The article reveals one small page in the development of metallurgical science and technology in the Soviet Union, namely, the history of establishing scientific contacts between American and Soviet metallurgical scientists in the second half of the 1950s. Unto middle of 1950s the successful recovery of the USSR economy after the war ended with a scientific and technological breakthrough in the field of atomic and space technologies. This significantly strengthened the political and humanitarian authority of the USSR in the eyes of the world community, making the country attractive for scientific and technical cooperation. The rush of the Soviet atom and rocketry would have been impossible without high achievements in the basic sectors of the economy, such as metallurgy. The United States and its Western European allies came to understand the prospects of limited scientific and technical cooperation with the USSR and the unproductiveness of the policy of its isolation. The establishment of scientific and business contacts with Soviet metallurgical enterprises, research institutes and educational institutions forced the Americans to critically rethink their own achievements in the industry.

This paper provides information regarding the application of niobium in industry and the scale of its production in the world and the Russian Federation. Most of the niobium deposits in Russia consist of pyrochlore, apatitepyrochlore and columbitepyrochlore types of ores. They contain a significant amount of phosphorus. Therefore, all enrichment schemes for these ores contain a dephosphorization stage which increases the price of the product and reduces the degree of niobium extraction. The paper explores the possibility of improving the end-to-end production scheme: niobium ore – beneficiation – niobium ferroalloy. The bulk of ferroniobium is intended for steel microalloying and can be replaced by complex ferroalloys with a reduced niobium content. The paper considers the issues of obtaining complex niobium ferroalloys from a rough concentrate with a weak content of niobium. It has been established that the addition of 25 – 40 % of silicon or 12 – 30 % of aliminum to the twocomponent metal system Fe – Nb causes the transfer of niobium ferroalloys (15 – 20 % Nb) from the refractory category to lowmelting materials. The crystallization temperatures are less than 1400 °C. The substantiation of using a complex niobium ferroalloy instead of ferroniobium is given. This alloy has reduced niobium content and increased silicon or aluminum content. Higher service characteristics of the complex ferroalloy are noted in comparison with ferroniobium (temperature of the initiation of crystallization and density). They indicate an increased assimilation of niobium when using a complex ferroalloy for steel microalloying. The paper presents data on the possibility of dephosphorization of niobium concentrates in the process of pyrometallurgical production of a complex ferroalloy. An improved scheme for the production of niobiumcontaining ferroalloys is proposed. This consists of the use of niobium concentrate for melting the intermediate ferroalloy containing a reduced concentration of niobium oxides and an increased concentration of silicon (aluminum). This ferroalloy can be used effectively for steel microalloying with niobium.

The paper considers the studies of bending of a plate made of A32 ship steel with a through-the-thickness gradient of strength properties. The grading was produced by accelerated one-sided cooling of the plate from the austenitic area. As a result, a spectrum of microstructures was formed over the thickness of the plate: from ferrite-bainite on the cooled surface to ferrite-perlite on the other. During elastic-plastic bending of a steel plate with a homogeneous microstructure, the neutral surface shifts towards the compressed fibers, which is explained by the greater resistance of the material to compression than to tension. The purpose of this work was to develop a finite plastic deformation model of bending of a steel plate with tension/ compression (T/C) asymmetry and a strength gradient to confirm the expediency of one-sided thermal reinforcement of rolled sheets. It is confirmed that the displacement of the neutral surface caused by T/C asymmetry depends on the asymmetry ratio and does not depend on the steel microstructure, and is directed towards the compressed fibers. The displacement caused by the strength gradient depends on the absolute value of this gradient and is directed towards it. Calculations revealed that the critical bending moment for a plate made of A32 steel with a strength gradient is not less than that for the normalized and thermally hardened (by quenching and tempering ) states, at any direction of the strength gradient with respect to the bending direction. It is concluded that the proposed technology of thermal reinforcement of heavy-plate rolled products made of carbon and low-alloy steels using accelerated one-sided cooling provides mechanical properties not worse than for the thermally hardened state. This saves up to 40 % of cooling water.

Analysis of the screw rolling process showed that change in axial speed of the roll along the length of the roll groove of cross rolling mill does not correspond to the required character of change in the speed of deformed billet. The process proceeds under intense axial compression, as a result of which a significant part of the metal crimped in the contact zone is displaced into the inter-roll area. It is shown that direction of the axial force in the corresponding zone of the roll groove depends on the value of inclination angle of the considered roll section generatrix to the rolling axis. The proposed modernization of screw rolling technology makes it possible to carry out deformation of the billet under the influence of intra-focal axial tension. The task is accomplished by rolls calibration when at the beginning there is a ridge section of the roll on which the axial force is directed against rolling direction; and behind it, a pulling one, on which the direction of the axial force coincides with rolling direction. Such a scheme of the axial forces action in the zone of intensive billet reduction creates the most favorable conditions for the metal flow in axial direction. A technical solution is proposed for the implementation of the stage of the billet gripping by rolls, and description of this stage and the process stationary phase is given. The cardinal change in the billet deformation condition after modernization makes it possible to reduce the power load on the work rolls, increase their efficiency and reduce energy costs during rolling. This will ensure the rolling of a solid billet in a roughing mill with a higher stretch, create the preconditions for expanding the size and grade assortment when obtaining rods in radial-displacement rolling mills and at production of pipes in rolling lines with the Assel mill. The range of finished products can be significantly expanded due to the production of thin-walled highprecision pipes.

The report considers development of a methodology for heating slabs with a system of flat jets interacting with the metal surface. Heating technology must meet modern requirements for uniformity of heating, energy efficiency and optimal heating rate. Multivariate calculations were performed with changes in location, number of devices and distance from the nozzle exit to the heating surface. In this work, using the ANSYS Fluent program, an instrumental system was used through the mechanism of blowing devices that form 8 and 9 jets. In the developed methodology, it is proposed to use heated nitrogen, which simultaneously performs two functions: heat engineering and technological (as a protective atmosphere).

The authors have investigated the structure of cutting seams obtained after cutting steel 09G2S with a new narrow-jet plasma torch of PMVR-5.3 type which has a number of design features in gas dynamic stabilization system (GDS) of plasma arc. To increase the efficiency of GDS in PMVR-5.3 plasma torch, a symmetrical input of plasma-forming gas (PFG) into the flow division system and a gas-dynamic flow stabilizer using two (forming and stabilizing) swirlers with a variable number of swirl channels were used. It is shown that the achieved advantage in GDS efficiency makes it possible to obtain high cutting quality of steel 09G2S with thickness of 40 mm with high productivity and lower energy costs. Analytical methods have proved a high degree of cutting precision of the new torch– a small cut width, no melting and rounding of the upper edge, as well as a grate in the cut lower part and splashes in the cut upper part, almost zero angular deviation, minimum values of the surface microrelief and width of the thermal impact zone. Metallographic analysis and determination of hardness showed the presence of three subzones in the thermal impact zone with significant structural changes in two of them. A number of factors were noted influencing the revealed changes in the structure formation, as well as changes in the elemental composition of the cutting seam surface layer revealed during the X-ray spectral analysis. Attention is drawn to the surface microrelief after plasma cutting, which in all quality indicators is commensurate with machining of the surface after milling and corresponds to the second class of quality in terms of surface cleanliness. It was proved that the use of the new narrow-jet plasma torch allows high-quality cutting of plate steel in thickness range up to 40 mm or more. However, welding of blanks without pre-machining can be carried out with a cutting thickness of no more than 20 mm.

Shipbuilding steels and alloys may be subjected to various types of corrosion damage when exposed to sea water. For reliable long-term operation of ships and marine structures, despite the use of corrosion protection, materials are chosen that, in addition to the required mechanical properties, have sufficient corrosion resistance to ensure a given service life. Evaluation of corrosion resistance of new materials for use in shipbuilding was made by carrying out mandatory delivery trials using methods that have been repeatedly tested experimentally and whose results have been confirmed in practice. The complex study of corrosion resistance of steels and alloys is based on step-by-step laboratory, bench, and field tests. The review provides a brief description of laboratory corrosion test methods that are part of mandatory delivery trials. Parameters determining the aggressiveness of seawater as a corrosive medium, including salinity, oxygen content are considered. Laboratory test methods include electrochemical studies with determination of potential and rate of corrosion, pitting potential on the basis of polarization curves construction, as well as the generally accepted gravimetric method of corrosion rate determination. Installations for testing in moving (with varying flow rate) seawater are given.

The studied numerical and analytical model of a semi-bounded body is used to simultaneously determine the thermophysical characteristics (TFC): thermal diffusivity a_t and thermal conductivity coefficient λ_t of the material which make it easy to determine the volumetric heat capacity с_t . Temperature distribution over the plate cross-section at the end of the calculated time interval τ is described by a power function, its exponent n depends on the Fourier number Fo. The values of TFC were calculated from the dynamics of changes in surface temperatures T(x_p = R_p , τ) and T(x_p = 0, τ) of the plate with a thickness R_p heated under boundary conditions of the second kind q = const. The temperature T(x_p = 0, τ) was used to determine the time moment τ_e , at which the temperature perturbation reached the adiabatic surface x_p = 0 (T(R_p , τ_e ) – T_b (0, τ_e = 0) = 0.1 K). Calculations of TFC (a_t and λ_t ) were performed using formulas whose parameters were found by solving a nonlinear system of three algebraic equations by selecting the Fourier number corresponding to τ_e . The author studied the complexity and accuracy of TFC calculation using the test (initial) temperature fields of a plate made of refractory material by the finite difference method. Dependences of TFC on the temperature a_i (T ), λ_i (T ) and c_i (T ) were set by polynomials. Temperatures of the plate with a thickness of R_p = 0.04 m with initial conditions T_b = T(x_p , τ = 0) = 300, 900, 1200, 1800 K (0 ≤ x_p ≤ R_p ) were calculated for a specific heat flow q = 5000 W/m². The heating time to τ_e was 105 – 150 s. The average mass temperature T_{m, pl} of the plate during the τ_e increased by 5 – 11 K. The TFC values were restored by solving the inverse thermal diffusivity problem for 10 time points    τ_{i + 1} = τ_i + Δτ. The arithmetic mean deviations of TFC (T_{m, pl} ) from the initial values for calculations at T_b = 300, 900, 1200, 1800 K were less than 2.5 %. It was established that the values of a_t and λ_t obtained for the time moments t_i are practically constant, therefore, a simplified calculation of a_{t, o} and λ_{t, o} is possible only from the values of temperatures T(R_p , τ_e ) and T(0, τ_e ) at the end of heating. The values of a_{t, o} and λ_{t, o} , which were calculated immediately for the entire heating time, differed from the initial values of the accepted heat exchange conditions by about 2 %. The parameters of simple algebraic formulas for calculating a_{t, o} and λ_{t, o} were found by solving a system of three nonlinear equations n = n( Fo), a_{t, o} = a(T_b , T(R_p , τ_e ), R_p , n, τ_e ), Fo = Fo(a_{t, o} , R_p , τ_e ) and expressions for λ_{t, o} = λ(R_p , q, n, T_b , T(R_p , τ_e )). The proposed method significantly simplifies the solution of the inverse problem of thermal conductivity.

The chemical process of iron reduction from magnetite by gaseous reducing agents is the basis of MIDREX technology implemented at the Oskol Electrometallurgical Plant (OEMK). In the paper, this process was modeled using the TERRA software package developed at the Bauman Moscow State Technical University. During the simulation, thermodynamic system Fe‒С‒О‒Н was analyzed at constant temperature (900  °C) and gas pressure (0.2026 MPa). Mixtures of carbon monoxide and hydrogen in different ratios, as well as individual components of natural hydrocarbon gases, were used as reducing agents. The chemical compositions of reducing agents were estimated by the gross formula С_рО_rH_q , where p, r and q are stoichiometric coefficients. The results of the calculations were the expenses of the reducing gas m, necessary for the complete iron reduction from magnetite, which corresponded to the degree of iron metallization φ  =  1. In the future, the values m were used to evaluate the reducing abilities of various gas mixtures, and the values of φm – to determine the required expenses of these mixtures for iron reduction. Subsequent analysis showed that the machine calculation of the value m can be approximated with a small error (up to 0.001) by the formula where m_C and m_H are the partial costs of carbon and hydrogen for iron reduction, respectively, and m_O is the partial oxygen consumption for iron oxidation. It was also established that the parameters of m_C and m_H depend on the process temperature and are interrelated in accordance with the equation where K is the chemical equilibrium constant of the “water gas reaction” CO + H₂ O = CO₂ + H₂ , simultaneously occurring in the gas phase. The m_O parameter is actually a constant independent of temperature and numerically equal to the value of (–4/3) moles per 1 mole of iron. The arguments of partial costs can also be characteristic molecular compounds accompanied with appropriate stoichiometric coefficients. In the practice of OEMK, natural gas consumption V is taken into account, measured in cubic meters per ton of sponge iron. The forecast of this value can be performed using the formula: In general, the proposed calculation algorithm of the chemical process can be correctly applied in the temperature range of 800 – 900 °C. Possible variations in the gas working pressure will not require significant adjustments in the calculation results.