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As a result of the analysis of the formation processes of fluidity and the conditions for feeding the castings during cooling after solidification, a significant effect of the properties of the melt and the dispersion of the primary structure on the fluidity and density of steel was established. It is theoretically substantiated and experimentally confirmed that the level of fluidity and density is determined by the dispersion of the dendritic structure, the magnitude of the melt overheating over the liquidus temperature, as well as the properties of the liquid metal, the thermal conductivity of steel at the solidus temperature, crystallization heat and crystallization interval. The established quantitative laws describe the real process with a probability more than 95% and a high degree of reliability (R = 0,709-0,837; ð = 1,2 – 13,8%). The article shows that in order to increase the effectiveness of the influence of integral factors on the fluidity of structural steels, they can be arranged in the following sequence: thermophysical conditions of solidification, dispersion of the dendritic structure, properties of liquid metal. In this case, an increase in fluidity occurs with an increase in the overheating of the melt above the liquidus temperature, the heat of crystallization and the dispersion of the dendritic structure. An increase in the values of other factors leads to the opposite effect. Alloying elements are arranged in the following sequence: Si, Cr, Mn, C, V, N, V + N according to the specific efficiency of increasing fluidity. The results of the studies performed show that according to the effectiveness of the influence of the considered factors on the steel density, they can be arranged in the following sequence: dispersion of the dendritic structure, properties of liquid metal and thermalphysic conditions of solidification. Alloying elements affect these parameters in such a way that a complex multiextremal change in density is observed during alloying of steel. The general trend is that carbon and chromium decrease, while silicon, manganese, vanadium, nitrogen, and co-alloying with nitrogen and vanadium increase the density of the steel. Alloying elements can be arranged in the following sequence: V, Cr, Mn, Si, N, N + V, C to increase the specific efficiency of changing the density.

Simulation of Fluidity and Density of Cast Steels

Aftandiliants¹,

KRUHLII²

2020

Effect of Pressing Modes on Physical and Mechanical Properties of Antifriction Polymer Materials

OSTAPENKO¹

2020

The article analyzes in detail the influence of curing modes on the physical and mechanical properties of polymer compositions. The research methodology is presented. The object of the study was: a composition based on phenol-formaldehyde resin modified with antifriction fillers (patent for a useful model No. 136085. "polymer antifriction composition"). The research was based on the study of the physical, mechanical, technological properties of polymer coatings obtained by the method of direct compression cutting. The study of adhesion strength was carried out by the method of normal pull-off of two cylindrical specimens connected butt and tapered pins. To study the adhesion strength, a special tooling was made. The influence of technological parameters of pressing on the adhesive strength of polymer coatings has been studied. The experimental study was carried out in accordance with the Box-Benkin planning matrix. The optimization parameters were: adhesion strength of the coating to the base, hardness, ultimate strength in compression, density. Thus, with different pressing parameters, the adhesion strength changes from 4 to 18.4 MPa, the HB hardness from 74 to 188 MPa, the ultimate compressive strength from 46.1 to 131.2 MPa, and the density from 1544 to 1694 kg/m3 . Pressing modes: holding time under pressure 0.8 min/mm, pressure 54-75 MPa, mold temperature 438- 463 K.

Thickness influence on element segregation in continuously cast steel slabs

Aftandiliants¹

2021

The article presents the results of a study of the effect of slab thickness on the element segregation of during continuous casting of billets. The process of accumulation of elements on the surface of dendrites during crystallization of steel slabs for various thicknesses is considered. The theoretical dependence of the process of accumulation of elements on the dendrite surface during the crystallization of steel slabs for various thicknesses has been established. It is shown that the efficiency of accumulation of elements on the dendrite surface depends significantly from the crystallization and cooling rate of the slab. The established dependence makes it possible to determine the permissible increased element content in strips, which is equivalent to their content in thick slabs during continuous casting of billets. The element segregation searching shows that at pouring of thin steel strips, an increasing of the element content is possible compared to continuous casting of thick slabs with an identical level of segregation. The elements are arranged as possible to maximize the impurities content in AISI 1006 carbon steel in the following decreasing sequence: S, O, N, P, H. Another sequence is observed for stainless steel AISI 304: O, S, P, H, N. The following sequences are observed in the case of residual elements: for steel AISI 1006 - Pb, Bi, Sn, As, Zn, Sb, Cu; for steel AISI 304 - Cu, Sb, Sn, Bi, Pb, As, Zn. The sequences are as follows for the alloying elements: for steel AISI 1006 - B, Se, Al, Te, Ca, Mg, Ce, C, La, Nb, Ti, Mn, Ni, Si, Cr; for steel AISI 304 - Ca, Te, Al, Ti, Mg, C, La, Ce, Nb, Se, V, B, Si, Cr, Mn.