International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this work it was studied the influence of low-carbon steel wire annealing at different temperatures from 500 to 750 °C that was obtained by cold drawing on its structure and properties. It was sown that bigger work-hardening during the drawing process leads to the decreasing of collective recrystallization starting temperature, which could resulting in obtaining less plastic properties than are appear after lower annealing temperatures with additional loss of strength. The found effects give valuable information for cases when it is desirable to obtain the minimal strength or the maximum plasticity of the wire.

The results of the effect of preliminary thermal-cyclic deformation on the microstructure of hot-rolled low-carbon steel Ст3пс are presented. It is shown that the regime of thermal-cyclic rolling leads to a decrease in the average grain size of ferrite from 8 to 6 microns in comparison with the structure of steel after industrial production. There is a decrease in the size of pearlite colonies and their volume fraction in the structure of steel after using thermal-cyclic deformation. The results of the effect of heat treatment: normalization and tempering on the electrical resistivity of the hot-rolled carbon steel sheet Ст3пс produced using thermal-cyclic mode of deformation processing (DTCT). DTCT preliminary thermal-cyclic was rolled (5 cycles at a reduction of 10-15 % in each cycle and cooled to a temperature below the Ar1). And normalizing annealing was carried out in the range from 100 to 900 °C increments to 100 °C for 1 hour. The possibility to reduce the magnitude of the specific electrical resistance of the hot-rolled steel manufactured using DTCT mode through the use of subsequent normalizing at 700 °C on average 10 %, and by annealing – no more than 5 %. A further increase in the time of normalization at 700 °C to 3, 5 and 10 hours has no significant effect on the value of the electrical resistance of the steel subjected DTCT. However, the downward trend in resistivity is maintained. Overall reduction of electrical resistivity of the hot-rolled steel Ст3пс by using
mode DTCT and subsequent normalizing at 700 °C for 1 hour is more than 12 %.

Quantitative analysis of the phase composition of the Ti-Al-V-Mo-Zr system alloys was carried out during operation using the Thermo-Calc program (TCW5 version, TTTI3 database). Polythermal and isothermal cuts are plotted, design temperature values of liquidus, solidus and transition into β-field during heating are given. Regarding the titanium alloy of the Ti-Al-V-Mo-Zr system the effect of annealing temperature on the microstructure of the alloy as well as on the alloying elements content in α and β–phases was studied using the scanning electron microscopy method.

Quantitative analysis of the phase composition of the Ti-Al-V-Mo-Zr system alloys was carried out during operation using the Thermo-Calc program (TCW5 version, TTTI3 database). Polythermal and isothermal cuts are plotted, design temperature values of liquidus, solidus and transition into β-field during heating are given. Regarding the titanium alloy of the Ti-Al-V-Mo-Zr system the effect of annealing temperature on the microstructure of the alloy as well as on the alloying elements content in α and β–phases was studied using the scanning electron microscopy method.

In this study, mechanical alloying (MA) of Al-WC powder system was studied to produce aluminium composite powders having finer tungsten carbide fraction in aluminium matrix. For this purpose, elemental mixtures of 70 wt. % aluminium (Al) powder and 30 wt. % of tungsten carbide (WC) powder were mechanical alloyed for the duration of 2, 4 and 8 hrs. MA’ed powders then annealed at 300 ºC, 400ºC and 500ºC for 2 hours under inert atmosphere. Apparent densities of powders were measured in order to characterize both mechanical alloyed and annealed powders. Compressibility of the powders was determined by green density measurements after pressing.

Microstructural characterizations were conducted with X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Strain rates and crystallite sizes were measured according to fundamentals parameter approach (FPA) by applying Lorentzian function using software TOPAS 4.2.

The results of the influence of preliminary thermal-cyclic deformation and subsequent annealing in the range of 100÷900 ºС with a step of 100 ºС on the microstructure, coercive force and linear expansion of hot-rolled sheet steel 10 are presented. It was found that the use of preliminary thermal-cyclic deformation results in increase in coercive force no more than by 8% in comparison with the steel sheet produced by an industrial technology. Decreasing feasibility in coercive force of the sheet steel produced with the use of thermal-cyclic forging almost by 3 times in comparison with the initial raw condition due to the subsequent annealing at 900ºС during 10 h. is shown. In addition, annealing in accordance with this mode reduces a temperature coefficient of linear expansion of a sheet steel on average by 6 % within the range of the test temperatures 50-450 ºС.

This study reports the structural evolution of equiatomic AlCuNiFeTi high-entropy alloy (HEA) from elemental materials to solid solution during mechanical alloying (MA), and further, to equilibrium phases during subsequent thermal annealing. It was justified experimentally that MA of Al-Cu-Ni-Fe-Ti powder mixture during 15 hours resulted in a single-phase nanocrystalline HEA with a structure of ВCC solid solution. During thermal annealing recovery and recrystallization of the BCC solid solution take place at temperatures ranging from 130 to 650 °C, and phase transformation, and grain growth of equilibrium phases occur at higher temperatures. The phase composition transforms to BCC and FCC solid solutions when the MA powder was annealed at 700 °C for 1 h. The BCC and FCC solid solution structure can be maintained even after the alloy was annealed at 1000 °C. The alloy powder was consolidated by pressure sintering at 800 °C with 5 GPa pressure for half an hour. The sintered sample exhibits 10.7±0.3 GPa in Vickers hardness.