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 0·06C or 0·3C 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 0·3C alloy. In the β region, both alloys exhibited steady-state flow behaviour. Dynamic recrystallisation of the β phase occurred in the 0·06C alloy, while was absent in the 0·3C 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 0·3C alloy are higher than those of the 0·06C alloy in the corresponding α+β or β phase regions.