The Effects Of Hot Extrusion And Aging Process On The Microstructure And Mechanical Properties Of 2219 Aluminum Alloy

2219 aluminum alloy is a kind of high strength aluminum alloy with heat treatment strengthening, which has been widely used in the field of aerospace, rail transit, and so on, mainly manufacturing rocket storage container in China. Current research of 2219 aluminum alloy mainly focuses on welding, including the influence of various welding processes and their technical parameters on the microstructure and properties, etc. However, there is little information about the systematic research on hot extrusion forming and later heat treatment strengthening in 2219 aluminum alloy, especially on the hot extrusion process parameters optimization, the microstructural change during the extrusion deformation, and the law of the precipitation of precipitated phase in the strengthening process of the heat treatment of extruded alloy, etc.In this paper, firstly, the aging phase composition, microstructure and mechanical properties of the hot extrusion and solid solution in 2219 aluminum alloy are analyzed, respectively, using XRD, optical microscope(OM) and transmission electron microscope(TEM), scanning electron microscopy(SEM) and electronic universal tensile testing machine and other equipment. Secondly, the influence of the different extrusion temperature, extrusion ratio, aging temperature and aging time on the microstructure and mechanical properties of 2219 aluminum alloy were systemically studied.The results show that solid solution effect increased with the increase of extrusion temperature. The ? phase cannot be able to completely precipitate in higher extrusion temperature, and still partly retains in matrix, which plays a role of solid solution strengthening on plastic deformation. With the increase of extrusion ratio, the degree of plastic deformation gradually becomes severe. The original coarse grains were stretched into vimineous grains as fibril shape along the extrusion direction, and theta phase is refined obviously in the microstructure. At the same time, the tensile fracture morphology was evidently affected by extrusion temperature, showing that the fracture mode is ductile fracture.The results of mechanical properties after solid solution aging show that the tensile elongation of 2219 aluminum alloy under different ageing temperature were significantly lower, and the higher the temperature, the more the influence. With the increase of aging time, the degree of recrystallization in alloy gradually increased and recrystallization area expanded unceasingly, which presents zonal distribution. The main recrystallization process occurred in the elongated grains, the more slender the grain, the higher the degree of recrystallization. According to the microstructure analysis, it shows that theta phase morphology of acicular was gradually coarsening with the increase of aging time.