抄録
The strain while undergoing allotropic transformation has been considered to be an important component for the transformation superplasticity. The fundamental characteristics of the strain due to a “both ways” passage through the (α+β) field under low stress, εtr, . has been investigated for a commercially-pure titanium.
The remarkable strain was found to occur in certain temperature range during heating and also cooling, in which the transformation takes place. The amount of εtr was changed by the rate of heating and cooling, T, showing a maximum at a rate of 0.1K/s. The strain generating during heating was always larger than that during cooling in the present study. This has been considered to be attributed to the strain of the transformation itself. The values of εtr increased with an increase in the applied stress. It was also shown that the orientation between the stress axis and the rolling direction had an influence on εtr. This has been explainable qualitatively in terms of both the orientation dependence of εtr under stress free condition and also the texture of the specimen.
A possible mechanism for the transformation superplasticity will be discussed on the basis of the stress dependence of εtr.
