Study Of Flow Behavior Of2A14Aluminum Alloy During Hot Compression Deformation

Abstract:2A14aluminum alloy is a type of Al-Cu-Mg-Si forged alloy which has high comprehensive properties of high strength, excellent thermoplasticity, excellent forgeability, high operating temperature and excellent welding property. It is mainly used in manufacture of structural forging which is working in condition of heavy load. It is widely used in fields of aerospace and civil transportation. The isothermal forging technology for big aeronautic forging parts of2A14aluminum alloy had been studied in this paper. The behaviors of the flow stress of2A14aluminum alloy during hot deformation were studied systematically with aids of OM and TEM conducted on the Gleeble-3500thermal simulation machine. The hot deformation constitutive equation for2A14aluminum alloy during peak and steady flow states were separately determined according to the modified flow stress curves. The deformation microstructure was observed and the effect of heat deformation processing parameters on the evolution of deformation microstructure of2A14aluminum alloy was analyzed. The processing map of2A14aluminum alloy was established, which based on dynamic materials model. The main conclusions are as follows:(1) The flow stress curves were corrected based on the affection of fiction and temperature factors. The relations among heat deformation processing parameters and the flow stress are that the peak flow stress decreases with increasing deformation temperature and increases with increasing strain rate. The peak stress and steady stress constitutive models were described respectively by the linear regression method. The peak stress constitutive model is:ε=2.28545×1011[sinh(0.01689σ)]6.65exp[-173.4×103/(RT)](2) The microstructure evolution of2A14aluminum alloy during hot deformation is revealed. The results indicate that both deformation temperature and strain rate have major impact on the microstructure evolution of compressed2A14aluminum alloy. The softening mechanism changes from dynamic recover to dynamic recrystallization with the minishing of strain rate or the rising of deformation temperature. The nucleation and growth of dynamic recrystallization grain are suppressed by the pinning effect on dislocation and grain boundary by the second-phase particles at some degree.(3) After analyzing the processing map and microstructure of2A14aluminum alloy, the results demonstrate that deformed in the areas with power dissipation above0.25in the map lead to the dynamic recrystallization and the areas with power dissipation below0.25lead to the dynamic recovery. The area with temperature range from350℃to415℃and strain rate range from1s-1to10s-1is the unstability area for the deformation of2A14aluminum alloy. The best hot working conditions for isothermal forging are at temperature range from420℃to460℃and at strain rate range from0.001s-1to0.01s-1.