The results of experimental analysis of the regularities of chemical and metallurgical process of iron-bearing ore desulfurization for different conditions of liquid phase sintering are presented. This process is conducted with addition of catalytic impurities and variation of chemical composition of the heat-carrying gas, in order to reveal the optimal procedure of chemical and metallurgical process of ore smelting, which provide maximal possible removal of impurities from ore composition. It was found out for iron-bearing ore raw material that the rate and temperature conditions of impurities sintering depend on chemical composition of additives and physical state of initial material. The data about the chemical and metallurgical process of iron-bearing ore desulfurization, depending on ore coarseness and addition of solid fuel at low temperature during smelting process, are obtained. It was also established that lowering of the starting temperature for impurities decomposition and acceleration of desulfurization in the area of charge heating can be achieved via charge fluxing by fluorine-containing limestone and decrease of oxygen content in a gaseous phase. Essential deviations from solid phase procedures in the mechanism of sulphate decomposition at the temperatures of liquid phase sintering are revealed. Analysis of the experimental data allowed to establish necessity of introduction of the dual-stage route in the technological process of ironbearing ore desulfurization; this route includes solid phase and liquid phase removal of sulfuric impurities, while liquid phase removal should be implemented with high oxidation degree of the slag phase.

Thermal effect, or heat treatment, as a part of each technological process for manufacture of metal constructions and components, is one of the most widely distributed methods for transformation and improvement of physicalchemical properties and structural features of metals and alloys. Several technological processes, such as quenching of metals, require cooling media. In comparison with conventional media (water and oil), which are characterized by essential ecological, technological and fire-proof technical restrictions, use of polymeric emulsions as quenching media is actual. This sort of quenching media has several advantages: it allows to control metal cooling rate and provides uniform cooling of product surface, what allows to prevent appearance of internal stresses, cracks, deformations and defects in material structure. To develop colloid-stable emulsion, using as cooling media in metal quenching, it is actual to apply polysiloxane resin as polymeric component, due to hydrophobic ability of emulsified polysiloxane. In this case, obtain of water emulsions of polysiloxane resins needs especial conditions of emulsification. The paper suggests use of polysiloxane water emulsion, which was obtained via the method of phase inversion at the optimal temperature conditions as cooling liquid in metal quenching; these optimal emulsification parameters include speed 9,500-10,000 min -1 , temperature 60 ႏ and time period 60 min. Obtained emulsion on the base of polysiloxane and polyvinyl alcohol is characterized by small size of particles (about 1-2 μm), low viscosity (0.2 Pa•s), owing to high shifting forces during emulsification and temperature procedure, while metal surface acquires hydrophobic effect after emulsification, with the value of wetting angle up to 146°. It is shown that consequent lowering of polysiloxane concentration in water emulsion provides low viscosity even during temperature rise. When polysiloxane concentration reaches 7.5 %, emulsion displays good heat-exchanging capacity, which provides quenching rates comparative with use of industrial oil and water-polymeric media. The structure with acicular troostite and cementite, which is typical for substantially lower cooling rate, are mainly forming as a result of polysiloxane water emulsion use during quenching of samples made of steel 35Kh.

In order to improve parameters of rails and railroad wheels, it is necessary to examine new microstructures, new technologies for production and processing of rails. Pearlitic steels are widely used in the railroad industry worldwide, due to their good wear resistance and satisfactory impact strength, as well as due to their relatively low production cost. Mechanical properties of pearlitic steels are controlled by microstructure, which is created as a result of thermomechanical treatment, especially by such parameters as austenite grain size, interlamellar spacing in pearlite and dimension of a pearlite colony. Essential microstructural variations occur along the heat-affected area in the process of butt welding of rails. Significant variations of hardness and other mechanical properties in a metal welded joint are connected with cementite morphology. A soft area, which is observed in the heat-affected area of a welded joint and which is caused by cementite spheroidizing, leads to local hardness loss. The experimental results on evaluation of cooling rate influence in a rail welded joint on hardness in the heat-affected area are presented in this research. It was confirmed that variation of cooling rate influence in a rail welded joint finalizes in variation of spheroidizing tendency in the areas of lowered hardness.