1. Clean Energy Research Center, Yangtze River Delta Research Institute,Northwestern Polytechnical University,Taicang 215400, China
2. Minta Aluminum Co., Ltd., Taicang 215400, China
The abnormal growth of grain in extruded aluminum profiles is one significant factor that affects the improvement of the mechanical properties of the alloy.Understanding the mechanism behind the abnormal growth of grain in extruded aluminum profiles and its effect on mechanical properties is crucial for controlling extrusion parameters and enhancing the properties of the aluminum alloy. In this paper, the effects of extrusion temperature and extrusion rate on the microstructure and properties of Al-Mg-Si-Cu alloys were investigated. The results show that the abnormal grain growth is due to the large shear deformation of the surface grain layer during the extrusion process and strain gradient and misorientation between the <100>//ED preferentially growing grains in core and the surrounding deformed grains, which promotes the recrystallization process of the alloy. According to the solid solution strengthening effect, the tensile properties of alloy are improved with the increase in the extrusion temperature and speed. Moreover, the tensile properties of the alloy are exceptionally good when the outlet temperature of the extruded profile exceeds 550 ℃.