| Because of its high specific strength and stiffness,aluminum alloy not only has important applications in the field of aerospace,but also has been widely used in automobile,rail transit and other fields.In recent years,with the launch of strategic projects such as automobile lightweight and rail transit weight reduction,higher requirements have been put forward for the comprehensive properties of aluminum alloy.This paper takes 2024 aluminum alloy as the research object,establishes the constitutive equation and the hot working diagram through the study of the hot deformation behavior,studies the microstructure,second phase,dislocation and recrystallization ofthe alloy after deformation,and optimizes the deformation process of the alloy.The 2024 aluminum alloy was subjected to isothermal compression by Gleeble-3800 thermal simulation machine.The experimental conditions are as follows:deformation temperature 573-723K,strain rate 0.01-10s-1,and deformation amount20%-70%.The stress-strain curves are analyzed,and the results show that the changes of peak stress and stable stress are negatively correlated with the changes of temperature,but positively correlated with the changes of strain rate.Based on the experimental data,the thermal activation energy Q of the alloy is calculated to be201.62k J/mol,and the hyperbolic sine constitutive equation is the most suitable one for 2024 aluminum alloy.The peak value calculated by the constitutive equation is in good agreement with the experimental peak value.The microstructure,second phase,dislocation,subcrystalline and recrystallized grains ofthe alloy under different deformation conditions were observed and analyzed by optical microscope and transmission electron microscope.The results show that the second phase of 2024 aluminum alloy increases with the increase of deformation temperature,strain rate and deformation amount.When strain rate drops,deformation temperature increases and deformation quantity decreases,the dislocation of deformed alloy decreases.When the strain rate decreases,the deformation temperature increases and the deformation amount increases,the formation and growth of subcrystals and recrystallization of the deformed 2024 aluminum alloy are promoted.There are instability and stability zones in the 2024 aluminum alloy hot working diagram.When the true strain is 0.5,the ideal deformation conditions are 573-685K deformation temperature and 0.01-0.03s-1strain rate.The temperature field distribution of2024 aluminum alloy under different conditions during hot compression was obtained by numerical simulation technology.It was analyzed that the alloy was isothermal compression under 573K deformation condition and 0.1s-1,and the temperature distribution was relatively uniform. |
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