Vacuum superplastic deformation behavior of a near-alpha titanium alloy TA32

Abstract

TA32 is a heat-resistant titanium alloy developed for superplastic forming in fabrication of near-space supersonic aerocraft. Clarification of superplastic deformation behavior is important to the optimization of forming parameters. Superplastic tensile test was conducted in vacuum to eliminate the effect of surface oxidation on experimental data, the test temperature and strain rate varied from 900oC to 960oC and 5.32×10-4 to 2.08×10-2s-1, respectively. It was observed that the size of equiaxed α grains exhibited a trend of coarsening with the increase of temperature and decrease of strain rate. Textures of deformed specimens exhibited random distribution with a decreased texture intensity compared with the as-received materials. The superplastic deformation mechanism of TA32 alloy was dominated by grain boundary sliding, which is accommodated by grain rotation and dynamic recrystallization.