National University of Science and Technology MISIS, Department of Pressure Metal Treatment (Moscow, Russia)¹ ; Moscow Polytechnic University (Moscow, Russia)²

N. А. Belov, Chief Researcher^{1, 2,} Doctor of Technical Sciences, nikolay-belov@yandex.ru

S. O. Cherkasov, Senior Lecturer¹, Senior Researcher², Candidate of Technical Sciences, ch3rkasov@gmail.com

National University of Science and Technology MISIS, Department of Pressure Metal Treatment (Moscow, Russia)
А. V. Fomin, Leading Engineer of the Scientific Project, Candidate of Technical Sciences

National University of Science and Technology MISIS, Department of Pressure Metal Treatment (Moscow, Russia)¹ ; JSC Aluminium Alloys Plant (Podolsk, Russia)²

М. V. Finogeeva, Master’s Student¹, Deputy Head of the Central Laboratory of the Plant²

A comparative analysis of the structure and thermal stability of extruded rods was carried out using the commercial heat-treatable alloy AD31 and the experimental non-heat-treatable alloy “Kalmar” based on the Al – Ca – Mn system. Pieces cut from an industrial cylindrical billet were used as the starting material for the commercial alloy. The experimental alloy was prepared from A7 primary aluminum with the addition of recycled materials to achieve the target composition (~2.2 wt.% Ca, ~1.0 wt.% Mn, and ~0.9 wt.% Zn). Cylindrical billets with a diameter of 43.5 mm and a weight of approximately 1 kg were produced by casting into a graphite mold. Extrusion was performed at 400 and 450 °C with a ram speed of 1 mm/s using a die with a diameter of 12 mm. It was shown that, despite the high eutectic fraction (~20 vol.%), the nonhomogenized billets of the “Kalmar” alloy exhibited sufficient workability, particularly at 450 °C, where the extrusion force was comparable to that required for homogenized AD31 billets. During extrusion, the structure of the “Kalmar” alloy was significantly refined compared with the as-cast condition: the eutectic phase particles acquired a nearly globular morphology, and their distribution became more uniform. The extruded rods of the “Kalmar” alloy demonstrated substantially higher thermal stability than those of the commercial AD31 alloy. In particular, the ultimate tensile strength after annealing at 400 °C was 158–165 MPa, compared with 106–132 MPa.
The work was carried out with the financial support of the Ministry of Science and Higher Education of the Russian Federation within the framework of the state assignment No. FZRR-2026-0005 (production of alloys, extrusion and heat treatment) and the grant of the Russian Science Foundation No. 25-19-00002 (structural studies and determination of mechanical properties).
Part of the research was carried out by the authors using the equipment of the Common Use Center “High-Tech in Mechanical Engineering” of the Moscow Polytechnic University.

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