Advance high strength steel with minimum UTS of 780 MPa is industrially developed utilizing continuous annealing line (CAL) and Gleeble thermo mechanical simulation. An outline of superior elongation, improved strain hardenability, enhanced strength of developed Fe – C – Mn – Si TRIP assisted steel is described. Correlation amid Simulated result and industrially annealed steel are stabilized for microstructure and mechanical property. Annealing condition is optimized for best combination of strength and formability accordingly. CCT diagram for the selected composition from JMatPro is utilized to optimize rapid cooling rate and over aging section temperature. Final microstructure of developed steel comprises tempered martensite, granular bainite with retained austenite distributed in polygonal ferrite matrix. An evaluation of developed TRIP steel is carried out with the help of microstructure and XRD analysis. It was concluded that strain hardening coefficient of new steel is comparable to that of drawing grades attributable to about 13 % retained austenite in microstructure.

The method for calculating indicators of blast furnace smelting with replacement of part of coke with additional fuels has been developed on the basis of full and complex compensation and compensating measures. Efficiency of the use of natural gas and pulverized coal in the blast furnace conditions of the Enakievo Metallurgical Plant was calculated and it has been confirmed as rather high. Increase in the consumption of natural gas from the baseline (71.8 m³/t of iron) to 110 m³/t ensures a corresponding increase in productivity of the blast furnace to 107.6 % and a decrease in the consumption of coke to 417.3 kg/t of iron (–38.4 kg/t, –8.42 %). Replacing natural gas with pulverized coal in the amount of 160 kg/t of iron made it possible to completely remove it from the blast. At the same time, coke consumption decreased to 354.59 kg/t of iron (–101.1 kg/t; –22.18 %). Increasing the consumption of pulverized coal fuel up to 200 kg/t of iron with compensation of the blast temperature of1200 °Cand oxygen of the blast of 25 % provides an increase in the productivity of the blast furnace to 105.8 % and reduction of coke consumption to 303.8 kg/t of iron (–151.9 kg/t, –33.33 %). High efficiency of the use of pulverized coal in conditions of the Enakievo Metallurgical Plant is explained by its lower cost compared to natural gas, high carbon content in coal and a significantly lower effecton the theoretical combustion temperature and other technological parameters.

The use of galvanized scrap as a charge material for electric steel-smelting production leads to formation of metallurgical dust suitable for extraction of non-ferrous metals. Chlorine and organic compounds content in metallurgical charge can lead to dioxins and furans formation in the process of electric smelting with their subsequent sedimentation on EAF dust. In the previous study we determined dioxins and furans content in dust at the level of 474 ng/kg of EAF dust. The methodology for conducting an experiment in a muffle furnace at temperatures of 300, 600, 900 and 1150 °Cwas developed for the study of dioxins and furans’ behavior during dust heating. Investigation of EAF dust chemical composition before and after the experiment made it possible to establish that desorption of dioxins and furans occurs during heating in the temperature range of 300 – 900 °C. In parallel with dioxins and furans’ desorption some chemical compounds evaporate indirectly and it is determined by calculation of changes in the content of C, Na, Cl, K, Pb, Zn in the sample. In the studied temperature range, the content of C, Na, Cl decreases to zero; K content is reduced by 81 %; Pb content is reduced by 83.5 %. Reduction of Zn content does not exceed 5 %. Change in content of the remaining components is insignificant. The obtained data confirm the predominant presence of chlorine in inorganic compounds in forms of NaCl and KCl, along with a slight presence in forms of ZnCl, PbCl, and PbCl₂ . The study revealed the need of consideration of dioxins and furans’ presence during development of technologies aimed at metallurgical dust processing. It is proposed to perform high-temperature processing of dust (>850 °С) with the subsequent irrigation of exhaust gases with lime milk. The most rational ways to decrease dioxins and furans’ content in EAF dust are conducting afterburning of exhaust gases, followed by rapid cooling in order to avoid secondary synthesis of ecotoxicants or reducing the amount of chlorine-containing and conventional materials during pretreatment of metals.

Alloys of boron and barium are applied to improve the quality of cast iron, steel, aluminum and other metals. The first industry produces mainly in the form of ferroboron, containing 6 – 17 % of boron depending on the brand. It is produced by an expensive aluminothermic method due to the use of boric anhydride and aluminum powder. At the same time, presence of aluminum in the metal is inevitable, it degrades the technological properties of cast iron and forms line alumina inclusions in steel. Extra-furnace removal of Al leads to oxidation of boron and its loss with slags. Therefore, the authors have proposed new methods for smelting boron-containing ferroalloys. Recent developments include the production technology of boron-containing ferrosilicon, which has been tested in industrial conditions. But its use may be limited in smelting of low-silicon steel grades. Barium is an effective modifier. Due to its low solubility in iron, it is produced in the form of alloys with silicon or aluminum. In the first case, silicides (BaSi, BaSi₂ ) are formed and therefore such alloys are called silicon barium or ferrosilicon with barium. In present work, there has been studied the possibility of producing modifier with boron and barium ferroalloy. It was believed that the simultaneous presence of barium and boron in it can be demand for industry. At the first stage, chemistry of transformations in BaO– B₂O₃ – C ironless system was considered using the carbothermic method. A complete thermodynamic analysis of chemical interactions in this system was performed in the temperature range of 1400 – 3000 K. Possibility of the formation of a condensed metal phase due to boron carbides (B4C) and barium (BaC₂ ), as well as barium hexaboride (BaB₆ ) is shown. The obtained data can serve as the basis for creation of a new ferroalloy simultaneously containing boron and barium.

Alloys Fe – Cu can be characterized as a system with immiscible components (IC). This statement is based on a weak mutual solubility in the solid state. In addition, with low carbon content, the Fe – Cu system is also stratified in the liquid state [1]. Alloys with IC have a simple phase composition of almost pure components. This determines a significant practical interest in these alloys. Certain successes have been achieved in the technology of manufacturing damping alloys of the Fe – Cu– Pb system. With optimally selected technology for their preparation, it is possible to obtain the final product combining the properties of pure alloy components in the proportion required for practical application. For example, in Fe – Cu alloys, diamagnetic copper has high electrical conductivity and thermal conductivity, and ferromagnetic iron has enhanced strength characteristics compared to copper. When structure of the alloy is organized in a certain way, it is possible to obtain either a final product with high electrical conductivity and thermal conductivity of copper, enhanced strength properties of iron, or – a hard magnetic material with ductility of copper. The ironcopper system alloys were considered in [2 – 13], in which the main attention was paid to structural studies and measurements of service properties. At the same time, the dynamics of macroand microstructure formation of alloys were not analyzed. In the present work, it was the dynamics of macrostructure formation of the solid phase enriched with iron in process of crystallization of the melt during its cooling that was studied using high-temperature viscometry. Considering the final influence of the melt cooling rate on the size and morphology of crystallizing inclusions, and a significant amount of the two-phase area, special attention was paid to thermophysical analysis of the measurement mode. Analysis of reliability of the results obtained was made by the method of viscosity measuring. Phase state of the melts of Fe – Cu system was investigated during cooling by changing the damping factor. The analysis of thermophysical processes occurring in the measurement of the damping factor was carried out. It has been established that the process of measuring the damping decrement takes place under quasi-equilibrium conditions and the cooling rate is close to zero. There are no temperature gradients, both in radius and in height. For compositions Fe₅₀Cu₅₀ , Fe₄₀Cu₆₀ , Fe₃₀Cu₇₀ the dynamics of precipitation of the solid phase were determined.

Low-carbon steels deoxidized by aluminum are the main group of structural steels produced in Russiaand all over the world. These steels work in key sectors of the economy – construction, automotive, mining and transportation of minerals, etc. The deoxidation of steel melt by aluminum leads to the formation of non-metallic inclusions, which can significantly affect quality of rolled products and reduce the manufacturability of production due to overgrowth of submerged

nozzles during continuous casting. So, ceteris paribus, only due to contamination of steel with non-metallic inclusions, the following differences in technical and economic indicators can be observed: sorting by surface defects, reduced yield of cast slabs, increased corrosion wear rate, sorting by ultrasonic inspection defects, etc. Due to the particular shape, size and state of aggregation, non-metallic inclusions based on aluminum deoxidation products are difficult to remove from the steel melt. An effective way to reduce steel pollution by similar inclusions is modifying their composition to a liquid state of aggregation with calcium, which requires careful preparation of the molten slag and metal. The article describes in detail the main thermodynamic features of this process. On the example of IF-steel, we present calculation of the target range of calcium content to ensure the inclusion modification to a liquid state depending on aluminum concentration in the steel melt. The limiting sulfur concentrations in the metal melt are determined depending on aluminum and calcium contents, which ensure prevention of the formation of refractory sulfide shells on oxide non-metallic inclusions.

Alloys of Ni – Co system are widely used in industry. Oxygen is one of the harmful impurities in these alloys; in metal it is present in dissolved form or in the form of nonmetallic inclusions. Getting the finished metal with a minimum oxygen concentration is one of the main tasks of production process of these alloys. With the complex deoxidation of the metal melt, the activity of oxides resulting from the deoxidation process is less than one, due to this, with the same content of deoxidizing elements, it is possible to obtain a metal with a lower oxygen concentration, therefore, more deeply deoxidized. At joint deoxidation with two deoxidizers, a stronger deoxidizer takes a predominant part in the reaction, however, if oxides of the deoxidizing elements form chemical compounds, it contributes to participation of a weaker deoxidizer in deoxidation process. A thermodynamic analysis of the joint influence of aluminum and silicon on the solubility of oxygen in the melts of Ni – Co system has been performed. Deoxidation reaction products may be formed as mullite (3Al₂O₃·2SiO₂ ), and kyanite (Al₂O₃·SiO₂ ). Presence of silicon in the melt enhances the deoxidizing ability of aluminum: insignificantly in the case of formation of compound 3Al₂O₃·2SiO₂ and significantly in the case of formation of compound Al₂O₃·SiO₂ . Oxygen solubility curves in the case of formation of compound Al₂O₃·SiO2 pass through a minimum, the position of which depends on the content of aluminum in the melt and doesn’t dependent on silicon content. Aluminum content in the minimum points is insignificantly reduced from nickel to cobalt as in the case of melts of Ni – Co–Al. Further additives of aluminum lead to an increase in oxygen concentration. Areas of compounds Al₂O₃ , 3Al₂O₃·2SiO₂ , Al₂O₃·SiO₂ and SiO₂ depending on aluminum and silicon contents in the melt are determined. In melts of the Ni – Co system, the deoxidizing ability of aluminum and silicon increases with an increase in cobalt content in the melt. However, silicon enhances the deoxidizing ability of aluminum the weaker the higher cobalt content.

The recrystallization processes in steel St.3 inthe ferrite state were studied. Samples with diameter of 8 mmand with height of 10 mmwere deformed by compression at 20 °Cfor 20 to 80 %, annealed at 400 – 735 °Cfor a period from 5 minutes to 10 hours, and cooled in the air. On the samples, the grain size was determined in longitudinal sections (with respect to the compression axis). After separation of the entire array of experimental data (degree of deformation ε, temperature T and time τ of annealing, grain size D) into 3 groups (no recrystallization, beginning and end of the primary recrystallization), the equations of hyperplanes best sharing these groups were found by the method of discriminant mathematical analysis. Recrystallization is not observed if the temperature is below 465 °C, or if the degree of deformation is lower than 20 % for any combination of other parameters. The deformed structure completely recrystallizes if the experimental points are in the parameter range: T > 550 °C, ε > 40 %, τ > 30 min. The largest grain refinement (up to 7 – 10 μm) was obtained after deformation with a maximum degree (80 %). The first critical (physical) degree of deformation, after which the size of the recrystallized grain is larger than the original one, is absent. The second critical (technical) degree of deformation is 25 – 35 % for temperatures of 530 – 735 °C. At such degrees grain refinement was observed in comparison with the initial deformed state. Mathematical relation between the size of the recrystallized grain and the experiments’ parameters was analyzed in two ways: according to Arrhenius in the form D=Aε^Nτ^Mexp (-Q/RT) , and according to Hollomon with linear temperature dependence (D ~ T). The Arrhenius solution gave the following equation: log(D) = 2,08 – 0,33log(ε) + 0,023log(τ) – 967,31 1/T. Therefore, activation energy of the recrystallization process is found to be ~18,000 J/mol. In case of the Hollomon analysis, it was proposed to use the function Р_Н = T/1000 [СН – log(τ) + log(ε)] as the Hollomon parameter, and the Hollomon constant of CH should be found by numerical methods. For these conditions, the equation D = –21,317 – 0,034T + 0,0032log(τ) T – 0,0032log(ε)T was obtained. The accuracy of both descriptions, defined as the sum of deviations squares of the measured grain sizes from calculated, is equal to ~3,3 μm or (when normalized to an average value) ~20 %.

The paper is devoted to examination of the effect of boron modification and temperature conditions for metal cooling in a mold on phase composition, morphology and chemical composition of structural components of heatand wear-resistant white cast iron of Fe – C– Cr– Mn – Ni – Ti–Al – Nb system. The phase composition of the metallic base changed from the dualphase (α- and γ-phases) to the completely single-phase (γ-phase). Boron modification influenced on the type of secondary carbides, while secondary hardening in a mold occurs through extraction of dispersed niobium carbides (without boron, but with chromium carbides). The structure of modified cast iron is presented by the primary complex carbides (Ti, Nb, Cr, Fe)C, as well as by solid solution dendrites, eutectics and secondary carbides MeC. Boron addition changes the chemical composition of primary carbides with decrease of niobium content from 44 to 2 % and increase of titanium content from 24 to 65 %; content of eutectic carbides rises as well. As for hypereutectic carbides, they are characterized by increase of ferrum content and lowering of chrome content. Parameters of the primary phases (MeC carbides and solid solution dendrites) were investigated using the methods of quantitative metallography. The special technique of Thixomet PRO image analyzer was used for evaluation of the F form factor which is the criterion of compatibility of the primary phases. The following parameters were used in this work as the parameters of dendrite structure: dispersity of the dendrite structure (δ), volumetric part of dendrites (V), distance between the axes of second order dendrites (λ₂ ), form factor (F), average dimensions of dendrites – square (S), length (l) and width (β). All the suggested characteristics (parameters) allowed not only to provide quantitative evaluation of the dendrite structure, but also to determine modification degree as relative variation (in %) of each criterion in modified cast iron in comparison with non-modified iron. Quantitative relation between modification degree and crystallization conditions were established as well.

The authors have studied cold resistance of thelaboratorymetal of a new austenitic grade of nitrogen-containing casting steel (21 – 22) Cr – 15Mn – 8Ni – 1.5Mo – V (Russian grade  5Kh21АG15N8МFL) with nitrogen content of 0.5 % and yield strength of ~400 MPa. The temperature dependence of impact toughness was constructed in the range +20 ... –160 °C and it was shown that the steel is characterized by a wide temperature range of the viscous-brittle transition with T _DBT = –75 °C, at which KCV = 120 ± 10 J/cm2. Comparison material – industrial, centrifugally cast 18Cr – 10Ni steel (grade 12Kh18N10-CC) has such a KCV level at +20 °C. It is not prone to viscous-brittle transition, its impact strength decreases more gently and at temperatures lower than –80 °C and its KCV level is higher than that of nitrous steel. However, in the entire range of climatic temperatures, nitrous casting steel with 0.5 % of N exceeds its impact strength. The studied steels have residual δ-ferrite in the cast structure in an amount of up to ~10 % in Cr– Ni industrial steel and a smaller amount in laboratory nitrous steel. It is enriched by chromium, up to 26 and 34 wt. % respectively, and contains ~14 % of Mn in nitrogen steel. Presence of Mn does not affect the nature of fractures at climatic temperatures. However, δ-ferrite of nitrous steel at –160 °C is beyond the cold brittle threshold. Therefore, its fracture obtained at this temperature contains numerous cracks in δ-ferrite crystals. The critical fragility temperature below which this material is not recommended for use is Тк ≈ –110 °С; it was determined by the criterion method. It corresponds to a level of KCV of 68 – 83 J/cm², higher than the level of KCU at +20 °C, allowed by the standard of the Russian Federation for castings from austenitic class of steels (up to 59 J/cm² ). Based on a comparison of literature and our own data, it was concluded that it is impossible to ensure high cold resistance and, at the same time, high strength, due to alloying of economically alloyed nickel (up to 4 %) corrosion-resistant steels by 0.5 – 0.6 % of N.