Microstructure evolution during hot forming of AA6060 and AA6082 alloys

In this work an innovative experimental method which can provide a wide range of process parameters within a limited number of tests has been developed and applied in order to determine reliable coefficients for the recrystallization phenomena during hot forming of aluminum alloys. An inverse extrusion test was performed on AA6060-O and AA6082-O alloys at four different temperatures and with two different ram speed and then the specimens were water quenched after testing so as to avoid static recrystallization. The extruded specimens were sectioned and analyzed by means of polarized metallographic techniques and the grain sizes distribution were recorded. The whole thermal and deformation sequence was simulated by means of thermo-mechanical FEM simulations and simulations results were used to calculate dynamic recrystallization coefficients. The recrystallization equations have been then implemented into the Deform FEM code and the thermo-mechanical simulations of the process were run again. The predicted grain sizes were compared in the whole section of the specimens, finding a good agreement with experimental data.