The paper presents the experimental data on the synthesis of finely dispersed powder of vanadium carbide (VC_0.88 ). Vanadium carbide was prepared by the reduction of vanadium oxide  (III) with nanofibrous carbon (NFC) in the induction furnace under an argon atmosphere. NFC is a product of catalytic decomposition of light hydrocarbons. The main characteristic of a NFC is a high specific surface area (~150  000  m² /kg), which is significantly higher than that of soot (~50  000  m² /kg). The content of impurities in the NFC is at the level of 1  %  wt. Based on the analysis of the state diagram of the V – C system, the composition of the charge and the upper temperature limit of the carbide formation reaction for obtaining vanadium carbide in the powder state are determined. Based on the thermodynamic analysis, the temperature of the onset of the carbothermic reduction reaction of vanadium oxide (III) at various CO pressures was determined. The characteristics of vanadium carbide were studied using X-ray and elemental analyzes, pycnometric analysis, scanning electron microscopy using local energy dispersive X-ray microanalysis (EDX), low-temperature adsorption of nitrogen, followed by determination of the BET specific surface area, sedimentation analysis, synchronous thermogravimetry and differential scanning calorimetry (TG/DSC). The material obtained at optimal parameters is represented by a single phase  – vanadium carbide VC_0.88 . The powder particles were predominantly aggregated. The average size of the particles and the aggregates equaled 9.2  –  9.4  μm within a wide range of size distribution. The specific surface value of the obtained samples was 1800  –  2400  m² /g. Oxidation of vanadium carbide began from the temperature of ~430  °C and practically ends at ~830  °C. Optimum parameters of synthesis are the ratio of reagents according to stoichiometry to obtain carbide of composition VC_0.88 at a temperature of 1500  –  1600  °С and a holding time of 20  minutes. It is shown that for this process nanofibrous carbon is an effective reducing agent and that vanadium oxide  (III) is almost completely reduced to carbide VC_0.88 

The prospects of development of combined continuous casting and deformation processes in production of steel sheets for welded pipes are considered. Design of a pilot plant for combined continuous casting and deformation process for production of steel strips is described. Technological possibilities of installation of combined continuous casting and deformation process are described from the point of improving the quality of steel sheets for welded pipes as well as operating conditions of comb mold backup-walls of combined casting and deformation plant in production of them. Problem of simultaneous determination of stress-strain state of metal with focus on cyclic deformation and stress is posed, depending on compression force in walls of the comb molds of the installation. Initial data and boundary conditions for determination of stress-strain state of metal in focus of  cyclic deformation are given using the ANSYS package. Diagrams of axial stresses are presented for preparation of sheets with section of  3×2250  mm made of 09G2S steel. Evaluation of the scheme of stressed state of  metal with focus on cyclic deformation from the position of high-quality steel sheets production for welded pipes was carried out. Technique of determination of axial stresses is described depending on compression forces in steel sheets production for welded pipes in continuous casting and deformation plant. Design scheme and loading pattern of the backup-wall are given. Stress state of the backupwall is calculated in five sections, the results are presented for typical lines. The values and regularities of distribution of axial stresses in contact layer, in height and width of the backup-wall were determined depending on compression forces. Values of the greatest compressive and tensile stresses are given in relation to compression forces and their distribution in the backup-walls during production of steel sheets for welded pipes in combined continuous casting and deformation plant.

Analysis of existing methods to increase the stability of rolls calibers has shown that one of the most effective methods is surfacing with solid or powdered wires, which is confirmed by the numerous research materials of domestic and foreign authors on improving the compositions of powder wires and welding fluxes. A promising direction in terms of reducing the cost of surfacing materials production and ensuring their required technological properties is the development of new compositions of powder wires and fluxes based on man-made metallurgical wastes. Experimental studies carried out within the framework of the development of this direction show the principal possibility and effectiveness of the use of barium-strontium carbonatite in the manufacture of welding fluxes based on ladle electric-furnace slags. When conducting laboratory studies on surfacing of steel samples, a barium-strontium flux was used. An additive was prepared in two ways: a barium-strontium modifier mixed with liquid glass and a barium-strontium fraction modifier of less than 0.2  mm. According to the data obtained, when using different variants of flux compositions with varying proportions of the above components, a satisfactory quality of the deposited layer macrostructure is ensured and the contamination of the welded joint is reduced by such nonmetallic inclusions as silicates that are not deformed, point oxides and silicates are brittle.

The article provides data on investigation of viscosity of welding melts of slags and electrode coatings using common technique of rotating electric viscometer operating on the principle of rotating coaxial cylinders. Molybdenum crucible with internal diameter of 20  mm and height of 70  mm, filled with test material had served as an external stationary cylinder. An internal rotating cylinder was molybdenum head 10  mm in diameter and 10  mm in height, mounted on a rotating molybdenum spindle with diameter of 4mm.To study viscosity of melts were used: electrode coatings tempered in advance at 1000  °C for 30  –  45  minutes in order to avoid foaming during melting process, and slags obtained through welding by electrodes at recommended modes. As a result of the investigations of welding electrodes with various types of coatings, viscosity of liquid welding slags (η_s) and electrodes coatings melts (η_c ) were determined. Analysis of the results was carried out on viscosity polytherms of melts of coatings and slags based on experimental data. Calculations of the temperatures of the start and intensive crystallization, of activation energy of viscous flow were performed based on dependence of viscosity logarithm on melt reciprocal temperature. It was revealed that in regard to influence on electrode metal transfer and weld seam formation during welding, the most interesting are physical properties of coatings and slags melts at temperatures of crystallization start and higher. Mineralogical composition and temperature dependences of viscosity of molten welding slags of the basic type play a major role in providing welding from downward with through penetration of the seam root. Basically coated electrodes for downward welding can be characterized by crystallization start in homogeneous area and high activation energy of melts viscous flow. Technological capabilities of electrodes in welding were determined by “manufacturability potential”, understood as difference in physical properties of melts of “primary” and “secondary” slags of the same electrodes. The higher the “manufacturability potential” is in terms of size and the wider range of determining parameters, the easier is downwards welding. In developing new basic electrodes for downward welding, a number of options for increasing “manufacturability potential” are possible through achieving necessary mineralogical composition of welding slags. For that reduction of fluorine content, increase of content of MnO, FeO and Fe₂O₃ oxide, partially replacement of SiO₂ with TiO₂ and K₂O with Na₂O are necessary, definite substitution of CaO for FeO and MnO oxides is appropriate.

The engineering mathematical model of development of physical and chemical transformations is considered in the volume of pellet, consisting of granules of iron-stone, limestone and coke (carbon-containing fuel). It is shown that according to the experimental information there are mathematical models, using the three-stage chart of renewal. Strict mathematical description of process of renewal on this chart requires the joint decision of kinetics tasks of successiveparallel reactions and diffusion of multicomponent gas in the pores of ore piece. Such approach cannot be used in the mathematical model of process of metallised pellets burning because of its complication. This complication increases at the account of characteristic feature of the gas and temperature mode of burning machine, producing metallised pellets: change of gas composition during material movement (transition from an oxidizing atmosphere to restoration or neutral). For the decision of the task of ore granule renewal it is important to know the distribution curves of the concentrations of reducing agents and gaseous reaction products along the radius. Because of complication of the equalizations of diffusion, heating of granules and chemical kinetics, the close method of decision of Stefan problem, developed by L.S.  Leybenzon, is used, essence of which is in supposition, quasi stationary distribution has time in the volume of granule to be set. All oxide reduction reactions occur not on the surface of the micropores of the corresponding granule layer, but on the frontal surfaces separating these layers and the restoration of the central volume of the original magnetite does not develop until the neighboring hematite region is recovered to Fe3 O4 . At  such conditions all complication of the simplified mathematical model is compensated by the proper choice of algorithm of numeral decision of the equalizations system. As a row of simplifications doesn’t correspond to reality (for example, the layer of metallic iron is not skipped by a gas-reducer), it is necessary to use effective coefficients, the value of which is set during the model adaptation.

The properties of high-temperature nickel alloys for modern engineering were determined by thermal stability of structure, size, shape and amount of hardening γ′-phase, and the strength characteristics of γ′-solid solution. These alloys are strengthened by alloying with rhenium and lanthanum. The aim of this work was qualitative and quantitative study of the alloy structure and the phase composition of a nickel heat-resisting alloy additionally doped with rhenium (0.4  %  at.) and lanthanum (0.006  %  at.). The investigations were carried out by two methods: the method of transmission diffraction electron microscopy and the scanning electron microscopy method. Investigation of the alloy’s structure was carried out in three states: sample 1 – initial state (after directional crystallization (DC)); sample 2 – DC, annealing at 1150  °C for 1 hour, annealing at 1100 °C for 480 hours;sample 3  –  DC, annealing at 1150 °C for 1 hour, annealing at 1100 °C for 1430  hours. The studies showed that the phases observed in the superalloy can be classified into primary and secondary phases. The main phases are γ′ and γ. They form structure of the alloy and are present as quasi-cuboids of γ′-phase separated by γ′-phase interlayers. The remaining phases are secondary. It was found that doping with rhenium and lanthanum leads to the appearance of secondary phases, namely: β-NiAl, AlRe, NiAl₂ Re; σ; χ; Ni₃La₂ . The formation of secondary phases introduces a serious violation into the structure of quasi-cuboids (γ  +  γ′)-phases. Rhenium and lanthanum do not fill the entire volume of the alloy uniformly but are present only in local areas. Therefore, in three states of the alloy only a part of the volume of quasi-cuboids (γ  +  γ′)-phases was affected. The morphology of the secondary phases was studied. It was found that the particles of the σ-phase are thin needles, while the Ni₃La₂ particles have an internal structure with a characteristic contrast and have a finite thickness. An interesting feature is that the σ-phase and Ni₃La₂ phase are distinguished in the same places. It was established that the introduction of lanthanum and rhenium changes phase composition of the alloy, suppressing the formation of γ-phase. Particles of secondary phases are localized in individual sections of the alloy with a certain periodicity. The resulting secondary phases are refractory: the melting point of the β-phase is approximately 1600  °C, for the σ-phase it is 2600  °C, and for the χ-phase it is 2800  °C. The formation of secondary refractory phases and their periodic distribution in the structure contributes to hardening of the superalloy doped with rhenium and lanthanum.

The results of comprehensive study of bimetallic samples obtained as a result of pouring St3 structural steel between plates of Kh18N9T stainless steel placed in a mold followed by hot rolling of the obtained three-layer plate are presented. Analysis of the interface boundary has confirmed its continuity and high quality. Investigation of microstructure of the interface area by means of optical, atomic-force, and electron metallography has shown that three structural components occur in the direction from pearlitic to austenitic steel: weakened section of ferrite layer; hardened section of ferrite layer and dark-etched interlayer on the austenitic steel side. Using atomic-force microscopy, contact method in “constant force” mode in particular, and optical metallography, it was established that from St3 steel side as it approaches interface, decarburized layer with purely ferrite structure is formed instead of typical low-carbon steel structure consisting of ferrite matrix with pearlite colonies, and on Kh18N9 steel side a carburized layer is formed. In addition, an intermediate layer (carbide) with a depth of up to 50  μm was detected at the boundary. The nature of micro-hardness change in the area of St3 carbon steel and cladding layer of Kh18N9T stainless steel interface shows significant increase in materials strength. Microelement analysis of the area of St3  –  Kh18N9T interface made it possible to establish nature of change in concentration of alloying elements as they approach the interface boundary. Presence of chromium in St3 steel and increase in carbon concentration in stainless steel confirmed the assumption of two mutually directed diffusion flows generation, namely, reciprocal diffusion of carbon from St3 steel and alloying elements of Kh18N9T steel. Resulting carbides explain increased hardness of both steels near the bound zone.

At present, intensive reinforced concrete constructions of various purposes have got considerable distribution, in which, as a rule, compressive stresses in concrete and stretching in the reinforcement are created. At the same time, the prestressed reinforcement better perceives the loads exerted on it by external forces during the whole lifetime of the construction, which allows increasing the load on the structure in comparison with the construction with non-tensioning reinforcement or at the same load value to reduce the dimensions of the construction and achieve savings in concrete and steel. One of the urgent problems of modern hardware production is considered to be development of the technology of nanostructured reinforcing ropes manufacturing, which are the main element of stressed reinforced concrete constructions for responsible use. The most important technological operation is patenting in which steel acquires the structure of a fine ferrite-carbide mixture (FCM), which has high strength and, at the same time, the deformation ability with large degrees of compression. The authors have investigated the effect of increasing speed of rod movement in the patenting unit on the structure and mechanical properties formation in steel of grades 80, 70 and 50 with the aim of determining the possibility to increase the productivity of the patenting unit without reducing the strength and plastic characteristics of steel in the production of nanostructured reinforcing ropes billets for reinforced concrete stressed constructions for responsible use. To determine temperature-time parameters of heat treatment, the isothermal diagram decomposition of the undercooled austenite was constructed using Gleeble 3500 research complex. A qualitative and quantitative analysis of the microstructure with the determination of the FCM interlamellar spacing was carried out at different speeds of the rod movement in the patenting unit. The mechanical properties under tension were tested. It was established that at all processing speeds, the values of the FCM interlamellar spacing in the range 0.1  –  0.2  μm are practically identical and optimal for the subsequent drawing. Due to the formation in the patenting of the disperse structure of FCM, an increase in the strength of the billet is achieved, which, with subsequent drawing, can withstand large crimps without breakage. It is shown that in the production of patented nanostructured billets for reinforcing ropes, one can increase the speed in patenting unit to 5 m/min without reduction of strength and plastic characteristics of the billet.

In recent years, the attention of researches in the field of physical materials science is focused on the study of facing of composite coatings hardened with the particles of carbides, borides and other high solid phases. The principal factor determining the service properties of the faced layers is phase composition of coating materials. In order to make substantiated choice of coating material corresponding to the conditions of their extreme service, high loads and abrasive wear it is necessary to carry out thorough studies of their properties and structure. Structure-phase states and tribological properties of coating faced on Hardox  450 martensite low carbon steel with Fe – C – Cr – Nb – W powder wire and modified by subsequent electron beam processing were studied in the research using methods of modern materials science. The regime of electron beam processing is the following: parameters of electron beam at the first stage – energy density of electron beam in pulse E_S   =  30  J/cm² , duration of pulses τ  =  200  µs, number of pulses N  =  20; at the second stage – E_S   =  30  J/cm² , τ  =  50  µs, N  =  1. The regimes of irradiation were chosen based on calculation results of temperature field being formed in surface layer of material in one pulse regime irradiation. It is shown that electron beam processing of ~5  mm thick faced layer results in formation of ~20  µm thick modified surface layer with α-Fe and NbC carbide major phases and negligible quantity of Fe₃C and Me₆C (Fe₃ W₃ C) carbides. The principle difference of the surface layer modified by electron beam processing from the unmodified volume of facing is morphology and dimensions inclusions of the second phases. In the facing modified layer inclusions have smaller dimensions and are located in form of thin interlayers along the grain boundaries. In the unmodified facing, basic morphological type of inclusions is particles of faceted shape located chaotically in grain volume. After electron beam processing wear resistance of the faced layer increases in more than 70  times in relation to wear resistance of Hardox  450 steel and friction coefficient decreases significantly (in ~3  times).

 

One of the important and difficult tasks of creation of Enterprise Resource Planning (ERP) of the enterprise is creation of the planned schedule of IT-services development, making the functional volume of the project by several, working groups acting in parallel. The complexity of the task, in particular, is connected with the need of coordination of planned schedules of groups among themselves caused by essential dependence of IT-services of various business processes as well as with the need for rational distribution of total amount of resources between the working groups. Mathematical statement and set of procedures of the problem solution of IT-services scheduling of Enterprise Resource Planning of the large metallurgical company is given. Each service is described by two characteristics: duration and design costs. Expenses on design depend on time of the beginning of service development. Problem definition is based on three indicators of efficiency of the planned schedule of the ERP-project: on the number of communications between separate IT service and other ERP-services, on duration of action of the design decisions made for each service and on the size of the project budget. The first two indicators are used for formation of criterion of a task which describes degree of coherence of planned schedules of the working groups, and the third is accepted as restriction of a task. The method of network programming is applied to the task solution. The method decomposes a difficult initial task on the basis of structural and similar network representation of criterion and restrictions for the sequence of significantly simpler subtasks which solution is carried out by the method of dichotomizing programming, and integration of solutions of subtasks – by means of application of consecutive composition. In article the example of the studied task solution is given in which structural and similar network representation of criterion and restrictions is described by a tree branch. The constructed planned schedule is a basis for the solution of determination problem of functional volumes of pilot testing of Enterprise Resource Planning and creation of technical structure of the corresponding test environment for the purpose of the design decisions verification made at IT-services developing.

The tasks of increasing strength of heat-strengthened rolled products require thorough search for technical solutions, determined by level of understanding of processes occurring in thermal strengthening devices, of which the main is the process of water interaction with hot rolled product. This complex set of phenomena includes movement of water flows relative to moving rolled metal, emergence of vapor gap between water and rolled metal, generation of nanosized droplets and their movement through the layer of vapor, the droplets impact on surface, excitation of elastic waves in rolled material. Analysis of previously derived dispersion equation for Kelvin-Helmholtz instability of vapor-water interface was carried out. It is shown that for 30–60  m/s difference in velocities of liquid and vapor layers, the maximum increment in nanoscale range of wavelengths is observed. Average size of generated drops is determined by wavelength at which the maximum increment dependence is reached. Thus, mechanism of accelerated cooling of rolled steel proposed earlier is confirmed by quantitative calculations. Drops, reaching rolled metal, excite thermoelastic wave which being distributed along its section promotes increase in impact strength. To reveal regularities of propagation of elastic waves created by drops in rolled metal, problem of theory of thermoelasticity in cooling was solved by method of Fourier and Laplace integral transformations. It turned out that the problem posed is analogous to the problem of heating the surface with triangular temperature profile. Evolution of stress waves was investigated. At initial moments, the front of wave appeared to be a stretching wave. When reflected from the free end, the wave becomes a compression wave with stresses leading to cracks closure, and thus it leads to increase in toughness. Obtained results can be used in search for optimal modes of heat treatment of rolled products, providing high mechanical properties.

Theoretical comparative analysis of cutting of straight and precurved strip of rolled metal has shown energy efficiency of the second method. It has been experimentally proved that during cutting of precurved strip of rolled metal in scissors with parallel knives, complex stressed state arises, while cutting force and correspondingly energy consumption of cutting process reduces as compared to cutting of straight strip.