Effect of Processing Parameters on Hot Deformation Behaviour and Microstructural Evolution of PM Ti-5553 Alloy at a Moderate-high Strain Rate

Abstract

Isothermal compression tests of Ti-5553 (Ti-5Al-5V-5Mo-3Cr) alloy, produced by a fast consolidation approach from blended elemental powder mixture, were performed on a Gleeble® 3800 thermal-physical simulator to investigate its hot deformation behaviour. The samples were compressed in a wide temperature range from 700 °C to 1150 °C and a moderate-high strain rate of 1 s-1, with the sample deformation degree of 30%, 50% and 70%, respectively. Flow instability occurred when the deformation temperature was less than 900 °C. Dynamic recovery (DRV) accompanied by dynamic recrystallization (DRX) become the dominated mechanisms at the medium temperature range between 900 °C and 1000 °C, while almost only DRV features could be observed at high temperature (1050 °C ~ 1150 °C). Moreover, α phase globalization could be identified in the alloy deformed in (α+β) region. DRV, DRX, α globalization and the transformation of α to β phase were promoted with the increasing deformation degree.