Studies On Isothermal Forging Of2A14Aluminum Alloy Wheels

Abstract:High-strength aluminum alloy wheels are the key structural parts of the aircraft. Its material performance and structural carrying capacity are playing a important role of the aircraft overall performance. Currently, we are facing the problem of the integration between shape-finishing and performance-optimization in aircraft wheels forgings.In order to meet the regulation requires, in this paper, focus on the isothermal low-speed forging process of aluminum wheels. The thermal processing behavior and microstructure evolution of extrusion billet have been studied by isothermal thermal compression and the constitutive equation have been established. The forming rules of aluminum hub forging process have been forecasted by finite element method(FEM). And tension test and microstructure observation were used to research the organization and performance of aluminum wheels. The main work and conclusions are as follows:(1)The microstructure evolution of extrusion and extrusion-annealed2A14aluminum alloy during hot deformation and solution have been studied. Results are showed as follows: a.isothermal compression under high strain rate situation, the recrystallization has been observed, cause the fibrous organization been destryed; under low strain rate situation, the recrystallization has not been observed and the fibrous organization have not been destroyed. Indicate that low-speed forging is the effective method to remain fibrous organization. b. Compared with the extrusion billet, extrusion-annealed billet occuerd recrystallization in original organization, but the fibrous has been remained. After continued deformation and solution-annealed, the degree of recrystallization has not been improved and the fibrous organization has not been destroyed. Indicates that the extrusion billets after annealing was more suitable for continued deformation.(2) The hot deformation behavior of extrusion-annealed2A14 aluminum have been studied. Concluded that isothermal compression under deformation temperature of370～490℃, the strain rate range of0.0005～0.01s-1, the flow stress increases rapidly at the deformation initial strain, and gradually softens into steady with increasing strain. The peak flow stress increases with increasing strain rate or decreasing deformation temperature. The constitutive equation of extrusion-annealed2A14aluminum alloy are as follows:(3) The platform of alloy2A14hub low-speed forging process simulation have been established on commercial FEM software Deform-3D. Wheel forming solutions has been identified, the forging die has been designed, and forging crafts have been optimized. Results shows that, lateral flow were increased by billet upsetting, and the uniformity of strain were optimized by billet upsetting. Load rose rapidly in late stage of forging. Process parameters of forging are as follows: forging temperature was460℃, forging speed was0.01～0.05mm/s (Stroke0-60mm:0.01mm/s, Stroke60-75mm:0.05mm/s)(4) Combined slow isothermal die forming and close molding, a good surface quality, good flow lines and performance uniform2A14wheels forging were obtained. Recrystallization was not observed, fibrous organization was inherited and distribution along the direction of forging geometric. The tensile strength, yield strength and extensibility of wheel forging was, the outer ring were440MPa、380MPa and9.1%, the inner ring were395MPa、352MPa and8.1%, bottom of forging were423MPa、375MPa and8.4%.