Model for Predicting the Machinability of Continuously Cast and Subsequently Rolled Steel Using the Artificial Neural Network

The paper presents a model for predicting the machinability of steels using the method of artificial neural networks. The model includes all indicators from the entire steel production process that best predict the machinability of continuously cast steel. Data for model development were obtained from two years of serial production of 26 steel grades from 255 batches and include seven parameters from secondary metallurgy, four parameters from the casting process, and the content of ten chemical elements. The machinability was determined based on ISO 3685, which defines the machinability of a batch as the cutting speed with a cutting tool life of 15 minutes. An artificial neural network is used to predict this cutting speed. Based on the modelling results, the steel production process was optimised. Over a 5-month period, an additional 39 batches of 20MnV6 steel were produced to verify the developed model.

Analysis of the causes and conditions for the formation of surface defects on hot‑rolled products from peritectic steel grades obtained under the conditions OJSC “BSW – Management Company of the Holding “BMC”

OJSC “BSW – Management Company of the Holding “BMC” produces a wide range of carbon, high‑quality, alloyed and high‑carbon steel grades, among which a signifi ant share is peritectic grade steels. Basically, the steel of this group is used to produce rolled products intended for the manufacture of components for the automotive industry. The process of production and casting of these steels is characterized by the greatest instability and is often accompanied by rejects and forced sorting of products. This situation is typical for other metallurgical enterprises. Therefore, the search for technological solutions that ensure an increase in the yield while maintaining the existing productivity of metallurgical units is an urgent aspect of improving the technology of continuous casting of peritectic grade steels. At the same time, the main scientific and technical task is to obtain a stable quality of continuously cast billets, aimed at preventing and eliminating the formation of a number of characteristic defects, primarily cracks on the surface of continuously cast billets and rolled products. The search for methods and technological solutions to improve the quality of products made of peritectic grade steel is the goal of the ongoing research.

Establishing the true causes of defects to ensure the quality of continuously cast billets and hot‑rolled products at all stages of the process chain at OJSC “BSW – Management Company of the Holding “BMC”

Establishing the true causes of defects is one of the main prerequisites for improving the quality of metal products. One of the undesirable phenomena in the production of continuously cast billets, hot‑rolled products is the oxidation of hot metal in the environment with the formation of scale on its surface. Defects, which are violations of the continuity of the metal and deviations from the normal specified macro‑and microstructure, signifi antly reduce the technological plasticity of the metal in the conditions of its processing and operational stability.After hot rolling of a circle of 95 mm steel grade 30MpV4, surface defects were found in the finishing line. To study and establish the nature of surface defects from hot‑rolled blanks, as well as continuously cast blanks, samples were taken.Analyzing metallographic studies of defects and the production technology of the studied steel grade 30MnB4, it was found that the defects were formed as a result of mechanical damage to the continuously cast billet in the area of the pulling‑correct unit. The reason for the formation of the defect is the ingress of scale on the guide rollers.

Improvement of the technological process of manufacturing bearing grades of steel at the 370/150 mill.

The actual problem of obtaining long products from bearing steel grades with specified microstructure characteristics is considered. The analysis of the capabilities of the existing equipment – a heating furnace and a rolling mill 370/150 of OJSC “BSW – Management Company of the Holding “BMC” was carried out in order to introduce technical measures aimed at reducing carbide heterogeneity in products made of bearing steel grades on the example of steel grade 100Cr6.The influence of different modes of preliminary thermal preparation of continuously cast billets from bearing steel grades on the carbide inhomogeneity in the finished rolling is studied. According to the results of the research, the optimal mode of heat treatment of a continuously cast billet was determined, which allows to produce rolled products that meet the highest requirements of consumers.

Technology of the Contact Wire Manufacture for High-Speed Railways

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.

Research of the Process of Production of Steel Square Continuous Billets for Rolling Balls of Large Diameter

The paper investigates the technology of production of steel billets continuously cast billets for rolling balls of large diameter. In Kazakhstan, in connection with the development of new copper deposits such as Aktogay and Bozshakol, the need for large diameter steel grinding balls for primary ore processing has increased. The main problem in the operation of large diameter grinding balls is the tendency of the grinding media to break during operation. The authors of the work investigated the process of production of steel billets continuously cast billets with a cross section of 150 × 150 mm for rolling balls of large diameter (d 125 mm) in the PB LLP "KSP Steel", which showed that the breaking of grinding balls is initiated mainly by the presence of internal discontinuities (gas axial looseness) in continuously cast billets. Studies have shown that the technological scheme for the production of grinding balls with a diameter of 125 mm from continuously cast billets with a section of 150 × 150 mm, including steel smelting in an arc furnace with steel finishing on a ladle-furnace unit, deoxidation with aluminum and degassing in a ladle vacuum apparatus, casting steel in a closed jet on a continuous casting and further production of rolled stock on a rough rolling mill ensures the absence of internal discontinuities (gas bubbles, axial looseness) in the workpieces and ensures the production of high quality balls.