Том 47, № 7 (2017)

The use of metallurgical wastes in welding fluxes is considered. A new welding flux based on slag from silicomanganese production is proposed, along with the corresponding manufacturing technology. The quality of the weld seams is studied by metallographic analysis. The grain size and content of nonmetallic inclusions are determined. An Olympus GX-51 optical microscope is used for metallographic analysis (magnification ×100–1000). The influence of the fractional composition on the performance of the fluxes is studied. The optimal fraction is chosen, ensuring low content of nonmetallic inclusions (in particular, nondeforming silicates and oxides) in the weld seam. If 30–40% of the small fraction of welding flux is employed, the content of nonmetallic oxide inclusions in the weld seam is reduced. Metallographic analysis shows that introducing the small fraction has no effect on the structural components of the weld seam. The seam is characterized by ferrite–pearlite structure. The ferrite is present in the form of grains extended in the direction of heat transfer. The optimal content of the <0.45 mm fraction in the welding flux is 30–40%. To improve flux performance, the small fraction may be mixed with liquid glass. The use of ceramic flux produced from the dust of silicomanganese slag (<0.45 mm fraction) bound by liquid glass reduces the content of nonmetallic inclusions in the weld seam. However, increase in the content of liquid glass from 15 to 40% has little effect on the content of nonmetallic oxide inclusions in the weld seam or on the microstructure. The microstructure in the weld seam consists of pearlite and ferrite. The optimal flux consists of the small fraction with 15–20% liquid glass.

In the production of steel, as the productivity rises and the resource and energy consumption declines, improvements in converter design are required to ensure preliminary scrap and batch heating and to intensify redox processes in the liquid bath and exhaust-gas combustion above the bath, without impairing the durability of the injection systems and the converter lining. The use of fuel–oxygen combustion flames in the converter resolves numerous technological problems. The hydrodynamics in the reaction zones and in the liquid bath may be greatly changed by fuel combustion in the converter’s working space with jet formation or by means of submersible combustion flames. In the present work, thermodynamic methods are used to analyze the dynamics of gaseous-fuel combustion and the oxidation of elements in the converter bath on interaction with high-temperature combustion products. The interaction of the combustion flame and chemical elements in the converter bath is calculated for equilibrium conditions. The use of the combustion flames is found to change the composition of the gas phase in the converter’s working space (above the bath), which contains H₂ and H₂O in addition to the traditional components associated with oxygen injection: O₂, CO, CO₂. The presence of H₂ and H₂O changes the thermal conditions and oxidative properties of the gas phase. In the combustion of gas–oxygen fuel, the optimal composition of the initial gas mixture (natural gas + oxygen) must correspond to the ratio 100% CH₄ + 69% O₂. The oxidation product is gaseous phase consisting of 40% CO₂ + 60% H₂O. The total enthalpy of combustion of the gas–oxygen fuel at converter temperatures, with an oxygen excess greater than 1.0 (up to 2.0), is about 200 kJ per mole of the initial reagents. In the oxidation of methane by carbon dioxide, the total enthalpy of combustion is between–7 and–14.5 kJ/mol of initial reagents at 1800 K. The process becomes endothermal at temperatures above 2000 K: ΔH₂₂₀₀ = 7.7–15.4 kJ/mol. In the oxidation of natural gas by water vapor, ΔH₁₈₀₀–2200 = 19.5–70 kJ/mol. Thus, flame temperatures above 1800 K may only be attained in the oxidation of methane by oxygen. The use of air, carbon dioxide, or water vapor as the oxidant does not yield the required thermal effect.

The software in information systems used by engineering personnel at metallurgical enterprises is considered. Such software operates automated workstations, support systems for decision making, information and modeling systems, expert systems, and so on. Typically, the software takes the form of desktop applications written in high-level programming languages (Visual C#, Visual Basic, etc.). The analysis of technological information from the enterprise’s database-management server entails the solution of programming problems, systems of differential equations, and mathematical-physics problems, for example. Such problems are unsolvable by the standard general-purpose programming languages. Therefore, the development of information and modeling systems requires access to outside software, such as Microsoft Excel and MATLAB. Interaction with Microsoft Excel depends on COM Interop technology, which requires the installation of Microsoft Office on each client computer. Interaction with MATLAB requires the preliminary assembly of a library in MATLAB Compiler and its connection to the program. MATLAB Runtime freeware must be installed on the client computer. However, desktop applications using Windows Forms do not meet the requirements of industrial information systems in terms of functionality, accessibility, and cross-platform compatibility. Accordingly, new technologies must be found for the creation of information systems. The best approach is the construction of web applications based on the ASP.NET MVC framework, which permits the transfer of mathematical libraries and modules for interaction with Microsoft Excel and MATLAB from Windows Forms, without modification. The structure of the web application employed in the development of information-system software is described. The web page employed has the following functional regions: the logo and title of the current page, the session-status menu, the function menu, group operations, notifications, and the working area.

The distribution of the temperature variation of the gas flux in the peripheral zone over the height (from the bosh to the upper levels of the shaft) and the temperature above the charge surface over the furnace radius was investigated in 2006 at a blast furnace at Metinvest Holding LLC, in various conditions: with gas-free charge and a wet blast; and with natural gas and/or pulverized-coal injection.

The lubricant action of emulsion in rolling is considered. The entrainment of multiphase liquids (rolling fluids) into the deformation zone in the course of rolling is analyzed. A mathematical model is proposed for the flow of emulsion to the roller–strip contact zone and its infiltration into the deformation zone. Analysis of experimental data shows that the thickness of the lubricant layer in the deformation zone is directly proportional to the viscosity and adhesive properties of the disperse medium (the oil in the emulsion) and inversely proportional to the degree of reduction and the yield point of the metal being rolled. Recommendations are made regarding the selection of rolling conditions and regulation of the process.

In twin-roll casting, the influence of the heat-transfer rate at the metal–mold boundary on the thickness and the proportion of solidifying metal at the exit from the water-cooled roller mold is analyzed. The corresponding analytical curves are plotted for the production of moderate-carbon and stainless steel strip (thickness 1–6 mm). The proposed method may be used in the development of twin-roll technology and equipment.