Microstructure Evolution During Isothermal Forging of 7A85 Aluminum Aviation Component

A 7A85 aluminum aviation component with high ribs and thin webs was successfully formed by the isothermal forging process, and its microstructure was investigated by optical microscope (OM), transmission electron microscope (TEM), and cellular automaton simulation. Metallographic images show the recrystallization phenomenon takes place all over the aviation forging, and a uniform grain size is obtained. The cellular automaton model of 7A85 aluminum alloy, including dislocation density model, nucleation rate equation as well as grain growth model was established, and the parameters of the cellular automaton models were determined by the hot compression experiment on the thermal-mechanical simulator Gleeble-1500. The cellular automaton simulation results agree well with the optical micrographs of the aviation forging, showing good homogeneity in both the size and the distribution of grain structure. The TEM images show that a homogeneous distributed dislocations and precipitates of the forging formed by the isothermal forging process can be attained, which can inhibit the migration of the grain boundaries, resulting in the small and uniform grains of the aviation forging.