Effect of carbon on hot deformation behaviour and microstructural evolution of near-α titanium alloy Ti–5·6Al–4·8Sn–2Zr–1Mo–0·35Si–0·7Nd

Abstract

The hot deformation behaviour and microstructural evolution of a near-α titanium alloy (Ti–5·6Al–4·8Sn–2Zr–1Mo–0·35Si–0·7Nd) containing 0·06%C or 0·3%C with bimodal or Widmanstätten starting microstructures were investigated using isothermal compression test at strain rates of 0·01–10 s⁻¹ in the α+β or β regions. In the α+β region, both alloys exhibited continuous flow softening. The globularisation of transformed β structure or the recrystallisation of globular α phase took place, which was more remarkable in the 0·3%C alloy. In the β region, both alloys exhibited steady-state flow behaviour. Dynamic recrystallisation of the β phase occurred in the 0·06%C alloy, while was absent in the 0·3%C alloy. Due to the solution hardening of carbon atoms for the phases and the pinning effect of the carbides on grain boundary, the apparent activation energies of the 0·3%C alloy are higher than those of the 0·06%C alloy in the corresponding α+β or β phase regions.

Keywords:

• Near-α titanium alloy
• Carbon content
• Hot deformation
• Microstructure

This work was financially supported by the National Natural Science Foundation of China (grant no. 50901063) and the Open Research Fund from the State Key Laboratory of Rolling and Automation, Northeastern University, China.