Superplastic Behavior of Ti-6Al-4V-0.1B Alloy (Preprint)

摘要

The superplastic behavior of Ti-6Al-4V-0.1B sheet was evaluated. The strain rate sensitivity (m) is 0.47 in the temperature range 775-900 C and at strain rate ( ) = 10-5 to 10-3 s-1. The material exhibits tensile elongations > 200% in the temperature range 725-950 C at = 3 10-4 s-1. The optimum superplastic forming temperature is 900 C, which is similar to conventional Ti- 6Al-4V. However, a lower flow stress is needed in the case of Ti-6Al-4V-0.1B. The superplastic deformation mechanism is suggested from estimates of activation energy to be grain boundary sliding (GBS) accommodated by dislocation motion along grain boundaries at = 10-4 s-1 and is diffusion- controlled dislocation climb at = 10-3 s-1. Microstructural observations also confirm that GBS is the operating deformation mechanism at 900 C and = 3 10-4 s- 1.