Study On Multi-scale Constructive Modeling Of Microstructure Evolution Of 6063 Aluminum Alloy

As the number of cars continues to increase,the problem of energy consumption and environmental pollution has become increasingly serious.Automobile lightweighting is one of the effective means to save energy and reduce emission.6063 aluminum alloy belongs to Al-Mg-Si alloy,which could be strengthened by heat treatment.It is widely used in the production of automotive parts because of its low density,high specific strength,good corrosion resistance and good formability.The hot forming of metal materials can not only obtain the shape and size of parts,but also change the micro-structure.The research on the mechanism of microstructural evolution during hot deformation can provide a basis for optimizing the process to control the properties of products.In this paper,the hot compression tests of 6063 aluminum alloy were carried out on Gleeble 1500 at deformation temperatures of 300?,350?,400?,450?and 500?,strain rates of 0.001s-1,0.01s-1,0.1s-1 and 0.5s-1.The hot deformation behavior of 6063 aluminum alloy under different deformation conditions was studied.The high temperature flow stress model and the hot processing map of 6063 aluminum alloy were established to determine the optimum hot working range.The effects of deformation parameters on the microstructure,second phase particles and grain thickness of aluminum alloy were analyzed by metallographic microscope,scanning electron microscopy and Nano Measurer software.The results show that in the initial stage of deformation,the flow stress increases sharply with the increase of strain,and tends to be stable after reaching the peak value.At the same deformation temperature,with the increase of strain rate,the flow stress increases gradually.While the flow stress decreases gradually with the increase of deformation temperature at the same strain rate.The softening mechanism of 6063 aluminum alloy at high temperature and low strain rate is mainly dynamic recrystallization,and higher temperature and lower strain rate are beneficial to the uniform deformation of the structure.The faster the strain rate and the higher the deformation temperature is,the less the amount of undissolved second phase in the tissue is.The grain thickness gradually increases as the strain rate decreases and the deformation temperature increases.The grain thickness under different deformation conditions was collected by metallographic photographs.The initial grain thickness,steady grain thickness and grain boundary migration rate were introduced to establish the micro-structure evolution model which can reflect the influence of macro-deformation parameters such as temperature,strain rate and plastic strain during the complete deformation of aluminum alloy.The critical strain and saturation stress for dynamic recrystallization of 6063 aluminum alloy were determined by using dislocation density.