Hot deformation behavior of the Ti6Al4V alloy prepared by powder hot isostatic pressing

Abstract

Ti6Al4V alloy have been prepared by powders HIP technology under 910°C/120 MPa for two hours. Surface chemistry composition of Ti6Al4V powders have been analyzed by XPS technology, results show that oxide layer exist on the surface of the Ti6Al4V powders. Microstructures of the HIPed alloy present a typical grid polygon structure which consist of the equiaxed grains and lamellar structures. And the lamellar structures are surrounded by the equiaxed grains which are formed through DRX process. Hot deformation behavior of the HIPed alloy was studied through a series of isothermal compression tests over the temperature range 645–1025 °C and strain rates range from 0.01s−1 to 10s−1. Hot processing maps and constitutive model were established based on the DDM model to give detailed information about hot deformation behavior. The activation energies for the α+β phase and the single β phase were estimated to be 365.5 kJ/mol and 447.8 kJ/mol, respectively. Microstructure evolutions of the samples after tests were observed. Results show that in the α+β phase field, dynamic globularizations as well as platelet buckling/kinking are found to be the softening mechanisms at both lower and higher strain rates. However, in the single β phase, DRX was found to be insufficient.