7136铝合金型材挤压过程动态再结晶演变模拟和实验研究

Simulation and experimental research on dynamic recrystallization evolution of 7136 aluminum alloy profile during extrusion

为研究7136铝合金型材挤压过程动态再结晶行为演变规律,通过实验和有限元结合的方法确定了7136铝合金本构模型和动态再结晶动力学模型的相关参数。基于上述材料模型,采用Qform有限元软件建立了7136铝合金型材挤压过程微观组织模拟模型,发现型材截面典型部位动态再结晶分数的有限元模拟预测值与实验统计值吻合很好,其中挤压态型材表层动态再结晶分数明显高于型材心部均匀变形区,由于型材挤压过程中表层复杂的变形状态使得动态再结晶分数最高达到70%,均匀变形区动态再结晶体积分数只有8%。采用有限元法进一步研究了不同挤压工艺参数对型材动态再结晶分布的影响规律,坯料温度和挤压速度对型材断面均匀变形区动态再结晶分数的影响较小,动态再结晶分数预测范围为7%~9%;但是随着坯料温度和挤压速度的增大,型材断面动态再结晶分数小于10%的面积显著减小,型材表层动态再结晶分数最大值明显增加。

To study the evolution of dynamic recrystallization behavior of 7136 aluminum alloy profile during extrusion process,the related parameters of the constitutive model and dynamic recrystallization kinetic model were determined with the combination method of experiment and finite element. Based on the above material models,the microstructure simulation model of extrusion process of 7136 aluminum alloy profile was established by Qform software. It is found that the calculated dynamic recrystallization fraction of typical areas on the profile section is in good agreement with experimental statistics. The dynamic recrystallization fraction of the surface layer of the extruded profile is higher than that of the uniform deformation zone in the core of profile. Due to the complex deformation state on the surface during the extrusion process,the dynamic recrystallization fraction can reach up to 70%,while the dynamic recrystallization fraction in the uniform deformation zone is only 8%. The finite element method was further used to study the influence of different extrusion process parameters on the dynamic recrystallization distribution of profile. The blank temperature and extrusion speed have a small effect on the dynamic recrystallization fraction in the uniform deformation zone,and the predicted range of dynamic recrystallization fraction is 7%-9%. However,with the increase of blank temperature and extrusion speed,the area where the dynamic recrystallization fraction is less than 10%significantly decreases and the maximum dynamic recrystallization fraction of profile surface layer significantly increases.