The Hot Spot in Al-Rod Extrusion Investigated by FEM-analysis

FEM-analysis is applied to study thermo-mechanical conditions in an industrial Al-rod extrusion process using long billets as stock material. In the analysis, focus is on the conditions in the hot spot present inside the metal of the billet material near to the die edge during extrusion. Here the strain-rate and the temperature in the hot zone reaches critical conditions if the extrusion ram speed is set too high. When overcritical conditions exist here, speed cracking will occur in the metal. The Lagrangian version of the software DEFORM 3D is applied to model the process numerically, and it is investigated how the distribution of the temperature as state-variable is predicted in the hot spot and else how inside the billet, and how it depends on the extrusion conditions. Through the analysis, new information on this important issue is achieved.