The paper presents the results of a microstructure study of the near-boundary regions of aluminum and the aluminum‑magnesium alloy AMg6 in three‑layer Ti/Al/AMg6 joints produced by explosive welding, with ultrasonic vibrations applied to the aluminum and the alloy. Electron backscatter diffraction (EBSD) results showed that ultrasonic treatment promotes dynamic recrystallization of aluminum in the region adjacent to titanium, accompanied by an increase in the fraction and extent of high‑angle boundaries and a reduction in mean kernel average misorientation (KAM). A wave profile formed at the aluminum–AMg6 interface, and the AMg6 structure consisted of three regions with different morphologies: a recrystallized layer, a layer with a fibrous morphology, and a region of heavily deformed grains. Focused ion beam (FIB) microscopy showed that ultrasonic application during welding increases the thickness of the recrystallized layer in AMg6.

The structure and properties of titanium/aluminum–magnesium alloy explosive welds and the influence of the magnesium content on the weld strength are studied. The welded joints of VT1-0 titanium with AMg5 and AMg6 alloys are found to fail during both welding and the application of an external load along the near-boundary zone of an aluminum alloy, and the fracture is brittle. This fracture is shown to be due to the formation of a thin aluminum alloy interlayer with a refined structure consisting of equiaxial grains less than 1 μm in size at the joint boundary, and the boundary of this structure with the base metal is a stress concentrator.

This study examines how the material of explosion-welded plates and the composition of shock-compressed gas (SCG) in the gap between them influence the preheating of plate surfaces before impact. A series of explosion welding experiments were performed using copper plates (in air, helium, and argon) and titanium plates (in air and argon) with lengths of 0.6 and 1 m, respectively. Low-inertia planar copper-constantan thermocouple sensors were placed in the gap to record the time-dependent temperature changes at the "hot" sensor junctions. Based on the obtained temperature curves, the numerical solution of the inverse problem of thermal conductivity was applied to reconstruct the heat fluxes from the SCG acting on the plate surfaces during the entire exposure period. Targets placed in the gap between the plates allowed for the investigation of cumulative processes during oblique plate collisions, as well as the analysis of metal particle distribution formed by the dispersed cumulative jet along the gap length. It was determined that the size of the SCG region and the distribution of heat flux power along its length were influenced by the density of both the gas and the dispersed metal particles, as well as the particle concentration along the length of the SCG. During the explosion welding of copper plates in helium and air, the particles are evenly distributed along the gap, with heat fluxes of 0.3 and 0.4 GW/m2, respectively. However, when the medium is replaced with argon, the denser medium causes deceleration, leading to a redistribution of copper particles along the SCG region. These particles concentrate near the point of impact, resulting in a peak heat flux of approximately 1.8 GW/m2. In the rest of the SCG, the heat flux remains at 0.2 GW/m2. In this case, the shock wave front velocity in air, helium, and argon is the same, equal to 1.3 times the collision velocity (Vc). When welding titanium plates, the braking effect of the light, dispersed titanium particles, and their accumulation in the impact area are noticeable in the air and reach their maximum in argon. This leads to an increase in peak heat flux values to 1.0 and 3.6 GW/m2, respectively. The average heat flux in the rest of the SCG is 0.3 GW/m2 for both air and argon. Additionally, when switching from air to argon, the shock wave front velocity decreases from 1.3 to 1.1 times the Vc. The SCG heat exchange process with the surface of the plates was analyzed using numerical modeling, providing the temperature values of the surface layers before impact. The results show that when welding copper in air, helium, and argon environments, the surface temperature reaches 50-180 degrees C. In contrast, when welding titanium in an argon environment, the surface temperature can reach the melting point of titanium.

Abstract—The parameters of the shock-compressed gas that forms between plates under their collision during explosive welding are investigated. A photosensor is used to determine the shock wave front velocity at a contact point velocity Vc = 1900–2600 m/s; this velocity is found to be ≈1.3Vc, which is higher than that calculated using a Hugoniot adiabat (≈1.2Vc). Ultrafine (50–200 nm) metallic particles, which form from a dispersed cumulative jet in the welding gap, are found to affect the shock wave front velocity substantially. Low-inertia thermopiles were used to determine the heat flow (≈0.24 GW/m2) induced by the action of the shock-compressed gas on the plate surface before a collision at a distance of 0.4–1.3 m from the beginning of welding, which made it possible to calculate the temperature of heating the surface layers of the plates before a collision.

In this work, using scanning electron microscopy, the joint zone of Cu-Al bimetal obtained by explosion welding near the lower limit of weldability was studied. Micro-X-ray spectral energy dispersive elemental analysis (EDS) of melts in the joint zone was carried out. It was revealed that the melts have a finely dispersed two-phase microstructure corresponding to the eutectic (Al) + θ. It was found that with an increase in the energy of plastic deformation W2 from 0.12 to 0.24 MJ/m2, the linear content of melts increases from 15 to 57%, and the ratio of Al/Cu elements changes from 80/20 to 50/50 At.%. In this case, the mechanical tear strength of bimetal layers with kinematic parameters corresponding to the intersection of the lower limit of weldability increases abruptly from zero to an equal strength value of 89 MPa.

The paper describes various methods of using ultrasonic vibrations in arc welding based on the analysis of literature data. The main attention is paid to the recently developed method of ultrasound action on the arc. The advantages and disadvantages of existing methods of using ultrasonic vibrations in non-consumable electrode welding are shown.

The paper presents the results of studies of the influence of the parameters of an alternating current arc with a non-consumable electrode on its current-voltage characteristics. It is shown that with increasing duration of pulses of reverse polarity trev, the voltage on the direct polarity decreases monotonically, approaching a value of 3 ... 4.5 V, when trev makes up the predominant part of the period.

This paper presents a study of the formation characteristics and properties of an explosion-welded steel - aluminum composite with a chromium layer diffusion barrier. The identified characteristics of joint formation allowed us to determine the weldability range of the steel - aluminum composite with a diffusion barrier and define the optimal ranges of the explosion welding parameters. The chromium layer thickness, impact velocity, and plastic deformation energy significantly affect the magnitude and characteristics of plastic deformation during explosion welding of the steel - aluminum composite with a diffusion barrier. Thus, the steel - aluminum composite with a diffusion barrier has a higher strength and better quality than the aluminum - steel bimetal.

A method and a device for testing materials for resistance to gas-abrasive wear at normal temperatures and temperatures elevated to 1000°C is developed. The test results provide a substantiated choice of surfacing materials for restoring working surfaces of parts of exhaust fans, industrial fans, top-charging gear, gas turbine units, and other equipment. The dependences of the wear of some surfacing alloys on the test temperature, gas-abrasive flow velocity, and the angle of its attack on the sample surface is determined. It is shown that under conditions of high-temperature gas-abrasive wear at small attack angles and increased speed of abrasive particles, it is advisable to use eutectic alloys with a reduced content of expensive carbide-forming elements and carbon, and at high attack angles and low-speed abrasive, heat-resistant and refractory austenitic steels. It is found that the foreign deposited C6.0Cr23Nb7Mo7W2Si2VT alloy, characterized by the highest alloying level and volume fraction of strengthening phases, has the highest resistance to gas-abrasive wear at normal temperatures among those tested. When the test temperature increases to 600°C, its wear resistance decreases by 2.5 times, yielding to the indicator of the experimental C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy. The processes of destruction of thin surface layers of alloys are studied using the electron-ion microscopy method, which makes it possible to evaluate the influence of their structural and phase composition on the high-temperature wear mechanism. The study of the wear pattern of the C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy showed that under the impact action of the abrasive, cracks are formed in lamellar carbides Me3C2 and Me7C3, but the high plasticity of nickel-alloyed austenite reduces the likelihood of breakdown of the resulting fragments. At the same time, small carbides (Ti,Nb,Mo)xCy and Mo2C of a compact form restrain the plastic deformation of the austenite-carbide eutectic without destruction.

The study experimentally proved the possibility of obtaining intermetallic materials of the Ti-Fe system from mixtures of titanium and iron powders using MIM technology and subsequent reaction sintering. It has been established that the structure of such materials is close to stable equilibrium and contains TiFe as the main intermetallic phase.

The work is devoted to the study of the effect of the introduction of ultrasonic vibrations during explosion welding of a pair of aluminum-steel compounds. A comparative study of the effect of the explosive loading scheme of joints obtained by the conventional method of explosion welding and explosion welding with the influence of ultrasonic vibrations in forced welding modes was carried out. It has been experimentally established that the introduction of additional ultrasound energy in the process of explosive loading of an aluminum-steel compound contributes to a significant reduction in the amount of molten metal at the junction boundary throughout the studied range. The chemical composition of the areas of the melted metal is considered. The results of the tensile strength of aluminum+steel composite layers are presented.

This paper describes a thermocouple method for measuring the heat flux from the shock-compressed gas in the welding gap to the surfaces of the impacted plates during explosion welding. A set of experiments was conducted to determine the heat flux during explosion welding of copper plates at a distance of 0.4-0.6 m from the beginning of welding. The heat flux from the shock-compressed gas was found to be independent of the contact point velocity in the range of 180 0-250 0 m/s. As a result, the temperature of surface preheating before collision was found to be quantitatively dependent on the size and material of the welded plates. Thus, the effect of preheating the plates with shock-compressed gas in the gap can be commensurate with the energy released in the weld at the subsequent collision of the plates.(c) 2023 Elsevier Ltd. All rights reserved.

During the study, based on the experimental data obtained, the influence of the parameters of modulated alternating current during automatic two-electrode submerged arc surfacing on the geometric parameters of the weld bead was revealed. It has been shown that the proportion of base metal can be reduced by reducing the balance between current phases to 25% and setting the current amplitude offset to -10 V. The results obtained can be used for the operation of cladding internal surfaces of petrochemical production equipment with corrosion-resistant alloys.