Production of low-scandium Al – Mg alloys

Abstract

The work was performed at the laboratory plant of semi-continuous casting of ingots (LPSCC) of the Institute of non-ferrous metals and materials science of SFU in order to obtain deformed semi-finished products with specified performance characteristics. The paper presents the results of obtaining an Al – Mg alloy doped with zirconium and scandium. Experimental rolling ingots were cast using casting modes that provide the structure parameters of the cast billet as close as possible to the parameters obtained in industrial conditions for ingots with a thickness of at least 300 mm. This paper presents the modes of two-stage diffusion annealing. The modes of hot and cold rolling of the experimental alloys obtained at the laboratory plant of semi-continuous casting of ingots are given. he paper presents the microstructure of the studied alloys in the cast and annealed state. The paper presents the results of research on the strength and plastic characteristics of deformed semi-finished products from experimental ingots of Al – Mg alloy with a scandium content of less than 0.1 %. The article presents comparative studies of six experimental alloys with an average content of the variable element Sc from 0.054% to 0.075%, respectively. The article shows that when the average concentration of Sc decreases to 0.054%, it is not possible to achieve the specified level of mechanical properties, due to the insufficient total concentration of the alloying element (Sc) in experimental alloys, which provides the effect of quench age hardening during the decomposition of solid solutions of scandium with the formation of intermetallic Al3Sc. It was shown that it is possible to reduce the concentration of scandium in the composition of Al–Mg alloys to 0.075% with the achievement of high performance characteristics: not lower than tensile strength — 390 MPa, proof strength — 275MPa, percentage of elongation — 12 %. The research was carried out within the framework of the State assignment by the laboratory of low-carbon metallurgy and power engineering of Siberian Federal University, as a participant company of REC «Yenisei Siberia» within the national project “Science and universities”.