Improvement of wear-resistant properties of steel 30Н3MF with additional microalloying

One of the directions of wear resistance improvement is microalloying of improved steels. In the studies conducted, the feasibility of adjusting the composition of steel 30Н3MF was determined by additional microalloying of V + Nb in order to give it wear-resistant properties. Microstructural studies of the experimental alloy were carried out. The microstructure is fairly uniform, represented by a matrix and inclusions. Matrix is represented by doped solution, which includes nickel. It is determined that in a chemically and structurally inhomogeneous ingot, even after heat treatment, structural components will remain. Characteristics such as the amount, morphology and distribution of non-metallic inclusions in the metal matrix are mainly laid at the stage of metal discharge from the steelmaking unit, as well as in the process of deoxidation and modification of steel during its off-furnace treatment.

CHANGES IN THE COMPOSITION OF NON-METAL INCLUSIONS AND CONTAMINATION STEEL D DURED BY ALUMINUM

Using optical and electron microscopy methods, the pollution of grade D carbon steel by nonmetallic inclusions in samples taken at the stages of metallurgical redistribution (EAF → LF → VOD → Casting). Metal contamination and chemical composition of non-metallic inclusions are determined. It was shown that deoxidation at the stage of production of the intermediate by aluminum leads to the formation of nonmetallic inclusions of corundum (Al2O3) in the metal melt, the proportion of which in total over all redistributions is 52%. Identification and assessment of contamination by non-metallic inclusions showed that subsequent stages of out-of-furnace treatment lead to a decrease in total pollution by inclusions. After evacuation and addition of Al and SiCa, corundum inclusions acquire a globular shape with a maximum size of not more than 6 μm. During solidification, the total contamination by non-metallic inclusions does not change, however. Contamination with silicate inclusions decreases, and the inclusion of corundum increases. The inclusions of corundum are irregular in shape, the high contamination with the inclusions of corundum is caused by secondary oxidation of aluminum during casting, as well as the ingress of products by overgrowing of the casting nozzle into the solidified continuously cast billet.

Prospects for the Use of Hollow Electrodes for Deep Desulfurization of Steel in the Ladle-Furnace Unit

The article discusses the possibilities of intensifying the process of desulfurization of molten steel in the process of after-furnace treatment of molten steel in the ladle-kiln unit. As one of the techniques, it was proposed to heat the melt with the help of hollow electrodes with argon feed during the operation of the electric arc plant. Comparative thermal balances of the installation in the basic and experimental versions and on the basis of the proposed mathematical model for calculating the mass-average temperature of the melt are given, and graphs of temperature changes during processing are plotted. To assess the efficiency of the desulfurization process, arrays of heats were processed in the basic and experimental mode and original three-parameter graphs were built, allowing to estimate the degree of desulfurization in both modes as a function of processing parameters.

Combined Technology for the Parts Recovery Operating in Stress Factor Conditions

The structural factor of samples microplasticity deposited with carbon steel construction tapes in connection with the different sensitivities of the deposited metal to stress concentration was investigated. The most favorable structure of the deposited layer, which is characterized by low sensitivity to stress concentration, is found. The combined technology of parts recovery modes operating in stress factor conditions is given. The covering agent composition, which allows to reduce the energy consumption during heat treatment of the deposited samples after treatment with high-frequency currents, to increase the thermal insulation effect approaching to the furnace treatment conditions, was developed. It was established that retarded cooling in the covering agent of deposited samples after local heating with high-frequency currents provides the increase in the average pressure ferrite during increase in the grain size. It was established that for parts operating under cyclic loading, the structure obtained as a result of combined treatment is the least sensitive to stress concentration.

Reasons for Breakage of Welding Rod and Wire

Reasons for breakage of welding rod and wire at drawing are analyzed. It is shown that the basic reason for breakage is microphysical tree-like segregation which is caused by irrational addition of boron-containing material at after-furnace treatment, low effectiveness of steel continuous casting process, unproven technology of metal electromagnetic agitation in a mold at continuous casting. Peculiarities of alloyed elements liquation, both in welding rod and wire are studied. It is shown that non-uniformity of boron, manganese and silicon distributions in the longitudinal and transversal welding rod cross sections will become the main reason for increasing wire breakage during further drawing.

Development of the organization of rational schemes for the use of technogenic waste in the processes of off-treatment of steel intermediate

The results of the experimental verification of the efficiency of complex out-of-furnace treatment of low carbon steel using a test mixture based on man-made waste, which is fed partly to the melting unit at the end of the oxidation period of melting and partly by pouring under a stream of liquid metal. is the use of slag-forming materials obtained by joint heat treatment of mixtures of components containing the above mentioned oxides and carbonaceous material of vegetable origin. Their weight ratio in the initial mixture is determined by the purpose and properties of the finished product. The positive technological effects that are achieved by applying the developed method of after-treatment will in future provide favorable conditions for the effective conduct of microalloying, modification, vacuuming and stable casting of low-quality and ultra-low carbon steel. A slight decrease in the temperature of the steel intermediate in the implementation of the method is about 10 - 15 ° C, which is easily compensated for the installation of the ladle, and a slight increase in electricity consumption is compensated by the effects achieved in the processing of low-carbon steel intermediate. Obtaining a higher degree of desulfurization and deoxidation of steel, as well as reducing the contamination of Al2O3 steel and improving the ecological purity of the process can be achieved by reducing the composition of the SHS used in the first stage of processing, the amount of slag aluminothermal production of ferromanganese and complete exclusion of melting, melting weight ratios of powdered waste production of lime, aluminum-thermal slag production of ferromanganese, sludge neutralization of electrocorundum and carbide cr emnia.

«Out-of-furnace cast iron processing» subsystem in the solution of tasks for the choice of rational technology for producing quality metal products under the applicable conditions of raw material and technological.

The creation of end-to-end technology for the production of competitive metal products in modern conditions puts on the agenda the task of choosing the optimal metal production technology scheme. In solving this problem, a significant role belongs to the development of an information-modeling system for analysis and decision making. An important link in end-to-end technology is the after-furnace treatment of cast iron. As the analysis of various technological solutions for pig iron desulfurization has shown, the process developed at the Institute of Ferrous Metallurgy is currently the most economical, rational and preferred. The process is carried out by blowing through the immersed tuyeres of dispersed granular magnesium without additives. A special dosing and injection system is used. The developed process has undergone numerous industrial testing at domestic and foreign factories. To optimize the process of end-to-end technology and its information-mathematical support, modular mathematical models have been developed. An integrated database has been created that summarizes information on the parameters of cast iron desulfurization technology with granular magnesium. The expert system «Out-of-furnace cast iron processing» is described and presented, which allows to obtain high-quality metal products. The adequacy of the developed model for predicting the specific consumption of magnesium in the after-furnace treatment of cast iron was studied. The completed developments created the prerequisites for building the architecture of the Expert Decision Making System. The replenishment of the database with information on current and other technologies for pig iron desulfurization will make it possible to refine the existing and obtain descriptive models for various reagents, which will serve as the basis for the algorithmic support of the analytical unit of the expert system.Key words: desulfurization, hot metal, magnesium, information system, model.

Stages of scientific and applied activities of the department of external processing of the iron of ISI NANU

The history of the creation and development of the research unit of the Iron and Steel Institute, the department of after-furnace treatment of cast iron is presented. From 1939 to 1983, this structural unit of the ISI was headed by Doctor of Technical Sciences, Professor Natalya Aleksandrovna Voronova, then for 34 years, until 2017, the student and associate of N.A. Voronova – Doctor of Technical Sciences, Professor Shevchenko A.F., from 2017 to the present, the department is headed by Kislyakov V.G. During this period, a set of scientific research and development has provided an opportunity for the department staff to defend 3 doctoral and 16 master's theses. Two employees of the department were awarded the academic title of professor, and ten – senior research assistant. The evolution of the technological process and equipment for the processing of cast iron by granular magnesium in ladles of various capacities is shown. In particular, it was not possible to inject granular magnesium without additives with lances used to inject mixtures of magnesium with fillers into the melt due to blockage of the channel of the magnesium wire at the outlet of the lance. To solve this problem, a lance of a new design was developed, at the outlet of the channel of which an evaporation chamber was installed, the task of which was to remove the section of the lance channel from direct contact with cast iron. The design of tuyeres with evaporation chambers made it possible to virtually eliminate blockages of the tuyere channel. The studies of the interaction of magnesium with molten iron became the scientific basis for the creation of a modern highly automated process for the secondary refining of cast iron by mono-injection of magnesium without additives. This technology received the most successful application in the creation of modernized complexes at Chinese enterprises. Since 2001, 84 complexes of out-of-furnace desulphurization of pig iron and slag download using ISI technology with a total capacity of over 100 million tons/year of low-sulfur and pig iron-free slag have been built and commissioned at 39 plants in China.