The columnar to equiaxed transition during solidification of Sn-Pb alloys

In the present article, some important trends are shown regarding the influence of solidification thermal parameters on the columnar to equiaxed transition (CET) during the unsteady state solidification of Sn-Pb alloys. A comparison of the results obtained in the present work with results from the literature concerning similar experiments, but undertaken under conditions of lower heat transfer efficiency at the metal-mold interface, has shown that a realistic CET criterion should be based on a critical cooling rate at the dendrite tips of about 0.014 K/s, which depends only on the alloy system. The effects of melt superheat, solute concentration and metal-mold heat transfer coefficient on the CET position are also investigated. (C) 2002 Elsevier Science B.V. All rights reserved.