Flow stress behavior and deformation characteristics of Ti-3Al-5V-5Mo compressed at elevated temperatures

Samples of Ti-3Al-5V-5Mo alloy were compressed in both β and α+β phase region on a Gleeble 1500 Simulator. Compression tests were carried out in the temperature range of 700–1000 °C and strain rate range of 0.05–15 s−1. Experimental results show that the flow stress of Ti-3Al-5V-5Mo alloy decreases with the increase of temperature and the decrease of strain rate. At high strain rate, typically 5 and 15 s−1, discontinuous yielding followed by flow oscillations was observed in both β phase region and α+β phase region; at low strain rate, the flows display single peak stress. The flow stress at a strain of 0.2 was analyzed with a stand constitutive equation. Activation energy parameters were obtained, and they are 133.46 kJ/mol for the β phase region and 661.90 kJ/mol for the α+β phase region. Microstructures of the compressed specimens in water-quenched conditions were critically observed. High temperature deformation mechanisms have been elucidated. In the β phase region, the operative deformation mechanisms are dynamic recovery at high strain rates and grain boundary sliding at low strain rates. In α+β phase region, the α phase undergoes dynamically recrystallization at both high and low stain rates.