Aleksandr Innokentyevich Bezrukikh

Bio: Aleksandr Innokentyevich Bezrukikh is an academic researcher from Siberian Federal University. The author has contributed to research in topics: Alloy & Materials science. The author has an hindex of 2, co-authored 8 publications receiving 11 citations.

Investigation of the structure and properties of cold-rolled strips from experimental alloy 1580 with a reduced scandium content

Abstract: The structure and properties of cold-rolled strips with a thickness of 3 mm from an experimental aluminum alloy 1580 with a lower scandium content of 0.03% (wt.) relative to the grade of the aluminum alloy and a 5083 similar alloy without scandium were studied. Ingots obtained at the laboratory installation of semicontinuous casting of the foundry department of the Siberian Federal University (Siberian Federal University, Russia, Krasnoyarsk) were used. The preparation of ingots for rolling included milling up to sizes of 40 × 100 × 145 mm and annealing according to a two-stage mode: at a temperature of 350 °C for 3 h (first stage) and at a temperature of 425 °C for 4 h (second stage). Hot rolling was carried out in the laboratory of the Department of Metal Forming at the Siberian Federal University at a temperature of 450 °C on a two-roll hot rolling mill with a roll diameter of 330 mm and a barrel length of 520 mm to a thickness of 5 mm, which corresponded to a total reduction of 88% with a single reduction of 2–5%. For cold rolling, a two-roll sheet rolling mill with a roll diameter of 200 mm and a barrel length of 400 mm grade LS 400 AUTO was used. Rolling was carried out to a thickness of 3 mm with a single reduction of 2–5%, and then the strip was annealed. The results of determining the mechanical properties by tension by the universal LFM400 machine showed that with an increase in the annealing temperature in the range from 250 to 350 °C for 3 h, ultimate tensile strength of the cold-rolled strips of aluminum alloy 1580 decreases from 385 to 365 MPa. For aluminum alloy 5083, a decrease in this strength characteristic is also observed from 345 to 320 MPa. A decreasing tendency with increasing annealing temperature was also observed for the conditional yield strength Rp, and over the entire range of annealing temperatures, the values ​​of Rp for strips of alloy 1580 were higher than for alloy 5083 by 35–40 MPa, which amounted to 14–17% The values ​​of the plastic properties, for which the value of the elongation to failure was analyzed, were close throughout the range of annealing temperatures for both alloys. The results of the analysis of micro- and fine structure allowed to conclude that an increase in the strength properties of cold-rolled and annealed sheets from the experimental alloy 1580, compared with alloy 5083, is a consequence of the addition of scandium in the experimental alloy 1580, which leads to an increase in the temperature of recrystallization of the alloy, preserving it contains a subgrain structure and dispersion hardening caused by precipitation of Al3(Sc, Zr) phase particles during the decomposition of a solid solution.

Investigation of cold rolling modes of 1580 alloy by the method of computer simulation

Abstract: A computer model was developed and a study of the cold rolling modes of 1580 alloy sheets was carried out. The model provided for the achievement of the maximum total degree of reduction in cold rolling of 60% in the minimum number of passes, the rolling force should not exceed 90% of the maximum allowable for the rolling mill, and the Cockcroft-Latham criterion was not reach value 1, so that cracks do not occur along the edges of the rolled products. The simulation results were tested on a billet cut from a large-sized ingot cast at an industrial enterprise by the method of semi-continuous casting. Hot rolling was carried out on a two-roll mill with a roll diameter of 330 mm and a barrel length of 520 mm. For cold rolling a two-roll mill with a roll diameter of 200 mm and a barrel length of 400 mm was used. Based on the simulation results, cold rolling was carried out, as a result of which a 2-mm-thick strip without cracks along the edges was obtained from a hot-rolled billet 5-mm-thick in 8 passes. At the same time in all passes, the rolling force values did not exceed 90% of the allowable for the rolling mill, and the Cockcroft-Latham criterion was less than 1. Thus, it is shown that computer modeling allows to optimize the rolling route of thin sheets of alloy 1580 and to carry out cold rolling with a total reduction rate of 60% for a minimum number of passes to obtain high-quality sheet semi-finished products.

Investigation the structure in cast and deformed states of aluminum alloy, economically alloyed with scandium and zirconium

Abstract: The structure and mechanical properties of an alloy of the aluminum-magnesium system with a scandium content of no more than 0.1% (wt.) (experimental alloy) at the stages of obtaining sheet semi-finished products have been investigated. The macro and micro structure of cast, hot, and cold rolled sheet semi-finished products has been studied by the methods of light and diffraction transmission electron microscopy, and their mechanical properties have been tested. Casting of ingots, hot, and cold rolling of the alloy was carried out in the conditions of a metallurgical enterprise. The section of the ingots was a rectangle 300 × 1460 mm in size. Preparation of ingots for rolling included milling of all surfaces and two-stage annealing at temperatures of 350 °C (first stage) and 425 °C (second stage). Rolling was carried out across the casting direction. For hot rolling, the billets were heated to 400–410 °C and carried out on a reversible hot rolling mill of grade quart with a roll barrel length of 2800 mm to a thickness of 8.2–9.2 mm. Then, the strips were rolled into rolls and annealed according to the following regime: temperature 390–400 °С, holding for 1 h, cooling with a furnace to 250–270 °С, and unloading into air. Cold rolling was carried out on a QUARTO mill of the CRM grade with a roll barrel length of 2800 mm to a thickness of 5.9–6.3 mm. Microstructural analysis was performed on a Carl Zeiss Axio Observer A1m light microscope using the AxioVision software package. The fine structure of semi-finished products was studied using Tecnai 30 G2 and JEM-2100 EX transmission electron microscopes. The chemical composition of dispersed particles of the secondary phases was determined using energy dispersive X-ray microanalysis (EDX) of thin foils in transmission using an INCA x-sight attachment. It is shown that alloying the experimental alloy with small additions of scandium, zirconium, and manganese leads to the formation of a supersaturated solid solution in the ingot. And upon annealing of the ingot and subsequent hot and cold rolling, a subgrain structure with inclusions of Al6Mn and Al3(Sc, Zr) phases of distribution density is formed in the alloy structure, explaining dispersion and structural hardening of sheet semi-finished products. It was found that the mechanical properties of cold-rolled sheets from the experimental alloy significantly exceed the properties of alloy 5083 with the same magnesium content. But without scandium and are approximately on the same level with alloy 1570 in which the scandium content in comparison with the experimental alloy is three times higher.

Preparation of Aluminum-Scandium Master Alloys by Aluminothermal Reduction of Scandium Fluoride Extracted from Sc 2 O 3

Abstract: Aluminium alloys containing small additions of scandium exhibit unique operating properties. Alloying material with scandium significantly improves product weldability, reduces the tendency towards hot cracks and improves welded joint mechanical properties. The aim of this work is to increase the scandium extraction into a master alloy by preliminary transformation of scandium oxide into fluoride and introduction into the composition of an aluminium powder alloying additive. Results are provided of laboratory experiments for preparation of aluminium-scandium master alloy by aluminothermic reduction of scandium fluoride using sodium fluoride and aluminium powder within the alloy composition. Scandium fluoride is prepared by treating scandium oxide with 40% hydrofluoric acid. The overall extraction of scandium from oxide into fluoride and from fluoride to the aluminium-scandium master alloy is 88.5% with an average scandium concentration in the master alloy of 1.90 wt.%. The microstructure of the master alloy obtained is represented by scandium aluminide Al3Sc crystals with a size from 10 to 25 μm uniformly distributed within the master alloy. An additional reserve for increasing the extraction of scandium into the master alloy and reducing its cost is processing of slags formed in the preparation of the ligature. The use of an aluminium powder with high specific surface area in the composition of the alloying additive increases scandium extraction into the master alloy due to better contact of the reacting phases. The resultant Al–Sc master alloy has uniform distribution of Al3Sc particles within the volume of the metal.

Deformation behavior during hot processing of the alloy of the Al-Mg system economically doped with scandium

Abstract: Hot deformation behavior of the new alloy 1580 sparingly doped with scandium (Al-5Mg-0.6Mn-0.10Sc-0.11Zr) was studied under the deformation temperature ranging from 350 to 450 °C and strain rate ranging from 0.01 to 10 s−1. Hot deformation by uniaxial compression and torsion was carried out on a Gleeble 3800 thermomechanical simulator. Hot deformation of the alloy 1580 is accompanied by dynamic softening with the establishment of a balance between the rates of nucleation and annihilation of dislocations. Alloy flow stresses increase with increasing strain rate and decreasing temperature. The experimental results for the new alloy are in full agreement with the known concepts that the combined effect of temperature and strain rate on the deformation behavior of metallic materials is described by the Zener-Hollomon parameter. The deformation activation energy of the alloy obtained by the regression analysis of steady-state flow stresses is 175.7 kJ/mol. When using the steady-state flow stresses normalized to the shear modulus, the deformation activation energy is 148.8 kJ/mol and is close to the activation energy of self-diffusion of aluminum. Analytical expressions are obtained for steady-state flow stresses as a function of the Zener-Hollomon parameter, which make it possible to predict the deformation resistance of the alloy 1580 in a wide range of temperatures and strain rates. This result is important for FEM modeling and for the choice of temperature and stain rate of hot deformation of the alloy under study. Comparison with the literature data showed that in the region of high temperatures and low strain rates, the flow stresses are weakly dependent on the scandium content in the alloy. However, with a decrease in the temperature and an increase in the strain rate, an increase in the scandium content in the alloys leads to a noticeable increase in the flow stresses. In torsion tests, a sharp increase in the ductility of the alloy is observed at a temperature of about 400 °C. One of its probable causes may be dissolution of particles Al3(Sc,Zr) during hot deformation in this high-temperature region.

Investigation of cold rolling modes of 1580 alloy by the method of computer simulation

Abstract: A computer model was developed and a study of the cold rolling modes of 1580 alloy sheets was carried out. The model provided for the achievement of the maximum total degree of reduction in cold rolling of 60% in the minimum number of passes, the rolling force should not exceed 90% of the maximum allowable for the rolling mill, and the Cockcroft-Latham criterion was not reach value 1, so that cracks do not occur along the edges of the rolled products. The simulation results were tested on a billet cut from a large-sized ingot cast at an industrial enterprise by the method of semi-continuous casting. Hot rolling was carried out on a two-roll mill with a roll diameter of 330 mm and a barrel length of 520 mm. For cold rolling a two-roll mill with a roll diameter of 200 mm and a barrel length of 400 mm was used. Based on the simulation results, cold rolling was carried out, as a result of which a 2-mm-thick strip without cracks along the edges was obtained from a hot-rolled billet 5-mm-thick in 8 passes. At the same time in all passes, the rolling force values did not exceed 90% of the allowable for the rolling mill, and the Cockcroft-Latham criterion was less than 1. Thus, it is shown that computer modeling allows to optimize the rolling route of thin sheets of alloy 1580 and to carry out cold rolling with a total reduction rate of 60% for a minimum number of passes to obtain high-quality sheet semi-finished products.

Computer technologies in the formation of computed models of monolithic reinforced concrete structures

Abstract: The areas of application of concrete and reinforcement of higher grades for strength in structural elements of a monolithic reinforced concrete frame are considered. Analytic dependencies, criteria and boundary conditions are proposed that numerically describe the relationship between increasing the strength of concrete and reducing the consumption of reinforcing steel for bent and compressed-bent elements. Calculation-analytical models of the deformation state of overlaps of a monolithic reinforced concrete multi-storey frame have been developed on the basis of multifactor numerical studies carried out for various values of the thicknesses of ceilings, spans, operating loads, classes of concrete and reinforcement. Calculated parameters of slabs are determined, which determine their bearing capacity. On the basis of computer technology, the optimum section of a reinforced concrete element is modeled according to the criterion of reducing the material consumption and rational combination of classes of concrete and reinforcement.

Investigation the structure in cast and deformed states of aluminum alloy, economically alloyed with scandium and zirconium

Abstract: The structure and mechanical properties of an alloy of the aluminum-magnesium system with a scandium content of no more than 0.1% (wt.) (experimental alloy) at the stages of obtaining sheet semi-finished products have been investigated. The macro and micro structure of cast, hot, and cold rolled sheet semi-finished products has been studied by the methods of light and diffraction transmission electron microscopy, and their mechanical properties have been tested. Casting of ingots, hot, and cold rolling of the alloy was carried out in the conditions of a metallurgical enterprise. The section of the ingots was a rectangle 300 × 1460 mm in size. Preparation of ingots for rolling included milling of all surfaces and two-stage annealing at temperatures of 350 °C (first stage) and 425 °C (second stage). Rolling was carried out across the casting direction. For hot rolling, the billets were heated to 400–410 °C and carried out on a reversible hot rolling mill of grade quart with a roll barrel length of 2800 mm to a thickness of 8.2–9.2 mm. Then, the strips were rolled into rolls and annealed according to the following regime: temperature 390–400 °С, holding for 1 h, cooling with a furnace to 250–270 °С, and unloading into air. Cold rolling was carried out on a QUARTO mill of the CRM grade with a roll barrel length of 2800 mm to a thickness of 5.9–6.3 mm. Microstructural analysis was performed on a Carl Zeiss Axio Observer A1m light microscope using the AxioVision software package. The fine structure of semi-finished products was studied using Tecnai 30 G2 and JEM-2100 EX transmission electron microscopes. The chemical composition of dispersed particles of the secondary phases was determined using energy dispersive X-ray microanalysis (EDX) of thin foils in transmission using an INCA x-sight attachment. It is shown that alloying the experimental alloy with small additions of scandium, zirconium, and manganese leads to the formation of a supersaturated solid solution in the ingot. And upon annealing of the ingot and subsequent hot and cold rolling, a subgrain structure with inclusions of Al6Mn and Al3(Sc, Zr) phases of distribution density is formed in the alloy structure, explaining dispersion and structural hardening of sheet semi-finished products. It was found that the mechanical properties of cold-rolled sheets from the experimental alloy significantly exceed the properties of alloy 5083 with the same magnesium content. But without scandium and are approximately on the same level with alloy 1570 in which the scandium content in comparison with the experimental alloy is three times higher.

Mechanical properties and microstructure of multi-pass butt weld of plates made of Al-Mg-Zr alloy sparingly doped with scandium

Abstract: Aluminum alloys doped with scandium represent a new generation of high-performance alloys that have numerous advantages compared to high-strength aluminum alloys. However, the cost of such alloys is quite high. Thus, scientists have been searching for new alloys sparingly doped with Sc that are suitable for industrial use. The current research aims to study the mechanical properties and microstructure of a multi-pass butt-welded joint of plates made of 1580 alloy of the Al-Mg-Zr system sparingly doped with Sc 0.1 wt%, depending on the shape of a weld groove and the chemical composition of the filler wire. Welding of plates with a thickness of 34.5 mm with X-groove and K-groove was performed by the TIG method in manual mode with filler wires from aluminum alloys. Good weldability and hot crack resistance of 1580 alloy providing ultimate strength of welded joints at the level of 0.84–0.93 of the ultimate strength of the base metal were established. The peculiarity of the thermal cycles of multi-pass welding affects the structure formation. The formed coarse-crystalline structure of the weld from 1580 filler wire leads to reduced mechanical properties of the welded joints, compared to the welded joints obtained with the use of 1561 filler wire. The analysis of the macro- and microstructure of the welded joints is given. The results of SEM and EDS studies of welds are presented.

Deformation behavior during hot processing of the alloy of the Al-Mg system economically doped with scandium

Abstract: Hot deformation behavior of the new alloy 1580 sparingly doped with scandium (Al-5Mg-0.6Mn-0.10Sc-0.11Zr) was studied under the deformation temperature ranging from 350 to 450 °C and strain rate ranging from 0.01 to 10 s−1. Hot deformation by uniaxial compression and torsion was carried out on a Gleeble 3800 thermomechanical simulator. Hot deformation of the alloy 1580 is accompanied by dynamic softening with the establishment of a balance between the rates of nucleation and annihilation of dislocations. Alloy flow stresses increase with increasing strain rate and decreasing temperature. The experimental results for the new alloy are in full agreement with the known concepts that the combined effect of temperature and strain rate on the deformation behavior of metallic materials is described by the Zener-Hollomon parameter. The deformation activation energy of the alloy obtained by the regression analysis of steady-state flow stresses is 175.7 kJ/mol. When using the steady-state flow stresses normalized to the shear modulus, the deformation activation energy is 148.8 kJ/mol and is close to the activation energy of self-diffusion of aluminum. Analytical expressions are obtained for steady-state flow stresses as a function of the Zener-Hollomon parameter, which make it possible to predict the deformation resistance of the alloy 1580 in a wide range of temperatures and strain rates. This result is important for FEM modeling and for the choice of temperature and stain rate of hot deformation of the alloy under study. Comparison with the literature data showed that in the region of high temperatures and low strain rates, the flow stresses are weakly dependent on the scandium content in the alloy. However, with a decrease in the temperature and an increase in the strain rate, an increase in the scandium content in the alloys leads to a noticeable increase in the flow stresses. In torsion tests, a sharp increase in the ductility of the alloy is observed at a temperature of about 400 °C. One of its probable causes may be dissolution of particles Al3(Sc,Zr) during hot deformation in this high-temperature region.