Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia:

A. M. Pesin, Professor
D. O. Pustovoytov, Assistant Professor, e-mail: pustovoitov_den@mail.ru
V. L. Steblyanko, Professor

Perm National Research Polytechnic University, Perm, Russia:
S. A. Fedoseev, Professor, Chair of Computational Mathematics and Mechanics

A deformable AMg6 (АМг6) aluminum alloy of Al – Mg system is characterized by good plasticity, high corrosion stability and good welding capacity. That’s why it is widely used in welded constructions of rockets and space vehicles. However, the essential weakness of AMg6 alloy is its rather low strength. Therefore, the topical task is a development of new non-cutting shaping technologies which can guarantee the improved strength properties of AMg6 alloy. One of the possible ways to solve this problem is to form in the melt a fine-graded or ultrafine-graded structure through the application of severe plastic shear-compression deformations by asymmetric cold rolling technology. To emulate such a technology and to define optimal deformation parameters, which provide the fine-graded or ultrafine-graded structure formation, a technique of high-cycle deformation of laboratory specimens according to a shear-compression scheme has been implemented on a Shimadzu AG-IC 300 kN precision universal testing machine. Special specimens have been produced in the shape of parallelepipeds 50 mm in height with a square cross-section of dimension 2525 mm with two parallel notches in 6 mm wide and 10 mm depth, implemented at the side surface at angle of 45 degrees to vertical axis with fillet radii of 3 mm. The objective of this work has been to experimentally test this technique and to study the distinctive features of changes of the AMg6 structural alloy structure and microhardness on achievement severe plastic deformations during shear-compression testing. As a result of the carried out investigations, it is established that ultimate plastic strains of the AMg6 aluminum alloy in a cold state are restricted by the value of true deformation e = 1, on achievement of which the cracks formation and material destruction take place. It is shown that high-cycle warm deformation of the AMg6 aluminum alloy in a shear-compression scheme with achieving severe plastic deformation e = 4 at a temperature of 200 ^oС leads to formation of fine-graded structure and significant increase of HV microhardness up to ~1350 MPa.

M. K. Sverdlik has participated in the investigations.
The research has been implemented at the expense of the grant of the Russian Science Foundation (project No. 15-19-10030).

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