Change of properties of the deformed aluminium alloys at retrofitting

Abstract

Purpose. Studying the dependence of mechanical properties of deformed welding aluminum alloys on the modifying treatment. Method. The object of the study is deformed aluminum alloys of Al−Mg, Al−Cu−Mn: AMg6, 1570 systems used in welded structures of aviation and spacecraft. The disperse powder of the Mg2Si compound obtained by gas phase synthesis was selected as the modifier. The mechanical properties of alloys before and after modification, both in casting and in deformed state, were studied. Results. Industrial smelting of AMG6 and 1570 alloys in induction furnace САТ−0.15 with a capacity of 50 kg crucible was conducted. A technological process of melting with the introduced modifier is developed, namely: amount of modifier, mechanism of introduction, temperature-time conditions of its action. The optimum amount of the modifier was 0.3 % of the weight of the melt. Modifier in the form of briquettes with a diameter of 15 mm was introduced at the end of the melting into the ladle bucket. After holding 5…10 minutes, the metal was poured into the molds, as well as wedge-shaped molds for the production of samples for mechanical tests. In modified alloys, strength parameters have been increased without loss of plasticity. Scientific novelty and practical value. The mechanism of action of the disperse particles of the modifier in the melt, as crystallization centers, has been established, which contributes to the reduction of the grain of alloys and the increase of strength properties. The mechanism of action of disperse particles in a melt and the technological process of modification of aluminum alloys for industry are proposed. The obtained results allowed to improve the technological process of production of aluminum alloys of responsible designation.