The authors discuss the investigation results of phase transformations in the slag of sulphuric cupreous melting during its reduction by the products of gasification of carbon at the temperatures 1100 and 1200 °С. It was experimentally found, that in belllike equipment at the temperature 1100 °С the most part of iron from dump slag of sulphuric melting of the cupreous concentrates may be reduced to metallic state by the products of carbon gasification. Subsequent rise of temperature up to1200 °Cenables to increase iron recovery. During the indirect reduction of the slag at the temperature above temperature of its melting, metallic iron concentrates mostly at the external surface of product of reduction, producing large inclusions, which may be easy extracted by magnetic separation. It’s mostly rational to reduce multilayer blend, consisting from slag layers with the thickness less than5 mmand separating them layers of grinded coal. 

The research group has investigated the infl uence of the cooling rate of a casting on the coefficient of abrasive wear resistance and has proved that wear resistance is determined by the thickness of the layer hardened by twinning-induced plasticity, which is formed on the wearing surface. It was found that the maximum thickness of the hardened layer is formed both at high and at low cooling rates, which is connected with the decrease in the value of the stacking-fault energy (SFE). This value, in its turn, varies depending on the content of manganese, chromium and silicon. At medium cooling rate the achieved doping level of austenite results in the increase of the SFE value. It also hampers the process of twinning-induced plasticity (TWIP) and results in forming of a hardened layer of minimum thickness or this layer is not formed at all. 

The work presents experimental data on influence of temperature, degree and speed of deformation on resistance of deformation of the carbonaceous low-alloyed steel. The research was conducted at test of samples on the torsion STD 812 plastometer of Chenstokhovsky University of Technology. According to the study of deformation resistance, hardening curves were constructed for carbon low-alloyed steel at different speeds and temperatures of deformation. Common to all curves is a high hardening speed of the hardening in the initial period of deformation when the action of relaxation processes is not apparent. The authors have installed important for the practical use quantitative characteristics of the influence of the temperature-rate conditions of deformation on the maximum value of the deformation resistance reduction as a result of relaxation processes and on the average speed of hardening at the interval 0<ε_u<ε_u^*.

The analysis of quality of large diameter welded pipes depending on the parameters and modes of the slab forming on press equipment is presented. Mathematical modeling of the processes was performed using the finite element method. The results of the stressstrained state of metal during round billet forming billets in forging equipment are shown. Established computer program allows calculating of process parameters settings of press equipment to determine the value of controlled geometric parameters of round billets, required in the regulations. The theoretical solutions were experimentally tested on assortment of large diameter pipes, produced at TESA 1420. It is recom mended to use this method to calculate the LDP forming parameters and pressing equipment settings that allows reducing the number of defects caused by the geometry of the fl anging press and JCO-press. 

The calculation methods of heat losses and temperature were adapted to the air tuyeres for blast furnaces. The influence of gas-thermal coatings and insulating paste on the thermal condition of the air tuyeres was investigated with the help of a linear program in EXCEL. It is shown that the presence of the inserts has a greater impact on reducing heat loss through the blow channel than the application of aluminum coatings. The creation of the air gap between the insert and the inner glass leads to a further reduction of heat loss. Thus, the greater thickness of the insert installed without a gap in the blow channel leads to the less heat loss through the blow channel. If the insert is installed with a gap, its thickness almost does not effect on the heat loss through the blow channel. 

The peculiarity of power parameters of screw rolling process of pipes on a three-roll rolling mill is the presence of two areas: reduction and compression with diff erent specifi c forces of metal acting on the roll. The reduction zone is formed by a tangential expiration, as well as plastic bending sleeve wall in the gaps between the rolls and depends on the mill chamber tuning parameters, geometric parameters of the derived pipe, namely, the ratio of the diameter to the wall thickness D / S. Computer modeling of rolling process has shown that a distributed force or stress of the metal on the roll in the reduction zone is 75% of the eff ort in the compression zone with either major deformation of the liner wall. Stress reduction in the deformation depends primarily on the wall thickness of the liner. With the change of the liner wall thickness along the length of the deformation zone specifi c force in the reduction zone is reduced by an average of 20 MPa. In the compression zone, the value of the metal eff orts on the roll depends on the width of the contact surface and the impact of additional compressive and tensile stresses from the reeling mandrel mill. Determination of compression forces in the drafting area makes it possible to calculate the estimated force acting on the mandrel, which is especially important in the calculation of rolling modes on the controlled movable mandrel. 

The authors have established the aim of mathematical modeling of gas dynamics and steady-state heat transfer in layer shaft furnaces, in which the gas stream moves to a complex system of curved channels of variable curvature and cross-sectional area. The problem of the development of complex mathematical models of layer metallurgical furnaces and units is to obtain the equations of gas flow in the moving bed, linking average speeds at space between pieces (true speed), its actual pressure and temperature, as from these values depends the intensity of physical and chemical transformations. The solution to this problem is performed using a parallel between the passage of the gas in the bed and the movement of a hypothetical fl uid, which occupies the entire volume of the device, including the amount of lump materials.

Metallic phase formation model in the barbotage process of oxide melt by gas-reducing is considered. The model includes following stages: bubbles formation during gas injection into the melt, redu cing of the metal on the bubble surface and its drops concentration on bubble stern and this system “gas bubble – metal drop” movement. The direc tion of this movement was determined by the balance of forces that provide bubble fl oating and metal drop sinking, drops ejection onto the surface, its coalescence and sinking after reaching sizes that provide excess over the sum of the gravity force and the hydrostatic ejection surface tension. The equations related to estimation of the sizes of gas bubble and metal drops moving in the oxide melt without fragmentation, direction of the “gas bubble – metal drop” system movement, the rate of its fl oating and sedimentation and separation conditions. The factors that aff ect stratifi cation processes were determined – that are surface properties of the oxide and metal melts and their interfacial characteristics. These parameters variation controls the formation processes of metal bottom phase.

Melting of steel and alloys is usual fi nished with casting a metal into a mold. It is necessary to know the liquidus temperatures of the casting alloy. The problem of casting is especially relevant for developing the technology of smelting the nickel-based alloys containing large amount of alloying elements. The aim of this work was to create a model for prediction the liquidus temperature of nickel-based complex alloyed steels. According to the literary data on the diagrams of the binary systems, the regression coefficients of the equations of liquidus and solidus lines of binary systems were defined. The data array of the regression coefficients is expanded from 21 to 27 elements, that allows to cover wider range of nickel-based complex alloyed steel. Testing of the model, formed with the data for double alloys, according to the array of experimentally defi ned liquidus temperatures of nickel-base complex alloyed steels shows that it is possible to predict the liquidus temperature of such alloys with an accuracy high enough for technological practice – ±19.8 °C– using the created model.

The article presents the results of the investigation of infl uence of the boundary conditions heterogeneity on the rate of cooling of the metal during the continuous casting of cylindrical billets of highquality steel grades. It was assumed that the boundary conditions are not uniform along the length of the billet. The authors have made the comparative analysis of temperature gradients and thermal stresses occurring in solidifying billet at diff erent cooling modes implemented in the secondary cooling zone. The conclusions about the impact of the cooling intensity on the quality of the cylindrical cast billets were obtained on the basis of these results. The article also provides recommendations on the organization of rational heating modes of casting of cylindrical cast billets.

The article describes the investigation of treatment processes of such alloys as Fe – Cr and Fe – Cr – Ni by oxygen-containing plasma. The laboratory unit, which is a plasma furnace with a tungsten cathode and a water-cooled copper anode, can simulate processes that occur in the contact area of plasma arc and melt surface. It was also developed a mathematical model describing the processes occurring in the interaction between plasma torch and surface of the molten metal. According to the results of the experiments the authors have determined the kinetic parameters of decarburization process of high-chromium melts by argon-oxygen plasma. The results allow to conclude that treatment of high-chromium melts by plasma which contents less than 15–17 % of oxygen provides a high degree of decarburization with low chromium haze. The comparison of model calculations and experimental data has shown good reproducibility.

The corrosion resistance of high-strength austenitic Cr – Ni – Mn steels alloyed by nitrogen and optionally copper was experimentally studied in comparison with chromium-nickel steels Cr18Ni9 and Cr18Ni9N using electrochemical station Zive MP2. There were received polarization curves and electrochemical parameters of general, pitting and intercrystalline corrosion in diff erent media: aqueous solutions of 3 % NaCl; (100 g/l) FeCl₃·6 H₂O; 0.5M H₂SO₄ ; 0.5M H₂SO₄ + + H₂S blowing; 0.5M H₂SO₄ + 0.01M KSCN. The conditional corrosion rate was calculated. According to the results of the research it was concluded that all steels are corrosion-resistant with high resistance to the general, pitting and intercrystalline corrosion in chloride media. Cr – Ni – Mn austenitic steels, alloyed by nitrogen, especially in conjunction with nitrogen and copper, with a balanced content of nitrogen and another alloying element in the composition, even at a lower content of nickel, aren’t subject to pitting corrosion in sea water and have not only great strength but also great corrosion resistance, including acidic medium (0,5M H₂SO₄ ) compared to traditional steel Cr18Ni9.

The structure and properties of the weld metal by arc method alloy of Fe – Cr – C – Mo – Ti – Ni – B iron were investigated. The eff ect of the modifi er on the basis of TiN titanium nitride on hardness and resistance of welded metal to abrasion was studied at normal and elevated temperatures.