Materials science

Dynamic resistance of VT23 titanium alloy with linear gradient and homogeneous lamellar structures

O.N. Gvozdeva, A.S. Stepushin, G.V. Gurtovaya, N.V. Ruchina, A.A. Smirnov

The work studies the resistance to high-speed impact of VT23 titanium alloy plates with different structure types. It is shown that the creation of a dispersed structure with an α-phase size of no more than 0.4 μm in the plates surface layer allows increasing the hardness up to 42 HRC units. It is established that plates with a linear gradient structure have higher dynamic resistance compared to plates with a homogeneous large-lamellar structure and can stop an impactor with an energy of no more than 1510 kJ.

Keywords: titanium alloy, phase composition, gradient structure, hardness, impact strength, dynamic strength, thermal hydrogen treatment.

Determination of rheological characteristics of titanium powder based on the analysis of the deformation process of an idealized powder body model

V.P. Leonov, Yu.Yu. Malinkina, S.D. Druganchuk, I.M. Garanina, E.V. Chudakov

The paper investigates the processes of plastic deformation of titanium powder using numerical methods, in particular, the finite element method. A computational and experimental technique for determining the rheological characteristics of a powder material based on the known mechanical characteristics of the particle material is applied based on an analysis of the deformation process of an idealized model of a powder body. An idealized model of a powder body is considered, which is used to mathematically simulate the deformation process of an elementary cell in the form of a cube with a spherical particle surrounded by a multifaceted pore. The simulation results are in good agreement with experimental data on die forging process. This indicates the practical possibility of using this computational and experimental technique for determining the rheological characteristics of a powder body based on known values of the yield strength of the particle material for mathematical modeling of the compaction processes of titanium powder materials.

Keywords: titanium alloys, hot isostatic pressing, titanium alloy powders, rheological properties.

Novel insights into inverse relationship between shear and tensile strength in high strength titanium alloys

A.S. Grebenshchikov, M.O. Leder, A.V. Volkov

Inverse relationship of shear strength and tensile strength observable in some pseudo beta titanium alloys contradicts theoretical relationship between these parameters based on Von Mises equation witch postulates that in the pure shear yielding occurs at the stress which is 0.57 fraction of yield stress in pure tension. In practice, the ratio between shear strength obtained from double shear test and yield or ultimate strength from tensile test of high strength titanium alloys varies between 0.4 and 0.75 and decreases with increasing tensile strength. Previous studies shown that microstructure obtained at various heat treatment have little to no influence on the ratio between shear strength and tensile strength. To elucidate the cause of this effect, FEM modelling of double shear test has been conducted. Based on the results of the experiment new explanation of the cause of inverse relationship between shear and tensile strength has been proposed. Considering stress distribution at the beginning of the double shear test, stress is concentrated at the point at the tip of the knife, while at the center of the specimen stress is considerably lower. When stress at the surface of the specimen reaches yield point yield begin while at the center of the specimen stress is still low for yield to start. Considering the fact that high strength titanium generally have pretty low ductility, the fracture occur while stress distribution is still uneven which causes final value of shear strength to be lower than expected.

Keywords: titanium alloys, shear strength, tensile strength, double shear.

Review of modern methods for the production of composite materials based on titanium alloy with the addition of graphene

E.A. Illarionova, V.N. Anikin, S.A. Eremin, S.D. Shlyapin

This article discusses the mechanisms of interaction between titanium alloy and graphene during sintering, based on the analysis of existing literature sources. The key aspects contributing to the improvement of the mechanical properties of composite materials are highlighted. Graphene acts as a reinforcing element, increasing the strength and rigidity of the titanium alloy due to structural reinforcement and slowing down plastic deformation. The chemical interaction between graphene and titanium leads to the formation of new phases and improved adhesion, which creates a more uniform load distribution.

The influence of graphene on the porosity of the composite is also noted, contributing to its reduction and improvement of density. The quality of the interface between graphene and titanium is becoming critically important for load transfer mechanisms, emphasizing the need for further study of processes at interphase boundaries. Each of the considered mechanisms requires in-depth analysis to understand their effect on the properties of titanium alloys with graphene. The development of new graphene-based materials can lead to the creation of unique materials that will find application in various industries.

Keywords: Composite materials, titanium alloys, technology, sintering, graphene, mechanical properties, strength.

Assessment of the fracture toughness of titanium alloy Ti-6Al-4V, calcethermic thorium, uranium, plutonium

S.V. Serikov

Using the computational and experimental method of identifying metals, already known from publications, a quantitative analysis of the assessment of destruction was performed using the following metals as an example: titanium alloy Ti-6Al-4V, thorium, uranium, plutonium. Their individual characteristics regarding operational reliability are revealed. The patterns of changes in the coefficient of dynamic viscosity and specific energy of destruction of the materials under consideration depending on the strain rate and test temperature are presented.

Keywords: metal identification, dynamic viscosity coefficient, specific work of fracture, fracture toughness, material endurance limit.

Manufacturing technologies

Surfacing with oxidized rods on titanium alloy parts

V.K. Shatalov, L.V. Lysenko

New additive materials and their manufacturing technology for surfacing on titanium alloy parts are being considered, which allow to increase the production capacity of shut-off valves. The results of the experiment of obtaining surfacing with filler rods with a surface treated with microarc oxidation are presented. The prospects of using the proposed method of manufacturing surfacing rods with higher productivity in comparison with the existing one are shown.

Keywords: titanium, thermal oxidation, microarc oxidation, electrolytes, surfacing.

The application of titanium alloys for the impellers of the sentrifugal compressors

A.I. Igolkin, I.A. Maksimenko, V.E. Kuzmin, Yu.V. Zelenin

The advantages of using titanium alloys for impellers of centrifugal compressors are considered. The technological process of manufacturing these products using diffusion brazing using amorphous titanium strip filler metal is presented. The features of the technology for the creating of the brazing joints with the equal strength to the base metal for the various titanium alloys are shown. In order to improve the erosion resistance of the parts it is useful to apply some high strength titanium alloys or special technology of tungsten carbide coating.

Keywords: titanium alloys, impellers, compressor, diffusion brazing, amorphous filler metal, erosion, tungsten carbide layer.

Application. Quality. Market

Opportunities for trading in metal products on the exchange

I.V. Chernyshev

The article provides a brief description of the Exchange’s areas of activity, in particular, the work of the SPIMEX Metals and Alloys Section. Particular attention is paid to exchange trading in reinforcement and the prospects for introducing other commodities, including titanium products, to organized trading.

Keywords: exchange trading, commodity market, metal products, reinforcement.