Dynamic globularization of a-phase in Ti6Al4V alloy during hot compression

Abstract

Ti6Al4V samples were isothermally compressed using a Gleeble (supTM) 1500D thermo-mechanical simulator. Differential scanning calorimetry (DSC), microstructural analyses, and thermodynamic calculations were used to investigate the sequence of transformation of ß into a or vice-versa and the presence of different phases in the compressed Ti6Al4V sample. Globular alpha phase was revealed in the isothermally compressed sample in addition to martensitic and lamellar a/ß structures. The transition temperature range of ß into a-phase was determined using the DSC thermograms and thermodynamic calculated diagrams. The fraction of a-phase globulized increased as the strain rate decreased from 0.01s(sup-1) to 10(sup-3)s(sup-1), and the spheroidization of the a-phase is only possible in a specific range of deformation temperatures.