plasma treatment, we obtained the modified layer with increased hardness in the range of 980 – 3558 HV with increase in 3.6 times. Metallographic studies showed that pearlitic-ferritic structure of the original metal transforms into needle martensite with high hardness and strength due to plasma hardening. It is recommended to determine the impact toughness by the Drozdowski method, in which a fatigue crack is pre-created on a special vibrator. Also, before the fatigue crack was grown, lateral V-shaped notches of different depths were made on the sample lateral surface. The relative crack length, λ, varied from 0.27 to 0.65. According to the results of compression tests, it was found that there was a small movement of cracks in the hardened samples in the range from 1.3 to 5.6 mm. The initial unstrengthened samples are in a more brittle state than the quenched ones, and accordingly, significant fracture is observed in the conditions of artificial cracking. The evaluation of 65G steel samples for crack resistance by impact bending tests with subsequent oscillographing showed that plasma hardening inhibits crack growth by increasing impact toughness. Thus, the use of plasma hardening is effective in surface hardening of 65G steel, in particular ploughshares which are constantly exposed to mechanical stresses, friction and wear.

Investigation of the surface layer of wheel steel by indentation method

The article considers methods of measurement of microhardness and modulus of elasticity of plasma hardened wheel steel by kinetic indentation method. It provides features of measurement of microhardness, modulus of hardness, elastic recovery, influencing on wear resistance of surface layers of steel. Measurement of these characteristics of material allows estimating and choosing optimum technology of surface modification by surface plasma hardening. It is confirmed that objectivity of determination of microhardness, modulus of elasticity, elastic recovery and flow stress depends on strict observance of imprint depth requirements depending on thickness of hardened layer. It is noted that in spite of the increased amount of factual information, obtained by indentation method, the physical substantiation of hardness micro-mechanisms remains poorly understood, which necessitates substantiation of physical representations of the nature of hardness of metallic materials. It is established that the measurement of microhardness, elastic modulus and elastic recovery by the kinetic indentation method is expedient to use for certification of the surface layer of plasma-hardened wheel steel according to the parameters of physical and mechanical characteristics.

Optimal ratio of hardnesses of wheel and rail steels, providing minimal wear of the wheel-rail friction pair

The determination of the optimal range of hardness of the hardened layer of the wheel rim and the tread surface of the rail head is considered in order to increase the wear resistance of the wheel-rail friction pair. Laboratory tests were carried out to establish the optimal ratio of wheel and rail hardness, which are tested under operating conditions. Keywords: hardness, wheel, rail, plasma hardening, crack resistance, fracture pattern, structure, martensite, troostite, sorbite. aliya-981@mail.ru

Product durability management using surface engineering technologies

The problem of managing the durability of products due to the creation of regions in materials with a given temporal and spatial non-locality is considered. A mathematical model of softening of materials under the action of external loads is proposed, allowing to take into account the special role in the formation of damaged places of exit of grain boundaries and their triple junctions on the outer surfaces of parts, as well as their interaction with stress concentrators formed after mechanical processing.
 The developed model representations are used to ensure the operational uniformity of structural elements with concentrators under stress by methods of surface engineering, in particular, when determining the role of changes in the quantitative parameters of the microstructure on the wear resistance of the surface layers of rolling stock parts of railway transport containing stressed concentrators. The optimal depth of the plasma hardening of the subsurface layers of the rims of wheel pairs of locomotives has been established, depending on the size, placement and geometric characteristics of the tension concentrators. It is shown that taking into account the dynamics of structural changes during the degradation of materials in the conditions of operation according to the proposed model ratios allows to achieve the specified life cycle of parts at minimal costs.
 Increasing the durability of products is achieved by optimizing technological modes of surface engineering, which ensure the formation of structures with a smaller gradient of properties.

Comparative Analysis of Wheelsets Tyres, Hardened Using a Laser or Plasma Heat Source

Lateral wear of the locomotive wheel flange is one of the main types of wear that occurs during rolling stock operation. An important characteristic of a rail wheel rim is its wear resistance, which directly depends on the carbon content in steel. The carbon content in wheel steel of group 2 in the amount of 0,55–0,65 is due to the fact that at its lower concentration, the proportion of grain boundary ferrite increases, which leads to a decrease in the contact strength of wheels, and a higher one leads to a tendency to brittle fracture.The increased carbon content makes it possible to harden the surface of steel. Plasma and laser hardening technologies can be used to reduce tyre flange wear and increase the service life of locomotive wheelsets.The objective of this work is to determine advantages and disadvantages of technologies for laser and plasma hardening of working surfaces of tyres of wheelsets of railway rolling stock.The comparative analysis related to microstructure and microhardness of wheelsets tyres of the 2TE25KM diesel locomotive which are made of wheel steel of group 2 according to GOST 398-2010 state standard and hardened respectively by plasma and laser hardening.The tasks set were solved using theoretical and experimental research methods. The preparation and study of hardened samples was carried out using the equipment of the testing laboratory of LLC Scientific and Technical Association «IRE-Polus».A study referred to hardened zones in various areas and sections of the tyre. Tribological tests concerned wear resistance of specimens hardened with a high-power fiber laser. The main advantages and disadvantages of laser and plasma hardening processes are revealed.The conducted studies allow making a conclusion that the use of laser hardening technology for hardening wheelsets tyres, as an alternative to the plasma hardening process, is highly promising.

Increase the resource and reduce the life cycle cost locomotive wheelset

The paper presents the results of research on the analysisy of modern technical means and technologies to increase the service life and reduce the cost of the life cycle of a locomotive wheelset. Calculations are performed and the results of technical and economic efficiency of the use of modern innovative comb-smearing devices lubrication (USGL) and plasma hardening devices (SCR) for locomotive wheel pairs, as well as clutch activation devices (UATL), are presented. The practice of operating USGL and UPU devices has shown that the most effective is their joint use with the achievement of a consolidatedого effect on increasing the service life of locomotive wheel bands. Technical and economic calculation of the efficiency of using UATL friction activation devices has shown the economic feasibility of using locomotive coupling activation systems которые обеспечиваю, which provide an increase in the mileage of locomotives between equipment in the conditions of field operation of the locomotive fleet and reduce the cost of building additional points for equipping locomotives with sand.

ИССЛЕДОВАНИЕ И МОДЕЛИРОВАНИЕ ПРОЦЕССА ПЛАЗМЕННОЙ ЗАКАЛКИ СТАЛИ 40Х

In this paper, the results of research and modeling of the process of plasma hardening of specimens from steel 40Kh are presented. Using experimental data on the size of hardening zones within the framework of thermophysical modeling, the effective radius and efficiency of the plasma arc are determined. The simulation of plasma surface hardening was carried out depending on the speed and current of the plasma arc. Based on the analysis, nomograms are proposed for determining the depth and width of the hardening zone of steel 40Kh depending on the speed and current of the plasma arc. Thermal cycles are constructed in the steel heating zone. The cooling rates of the material are determined depending on the speed of movement and the depth of hardening in comparison with the critical rate of steel hardening.

Modification of the Surface of 40 Kh Steel by Electrolytic Plasma Hardening

The high-strength, medium-carbon alloy construction steel 40 Kh is commonly used in the manufacture of tools and machine parts. This paper experimentally investigates the effect of electrolytic plasma thermocyclic hardening on the surface hardening and microstructure modification of 40 Kh steel. The research was carried out using optical microscopy, scanning electron microscopy, X-ray diffraction analysis and micro-hardness measurements. Modified samples were obtained at different electrolyte plasma thermal cycling modes. As a result of the heat treatment, hardened layer segments of different thicknesses and structural composition formed on the surface of the steel. The parameters and mechanisms of surface hardening were determined by examining the microstructural modification and phase transformation both before and after treatment. It was revealed that the main morphological structural-phase component of the initial state of 40 Kh steel was a ferrite–pearlite structure, and after electrolytic plasma thermocyclic hardening, the hardened martensite phase was formed. It was found that in order to achieve a hardening depth of 1.6 mm and an increase in hardness to 966 HV, the optimum time for electrolytic plasma treatment of 40 Kh steel was 2 s. The technology under discussion gives an insight into the surface hardening potential for improving the service life and reliability of 40 Kh steel.

Low-temperature plasma hardening impact on the properties of the surface layer of the cutting tool working part

Low-temperature plasma hardening impact on the properties of the surface layer of the cutting tool working part

The Method of Calculating Ploughshares Durability in Agricultural Machines Verified on Plasma-Hardened Parts

Reliability consists of four components: failure-less operation, maintainability, durability, and preservation ability. For different machines and different conditions of operation, different combinations of these properties, and differences in how they are balanced and proportioned are essential. For tractors, the most important aspect of reliability is maintainability, while for agricultural machines, durability is most important. Using the example of a ploughshare, the issue of increasing the durability has been studied; a method for calculating the durability of a ploughshare for various types of soils has been described. The use of plasma hardening of the surface of a 65G-steel ploughshare has been proposed; the effectiveness of plasma hardening of soil-cutting parts and its economic feasibility have been proved. Due to hardening to a depth of 1–1.8 mm, the service life of parts increases by 2–3 times; moreover the downtime of expensive machine-tractor units for replacing worn-out parts is reduced.

EFFECT OF THE STRUCTURE FORMED AFTER BULKAND SURFACE HARDENING ON THE HARDNESSAND WEAR RESISTANCE OF 20Cr2Ni4A STEEL

The article presents the results of a comparative study of the effect of bulk and surface hardening on the structure and properties of 20Cr2Ni4A steel. Surface hardening was carried out by the electrolytic plasma method. Bulk quenching was carried out by heating to a temperature of 870 °C, followed by cooling in water and oil. The structural-phase states of20Cr2Ni4A steel samples were studied by metallographic and X-ray structural analysis. Tribological tests of the samples were carried out according to the ball-disk scheme, and the microhardness of the samples was also determined. It has been determined that after volumetric and surface hardening, the hardness and wear resistance of 20Cr2Ni4A steel increase. In this case, the most significant change is observed in samples that have undergone electrolytic plasma hardening. It has been established that high values of hardness and wear resistance of 20Cr2Ni4A steel after electrolytic plasma hardening are associated with the formation of fine-needle martensite

Modernization of the Surface Layer Structure of Heavily Loaded Parts of Tillage Machines with Plasma Hardening

Modernization of the Surface Layer Structure of Heavily Loaded Parts of Tillage Machines with Plasma Hardening

АДГЕЗИОННЫЕ ХАРАКТЕРИСТИКИ ТОНКОПЛЕНОЧНОГО ПОКРЫТИЯ, ОСАЖДАЕМОГО ПРИ ФИНИШНОМ ПЛАЗМЕННОМ УПРОЧНЕНИИ

The methodology for determining adhesion characteristics of thin-film coatings applied from the vapor phase and used to protect parts against wear and corrosion has been considered. The study of adhesion properties, along with deter-mination of thickness, composition of elements, structure, physical-mechanical, and tribological characteristics, as well as wear coefficient, al-lows evaluating and selecting the optimal coat-ing and best technology for its application for a specific industrial application. On the example of studying DLCPateks diamond-like coating of aC:H/a-SiOCN system deposited during final plasma hardening, adhesion characteristics were assessed according to ISO 20502:2005 by scratch testing and according to ISO 26443:2008 by indentation of Rockwell diamond indenter. The first tests were performed to determine the load at which the depth of penetration of the indenter into the coating - substrate composition stops growing smoothly, which characterizes the moment of destruction of the coating. The ratio of the load on the indenter, determined at the end of the passage of the coating thickness, to the load of occurrence of the first cracks or delamination, in these tests is conventionally called the adhesion coefficient. The influence of the coating thickness on the adhesion coefficient has been studied. The tests associated with the use of a Rockwell diamond indenter punch qualitatively evaluate the adhesion properties of the coating by comparing the obtained and normalized impressions. The results of the tests proved improved adhesion characteristics of DLCPateks coating.

EXPERIMENTAL STUDIES OF OPERABILITY OF HARDENED CUTTING EDGES OF PARTS

The operability of machine and tool parts is often determined by the state of the working surface. It is on the surface that cracks arise, wear and corrosion processes begin. The presence of defects, the degree and depth of hardening, the level of residual internal stresses, the structure, the nature of the transition to the base material, most often determine the reliability and service life of parts and structures. Based on a critical review of hardening methods, it was found that one of the promising ones is the effect on the treated surface of a plasma jet of different power density. To ensure wear resistance of the working edges, the surface was treated with low-temperature plasma at an indirect arc plasmatron installation. The work investigated the phase and structural transformations after plasma coating on model samples of steel 65G, studied the structure and built microhardness profiles. Optimal parameters of plasma processing of articles are determined: distance from plasmatron - 30 mm, rotation speed - 10 s-1, heating time - 10 s. The established optimal modes of hardening treatment were used for plasma hardening using the example of an instrument (spiral drills made of steel grades R6M5, R6AM5 and 11R3AM3F2) under production conditions. For all types of drills, it was possible to obtain a hardened layer of 1-1.5 mm deep from the surface. According to the results of metallographic analysis, the microstructure of the hardened layer contained a white, non-etchable in acids zone with a high microhardness of up to 12000 MPa, the depth of which reached up to 0.4 mm; then there was a structure consisting of martensite and residual austenite with a microhardness of up to 9000 MPa. Tests of experimental drills for resistance, carried out in production conditions, showed an increase in their resource by 2 times compared to a tool that did not undergo plasma hardening, confirmed the possibility of multiple regrind within the hardened layer.

Improving the Surface Structure of Structural Steel by Plasma Hardening

Improving the Surface Structure of Structural Steel by Plasma Hardening