.2124 Aluminum Alloy Homogenization And Thermal Simulation

The phase constituents and composition distribution of the as-cast and homogenized 2124 aluminum alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Then hot compression tests were performed on the as-homogenized 2124 aluminum alloy. The flow stress constitutive equations were established. The flow stress constitutive equations and the processing map were established. And the effects of deformation parameters on microstructure of 2124 aluminum alloy were studied by OM and transmission electron microscopy (TEM). The conclusion can be summarized as follows:(1) The main phases in as-cast 2124 aluminum alloy are a(Al),θ(Al2Cu), S(Al2CuMg) and Al6Mn. Severe dendritic segregation exists in 2124 aluminum alloy ingot. There are many massive secondary phases in grain boundary, and Cu, Mg and Mn elements are uneven distributed from grain boundary to inside. The main secondary phases are Al2CuMg and Al2Cu with some Mn contained.(2) With increasing the homogenization temperature or prolonging the holding time, the residual phases are dissolved into the matrix gradually, grain boundaries become sparse and the distribution of all the elements becomes more homogenized. The S(Al2CuMg) phase completely dissolved back into a(Al) matrix after homogenization. The suitable homogenization treatment of 2124 aluminum alloy is 490℃for 24h, which is consistent with the results of homogenizing kinetic analysis.(3) The flow behavior of 2124 aluminum alloy during high temperature compression can be described using the Arrhenius equation which is ameliorated by hyperbolic sine fuction and Z parameter. This indicates that the high temperature plastic deformation of 2124 aluminum alloy is a thermal activation process. The four characteristic constants of materials are obtained as follows:n=4.1093, a=0.0173, A=1.4084×1011s-1, Q=170.13kJ/mol.(4) When the deformation temperature is below 420℃, the hot deformation structure is mainly dynamic recovery structure:sub-grain structure. As deformation temperature is higher than 420℃, and the value of 1nZ≤25.6, dynamic recrystallization occurred in the alloy. The nucleation mechanism of recrystallizing process is subgrain coalescence and subgrain growth.(5) 2124 aluminum alloy processing maps were established by Dynamic material model(DMM), and the results show that the area of regional temperature and low strain rate (deformation temperature of 440～480℃, strain rate of 0.01～0.1s-1) is the best processing region of the alloy. Meanwhile, in order to obtain a wider range of optimum processing performance area, the multi-pass processing of small deformation process should be selected.