Papers by Keyword: Continuous Casting

Abstract: The article discusses the features of improving the technological processes of electric smelting, out-of-furnace processing, continuous casting and heat treatment of steel pipe blanks used for oil and gas production. To this end, ways to improve steel processing processes in electric furnaces and non-furnaces were shown, processes for the production of continuous casting pipes with special properties for oil and gas production were studied, the design of an alloying-refining lance (LRF) was developed, refining processes by blowing magnesium-based powders were studied, heat treatment modes for continuously cast billets during pressure treatment of pipe billets have been developed. The conducted research created the basis for the development of measures to organize the production of high-quality pipes for oil and gas production in the conditions of Baku Steel Company LLC. It has been established that blowing liquid steel with inert gases (for example, argon) in an intermediate furnace or treating it with a special composition of synthetic slag, the use of LRF in an electric furnace, the correct setting of the cooling system on a continuous casting machine (CCM), the use of a vacuum system on a continuous caster, the process of refining steel by blowing Powders based on magnesium oxide instead of lime are considered more effective means of improving the quality of steel. Based on the application of these measures, low-carbon low-alloy steel 13HFA was developed and seamless pipes with a ferrite-pearlite structure were obtained from it using continuous casting technology. The strength characteristics of this steel after casting and heat treatment fully comply with the requirements of the European standard. After heat treatment (hardening and high-temperature tempering), the surface of the pipes becomes harder (troostite + sorbitol), and the core has a soft, i.e., viscous (perlite + sorbitol) structure. This “layered” structure allows the pipes to operate successfully in difficult oil and gas production conditions.

Abstract: Optimizing the manufacturing process to increase the product quality is a major challenge most industry branches just like aluminum production have to face. To continuously improve the production quality, it is necessary to develop new methods to identify parameters which may influence the product quality. Influencing parameters can be found at various production steps. Production data is recorded by numerous sensors throughout the entire manufacturing process. The goal is to develop methods for analysing the sensor data from each step of the production process to effectively identify specific patterns that may indicate critical process parameters along the production chain. The work shows feature extraction methods to find characteristics in the sensor data that could affect the product-quality.

Abstract: The effect of Ti/Al ratio (mass%) on the evolution of the microstructures after casting and hot rolling of Ca treated 441 dual stabilized ferritic stainless steel (FSS) was investigated in order to understand its effects on grain refinement mechanism. Industrially cast and lab simulated hot rolled samples, were subjected to similar processing conditions but with different Ti/Al ratios of 2.4 and 7.8. The microstructures and inclusions were analysed by the OM, SEM-EDS, SEM-EBSD and AzTecFeature software. The results showed that the steel with higher Ti/Al ratio exhibited finer grains after continuous casting and hot rolling, i.e., the initial finer as-cast structure resulted in finer grains and less substructure after hot rolling. The steel with higher Ti/Al ratio contained more Ti-rich complex inclusions and precipitates (especially TiN), which led to more heterogeneous nucleation of the 𝜹-ferrite and grain refinement during solidification. On the contrary, the steel with low Ti/Al ratio exhibited coarser as-cast grain structure, less recrystallization and higher volume fraction of substructure after hot rolling. Therefore, it was deduced that the Ti/Al ratio is one of the essential parameters to achieving grain refinement in Ca treated 441 FSS during continuous casting.

Abstract: In continuous casting, the cooling rate, casting speed, and molten metal temperature significantly affect the quality of cast steel billets. Appropriate casting parameters can minimize quality problems such as surface, subsurface and interior crack, rhomboidity, oscillation mark depth, and central porosity. This research determines the relationship between defects and three significant factors temperature, cooling rate, and casting speed. The work has been performed on the two-strand continuous casting machine to investigate the billet (BS-4449 steel grade) cross-section of 150 x 150 cm². The defects analysis through macro examination at different tundish temperatures (1510 °C to 1560 °C), varying cooling rates, and casting speeds (0.9 to 1.6 m/min). The present study provides detailed insight into the three parameters mentioned earlier, which directly affect the quality of cast steel billets.

Abstract: A twin-wheel caster for casting thin aluminum alloy wire was designed, assembled, and tested. Molten metal was ejected from the nozzle (cross-sectional area: 4 mm²) of a crucible into a triangular groove that was machined on the outer surface of the lower wheel. The metal was solidified by the upper and lower wheels. Wire made of Al-1.2%Fe or 6061 aluminum alloy, whose cross-sectional area was smaller than 20 mm², could be cast at a speed of 6 or 7 m/min. The upper and lower wheels were made of copper to increase the cooling rate. The diameter of the upper and lower wheels was 200 and 600 mm, respectively. The thickness of the wheels was 10 mm.

Abstract: The results of assessment of macrostructure and surface quality of round blooms 455 mm in diameter, cast on 4-strand continuous casting machine (CCM) at JSC “Ural Steel” are presented. The analysis of technological casting parameters of round blooms 455 mm in diameter (from steel grade “2”) at bloom caster of JSC “Ural Steel” are completed. Violations in casting temperature and rate parameters, which deteriorate thermal conditions of solidification and quality of continuous casting blooms, have been revealed. The main causes of unsatisfactory bloom quality have been determined, which are the increased overheating of cast metal and irrational secondary cooling mode. The results of the experiment to evaluate the surface temperature dynamics of a round bloom in the secondary cooling zone are presented, which confirmed the inefficiency of the secondary cooling mode for the defect-free bloom formation. As a result of thermal calculations of round blooms solidification of 455 mm in diameter, rational coolant flow rates by secondary cooling sections for bloom caster of JSC “Ural Steel” have been proposed. Optimized secondary cooling parameters provide a softer secondary cooling of the round bloom, which reduces the probability of the surface and internal defects development.

Abstract: The article presents an overview of possible technological schemes to produce an overhead contact wire for railways. Pilot experiments were carried out on the manufacture of a contact wire made of CuMg0.3, CuMg0.4 and CuMg0.5 alloys and having a nominal cross section of 100 mm². The contact wire was obtained from a continuously cast rod with small section, which was subjected to plastic deformation using the Conform technology and cold drawing of the extruded rod. In the casting process, we encountered the formation of cracks on the cast rod surface and the rods breakage. The inner surface of the graphite bushings of the mold after casting the rod was studied and a thin gray layer was found on the inner surface of the graphite bushings. Areas of the graphite bushing with gray layer were studied by scanning electron microscopy and element-by-element mapping was performed with the selection of a spectrum in the sediment layer area. In order to determine the phase composition of the sediment layer it was analyzed by the method of full-profile analysis of the X-ray diffraction pattern according to Rietveld. X-ray phase analysis showed the CuMg₂ and Cu₂Mg phases presence. This allowed us to assume a possible mechanism for the formation of the sediment layer. Ultimate tensile strength, elongation and electrical resistivity was determined. Analysis showed that the overhead wires made of CuMg0.3, CuMg0.4, CuMg0.5 alloys meets the requirements of GOST R 55647-2018 for wires made of the second conditional group bronze.

Abstract: The quality of the hot-rolled plate up to 36 mm thick was estimated by the percentage of rolled products, sorted due to the presence of a surface defect "Non-metallic inclusions", and internal defects, detected by ultrasonic plate control. The analysis of the data on the total sorting of hot-rolled plates demonstrated that the amount of sorting differs significantly on the melting from which each series of tubular metal casting commenced, compared to all the other melting in the series. The sorting of the sheets rolled from the metal of the first in a series of melting proved to be 1.9 times higher than that of the metal of all other melts. The main reason (in 68% of cases) of sorting is the presence of non-metallic inclusions on the surface of the plates. The effect of sorting of hot-rolled plates on non-metallic inclusions of various parameters has been studied: the duration of the intermediate ladle-heating; the length of time from the end of the heating of the intermediate ladle, prior to the beginning of the casting; lining temperatures of the intermediate ladle before the beginning of casting; duration of filling the intermediate ladle; the filling rate of the intermediate ladle with metal; mass of metal in the intermediate ladle before the beginning of casting into the crystallizer; chemical composition of metal; overheating of the metal over the liquidus point at the beginning, middle and end of the casting. On the sorting of flat products for non-metallic inclusions, of all the parameters considered, a statistically significant effect is due only to the overheating of the metal above the liquidus point, which varies in the range from 19 to 35 ° C. In order to obtain an acceptable quality of both the surface of slabs and the surface of hot-rolled plates for non-metallic inclusions, the first in a series of melts recommends overheating of the metal in the intermediate ladle above the liquidus temperature of 30-35 ° C.

Abstract: The paper compares the internal structure of two continuously cast slabs with a section of 300 × 2600 mm from a tube steel of the strength class K60, one of which is molded with a soft reduction, and the other is without external influence. A comparative analysis of the structure of two templates showed that the location of areas with an increased metal pickle ness in the axial part of the templates varies. On the template from a slab cast without reduction, this section is below the geometric center of the work-piece in thickness, at a distance of 49.2% from the underside, that is, the "lower" asymmetry of the slab structure is observed. On the template from the slab cast off with soft reduction, the area with an increased pickle-ness is located above the middle of the work-piece: at a distance of 51.7% of the side of the large radius, an "upper" asymmetry of the slab structure is formed. Consequently, as a result of the external action on the cast work-piece, the location of the axial sponginess, relative to the geometric centre of the slab, is changed by moving from the lower to the upper half of the work-piece. The metal of the axial part of the reduced slab has a denser structure, the degree of development of axial looseness in the metallographic evaluation is reduced by an average of 0.5 points. The work shows the change in the content of chemical elements along the thickness of slabs. In the reduced metal, the maximum value of the degree of zonal inhomogeneity of the most impurities is higher than in the metal without external influence. This is explained by the fact that, as a result of reduction, the zone of location of the axial chemical heterogeneity in the slab becomes smaller in width.

Abstract: The article presents the results of pilot-industrial experiments in the field of manufacturing technology of contact wire made of Cu-Sn alloys. Cast rods with a diameter of 20 mm, made of CuSn0.04, CuSn0.1, CuSn0.2, CuSn0.3, CuSn0.4 alloys, were obtained in a continuous casting plant on an Upcast system. Cast rods were deformed using a Conform technology, and extruded billets with a diameter of 18 and 20 mm were produced, which were subsequently drawn on a shaped contact wire with a cross section of 100 mm². Cast rods macrostructure and microstructure were studied. The macrostructure quantitative assessment of samples was studied in a cross and longitudinal section. A plot of the effect of the tin content in the alloy on the average grain area in cross section is obtained. An increase in the tin content in the alloy leads to a decrease in the average grain area. An analysis of the rod microstructure in a cross section showed that the structure is a grain of an α-solid solution of tin in copper, and the grain boundaries are thin and clean. After deformation by Conform technology a uniform fine-grained structure is ensured. The effect of the tin content in the alloy on the Brinell hardness of cast billets, made by Conform technology, is determined. An increase in the tin content in the alloy leads to an increase in the hardness of both cast and deformed billets. The microstructure analysis of the contact wire in the cross section is carried out. The mechanical and electrical properties of the contact wire with a cross section of 100 mm² are determined. An analysis of the results showed when the tin content in the alloy is up to 0.4 wt. %, the required level of mechanical and electrical properties of the contact wire is not provided. It may be necessary to change the size of the initial billet before drawing or to increase the tin content in the alloy more than 0.4 wt. %.