Influence of the Process Setup on the Microstructure and Mechanical Properties Evolution in Porthole Die Extrusion

Industrial needs are becoming always more complex pushed by an ever more demanding market and an increasingly fierce competition. Innovation and new products are the way forward if customers' attention has to be captured. On this direction, extrusion processes can be properly designed for the manufacture of complex shape parts. Furthermore, taking into account the current requirements related to the reduction of weights and volumes for fuel saving in the automotive field, the production of components with thinner thickness is increasingly on demand. Therefore, the process complexities have been growing up but, at the same time, companies have to assure quality and productivity in a more and more competitive scenario. In this work, porthole die extrusion was investigated and an "I" shaped section with the welding line in the middle of the tongue was the chosen profile. Different extrusion conditions were experimentally analyzed by changing both the profile thickness and the ram velocity; the impact of these variables on the product quality was evaluated by microstructural observations and tensile tests. The aluminum alloy, AA6060, was the investigated material. The die optimization was carried out by numerical analyses for homogenizing the flow velocity at the die exit; the simulations were also utilized for locally calculate the pressure and temperature distributions in the die and at the exit of the bearing zone for a better explanation of the experimental evidences. A wide discussion on the obtained results is here reported. (C) 2014 Elsevier Ltd. All rights reserved.