1992 Volume 78 Issue 8 Pages 1398-1405
High temperature deformation of pure titanium, (α+β) and β titanium alloys were studied by means of compression tests over the range of strain rate from 10-1s-1to 10-3 s-1 and at temperatures between 973 K and 1473 K, and the results obtained were analysed by using Zener-Hollomon parameter (Z).
The following results were obtained ;
(1) Maximum flow stress, σmax, was correlated with working temperature, T, and strain rate, ε, approximately by the following deformation equation;
Z(=ε exp(Q/RT))=A(sin h(ασmax))n
whereQ: hot-working activation energy, n: stress exponent, R: gas constant, A and a: constants.
(2)The value of Q in α+β phase was much larger than that in β phase. So the deformation mechanism in α+β phase must be different from that in β phase. The value of Q in β Ti was almost the same as the activation energy for the self-diffusion of Ti.
(3) Deformation structure became to equiaxed microstructure by continuous recrystallization in the range of Z less than the critical value, Zc. The recrystallized grain size was determined only by the deformation condition Z, and did not depend on the initial grain size.
