Flow Behavior And Process Optimization Of2124Aluminum Alloy

2124aluminum alloy is widely used to manufacture aerospace vehicles structure and load-bearing components in the aerospace industry. Though there are some researches about influence law of composition or heat treatment or technology on performance of2124aluminum alloy, its high-temperature flow behavior and microstructure evolution still need to be further investigated. High-temperature rheological characterization of2124aluminum alloy was investigated through experiments and theoretical analysis, a constitutive model of high-temperature flow behavior was established, and workability of2124aluminum alloy was discussed and forming parameters was optimized. The main contents and results are as follows:(1)The influence law of deformation conditions on flow stress and microstructure evolution of2124aluminum alloy during hot deformation was investigated through thermo-compression experiments and optical microscope. The results show that flow stress of2124aluminum alloy increases with increase of strain rate or decrease of the deformation temperature, and intensity of dynamic recrystallization and grain size both grow. Initial dynamic recrystallization happens when the deformation temperature is higher than713K and natural logarithm of Zener-Hollomon parameter is smaller than44, besides, strain must be higher than critical strain (εc), the quantitative correlations between critical strain (εc) and the strain (εp) corresponding to peak stress can be expressed as:εc=0.43εp.(2)Based on the experimental results, a phenomenological constitutive model was established, considering the coupled effect of strain rate, strain and forming temperature on the high-temperature flow behavior. The results show that the maximum error between the predicted values and experimental results is only2.99%. So the established constitutive model can accurately predict the flow behavior of2124aluminum alloy at elevated temperature.(3)Based on the principles of dynamic materials model, processing maps were established. The effects of deformation processes on the efficiency of power dissipation and instability parameters were discussed. Combined with microstructure of2124aluminum alloy, the relationship between processing maps and microstructure was obtained, and the optimized forming parameters were obtained at the strain rate of0.01～0.08s-1and forming temperature of700-743K.(4)DEFORM-3D was adopted to simulate the isothermal hot compression experiments. The simulation result indicates that maximum effective stress appears at top of specimens. The maximum stress decreases with increase of the deformation temperature or decrease of strain rate. The damage value of hot compression processes increases with decrease of the deformation temperature or increase of strain rate.