Improvement of technology for strengthening aluminum alloy profiles

Abstract

Based on literature data, the possibilities and mechanisms of strengthening of wrought aluminum alloys of the 2xxx, 4xxx, 6xxx and 7xxx series during quenching and heat treatment, methods of increasing their strength and ductility are considered. It should be noted that this issue is stated very vaguely and ambiguously in domestic standards. Quenching from the temperature of hot deformation is called incomplete quenching and is designated T5. Under full quenching is understood only quenching from separate heating with the designation T6. There is no mention of any possibility of achieving a state of complete quenching without separate furnace heating. To obtain maximum physical and mechanical properties of this alloy, it is necessary to optimize all technological processes: melting, refining, modification, obtaining ingots, homogenization, pressing and heat treatment. The economic advantages of using the technology of heat treatment of profiles with hardening on the press compared to hardening with separate heating are analyzed and shown, a necessary condition for the implementation of which is the identity of the temperature intervals of heating for hardening and exiting the press. To obtain a supersaturated solid solution, which during further processing operations contributes to dispersion aging and increasing the strength of profiles, their cooling at the exit from the press should be at a speed not lower than the critical one, which depends on the chemical composition of the aluminum alloy. The greatest efficiency of thermal hardening of aluminum alloys of the 6xxx series is achieved with a three-stage heat treatment. Possible ways of implementing this process, their advantages and disadvantages are described. The requirements of American and European standards for deformable aluminum alloys are discussed, as well as the features of the technological process for obtaining high-quality profiles depending on their chemical composition.