Intense Plastic Research Articles

О механизме формирования микроструктуры композиционного материала при сварке разнородных компонентов в режиме трения с перемешиванием

The problem of joint formation under friction treatment of composite materials based on immiscible components is viewed. The role of adiabatic shear bands (AShB) in the interaction with the elements forming the composite material is shown. The effects of migration of heavy low-melting components compared to adiabatic shear bands at speeds much higher than the speeds of traditional diffusion are described, making possible to take a fresh look at the possibilities of the effect of friction welding with stirring not only as an effective welding method, but also as the basis for an alternative technology for the production of alloys for immiscible components in bulk samples. It was found that the temperature in the stirring zone was high enough for intensive formation of solid solutions and intermetallic phases. The structure of such particles was formed under the influence of heating and intense plastic deformation under the conditions of the possible implementation of two mechanisms of component migration – diffusion and migration ones along AShB, reproduced with each rotation of the tool. An increase in the lead content in the composite material from 5 to 44 % led to a decrease in the coefficient of friction from 0,28 to 0,13. The main reduction in the coefficient of friction of the composite material of the Al – Pb system is achieved in the range of lead content of 0…30 wt. %. The development of the alternative technology for the production of special–purpose composite materials (CM) discussed above provides for two interrelated directions - expanding the range of new functional CM using the unique capabilities of FSW technology and clarifying the mechanism of structural and phase transformations underlying this technology. In particular, it is obvious that the mechanism and kinetics of AShB formation and their role in the formation of the microstructure and properties of composites need additional research.

MODELING IN THE DESIGN OF TECHNOLOGICAL PROCESSES FOR DRAWING WITH WALL THINNING OF HOLLOW AXISYMMETRIC PARTS FOR VARIOUS PURPOSES

There are a number of products that operate under extremely difficult conditions of complex loading, the manufacture of which by traditional stamping operations does not provide the required properties, which leads to a large number of defects. One of the possible directions for the manufacture of products of increased strength is the introduction into the technological process of methods of intense plastic deformation, which can be either volumetric (equal-channel angular pressing, longitudinal extrusion through a channel of variable cross-section, drawing with wall thinning along the internal contour) or surface (grinding holes, rolling with rollers or balls). The study demonstrates the application of the approximate monotonicity criterion and its relationship with technological parameters, using the example of a deep drawing process with wall thinning. A case is presented where technological parameters, including friction conditions and the degree of deformation, are selected to ensure approximate monotonicity during the thinning process. The findings provide a basis for the rational selection of the "strain-stress" curve, contributing to a more accurate and efficient design of deformation processes.

Microstructure Development of Powder-Based Cu Composite During High Shear Strain Processing

Commercially pure Cu features excellent electric conductivity but low mechanical properties. In order to improve the mechanical properties of Cu, strengthening elements can be added to prepare alloys or composites featuring enhanced performances. This study focuses on the detailed characterization of the microstructure of a Cu composite strengthened with Al2O3 particles during high shear strain processing. The Cu-Al2O3 mixture was prepared by powder metallurgy and directly consolidated by the intensive plastic deformation method of hot rotary swaging. Samples cut from the consolidated piece were further processed by the severe plastic deformation method of high pressure torsion (HPT). The primary aim was to investigate the effects of varying degrees of the imposed shear strain, i.e., the number of HPT revolutions, microstructure development (grain size and morphology, texture, grain misorientations, etc.) of the consolidated composite; the microstructure observations were supplemented with measurements of Vickers microhardness. The results showed that the added oxide particles effectively hindered the movement of dislocations and aggravated grain fragmentation, which also led to the relatively high presence of grain misorientations pointing to the occurrence of residual stress within the microstructure. The high shear strain imposed into (the peripheral region of) the sample subjected to four HPT revolutions imparted equiaxed ultra-fine grains and an average Vickers microhardness of more than 130 HV0.1.

Grain-scale microtribological behavior of VCoNi medium-entropy alloy

The tribological behavior of equiatomic face-centered cubic (FCC) VCoNi medium-entropy alloy (MEA) remains underexplored despite of the alloy’s notable tensile strength and ductility. In this study, the tribological performance of VCoNi MEA is investigated using microscratching techniques, with emphasis on the effects of grain orientation, normal force, and scratch velocity. The study has demonstrated that the grain orientation in VCoNi MEA determines the activation of slip systems during the scratching processes, which significantly affects the morphology of wear tracks, slip steps and pile-up, as well as changes in microtribological behavior. As the normal force increases, the degree of wear intensifies, which is attributed to the significant material pile-up and more intense plastic flow. The plastic deformation of VCoNi MEA is found to be independent of scratch velocity within the 0.1–2 µm/s range. Ploughing and micro-shearing are identified as the primary wear mechanisms under various friction conditions. Furthermore, during the ploughing process, the deformation mechanism of the alloy is still dominated by dislocations. The direction of dislocation motion aligns with the direction of pile-up resulted from plastic deformation. The present study offers critical insights into the tribological behavior of medium-entropy alloys and broadens the potential for their applications in friction-intensive environments.

Development of structures and production technologies of reinforcing wire with a screw profile

Reinforcing wire is the main structural element in reinforced concrete structures, widely used in the construction of buildings and structures for various purposes. The type of profile is important factor which determines the consumer properties of fittings. This indicator directly affects the quality of reinforcement adhesion to concrete and the properties of the wire. Currently a periodic profile is the most common type, but a screw profile is the most promising form of the profile. Two methods are used in the production of cold-formed screw profiles: applying a screw profile and torsion process. The first is carried out by rotating the profiling element, and the second by torsion of the workpiece of the shaped section. The patent and literature review of methods for obtaining cold-formed screw profiles has shown that the most effective way to obtain reinforcing wire with a screw profile is torsion, which provides, in addition to profiling, an increase in the mechanical and operational properties of the wire. With the help of the Deform-3D software package we identified impact of the profile, namely the shape of the cross section on the tension. By choosing rational torsion parameters, it is possible to achieve a favorable stress-strain state and respectively the properties of the product. One of the promising areas of development is the combination of a periodic and a screw profile, and it is necessary to obtain a screw profile using torsion deformation as a method of intense plastic deformation in order to form a uniform structure in metal with a minimum stress state in addition to the profile. We justified the application of radial shear broaching, an analogue of the radial shear rolling process, which allows to obtain a screw profile reinforcing wire with high mechanical properties due to the production of a finely dispersed structure. This method is implemented on standard drawing equipment and provides an increase in the productivity of wire production by torsion compared to other methods

Experimental investigation of FSW induced property changes in welded dissimilar Mg–Al–Zn alloys

Intense plastic deformation and intermixing during friction stir welding of dissimilar alloys may suppress the properties in welded zone. To suitably control these changes, careful study is required. Present research investigates microstructure, mechanical performance and corrosion behaviour at different rotational speeds in friction stir welded dissimilar AZ31–AZ91 Mg alloys. Very small cracks were present in welded zone due to formation of magnesium oxide (MgO). The EBSD analysis suggest more concentrated fibre texture at 1000 rpm tool rotational speed as compared to 700 rpm tool rotational speed in welded zone and the texture maximum intensity was 39.447 times of random distribution at tool rotational speed of 1000 rpm. The obtained maximum microhardness was 82 Hv at tool rotational speed of 700 rpm. The maximum values of tensile strength (234.86 ± 7.77 MPa) and flexural strength (350.89 ± 17.67 MPa) of welded samples were decreased as compared to base materials. The corrosion rate of welded samples was increased and corroded surface have some pits and corroded rings. The highest corrosion rate (2.1596 mm / year ) was obtained at 700 rpm. This experimental work suggests that in overall, sample welded at 1000 rpm tool rotational speed has better weld property.

EXTREMELY DEFORMED SINTERED COPPER NANOCOMPOSITES STRUCTURE AND PROPERTIES EVOLUTION

The purpose of the work is to determine the structure and mechanical properties of sintered copper (including those containing carbon nanotubes) after intensive plastic deformation by torsion. Methodology: The research objects are samples of copper powder PMS-1 (GOST 4960-75), copper powder with a 45 microns’ fraction, copper powder PMS-1 with the carbon nanotubes addition 1 % by weight, manufactured by double pressing − sintering, with a 700 MPa final pressure, temperature of 950 °C, and subjected to intensive plastic deformation by torsion on a Bridgman anvil. The structure is investigated using a Tescan Micra 3 LMU scanning electron microscope. Micromechanical tests were carried out using the “Micron – Gamma” device. Originality. At first, the microstructure and mechanical properties of sintered copper and nanomaterial “copper − carbon nanotubes” after intensive plastic deformation by torsion were investigated. It has been established that intensive plastic deformation by torsion significantly affects the sintered copper samples structure and mechanical properties. The sintered copper grain shape changes from approximately spherical to elongated in the deformation direction, and the grain size decreases by 5−7 times. In the case of “copper + 1 % CNT” nanomaterial intensive deformation, the grain refinement effect is significantly less pronounced. A significant increase in the mechanical properties of sintered copper during intensive plastic deformation has been established. The highest indicators were obtained for the “copper + 1 % CNT” nanomaterial. Practical value. The results of the work can be used in the manufacture of copper products for electrical and thermal purposes with increased wear resistance.

An efficient synergistic double-sided friction stir spot welding method: A case study on process optimization, interfacial characteristics and mechanical properties of 2198-T8 aluminum‑lithium alloy joints

Friction stir spot welding has important applications in the joining of thin metallic plates. However, the asymmetric thermomechanical action inherent in the single-sided friction stir spot welding inevitably generates the hook defect at the joint interface, and the defect deteriorates with the improvement of the interfacial metallurgical bonding, which causes the irreconcilable contradiction and significantly restricts the breakthrough of the process stability and welding efficiency. The synergistic double-sided probeless friction stir spot welding (SDP-FSSW) technology proposed in this study adopts a dual-axis synergistic control system, which introduces intense plastic deformation from both sides of the interface to form a wavy hook by accurate axial motion during the welding process. This innovative process solves the problem of hook warpage while realizing rapid metallurgical bonding and mechanical interlocking at the interface, thus obtaining AA2198-T8 aluminum‑lithium alloy spot joints with a tensile/shear strength exceeding 9kN in a short dwell time (0–3 s). Through response surface methodology, the optimal process parameters are identified, i.e. rotation speed of 603 rpm, dwell time of 3 s, and plunge depth of 0.26 mm, at which condition the average joint strength is 13.0 ± 0.5kN, a 47 % increase compared to an optimized joint of single-sided probeless friction stir spot welding (8.9kN). The optical microscope examination shows that the wavy hook can be adjusted by the rotation speed and the higher rotation speeds will make the wave disappear and produce an approximately straight interface. The fractographic analysis shows that the wavy hook can inhibit crack propagation and has good mechanical interlocking effect, but the flat hook at high rotation speeds leads to crack propagation directly along the interface, and the failure mode is changed from plug-pull fracture to interfacial fracture. Therefore, the joint strength at 1000 rpm is only 7.0kN, which decreases by about 47 % compared with the optimal strength. The electron backscattering diffraction analysis shows that continuous dynamic recrystallization occurs in the hook region and good metallurgical bonding is formed, and there are also some discontinuous dynamic recrystallized grains distributed between the large grains due to the larger strain rates and lower temperature at the interface during the SDP-FSSW process. It has been found that the wavy hook with good metallurgical bonding and mechanical interlocking can be introduced in spot welded joints by controlling the interface forming, which is a viable method to create high quality, efficient and reliable spot joints.

Fine evaluation of surface integrity of hardened 1.4418 stainless steel after finish dry turning

1.4418 hardened stainless steel (SS) is widely used in mechanical engineering because of its high functional properties. They can also be enhanced by procuring improvements in the state of the surface layer (SL) and, above all, in the factors of its strengthening, among others the average size of coherent scattering regions (ASCSR), dislocation density (DD), residual stresses (RS) of first and second orders, and relative micro-deformations of the crystal lattice (RMCL). This study investigates the effect of cutting speed (vc) ranging from 100 to 250 m/min and feed rate (f) ranging from 0.005 to 0.25 mm/rev on the indicators of SL condition after finish turning the steel tested. A reduction in ASCSR values below 8 nm was obtained for vc = 100–135 m/min, while an increase of ~ 20% was obtained for 180–250 m/min and with the f ranging from 0.2 to 0.25 mm/rev. An increase in RMCL of ~ 90% was registered for vc = 170–230 m/min and f = 0.2–0.25 mm/rev. A decrease in DD below 109 cm−2 was obtained for vc = 180–250 m/min and its ~ 25% increase for vc = 100–135 m/min. A high correlation between ASCSR and DD was shown. In the deformed material, the dislocation’s resistance to motion increases in proportion to the increase in its density. A high linear correlation coefficient in the range of 0.8–0.9 is found between ASCSR, DD, and first-order RS on the one hand, and Sa and Sz surface texture parameters, which are used in the industry to assess product quality, on the other. Additionally, the effect of plastic side flow (PSF) was observed and described. When machining with vc = 119 m/min and f = 0.22 mm/rev, the intense plastic deformation of the material causes outflow and shearing of the surface micro-hills. Favorable compressive stresses (below − 100 MPa) were registered in the range of vc = 225–250 m/min at f = 0.005–0.05 m/rev and 0.2–0.25 mm/rev, as well as vc = 115–180 m/min and f = 0.05–0.17 mm/rev. The study proved the existence of a relationship between the cutting parameters and indicators of the thin crystalline structure of SL. This means that by proper controlling of these parameters, it is possible to obtain such a state of the SL workpiece, which will ensure its long-term use.

Simulation study of Rayleigh wave inspection of subsurface white etching crack in bearing rollers

Abstract Rolling bearings are widely used in wind energy and electric vehicle industries. One of the premature failure mode due to the contact fatigue is White Etching Crack (WEC) in the subsurface. WEC occurs preferentially in the Hertzian contact region of bearings, preferentially around multi-phase inclusions containing aluminium, manganese, and sulfur. The formation process undergoes intense plastic deformation and recrystallization. Most of WECs are 100~300 μm below the contact surface in a butterfly shape. Its principal axis is 30°~50° to the rolling direction. Since the sample preparation is difficult, this simulation study enables to better understand the interaction between WEC and ultrasonic waves for a better measurement system design. Rayleigh surface wave penetrates to a depth of about an order of magnitude of one wavelength. Its energy is concentrated near the surface containing rich WEC information. The Rayleigh wave propagation process is first analyzed based on the grain scale model established. Then the immersion inspection of WEC is simulated based on the finite element method at 15 MHz in order to compromise between the detection accuracy and defect depth. Finally, by analyzing the time and frequency domain information of the scattered signals, the quantitative relationships between crack characteristics (depth, length and tilt angle) and those of Rayleigh waves (amplitude and attenuation) can be obtained. This study paves the way for the quantitatively characterization of WEC in bearing rollers with surface integrity evaluation possibility at early stage.

Mechanical properties of aluminum matrix composite reinforced with titanium carbide

Abstract An original method for the production of metal matrix nanocomposites has been proposed, which consists of depositing carbide structures 4–12 nm thick onto the surface of particles of aluminum powder by molecular layering, mixing the resulting dispersed particles with particles of pure metal in the required concentration, then pressing and sintering the resulting mixture. The resulting workpieces are subjected to intense plastic deformation by high-pressure torsion, which not only significantly reduces porosity, ensures a uniform distribution of reinforcing particles throughout the volume, and destroys carbide shells on the surface of dispersed particles, but also grinds aluminum particles. Experimental stress-strain curves of the synthesized composites were constructed and the contribution of various hardening mechanisms to the final hardening of the metal matrix composite was assessed. In metal matrix composites synthesized by this method, with small fractions of the volume content of reinforcing titanium carbide particles (less than 0.1%), almost twofold hardening and a threefold increase in the yield strength are observed with a slight reduction in plastic deformation before failure.

Effect of power density on microstructure characterization and fatigue behavior of laser shock peened Rene-80 Ni-based superalloy

The microstructure plays a crucial role in determining the mechanical properties and performance of materials, particularly in high-strength alloys such as Rene-80. This study focuses on the microstructure characterization of Rene-80 nickel-based superalloy after undergoing Laser Shock Peening (LSP), an advanced surface treatment technique imparting beneficial residual stresses and improving fatigue life. The primary objective of this research is to investigate how varying power densities during the LSP process affect the microstructure of the Rene-80 superalloy. The power density in LSP is a critical parameter that influences the intensity of shock waves imparted onto the material’s surface, consequently impacting the microstructure. Through advanced microscopy techniques and analysis, the study explores the resulting microstructural changes, including surface roughness, dislocation density, and the presence of defects like dislocations and dislocation cells. These alterations are vital indicators of the material’s mechanical properties, such as tensile and fatigue strength. LSP samples were characterized using various techniques, including field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) analysis. Additionally, the mechanical performance of the samples was assessed through low-cycle fatigue tests and tensile tests, both conducted before and after LSP treatment. The optimal power density for Laser Shock Peening is determined to be 2.5 HEL. At this power density, the shock wave generated does not create a molten layer on the surface but accumulates defects, resulting in maximum compressive residual stress at the surface. LSP induces intense plastic deformation in the sample, distorting γ’ precipitates. Higher power densities lead to the formation of cross-linked sets of slip bands, highlighting defect slip as the main mechanism of plastic deformation in the LSP process. Understanding these effects is essential for optimizing the LSP process parameters to achieve desired mechanical properties and enhance the performance and longevity of components made from Rene-80 nickel-based superalloy in high-stress applications. It was found that the fatigue life of the samples increased by 500% and optimizing the effect of power density on the LSP process led to an improvement in the fatigue life of the Rene 80 samples.

Effect of shoulder diameter, tool rotation speed, and arrangement of plates on mechanical and metallurgical properties of dissimilar aluminum 2024-T3 and 7075-T6 friction stir spot welding (FSSW)

In most studies conducted on friction stir spot welding, the focus has been on process parameters and the tool pin geometry. One of the influential parameters in this process, which has received less attention, is the tool shoulder diameter. The spread or concentration of the weld can significantly affect the weld strength and mechanical properties of the joint. In this research, two tools made of H13 hot-work steel with different shoulder diameters of 20 and 25 mm were prepared. Three rotation speeds of 1000, 1600, and 2400 rpm were considered for the welding process. The arrangement of aluminum plates on top of each other was varied in two configurations, parallel and overlapped. Mechanical properties, including tensile shear strength and Vickers micro-hardness, were investigated. The microstructure of different weld zones was also examined using an optical microscope. The results showed that increasing the tool shoulder diameter could enhance the breaking force and tensile shear strength of the joints. Meanwhile, the rotation speed had an optimal value, and with its increase, the breaking force initially increased and then decreased. Placing the 2024-T3 aluminum plate on top of the stack also increased the tensile shear strength of the samples. The fracture mode of the broken specimens was entirely nugget pull-out, which became more pronounced during the use of optimal parameters. Micro-hardness in the region influenced by heat decreased, reaching a minimum in the thermo-mechanically affected zone. In the stir zone, micro-hardness increased significantly due to intense plastic deformation and material compression. The microstructure in the nugget region appeared fine-grained and compact, while the region affected by coarse grain experienced significant heat effects. Increasing the tool shoulder diameter led to an increase in the nugget zone and the length of the bonded region. However, it did not have a significant effect on grain size in the nugget region.

Direct consolidation of an oxide dispersion strengthened alloy by hot rotary swaging

AbstractSteels strengthened by alloying elements and precipitates typically maintain their enhanced properties up to the ferrite‐austenite transformation. However, oxide dispersion strengthened ferritic steels are creep resistant even at much higher temperatures given by dispersions of nanosized oxides. To ensure homogeneous dispersion of the oxides, powder metallurgy is used for preparation of the original material. The presented study investigates the effects of direct consolidation of powder of ferritic steel strengthened with yttrium oxide nanoparticles. The powders were mechanically alloyed and sealed into evacuated steel containers, which were subjected to gradual hot consolidation via the industrially applicable intensive plastic deformation method of rotary swaging. Investigations assessing the effects of several reduction ratios showed that the direct consolidation of the oxide dispersion strengthened steel was successful – in the macroscale – at the swaging ratio of 1.03; the quality of consolidation further increased with increasing swaging ratio. At the swaging ratio of 1.83, the consolidated bulk material featured ultra‐fine grains characterized with high angle grain boundaries, homogeneous dispersion of oxide precipitates, and the average Vickers microhardness of 706.6 HV 1.

Local crack arrestability and deformation microstructure evolution of hydrogen-related fracture in martensitic steel

Intergranular cracks in the uncharged specimen were arrested at low-angle prior austenite grain boundary (PAGB) segments of several micrometers. In contrast, even small, low-angle PAGB segments with sub-micrometer sizes impeded the propagation of hydrogen-related intergranular crack. At the hydrogen-related quasi-cleavage crack tip, the crystallographic orientation changed abruptly, and deformation microstructures developed, including the formation of low-energy dislocation structures. A certain degree of crack growth resistance (intrinsic crack growth resistance) in the hydrogen-related fractures could be attributed to the intense localized plastic works involved in the arrest of intergranular cracks and the propagation of quasi-cleavage cracks.

Износостойкость теплостойких сталей ВКС-7 и ВКС-10 после ионно-плазменного азотирования, вакуумной цементации и вакуумной нитроцементации

Tribotechnical characteristics of martensitic grade steels HSM-7 (16Cr2Ni3MoVNbNAl) and HSM-10 (13Cr3Ni3Mo2VNbNAl) were analyzed. Steels underwent ion plasma nitriding, low-pressure carburizing and low-pressure carbonitriding. The concept of a two-stage hardening technology has been implemented: the creation of a thermally stable finely dispersed state of steel at the first stage and the use of such a state for accelerated and qualitative saturation of the surface layer with nitrogen or carbon at the second stage. To create an ultra-finely divided state in the samples of steels under investigation, the method of intensive plastic deformation (IPD) was used. The method is based on the grinding of the microstructure due to large shear deformations. IPD was performed by the method of warm precipitation in a die with a degree of deformation of 80 % at a temperature of 700 ℃. The wear resistance tests of the samples were carried out on a special stand with reciprocating motion in the medium of a plastic lubricant material of mating samples having flat friction surfaces at a pressure of 10 MPa and an average velocity of 0,19 m/s. It is shown that HSM-7 and HSM-10 steels after ion-plasma nitriding and vacuum cementation have high wear resistance (wear intensity I  10-10). After low-pressure carbonitriding, the values of the wear intensity of the friction pair samples are almost the same and amount to 0,3·10-10, which is ~3,0 times less than after low-pressure carburizing. As a result of ion-plasma nitriding and low-pressure carbonitriding, a nanostructured surface layer is formed on steel surfaces contributing to wear resistance increase. The ideas concerning nitrided steel score resistance increase are given.

Parts repairing and microstructural refinement of high-pressure die cast aluminum alloys through friction stir processing for bulk production

A key challenge in the production of high-grade automotive aluminum components through the High-Pressure Die Casting (HPDC) process is the imperative to minimize imperfection. In addressing this concern, this study utilizes friction stir processing (FSP), a widely recognized intense plastic deformation technique. FSP is applied to systematically alter the microstructure of HPDC Al-4Mg-2Fe, a prominent alloy extensively used in the die-casting sector. By using the pass strategy to incorporate both one-pass and two-pass approaches, the microstructure is selectively altered to establish a defect-free processed zone. The utilization of FSP demonstrates its efficacy in breaking aluminum dendrites and acicular silicon particles, leading to a uniformly dispersed arrangement of equiaxed silicon particles within the aluminum-based matrix. In addition, FSP eradicates porosity and disintegrates needle-like Fe particles, resulting in a more refined and homogeneously distributed structure. Subsequently, the material's mechanical properties processed by FSP were assessed in the longitudinal direction concerning the processing axis and then compared with those of the original base material.The microstructural refinement and reduction in porosity induced by FSP result in a notable enhancement in hardness, with an increase of 23 % after one pass and 37 % after two passes. The substantial improvement in mechanical properties during the FSP process is predominantly attributed to modifications in the morphology, refinement, and dispersion of intermetallic particles within the matrix. This improvement is further complemented by the ultrafine dispersion of casting defects.This study underscores the efficacy of FSP as a valuable tool for modifying microstructures and improving mechanical properties in HPDC Al-4Mg-2Fe alloys. Such advancements align with the lightweighting objectives pursued by the automotive industry.

Effect of al/si multilayer foil on microstructure and mechanical properties of SiCр/Al composites vacuum diffusion bonded joints

The peculiarities of joint formation in vacuum diffusion bonding through an intermediate multilayer foil (MF) of Al/Si produced by electron beam physical vapour deposition (EB-PVD) in vacuum were studied on SiCр/Al aluminium matrix composites with different alloying systems of the aluminium matrix. It is shown that Al/Si interlayer enables making permanent joints without degradation of the composite properties at the temperature of 500°С, which corresponds to the start of intensive plastic deformation of the interlayer at thermomechanical loading. It is found that the microstructure and phase composition of the joint zone (JZ) depend on the interlayer and aluminium matrix of the composite. It is demonstrated that reduction of the bilayer thickness of Al/Si MF and its alloying by manganese ensures intensive mass transfer of the components in the butt joint and equivalent joint formation. The maximum value of shear strength was 105 MPa in the case of an interlayer with a nano-scale period of the layers.

Cryogenic rolling impacts on microstructures and properties of a novel Ni–W–Co–Ta medium-heavy alloy

A high-strength Ni–W–Co–Ta medium-heavy alloy (MHA) was prepared through the melting–casting–forging followed by cryogenic rolling process. Detailed microstructure and mechanical property characterizations were conducted to unveil the influence of cyrorolling on Ni–W–Co–Ta MHA. The results revealed that initial equiaxial grains were elongated along the rolling direction firstly and then transformed to fibrous texture with increase in accumulated deformation, in which a large number of slip bands were generated to coordinate the intensive plastic deformation. A sharp increase in dislocation density significantly promoted the dislocation interactions, which, in turn, refined the grains down to nanometer scale. The strength and hardness increased significantly with the increase of the deformation, whereas the elongation decreased sharply. The fracture morphology changed from a typical ductile mode for the undeformed sample gradually to quasi-cleavage and ductile mixed mode for 90% deformed material.

Застосування ультразвукових технологій поверхневої обробки в адитивному виробництві металевих сплавів

In a modern world, additive manufacturing of metal products has reached significant volumes and variety of applied alloys. 3D-printing technologies make it possible to obtain parts with reduced mass, increased reliability, single products, experimental parts and elements designs with complex geometry and configuration. Disadvantages of metal parts additive manufacturing include anisotropy of chemical composition and properties, non-equilibrium structural-phase state, structural micro- and macrodefects and some other features, that require post-processing of as-printed products. Most often, heat treatment and its combination with microforging or intensive surface plastic deformation are used for this purpose. The manuscript provides an analytical review of the advantages of using ultrasonic technologies to support 3D-printing and post-processing of additively manufactured products. Special attention is paid to ultrasonic impact treatment (UIT). The equipment for providing UIT is compact, energy-saving and easy to use. It is noted, that this technology makes it possible to effectively reduce surface defects of printed parts, increase its hardness and fatigue strength. At the same time, nanostructuring and changes in the structural and phase state of the modified layers are also occured. It is also noted, that UIT may provide surface strengthening to a depth of ~500 μm, saturating it with alloying elements and compounds, and for conventionally produced parts, like as–cast, deformed and powder sintered – it is significantly more effective than most other similar methods. The prospects of using ultrasonic technologies to improve quality and level of operational and mechanical characteristics of additively manufactured metal parts, including the needs of aircraft construction, are outlined. Keywords: additive technologies, 3D-printing, ultrasonic impact treatment, UIT, surface strengthening, cavitation, vibration polishing, fatigue strength, Grade5, AlSi10Mg, Inconel-718.