A FINITE-ELEMENT ANALYSIS ON THE UPSETTING PROCESS OF SEMISOLID ALUMINUM MATERIAL

The behavior of alloys in the semi-solid state depends strongly on the imposed stress state and on the morphology of the phase, which can va ry from dendritic to globular. A finite-element model for semi-solid m aterial in the upsetting process is presented. The semi-solid material is assumed to be described by compressible rigid visco-plastic model for the solid region and by Darcy's law for the liquid flow saturated in the interstitial space. The variation of the distribution of the so lid fraction and the material behavior under the upsetting process is investigated for the various values of friction and die speed, the com puted results being compared with experimental data. The semi-solid ma terials of the experiments are fabricated by mixing and cooling of the molten metal. The application validity of the yield criteria for semi -solid material is investigated in the upsetting process analysis. (C) 1997 Elsevier Science S.A.