Abstract
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Superplastic tensile tests were carried out for Ti-6%AM%V (mass fraction) alloy at 700-850°C with initial strain rates of 3 × 10-4-5 × 10-3 s-1. The tensile results show that Ti6Al4V alloy exhibits good low temperature super plasticity. The elongation of 536% was obtained at 800°C with an initial strain rate of 5 × 10-4 s-1, and the elongation over 300% were obtained even at 700°C (with an initial strain rate of 5 × 10-4 s-1). The strain rate sensitivity value m kept about 0.3 in the whole deformation temperature range, and the maximal m value was 0.63. At 850°C, the deformation activation energy was very close to self-diffusion activation energy of grain boundary, which shows the main deformation mechanism is grain boundary sliding controlled by grain boundary diffusion. Yet, in the temperature range of 700-750°C, the deformation activation energies were much higher than the self-diffusion activation energy of grain boundary. The reason may be active dislocations motion. The deformation activation energy of 800°C was between them, which shows a transition of deformation mechanism during temperature lowering.