Metallurgist

A research has been conducted to study the effect of the thickness of a thermal insulation insert inside the air passage of a blast furnace tuyere and the size of the air gap separating it from an inner sleeve on the temperature distribution and stresses within such insert and inner sleeve. A steady-state problem was solved in MS Excel, a non-steady-state problem – in DEFORM-2D, and both the steady-state and non-steady-state problems – in Ansys Fluent. A Static Structural modulus was used in Ansys to calculate stresses. The insert thickness values were assumed to be 10 and 13 mm, and the size of the air gap was 0, 1, and 2 mm.

In the steel industry, ferromanganese is an important additive. During the production of ferromanganese the ore goes through prereduction and reduction. The prereduction step is very important, as the degree of reduction during ferromanganese is important. Although many investigations have been conducted on different manganese ores, the current study investigated different phases that formed during prereduction when South African ore was used. The ore was mixed with carbon in excess as the reducing agent, and no fluxes were added while CO gas was blown in the furnace. The temperature was varied from 1000°C to 1200°C with 100°C interval. For each temperature, the time varied from 30 min to 90 min with 30 min interval. The ore to carbon ratio was 4:1. After the experiments, the resulting products were subjected to chemical and phase analysis using XRD, XRF and SEM.

On the basis of the data of computer simulation, we perform the analysis of the influence of the geometry of ingots and the procedure of their thermal insulation on the specific features of their solidification and the development of shrinkage defects. A 2⁷ complete factorial matrix of the experiment was designed and realized for the description of the dependence of the diameter of axial sponginess on the values of geometric, thermal, and engineering parameters of the molds and the melt. We establish the relationship reflecting the influence of each factor on the development of shrinkage defects. On the basis of the results of processing of the data of simulations, we determined the geometric and technological parameters of a 7.0-ton ingot. The pilot-production testing of the designed 7.0-ton ingot shows that its application makes it possible to increase the directedness of the process of solidification due to the 1.3-fold decrease in the rate of propagation of the solid phase in the horizontal direction, which improves the process of feeding of the axial zones of the ingot with head melt. The choice of the most efficient heat-insulating materials makes it possible to increase the thermal power of the head by 20.8%, which guarantees the possibility of efficient replenishment of shrinkage in the axial zone of the ingot. The realization of the procedure of directional solidification in combination with a more effective thermal insulation of the head makes it possible to reduce the development of shrinkage defects in the ingot and in the rolled bars produced from this ingot. The analysis of the quality of 320 mm rolled bars produced from the 7.0-ton ingot shows that its application makes it possible to reduce the level of rejection based on the ultrasound control, while the ingot-to-product yield increases by 2.0%.

Symmetric rolling (SR) where the roll speeds are equal and rolling-drawing (RD) where the roll speed ratio is limiting are versions of general rolling (GR). An advantage of GR is in a greater number of independent control parameters than in SR and RD (three against two and one, respectively). In this regard, GR is more flexible, thus allowing rolling schedules that ensure a fuller utilization of equipment capabilities, a reduction in the number of passes or intermediate heat treatments, a reduction in the minimum possible thickness of the strip, etc. The developed mathematical model of GR, the program for optimizing the rolling schedules against various criteria, and its numerical implementation confirm these conclusions. If compared with SR, the efficiency of GR increases with increase in the friction coefficient and the diameter of the work rolls, decrease in the elastic characteristics of the rolls, expansion of the range of mill products, increase in the strength of the strip, and decrease in its thickness. When compared with RD, the situation is opposite. An analysis of the variation in the control parameters during passages shows that as the thickness of the strip increases (decreases), the rolling schedules of GR tend to those of SR (RD).

Selective laser melting (SLM) technology, which exhibits high printing resolution capacity, in used in order to prepare objects with cellular structures corrosion-resistant steel (316L). Cellular structures are considered as promising elements for topological optimization with the aim of reducing weight and giving an object special properties. The effect is studied in this work of strategies for laser beam scanning on an object being formed with a cellular BCC structure of steel 03Kh16N15MZ during SLM in an SLM280 unit. It is shown that depending on production regimes for object preparation with these structures there are changes in cellular structure strut minimum diameter, nature and distribution of defects, and mechanical properties.

On the basis of geological assessment of reserves of copper ore in the territory of the Khanty-Mansiisk Autonomous Okrug–Ugra possibilities are considered for developing potential pyrite ore regions considered to be priority for development of pyrite copper-zinc ores. The volumes of primary ore extraction are proved, and the main approaches to developing deposits, parameters of priority quarries and the composition of the main technological and processing equipment are determined. Approaches and a fundamental qualitative-quantitative scheme are developed for pre-concentration of ore using dry methods for pre-enrichment whose implementation will make it possible to minimize adverse environmental impact on the Circumpolar Ural environment. A production scheme is developed for the chain of concentrating processing mining and processing plant devices for treating copper ore. Volumes of raw material and intermediate concentrate processing are determined that ensure the economic effective development.

Results are provided for a study of the effect of mechanical and ion-beam treatment on titanium alloys surface relief parameters. The possibility is demonstrated of changing component surface roughness over a wide range after comprehensive surface treatment including successive mechanical treatment and irradiation with powerful ion beams in order to improve adhesion properties that expands the range for application of titanium alloys, in particular in medicine. Surface modification and its treatment is a problem for titanium alloys since in view of physical properties titanium alloys exhibit very poor tribological properties and low adhesive strength.

High-strength multi-component chrome pellets with specified physical and chemical characteristics were obtained for smelting chromium ferroalloys in the electric arc furnaces by mixing finely dispersed chromium concentrates, refined ferrochrome slags, and ferriferous diatomite ore with subsequent pelletization and sintering of the composition at 1050–1200 °С. The process of roasting pellets containing carbon component includes pre-reduction of iron and chromium oxides at lower temperatures yielding high-carbon ferrochrome beads. The process can be implemented by using conventional equipment and does not require high capital investments.

The article discusses factors determining the reproducibility of measurement results for a banded microstructure in sheet steels St3sp and 09G2s using computerized procedures.

Physical modeling of metal flows in a continuous casting machine tundish of the ESSW of AO VTZ is conducted. It is established that the existing tundish design does not allow non-metallic inclusions to float sufficiently and be assimilated by slag, which leads to clogging of the submerged nozzle and a reduction in C45E steel castability. Technical solutions for changing the geometric parameters of the tundish and tundish turbostop are proposed and implemented from results of simulation, including an increase in tundish depth and use of a turbostop of original construction. The technical solutions developed make it possible to increase the degree of non-metallic inclusion assimilation by the tundish slag cover, both at the start and throughout an entire series of casting, and also to reduce submerged nozzle clogging during casting steel C45E by a factor of 5.9.

Extensive research is conducted and a production scheme is proposed, including recovery of copper-containing slag with coke carbon and neutralization of waste copper electrolyte with the product obtained.

A hot-pressing technology for producing aluminum-based metal-matrix composite materials used to manufacture liquid-cooled base plates of electronic modules of active phased antenna arrays (APAA) was developed and tested. The technology involves the following operations: mixing of the starting components, adding of a binder, forming of blanks, hot pressing of the blanks, sintering in a controlled atmosphere, grinding of the sintered blanks, cutting of the blanks to size, coating, and controlling of the material parameters. The curves of the density of SiC–Al composite material versus the isothermal-holding time and the compaction pressure are plotted. It is established that combining hexagonal silicon carbide (6H α-SiC) and aluminum alloy with a silicon content of 7–12%, it is possible to obtain a SiC–Al composite with a thermal conductivity of up to 240 W/(m·K).