Dynamic globularization behavior of Ti–6Al–3Mo–2Zr–2Sn–2Nb–1Cr alloy with initial lamellar microstructure during hot working

Abstract

Dynamic globularization behavior of Ti–6Al–3Mo–2Zr–2Sn–2Nb–1Cr alloy with a colony microstructure was inverstigated through hot compression tests at the temperature range of 830–920 °C and strain rate of 0.001~1s−1. The experimental results show that the stress–strain curves exhibit a peak stress followed by a flow softening at smaller strain, and the globularization of α plate are the main softening mechanisms. It is very much evident that new globularized grains are evolved by the wedgesing mechanism as well as geometric dynamic recrystallization. Both the globularization fraction and globularized grain size depends sensitively on deformation conditions. Small globularized fraction at temperature of lower than 830 °C and coarsened globularized grains predominantly at higher than 920 °C. Additionally, the deformation activation energy of 665.6 kJ/mol was determined. Based on Arrhhenius equation, the flow stress model of the alloy with the correlation coefficient R was 0.99236 was established.

Keywords

• Ti–6Al–3Mo–2Zr–2Sn–2Nb–1Cr alloy
• Hot deformation
• Globularization
• Flow stress model