THERMOMECHANICAL PROCESSING OF HIGH-STRENGTH CAST ALUMINUM ALLOYS

Abstract

The aim of the work is to improving the complex properties of cast aluminum alloy by strain hardening. The paper presents the results of experiments on the possibility and use of plastic deformation of the cast-ing alloy VAL14 in order to improve the complex of mechanical characteristics. For this purpose, special samples were made and the tendency of the alloy to plastic deformation was evaluated on a plas¬tometer. It is shown that this alloy can be subjected to plastic deformation at room and elevated temperatures up to 30 % without the appearance of cracks. Additionally, the ductility of the alloys was evaluated at a deformation temperature of 20–545 °C by the appearance of the first cracks on the generatrices of the samples. It was established that the strength characteristics depend on temperature and the magni-tude of plastic deformation. Plastic deformation of the samples was carried out by rolling at temperatures of 20, 170 and 545 °C with degrees of 15 and 30 % at a rate of 1 s–1, followed by aging at a temperature of 170 °C. The greatest strengthening effect is achieved with LTMT with a deformation of 30 % in the region of optimal aging temperatures. HTMT provides some increase in the strength characteristics of the alloy compared to the quenched state, with a simultaneous increase in ductility. It was established that plastic deformation has an intensifying effect on the aging processes of a cast aluminum alloy. Particularly inten-sively accele¬rates the decomposition of the solid solution during aging, the preliminary deformation carried out during precipitation hardening of the alloy.