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Electromagnetic stirring is a technique of influencing the crystallization pattern of a continuously cast workpiece and suppressing the development of a number of macrostructural defects in it. In this study, technological schemes are presented for application of electromagnetic fields in continuous-casting machines (CCMs) while discussing the resultant physical effects. We present actual results on the quality of steel obtained using a roller-type EMS system installed in the secondary cooling zone of a slab CCM at Novolipetsk Iron and Steel Work. [ABSTRACT FROM AUTHOR]

The ladle refining of iron-carbon melts is an essential component of the modern technology used in the production of iron and steel, ensuring the high quality of metal products. However, in the context of mini- and micro-factories using technological units of a limited volume, it is often unfeasible to implement modern, highly efficient refining, deoxidation-alloying, and heating schemes that are commonly used by ladle furnaces and degassers. In addition, the issue of the widespread use of various production wastes for the production of cast iron and steel in order to recycle them and reduce the consumption of conventional charge materials is relevant. Therefore, a new method of submerged arc reduction of elements useful for metallurgy from industrial waste and secondary materials directly into an iron-carbon melt for its deoxidation-alloying (refining), homogenization, and heating by a submerged electric arc is proposed. This technology eliminates the use of expensive reagents, ferroalloys, and alloying elements. Based on the conducted research, a scheme of the processes of submerged arc reduction of elements was established, the design of submerged arc furnace assemblies and their composition were proposed, and the high efficiency of the new method of ladle refining in comparison with conventional analogs was demonstrated. [ABSTRACT FROM AUTHOR]

The article compares the efficiency of technologies for feeding liquid metal into the mold of a continuous casting machine (CCM) and its flow within the mold volume under conditions of free and forced mixing. The influence of various designs of the developed mixing devices on the nature of the melt flow in the mold volume is analyzed. The objects of research are the hydrodynamic and thermal flows of liquid metal during the casting of steel into the CCM mold. [ABSTRACT FROM AUTHOR]

The behavior of the steel structure of cast ingot during rolling at the radial rolling mill RSP-10/30 was studied. The ingots for rolling were produced by vacuum induction melting from stainless steel 12H13. The ingots were rolled from a single heating in several passes from a diameter of 32 to 26 mm at 1200 °C and from 25 to 13 mm at 800 °C. This enabled, per one operation, to substantially change the sample structure from a coarse-grained cast dendritic structure of 0.5–1.5 mm to an equiaxed fine-grained structure with grain size 1–4 μm in the peripheral part and elongated grains of larger size in the axial part of the rolled billet. [ABSTRACT FROM AUTHOR]

Electromagnetic stirring (EMS) of the liquid phase of billets is one of the most technologically advanced methods to enhance the macrostructure quality of continuously cast slabs produced on high-performance continuous casting machines (CCMs). Under the influence of EMS, a forced movement of the melt is created relative to the crystallization front. The temperature gradient across the cross-section of the slab and the chemical composition of the steel are stabilized via heat and mass transfers. A project was implemented at Novolipetsk Iron and Steel Works to equip a slab CCM with an EMS system in the secondary cooling zone of a continuously cast ingot (CCI). This paper presents the industrial development results of the teeming electrotechnical steel technology using the EMS system. Furthermore, the key aspects of stirring and technological parameters of teeming electrotechnical steel are presented. The effect of EMS on the quality of a CCI is confirmed in terms of crystallization structure variations with an increase in the zone of equiaxed crystals by more than twice in comparison with the typical teeming practice. Furthermore, it has been established that using EMS can effectively influence liquid steel and considerably enhance the quality of the CCI macrostructure and the uniformity in the properties of finished rolled products. [ABSTRACT FROM AUTHOR]

The paper considers stresses emerging in the skin of a continuously cast steel billet, as well as their values under the influence of temperature expansions in a novel patented design of a nickel mold with a two-circuit cooling system. According to the known values of heat flux densities at various distances from the top of the mold, the temperature of the slag-forming mixture and the average temperature of the steel billet skin are determined. Based on the established thickness of the billet skin, the temperature gradient therein is determined. At a steel casting speed of 4 m/min, the values of temperature stresses in the billet skin at various distances from the top of the mold were established not to exceed the values of the metal flow stresses at corresponding temperatures. [ABSTRACT FROM AUTHOR]

The solidification structure of a continuous-casting slab of high-SiMnTi steel at different drawing speeds was predicted by performing experiments using a thermal-simulation device for dendrite growth. The microstructure of a characteristic cell of the solidified steel was mainly composed of fine equiaxed crystals in the chilling region, coarse equiaxed crystals in the core, and columnar crystals in between. Increasing the drawing speed of continuous casting improved the quality of the slab. When the drawing speed reached 1.2 m/min, the proportion of equiaxed crystals in the core was approximately 64.2%, and the degrees of segregation of the major solute elements, C, Mn, Si, and Ti, were the lowest (1.02, 0.98, 0.74, and 1.13, respectively). Our strategy to optimize the continuous-casting process was to adjust the parameters such that the slab more easily experienced CET transformation and had a larger chemical supercooling width. Therefore, our study provides an effective means of characterizing and a technical reference for the continuous casting of high-SiMnTi steel, and enables its process optimization. [ABSTRACT FROM AUTHOR]

We study metal samples taken from two batches of hot-rolled, semi-finished steel products and two batches of grade HC340LA cold-rolled steel, annealed in bell-type furnaces, produced from transitional slabs obtained by continuous casting of the developed high-strength, low-alloy, microalloyed, auto-sheet steel microalloyed with titanium (Ti) onto steel microalloyed with niobium (Nb). Based on the results obtained, for the first time, the possibility of continuous casting of the developed high-strength, low-alloy, auto-sheet steel microalloyed with Ti onto steel microalloyed with Nb is established. It is revealed that both grade S420MS hot-rolled steel according to EN 10149 and grade HC340LA cold-rolled steel, annealed in bell-type furnaces, can be simultaneously produced from transitional slabs while meeting EN 10268 requirements with reduced costs. [ABSTRACT FROM AUTHOR]

The Nb effect on long-term strength of Cr18Ni10Ti steel is considered. A justification is provided for selecting this steel to obtain cast parts for metallurgical furnaces. It is shown that an introduction of Nb in the amount of 1% into the steel of a given composition increases tensile strength and longterm strength by 15%. Improvement of properties is associated with the formation of niobium carbides (NbC). [ABSTRACT FROM AUTHOR]

A description is provided for a new patented design of a slab crystallizer and its cooling system with calculation results and identified shortcomings obtained previously. In the work using Autodesk Simulation CFD software, heat transfer is simulated in slab molds of two designs with different wall materials and cooling systems. Melt is supplied to the crystallizer through a submersible deep-bottom nozzle with two outlets. Results of heat transfer modeling using the program are presented in the form of temperature distribution along the length of the mold wide wall. Workpiece crust thickness is considered according to previous calculation results. Maximum values of wall temperatures obtained are comparable with calculations performed previously. Based on results of the color images shown in pictures of the wall surface temperature maximum and minimum values, temperature differences along the length of the walls are established, which are compared for various mold designs, cooling systems, and wall materials. Use of the new slab crystallizer permits an increase in wall working surface temperature up to 300°C and a reduction in temperature drop along the length of the wide wall by a factor of 4–5 compared with the existing copper design of the slab crystallizer. The result obtained points to the possibility of preparing highly-alloyed steel slab billets with a better surface. [ABSTRACT FROM AUTHOR]

Work was carried out to improve the macrostructural quality of a continuously cast round billet for solid-rolled railroad wheels and axles of locomotives. The influence of secondary cooling and the temperature and speed of steel casting on the formation of centerline porosity (axial looseness) as a macrostructural defect is analyzed. It is established that the deviation of the water distribution in the secondarycooling zones from parabola has a significant effect on the formation of this defect. The optimal secondary-cooling and temperature–speed conditions that improve the macrostructural quality of the billet were established. The implementation of these conditions resulted in deterioration of the surface quality of the billet. To maintain the required surface quality, a new slag-forming mixture, an automatic mixture feed technology, and a mold oscillation mode were developed. [ABSTRACT FROM AUTHOR]

The paper draws attention to the existing problem of the formation of a defect in the form of a carbide network in cast high-speed steels, which makes products made of such material susceptible to brittle fracture during their operation. The paper also points out high hardness of the particles of pulverized high-speed steel powders, which is why compact products made of these powders are currently obtained by a technologically complex method of hot isostatic pressing. As an alternative to such a powder, a powder mixture of R6M5K5 grade steel is considered, which contains a diffusion-alloyed spongy powder based on tungsten, molybdenum, cobalt, and iron, and can be compacted by cold pressing. A study of the structure of a billet made of such mixture and sintered at 1,000°C revealed the formation of fine-sized carbides, which takes place inside the iron matrix both between and within the grains. Such carbides have a needle-like and flaky shape. Their presence has a positive effect on the hardness of the products. The structure of a billet made of a smaller-fraction powder and sintered at 1,200°C was denser and had finer grains; however, carbides were larger in size and were located as separate inclusions in the structure. It is noted that by selecting the optimal particle size distribution of the powder mixture, compaction pressure, temperature, and soaking time during sintering and subsequent heat treatment, it becomes possible to obtain high-density blanks with fine-grained homogeneous structure. [ABSTRACT FROM AUTHOR]

During casting of steel, especially alloyed and high-carbon steel, in billet and bloom CCMs, segregation, shrinkage, and crystallization macrostructural defects may appear, and they cannot be completely eliminated even with rational design and process parameters. Various methods of physical action on crystallizing continuously cast ingots can be used to improve the quality of billets and rolled products. One of the most technologically advanced methods is electromagnetic stirring (EMS) of the liquid phase of crystallizing billets. The industrial CCMs currently operating in Russia and designed for the production of high-quality billets are mainly equipped with foreign-made EMS systems. Having a number of advantages, such as efficiency and commonality, such stirrers also have some disadvantages, including undismountable housing (cannot be repaired locally) and the need for several cooling circuits and boiler-type demineralized cooling water. Currently, the VNIIMETMASH Holding Company (Moscow) is the main developer and supplier of electromagnetic stirring systems for CCMs in Russia. Implementing an import-substitution program, the VNIIMETMASH has developed and put into operation mold EMSs (M-EMS), strand EMSs (S-EMS), and final EMSs (F-EMS) in billet and bloom CCMs, including horizontal ones. The stator poles are cooled with mold water in M-EMSs and with water for the process equipment in S-EMSs and F-EMSs. The coils are wo++und with a submersible double-insulated wire. A methodology for creating and testing EMS systems for billet and bloom CCMs has been developed based on theoretical and experimental studies, physical modeling, and industrial tests of electromagnetic stirrers designed by the VNIIMETMASH. [ABSTRACT FROM AUTHOR]

A review of the literature on the development of electric steelmaking at metallurgical plants indicates the possibility and efficiency of combining arc melting of steel and its extra-furnace treatment by well-known methods. The possibilities of combined steel melting using metallized iron-ore raw materials (MIORM) and scrap metal, followed by extra-furnace treatment of liquid steel with inert gases and continuous casting of steel are analyzed. This study is novel in the use of gas afterburning and distributed feed of MIORM to the bath of an electric ladle furnace unit, partially or not using scrap metal. It is shown that the energy and technology features of the new ladle furnace during arc steel melting combined with extra-furnace treatment are comparable in efficiency and steel quality to those of a typical arc furnace. [ABSTRACT FROM AUTHOR]

It is proposed to use a new submersible nozzle with eccentric apertures in order to improve continuously-cast slab quality. Calculations show that up to 38% of the heat of steel overheating is removed in the upper part of the crystallizer. The number of equiaxed crystals increases by several factors with an increase in crystallization rate. Pilot plant approval of advanced continuous casting of low-carbon and low-alloy steels makes it possible to improve hot rolled metal strength and toughness. Forecasting low-carbon steel sheet ultimate strength and relative elongation is conducted using known experimental equations. Rolled steel quality is evaluated from slabs selected from eight melts. The slab sulfur content obtained using a nozzle with eccentric apertures is somewhat higher than in slabs cast through existing nozzles. [ABSTRACT FROM AUTHOR]

An electric arc furnace with a liquid steel capacity of 30 t was analyzed using the second law of thermodynamics. To carry out the exergy analysis, materials and energies entering and exiting the electric arc furnace were determined. The materials included several types of scrap, cokes, fluxes, oxygen, liquid steel, stack gases, and dust. Electrical and exothermic chemical energies of these materials were considered. Energies of the materials leaving the furnace, including liquid steel, slag, stack gases, and dust, were determined, as were the chemical reactions and exergies entering and leaving the electric arc furnace. Exergy efficiency and lost exergy were calculated. It was found that 42.6% of exergy is lost because of the chemical reactions, heat transfer, and other reasons. The overall exergy efficiency of the entire system was found to be 46%. [ABSTRACT FROM AUTHOR]

The quality of railway wheels significantly affects the economy and security of railway transportation. In order to improve the properties of railway wheels steel is used currently with a controlled aluminum content. A feature of this steel is the increased risk of forming large alumina non-metallic inclusions. Nonmetallic inclusions in the defective and defect-free zones of a rejected wheel are studied. The causes of defect formation and a new comprehensive technology of smelting are determined, and ladle treatment and continuous casting of steel are developed, which provide avoidance of forming these defects.The main essence of the technology is the diffusion deoxidation of metal with slag of optimum composition, control of aluminum content during ladle treatment, and use of aluminum exclusively for steel alloying. [ABSTRACT FROM AUTHOR]

Residence time in a tundish equipped with the Turbostop system and dams is compared to the same parameter in a Turbostop-equipped tundish with dams and weirs. The symmetrical dual-strand tundishes are tested at two different casting speeds. The tundish design with Turbostop, dams, and weirs is currently being used at U.S. Steel Košice, s.r.o. to cast steel that must satisfy stringent requirements on quality. The main objective of the comparison testing was to substantiate the use of the weirs. The tests were performed in the Steel-Flow Simulation Laboratory at the Technical University of Košice with the participation of specialists from U. S. Steel Košice. A water model of a continuous caster was built on a scale of 1:3. The rate of flow of the test solution was measured by adding calcium chloride to the inlet of the model tundish and visually evaluating its flow with the use of KMnO as an indicator. [ABSTRACT FROM AUTHOR]

A technique has been developed for computer prediction of the soft-rolling-related reduction in the axial chemical inhomogeneity of a continuous-cast steel billet. The resulting computer software enables the amount of axial chemical inhomogeneity in continuous-cast billets to be explored as a function of the continuous-casting parameters and the physical properties of the steel. Calculations performed for steel with two different initial carbon contents (0.09% and 0.6%) indicated that the proposed method for calculating the effects of soft reduction predicts a substantial (50–55%) reduction in the axial chemical inhomogeneity of continuous-cast billets. [ABSTRACT FROM AUTHOR]

The mechanical characteristics of metal obtained by rotary rolling are 30–50% higher than the requirements of GOST and TU standards. By changing the feed angle in the rolling operation in order to change the degree of fragmentation and homogeneity of the structure of the metal over the cross section of the semifinished product, it is possible to obtain rolled products with different amounts of induced anisotropy. Goods made from such products function well in systems that are subject to cyclic loads. It might be possible to eventually use rotary rolling to obtain sections with a controlled structure corresponding to the requirements established by the customer for the service properties of the final product. [ABSTRACT FROM AUTHOR]

This article examines the feasibility of using ultrasound to inspect cast semifinished products of steel 04Kh13T3R1F (ChS82-Sh) obtained by electroslag remelting. A method for such testing has been developed with the use of a USK 7S flaw detector (made by the company KRAUTKRAMER) and a set of AVG scales of type ONMK ITTs for the B1S transducer. Good agreement was obtained between the ultrasonic test reults and the results of a macrostructural evaluation performed by etching. [ABSTRACT FROM AUTHOR]

This article cites a study investigating the suppression of axial nonuniformity in continuous-cast steel by inoculating it with a clad powder inoculant. A metallographic analysis showed that microcracks up to 10 mm wide and up to 5000 mm long are formed in the region where the steel is structurally and chemically nonuniform. Researchers have attempted to determine the reasons for the formation of the microcracks by studying the fracture surface, which passed through the axial zone. The study was conducted with the use of electron fractography, spectral microanalysis, and micro-diffraction. It was determined that the cracks are formed mainly on inclusions of manganese sulfides and titanium carbonitrides, which occupy a substantial percentage of the fracture surface in the axial zone. Researchers have also devised a method of using the same type of standard specimen to separately determine the mechanical properties for the matrix and the metal in the in the axial segregation zone.

Pilot industrial-scale testing of TSK-25 and TSK-10 compounds produced by NPP Tekhmet has been performed at Ruspolimet for siphon casting of 0.7–1.5-metric-ton ingots which are broader on the top (“flowers”) used for production of all-rolled rings; this is as an alternative to the existing process of pouring the steel into molds lubricated with petrolatum. The evaluation tests led to recommendation of the TSK-10 compound for industrial-scale testing; use of this compound enabled the petrolatum-lubricated steel casting process to be abandoned, thereby improving working conditions, and reducing rejects of the all-rolled ring products. [ABSTRACT FROM AUTHOR]

The company Mechel has developed and is successfully using slag-forming mixtures (SFMs) to cast steel on continuous casters and in ingot molds. The use of new SFMs for continuous casting has significantly improved the quality of the steels and reduced the amount of conditioning required for stainless-steel slabs by 2–3% (abs.). [ABSTRACT FROM AUTHOR]