Moscow Polytechnic University, Moscow, Russia:

I. A. Burlakov, Professor at the Department of Materials Forming and Additive Technology
V. Ch. Bach, Postgraduate Student at the Department of Materials Forming and Additive Technology
A. N. Petrov, Professor at the Department of Materials Forming and Additive Technology, e-mail: alexander_petr@mail.ru

Zavod PROTON, Moscow, Russia¹ ; National Research University of Electronic Technology MIET, Moscow, Russia ²:
B. A. Loginov, Lead Designer¹, Head of Laboratory², e-mail: b-loginov@mail.ru

This paper examines the effect of severe plastic deformation during multiaxial forging and further torsional upsetting on the structure of specimens made of the titanium alloy VT1-0. A typical grain size in the microstructure of the specimens following multi-axial forging was 2–3 μm. The following working of the specimens by torsional upsetting helped obtain a nanocrystalline structure. A scanning probe microscope SMM-2000 was used to determine the grain size after torsional upsetting. The total deformation after the two processes (i.e. multi-axial forging and torsional upsetting) reaches  = 5.6–6.2. The typical grain size was 74–112 nm, which is twice smaller than the initial grain size — 30–40 μm. Analysis of the results of an experimental study conducted with the help of an LFM50 tensile testing machine at the rate of 2 mm/min shows that refinement of the structure produces a significant effect on the strength of the material and can help obtain a material with pre-defined properties. A relationship was found between the strength of the titanium alloy VT1-0 and the strain degree and grain size. Structural refinement increases the strength of the titanium alloy VT1-0 to 1,400 MPa, which exceeds the strength of the initial material by more than three times. Optimum regimes of heat treatment were identified to stabilize the structure and increase the specific elongation of the material before possible forming.

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