Materials science

Features of the kinetics of direct and reverse martensitic transformation of NiTi during deformation and realization of the shape memory effect

M.Yu. Kollerov, D.E. Gusev, O.S. Alsaeva, G.V. Gurtovaya

The features of athermal and deformation martensitic transformation in NiTi-based alloy are considered. For this purpose, the samples were deformed by stretching to different degrees and heated with measurement of sizes and X-ray structural analysis of the phase composition and microstresses in the B2 phase. It was found that at deformation to the first critical degree, the martensitic transformation is thermoelastic in nature. Above this deformation, an intensive growth of microstresses occurs, associated with the material shape change by the mechanism of formation and sliding of dislocations, which competes and above the second critical degree of deformation begins to suppress the shape change by the martensitic mechanism. In this case, the martensitic transition acquires features of an explosive transformation mechanism.

Keywords: shape memory effect, NiTi, phase composition, deformation, transformation.

The influence of the hot isostatic pressing modes and subsequent heat treatment on the properties of compacted semi-finished products made of pseudo-β alloy

V.P. Leonov, E.V. Chudakov, Yu.Yu. Malinkina, I.M. Garanina, S.D. Druganchuk, Yu.M. Markova, S.Yu. Kuznetsov, S.A. Osipov

The results of mechanical tests of samples made of pseudo-β titanium alloy produced using various gas control modes were obtained, both in the initial state and in the state after heat treatment. Studies of the influence of various heat treatment modes on the mechanical properties and microstructure of the obtained compacted samples of pseudo-β titanium alloy were carried out.

Keywords: pseudo-β titanium alloy, compacted material, hot isostatic pressing, heat treatment, mechanical properties, microstructure.

Study of impact tightness of annealed semi-finished products from titanium alloys

Yu.B. Egorova, L.V. Davydenko, S.B. Belova

The article presents the results of statistical studies of the dependence of impact toughness of titanium alloy rods and forgings on the strength level. Based on the generalization of literary and industrial data, a regression relationship has been obtained that allows estimating the average typical value of impact toughness depending on the tensile strength of α-, pseudo α- and α+β-titanium alloys after annealing. The impact toughness of VT6 alloy rods with different structures has been compared. It has been shown that, with the same chemical composition, annealed VT6 alloy rods with a lamellar structure have, on average, higher impact toughness values ​​compared to those with a globular structure. The properties of samples with mixed (globular-lamellar), transitional and basket structures lie between the globular and lamellar structures.

Keywords: titanium alloys, aluminum and molybdenum equivalents, structure, tensile strength, impact toughness, statistical studies, property prediction.

Manufacturing technologies

Status of production of cold-formed and hot-formed pipes made of titanium alloys for nuclear power and shipbuilding

L.P. Rtishcheva, P.S. Krylov, A.A. Kiselev, T.A. Martynova, E.S. Evstigneeva

General information of the main characteristics of hot-formed and cold-formed pipes made of titanium alloys, manufactured using the technologies of the National Research Center «Kurchatov Institute» – Central Research Institute of Mechanical Engineering «Prometey» is presented in this article. The results of a study of pipes made of PT-7M alloy with a regulated fine-grained structure and pipes made of high-strength titanium alloys 5V and 37 are presented.

Keywords: pipes made of titanium alloys, hot-formed pipes, cold-formed pipes, alloy 5V, alloy 37,fine-grained structure.

Titanium production by centrifugal conversion

A.E. Volkov, A.A. Volkov, E.Yu. Raskatov

New titanium reduction process is intended to reduce energy consumption and improve the production rate. The objective is achieved with a centrifugal conversion unit combining the reduction and separation equipment into a single production system. The centrifugal conversion unit performs the reactor retort and the condenser retort functions simultaneously.In the course of the reaction the reagents are separated by centrifugal forces of the retort shell rotation where titanium particles in the course of the reduction form a dense annular ingot without cavities.

The new process allows elimination of time-consuming operations of titanium block withdrawal from the retort, titanium sponge crushing and manual sorting, sponge packaging into special containers as well as sponge compaction into consumable electrodes.

Keywords: centrifugal conversion, exothermal reaction, reduction, separation, chemical elements, density.

Application. Quality. Market

Actuators made of polyethylene plates and titanium nickelide plates for transformable structures with shape memory effect

D.E. Gusev, D.V. Burdin, A.P. Neiman

Thermomechanical behavior of model samples of transformable metal-polymer structures made of 3 mm thick polyethylene sheets and 0.6 mm thick titanium nickelide sheets was studied. Two types of polyethylene were considered: high-pressure (LDPE) and low-pressure (HDPE). It was shown that high-pressure polyethylene (LDPE) has the best mechanical compatibility with titanium nickelide. This determined a higher level of shape memory effect characteristics in LDPE - titanium nickelide actuators compared to HDPE - titanium nickelide actuators.

Keywords: actuators, NiTi alloy, polyethylene, shape memory effect.