Thixoforging experiments with 6082 extrusion feedstock

Thixoforming of wrought aluminium alloys, which are relatively more difficult to form in the semisolid state, almost always employs thermomechanically processed billet. This limits the size of the feedstock and, by adding an extra step in the production cycle, is not attractive cost-wise either. An attempt was made in the present work to use 6082 billets for thixoforging without prior thermomechanical processing to improve the competitiveness of this emerging technology in the manufacture of wrought aluminium parts. The primary phase morphology in the 6082 billet has transformed completely into a non-dendritic one upon isothermal heating in the semisolid state. The slugs machined from the 6082 billet were successfully thixoforged after they were isothermally heated at 645 degrees C for 5 min. Further processing to the T6 temper has produced a hardness of 95 +/- 3 HB in the thixoforged parts. While the temperature of the isothermal heating step was slightly higher with respect to the extruded 6082 billets, thixoforging of an aluminium part directly from a DC-cast 6082 billet offers considerable cost savings and is thus much more attractive. (c) 2007 Elsevier B.V. All rights reserved.