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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. [ABSTRACT FROM AUTHOR]

Based on an overview of methods for hardening and restoring parts of agricultural machines, it has been found that the methods currently used are highly labour intensive and are not well suited for hardening the cutting edge of tillage machine discs. A method of electromechanical hardening of ploughshare discs due to simultaneous thermal action and plastic deformation is disclosed. Electromechanical hardening modes are justified on the example of standard cylindrical samples. The developed technique contains the following stages: determining the steel grade of a part; planning of the experiment based on the plan of the full two-factor three-level experiment with selection of influences and response function; experimental hardening of laboratory samples at the installation; microstructural analysis of hardened samples; numerical processing of experiment results. Based on the optical emission analysis, it was found that the samples are made of steel 65G. The factors of influence are: current strength X1(Ir) = 800...1200 A on the reinforcing tool in the form of a roller and the pressing force X2(Fk) = 100...300 N of the tool to the part. The hardness of the surface layer Y(HRC) is adopted as the response function. Microstructural analysis showed that a layer consisting of several zones was formed on the hardened surface of the sample: white, light non-flowing and dark martensitic, passing into the ferrite-pearlite structure of the base. On the basis of multiple regression analysis, an empirical mathematical model is obtained and its graphical interpretation in the studied area of factors values is given. According to the criterion of providing wear resistance of working edges of disks, maximum hardness is achieved at current strength X1(Ir) = 1060 A and force X2(Fk) = 210 N in the contact zone. Developed technique and tested modes of electromechanical hardening are suitable for development of process of hardening of disk ploughshares of grain-grass seeders. [ABSTRACT FROM AUTHOR]

The quality of agricultural engineering education and the ability to innovation activity determine the prestige and competitiveness of universities, the possibility to attract intellectual and material resources and therefore to create the necessary conditions for training of agricultural engineering personnel. An analysis of workforce needs shows that manufacturing enterprises need specialists with a high level of practical skills. Universities are trying to cancel for this effect by implementing practical aspects of agricultural engineering education as a basic criterion for acquisition of general professional and professional competencies. The competencies of graduates of agricultural engineering direction have been determined on the basis of the analysis of existing methods of education, the modern state of technologies and equipment of the agro-industrial complex. They require strengthening of practical training in the process of education. It has been experimentally confirmed that the possibility of obtaining additional working professions during the training period not only strengthens the practical component, but also contributes to increasing interest and general motivation to improve professional skills. A training methodology has been developed. It has been tested on the disciplines "Perspective Geometry. Engineering Graphics" and "Material Science and Construction Material Technology" based on the application of practical-oriented forms of interactive training in the form of round tables, master classes and trainings. The methodology is recommended for wide application in universities of the system of agrarian education of the Russian Federation in the field of education 35.03.06 "Agricultural engineering". Research prospects are conditioned by the need to continue programs in the sections of the disciplines "Mechanics", "Metrology, Standardization and Certification", "Machine Elements and Principles of Design" and extension of the present experience within the framework of international cooperation. [ABSTRACT FROM AUTHOR]

The work presents researches in the microstructure of surface layers after laser hardening of C 45, laser processing with pre-printed slip coatings, as well as after the complex treatment, which includes plasma welding and laser processing. The studies established the presence on the surface after modification three zones: the zone of welding - transition zone with a pronounced needle-like fine structure and framework with a ferritepearlite structure. Electron microprobe analysis carried out on the scanning electron microscope TESCAN VEGA//LSU showed the presence in the melted layer increased content of tungsten in the sample with HS 18; tungsten, vanadium and molybdenum in the sample with HS 5-6, as well as tungsten, cobalt, chromium and vanadium in the sample with HS 13-0-4-5. As the distance from the deposited layer in the transition zone and the original C 45 there were observed the disappearance of peaks of the alloying elements and the increase of the content of iron, silicon and carbon. The results of measurement of microhardness for all studied samples showed that the microhardness reached the maximum values of up to 16000 HV, when welding with powder HS 18 and the height of the laser head l = 15 mm; to 14720 MPa, when welding with powder HS 5-6 and the height of the laser head l = 20 mm; and 22400 HV, when welding with powder HS 13-0-4-5 and the height of the laser head l = 15 mm, which exceeds the microhardness of C 45 in the initial 8-11 times and 3-4 times in comparison with laser treatment of C 45 with no preliminary welding. The presence of a dense layer with high microhardness indicates that the method of plasma micro alloying and subsequent laser treatment can be used to restore worn parts with a sharp increase in the microhardness of the surface, and to process new parts for their surface hardening. The choice of a particular composition for plasma deposition and subsequent regimes of laser treatment depends on the specific operating conditions of the modified products of C 45. [ABSTRACT FROM AUTHOR]