DEVELOPING MODES TO OBTAIN DEFORMED SEMI-FINISHED PRODUCTS FROM EXPERIMENTAL SCANDIUM CONTAINING ALUMINUM ALLOY AND STUDYING THEIR MECHANICAL PROPERTIES

Abstract

The paper demonstrates the urgency of studies focused on creating new Al-Mg alloys doped with scandium and featuring by an advantageous combination of operational and mechanical properties such as weldability, corrosion resistance and sufficient strength. In production conditions, 560×1360×4520 mm flat ingots were obtained from an experimental scandium-containing alloy. They were cut into billets with a maximum thickness of 40 mm and then heat treatment and sheet rolling modes were developed for them and tested. The DUO 330 mill with smooth rolls having an initial diameter of 330 mm and a barrel width of 540 mm was used as rolling equipment. Experimental studies consisting in blank preparation for rolling (homogenization annealing and face milling), hot rolling at 450 °C, cold rolling to a thickness of 3 mm and annealing of cold-deformed semi-finished products at 350 °C for 3 hours allowed making deformed semi-finished products by various drafting patterns at rolling that were subjected to heat treatment. The maximum total degree of deformation during billet rolling to the 3 mm thickness was 92,5 %, and the draw ratio per pass changed from 1,04 to 1,2. The LFM400 400 kN universal test machine as per GOST 1497-84 was used to determine mechanical properties of deformed and annealed semi-finished products of various thicknesses made of an experimental alloy and identify regularities of their changes depending on the total degree of deformation during rolling. It was found that when rolling strips of an experimental scandiumcontaining aluminum alloy the ultimate tensile strength and yield strength of the metal grow, and the percentage elongation decreases with an increase in the total degree of deformation. This corresponds to the general ideas of metal forming theory. The mechanical analysis of semi-finished products showed that the level of strength and plastic properties is quite high, wherein the ultimate tensile strength reaches 453–481 MPa, yield strength – 429–457 MPa, and percentage elongation – 3,8-5,0 % for cold-deformed samples. Annealing made it possible to increase percentage elongation values to 14–16 % at sufficiently high yield strength (up to 277 MPa). The results of the conducted studies were used to develop casting, rolling and annealing modes for making semi-finished products of the Al–Mg alloy sparingly doped with scandium within 0,10–0,14 % that will be used when mastering machining technologies in production.