Vol 2019, No 4 (2019)

The plastic flow macrolocalization in single crystals and polycrystalline alloys at various stages of strain hardening is considered. The macrolocalized plastic flow at these stages is shown to be an autowave self-organization process. The ultrasound velocity is found to be an informative parameter of autowave plastic deformation.

The Ti–Zr and Ti–Nb coatings fabricated by the electric explosion of conductors are studied by scanning electron microscopy, and the behavior of the coating/substrate interface is theoretically investigated. The results obtained are used to propose a mechanism for the interface relief formation. The wavy interface relief is assumed to be caused by the Rayleigh–Taylor instability. An analysis of a dispersion equation shows that the wavelength corresponding to the maximum increment is 0.92 μm for the Ti–Zr system and 1.67 μm for the Ti–Nb system. The distance between relief ridges detected in experiments is 2.5–8.7 μm for Ti–Zr and 5–11 μm for Ti–Nb. This difference is explained by the fact that the second maximum in the wavelength dependence of the instability increment can be observed in experiments.

A model is proposed to describe the interaction of a rigid penetrator (string) with a deformable target at high-velocity impact. The problem is considered in the plane deformation approximation. The target material is assumed to be incompressible and ideally plastic. The penetrator velocity is determined as a function of the penetration depth in an explicit form. The solutions for the crater shape and the free target surface adjoining the crater are written through universal functions, which can be approximated by simple analytical expressions at good accuracy. The penetration depth and the crater shape are calculated for an impact velocity of 1.36 km/s. The calculated crater shape agrees qualitatively with the well-known experimental data.

The effect of the structure, the temperature, and the deformation scheme on the deformation behavior of titanium nickelide-based alloys is studied. One of the most important characteristics of the material is shown to be the temperature dependence of the critical strain corresponding to the onset of intense development of slip mechanisms.

The microhardness of VT1-0 titanium subjected to megaplastic deformation by torsion under a high hydrostatic pressure at room and cryogenic temperatures and its corrosion resistance in a 1 M solution of HCl are studied. It is shown that megaplastic deformation changes the passivation ability of titanium during anodic polarization: dissolution peaks appear in polarization curves and increase with the deformation.

The composite material consisting of a carbon fiber reinforced plastic matrix and reinforcing titanium nickelide elements is studied and subjected to static and cyclic three-point bending tests. At the same rigidity, the elastic deformation and the fatigue life of the material are found to increase with the volume fraction of titanium nickelide. The developed material can be used to produce prosthetic–orthopedic medical articles.

A mathematical model is developed to study the influence of the crystallographic texture of aluminum sheets on the fracture toughness of glass laminate aluminum reinforced epoxy (GLARE). The most favorable ideal crystallographic orientations of the aluminum sheets and the directions of arrangement of fibers in glass-reinforced plastic that increase the fracture toughness of GLARE by more than 15% are determined.

The effects of alloying and a treatment technology on the texture and the anisotropy of the mechanical properties of magnesium-based alloys are reviewed. Quantitative methods are proposed for the investigation and control of the texture and anisotropy parameters of the alloys. Various aspects of the application of granular metallurgy to enhance a complex of the properties of magnesium alloys are discussed.

The adhesion of IPS InLine ceramics to a cast dental Ni–Cr (Wiron light) alloy is experimentally studied during the tensile test of flat coated specimens, and the results of a numerical simulation and multicriteria optimization using the MADMML software package are presented. Casting patterns were printed on a 3D Rapidshape printer at angles of 0° and 90° by a layer 35 and 50 μm thick. The adhesion strength of the coating is 77.9–79.9 MPa under optimum conditions.

The influence of the tempering temperature in the range 125–700°C on the structure and mechanical properties of an austenitic–martensitic VNS9-Sh (23Kh15N5AM3-Sh) sheet TRIP steel is studied. A stable high level of the mechanical properties of the steel is found to be retained up to a tempering temperature of 450°C. At higher tempering temperatures, the mechanical properties decrease sharply against the background of the reverse transformation of strain-induced martensite into austenite. After tempering at 650°C and furnace cooling, the structure of the steel consists of α ferrite.

Finite element simulation is used to study the influence of the anisotropy of the properties of thin-walled tubes made of a Zr–1 wt % Nb alloy on the geometric sizes, the residual stresses, and other parameters of spacing grid cells. The anisotropy of the mechanical properties and the initial structural state are shown to substantially affect the cell sizes. The distributions of the axial and tangential residual stresses in a stamped cell are calculated and measured, and their maximum values agree well with each other.

The influence of long-term annealing (at 700°C, 30 h) on the structure and mechanical properties of ferritic chromium steels 08Kh17T and 15Kh25T has been comparatively studied after high-temperature nitriding and heat treatment (annealing). Both steels in all considered states are characterized by high resistance against oxidation during long-term annealing. Long-term annealing of the steels in the initial non-nitrided state and after nitriding and intermediate annealing at 700°C leads to a decrease in the ultimate tensile strength and yield strength by 10–15%. The maximum decrease in the strength (by 1.2–1.7 times) upon long-term annealing is observed in both steels after preliminary nitriding and annealing at 550°C due to partial coagulation of the nitride phase.

The mechanical properties of a 08GBYu sheet steel ((wt %) 0.08 C, 1.0 Mn, 0.04 Nb, 0.04 Al) with a zinc coating and after its electrolytic removal are studied. The mechanical properties of the galvanized steel are shown to change insignificantly in the strain rate range from 8.3 × 10^–5 to 25 × 10^–3 s^–1. The fatigue limit under repeated tension is 400 MPa. The strength properties and the fatigue limit of the steel base increase by 11–13% after electrolytic removal of the coating. The load on an indenter is determined to analyze the hardness of both the coating and the steel with the coating.

The elastic hysteretic properties of various polymer damping composite materials, namely, a composite material based on a rubber mixture, a rubber fiber composite material, and thermoplastic elastomers, are studied during static and dynamic loading at a load of 20–90 kN and a temperature of 23 and –40°C. The conditions of effective application of each composite material for a damping element for the upper structure of a railway track and rolling stock are determined.

Earlier, we proposed a technique to estimate the fracture toughness of a metallic material. It differs from standard techniques in the determination of the operating stresses in an improved compact specimen with an edge crack. Using this technique, we determine the corrosion damage resistance of martensitic 30KhGSA (σ_u ≈ 1080 MPa) and VKS-9n (σ_u ≈ 2010 MPa) steels under full-scale and laboratory conditions and analyze their corrosion fracture kinetics. The corrosion fractures of the steels with different strength levels are found to have different characters: the 30KhGSA steel is likely to undergo anodic dissolution at the crack tip, and the high-strength VKS-9 steel undergoes hydrogen embrittlement.

The tensile deformation behavior of the steel/CFRP (carbon fiber reinforced plastic) adhesive joint is studied. The evolution of the deformation fields in the surface layer of CFRP is investigated by digital image correlation. The specimen is shown to fail along the adhesive joint at a strain of 0.17%.

The methods of determining strain-hardening exponent n using dynamic indentation data with allowance for loading conditions, namely, the energy before an impact and the indenter parameters, are considered. The values of n that are characteristic of impact interaction with materials having various hardnesses (steel, aluminum, copper) are obtained and compared with the values measured in static indentation. n is found to depend on the strain and the strain rate.