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

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.

In the work effect of the rare-earth metals (REM) on structure of the decomposed Mg supersaturated solid solution after hot deformation was investigated. Investigation indicated Mg solid solution decomposition during hot deformation with precipitation of the RErich particles preferably on the Mg grain boundaries and boundaries between originated blocks. Precipitations on the grain and block boundaries prevent recovery, recrystallization, the grain growth, and increase plasticity of alloys.

The composite materials based on polymer and oligomer blends with different thermodynamic compatibility have been developed. It is shown that for polymer and oligomer blends of products formed as result of the thermogasdynamic synthesis of fluorine-containing compounds, the ability of oligomeric matrix to multiply deformation and alternating transfer is the most important. In polymer-polymer systems formed in a melt by various technologies the most important factor is the structure of the boundary layers determining the parameters of the stress-strain and tribological characteristics of the composites. The effect of physical compatibilization during the introduction of nanoscale metal-containing and carbon-containing particles into the blend compositions has been established. This effect promotes the thermodynamic compatibility and resistance to the action of thermal-oxidative medium on composites.

It was investigated the structure, phase and chemical composition, thickness diffusion boride layers obtained after boriding and complex saturation boron and copper with simultaneous action an external magnetic field (EMF) on solid alloy T5K10. It was established that the application of an external magnetic field allows to intensify the process of diffusion saturation hard alloys boron and by 2 hours chemical – thermal treatment with simultaneous action EMF get such thickness diffusion boride layer which is formed by 4 hours chemical – thermal treatment without EMF. It was found increase microhardness diffusion layers formed on the hard alloys on 2 – 2.5 GPa (30 – 30.5 GPa) that is associated with a decrease areas of coherent scattering and as a result increase operating parts that work in conditions of intensive wear.

The results of the influence of preliminary thermal-cyclic deformation and subsequent hardening heat treatment on the microstructure and mechanical properties of hot-rolled sheet steel 10 are presented. It is shown that the use of preliminary thermal-cyclic deformation of the steel 10 stock material results in a fine-grained structure of a hot-rolled sheet (3 mm thick) produced by an industrial technology. Deformation occurred at a temperature above A_C3 (1250 °C), with cooling to 200-300 °C during 10 cycles and the deformation ratio per cycle being 6-8 %. The magnitude of the overall reduction ratio was 1.90 and the total amount of deformation was 65÷68 %. Such a treatment before sheet hot-rolling allows increasing the strength characteristics (tensile strength, yield strength) by almost 30 %. It has been established that the use of subsequent heat treatment (quenching, 900 °C, water and tempering 1 h, 600 °C) leads to a further increase in strength characteristics by 15-20 % while maintaining a sufficient level of ductility of sheet steel.

The results of studies wear resistance of boron coatings alloyed with Сu, V, Nb, Cr or Ti under dry friction – slip in the air, and it was determined that the best coatings are the boride layers alloyed with copper. Alloying with copper inereases wear resistance of boride layers in 3 times. When alloying of boride layers with niobium wear resistance increases in 2,8 times, with titanium – in 2,4 times, with chromium and vanadium – in 1,5 times. Wear resistance of boride coatings alloyed with copper under dry friction – slip 14 times higher than wear resistance of bronze of Cu – Al – Mn system and wear resistance increases when applying boride layers alloyed with copper.

In this paper it was investigated the formation of complex boriding diffusion layers on metastable austenite Cr-Mn-N steel powder method. Defined phase and chemical composition, thickness, microhardness and wear resistance obtained by layers of metastable austenite Cr-Mn-N steel. It is established that the application of an external magnetic field (EMF) leads to a redistribution of the proportion boride phases in the surface layers of the crystal lattice period changes. EMF allows in 1.5 – 2 times to reduce the period of saturation details, microhardness diffusion boride coatings increase to 20,5 – 21 GPa and increase their wear resistance in 2.4 – 3 times compared to steel without protective coating. Boriding a magnetic field will increase the microhardness boride coatings 6 – 7 GPa compared to the boriding without application of a magnetic field.

The capabilities of powder hot forging for manufacturing of Fe₃Al intermetallics and effect of forging and following thermal treatment routines on their structure and properties had been investigated. Fe₃Al intermetallic powders were produced by means of thermal synthesis at 1000°С in vacuum from a mixture of Fe and Al elemental powders. Hot forging of consolidated preforms had been carried out from 1000, 1050, 1100 and 1150°С and afterwards the hot forged preforms were subjected to supplementary sintering in vacuum at 1100÷1450°С. It is foud, that thermal synthesis of Fe + 14% Al powder mixture results in formation of Fe₃Al phase. Sintering of hot forged specimens result in increasing of strength and crack growth resistance, which values enhance with increasing of sintering temperature. Otherwise the hardness of hot forged intermetallics decreases after their sintering. The influence of modes of treatment on the structure and properties of the materials was investigated. It has been established that the strength and fracture toughness of the intermetallics obtained from milled blend after hot forging had the higher values as compared with the alloy made from the batch without its milling.

The results of studies on the application of complex boron coating powder method on hard alloys. Defined phase and chemical composition, thickness and microhardness of the coating on alloys.

It was established that after diffusion saturation of hard alloy in boron mixture for 4 hours formed coating with boride phases TiB, WB, CoB and WC, TiC, whose thickness is 50-60 microns. At complex saturation with boron and copper for 4 hours diffusion saturation formed coating with boride phases TiB, WB, CoB and WC, TiC and separate inclusions of copper with a thickness of the diffusion layer up to 70-80 microns.

Boriding and complex saturation with boron and copper allows in 2 – 2.5 times increase the microhardness of the surface layers of hard alloys, that in turn leads to increased wear resistance.

The results of studies wear resistance of boron coatings alloyed with Сu, V, Nb, Cr or Ti under dry friction – slip in the air, and it was determined that the best coatings are the boride layers alloyed with copper. Alloying with copper inereases wear resistance of boride layers in 3 times. When alloying of boride layers with niobium wear resistance increases in 2,8 times, with titanium – in 2,4 times, with chromium and vanadium – in 1,5 times. Wear resistance of boride coatings alloyed with copper under dry friction – slip 14 times higher than wear resistance of bronze of Cu – Al – Mn system and wear resistance increases when applying boride layers alloyed with copper.