Abstract: Effects of deformation temperature and deformation rate on microstructure of the 7N01 aluminum alloy were studied through high-temperature compression test and metallographic observation. Based on these studies, extrusion process parameters were formulated, and the microstructure and fatigue properties of the T5-state 7N01 aluminum alloy profiles under different extrusion processes were observed and tested by using scanning electron microscope (SEM) backscattered diffraction technology and fatigue test lifting method. The results indicate that the alloy undergoes dynamic recovery and recrystallization during high-temperature compression. And with the increase of deformation temperature, the degree of dynamic recrystallization in the alloy increases. Meanwhile, with the increase of the deformation rate, the dislocation density of the alloy increases sharply, but the dynamic recovery in the alloy is impeded, which resulting in the degree of dynamic recrystallization decreasing first and then increasing. During extrusion, increasing the extrusion temperature and extrusion rate results in an increase in the recrystallization fraction within the 7N01-T5 profile, leading to a decrease in the median fatigue strength of the profile. However, when the extrusion temperature is 485 ℃ and the extrusion rate is 1.0 m/min, the recrystallized grains and subgrains within the profile are alternately arranged in a wide layered structure, effectively inhibiting the propagation of fatigue cracks, and the fatigue strength of the alloy reaches maximum.

Key words: 7N01 aluminum alloy profile, extrusion process, microstructure, fatigue behavior