Plastic flow and microstructural evolution in Ti–6Al–2Zr–1Mo–1V alloys during hot deformation

Abstract

The hot deformation behaviour and microstructural evolution in Ti–6Al–2Zr–1Mo–1V alloys have been studied using isothermal hot compression tests. The processing map was developed at a true strain of 0·7 in the temperature range 750–950°C and strain rate range 0·001–10 s⁻¹. The corresponding microstructures were characterised by means of a metallurgical microscope. Globularisation of lamellae occurring to a greater extent in the range 780–880°C and 0·001–0·01 s⁻¹ had a peak power dissipation efficiency of 58 at about 850°C and 0·001 s⁻¹. The specimens deformed in 750–880°C and 0·01–10 s⁻¹ showed an instability region of processing map, whereas the specimens deformed in 880–950°C and 1–10 s⁻¹ indicated three kinds of flow instabilities, i.e. macro shear cracks, prior beta boundary cracks and flow localisation bands.