Study Of Microstructure And Mechanical Properties Of2A14Aluminum Alloy During Multi-directional Forging

2A14aluminum alloy is a typical Al-Cu-Mg for forging due to its high strength, excellent thermoplasticity and forgeability, high operating temperature and excellent welding property. It is widely used in forge pieces which bear heavy load such as structural components in aerospace and civil transportation. The study of the forging methods and the microstructure evolvement during the process of this aluminum alloy, have great significance in controlling the forging deformation of this aluminum alloy. In this study, large scale2A14alloy were processed through the multi-directional forging technology. The microstructure and mechanical properties of2A14aluminum alloy during multi-directional forging process(including homogenization pretreatment, multi-directional forging experiments and subsequent T6heat-treatment) were observed systematically with aids of OM, SEM, TEM, XRD, Vikers hardness and room-temperature tensile test, et. al. The main conclusions are as follows:(1) The microstructure of as-cast2A14aluminum alloy segregated severe and consisted of the α-Al matrix, sheet Al2Cu phase and bone-shaped FeMnSiAl6brittle phase distributed along the grain boundary and its intercourse. The optimum homogenization treatment condition for the cast alloys was485℃/12h, considering the microstructure evolution and mechanical properties. Based on the diffusion principles of the main element Cu between the adjacent dendrites, the homogenization kinetic equation of2A14aluminum alloy was established. The most proper homogenization regulation determined by our optimized equation was485-490℃/13.6h consistent with the experimental results.(2) The microstructure of2A14aluminum alloy during multi-direction forging was influenced by both the deformation temperature and cumulative strain. In the temperature range of300℃-450℃with the strain of2.4, the softening mechanism transformed from dynamic recover to dynamic recrystallization. As the temperature increases, the dislocation density decreases; while the subgrain size increases. In the strain range of0.4-7.2at350℃, the grain was gradually refined and the dislocation density increased firstly then decreased with the increase of cumulative strain. The dynamically precipitated second phase particles during multi-direction forging process can hinder the motion of dislocation and stabilized the recrystallized grain effectively in the deformation process. According to the evolution of grain (or subgrain) boundary, it is suggested that there exists continuous dynamic recrystallization.(3) Non-continuous recrystallization occurred in the recovery matrics during T6heat-treatment process of2A14aluminum alloy deformed by multi-direction forging. After T6heat-treatment, it was easy to obtain small and equiaxed recystallization grain with high angel grain boundary when deformed at lower temperature and higher cumulative strain. The room temperature tensile mechanical properties of2A14aluminum after T6heat-treatment are excellent. Meanwhile,2A14aluminum alloy deformed with cumulative srains of3.6at350℃and processed with T6heat-treatment, had a better mechanical performance, withσb=505MPa,σ0.2=435MPa,δ=16.8%, and hardness is178HV1.0.