Studio della ricristallizzazione durante il processo di estrusione della lega AA6060 mediante simulazioni FEM

In this work an experimental methodology to evaluate the prediction of recrystallized structures in aluminum extrusion was presented and validated. In the first part of work an experimental procedure to investigate the evolution of recrystallization in aluminum alloys is presented and discussed. Several cups, obtained by means of inverse extrusion, were produced at different temperatures and process speeds. The specimens were analysed in order to examine the grain size distribution. The coefficients for dynamic recrystallization models were obtained by regression analysis after thermo-mechanical FEM simulations of the experiments realized with the code Deform 3D. A complete set of coefficients was regressed for the available microstructure evolution models inside the code environment. The specimens were then heated in a furnace and cooled in order to reproduce static recrystallization of the material. The grain distribution was examined and the coefficients for the equation for static recrystallization prediction were regressed, too. In the second part of the work the extrusion of a round-shaped profile is described and the grain size distribution on the profile and on the billet rest is analyzed. The obtained models were applied to the real extrusion of a round profile and a comparison between experimental measurements and simulation results was performed. The simulated results were in very good agreement with experimental data, except in zones where peripheral coarse grain and grain growth appeared. Here, a further investigation effort and specific modeling equations are required.