Effect of die geometry on the microstructure of indirect squeeze cast and gravity die cast 5083 wrought Al alloy and numerical analysis of the cooling behavior

The indirect squeeze-casting of wrought Al-4.7Mg-0.7Mn (5083) Al alloy has been investigated as functions of die geometry and applied pressure. The tw o-dimensional implicit finite element computer code for heat-transfer analy sis, TOPAZ2D, was used to simulate the cooling curves obtained from the ind irect squeeze-casting process. In order to account for latent heat release and the boundary conditions, the equivalent heat capacity method and pressu re-dependent heat-transfer coefficient were employed, respectively The temp erature profile and the porosity locations were predicted accurately with t he model. The macro shrinkage cavities that were formed at the hot spot wer e completely eliminated with 100 MPa of applied pressure; however, the hot spot areas were segregated with solute-enriched liquid. Uniform SDAS rangin g from 3.19 to 10 mu m have been obtained from the billets manufactured by the squeeze-casting, whereas large deviation and coarse scale, from 10 to 3 5.89 mu m have been shown in the gravity die cast billets. (C) 1999 Elsevie r Science S.A. All rights reserved.