Vacuum Superplastic Deformation Behavior Of A Near- Alpha Titanium Alloy Ta32 Sheet

The superplastic deformation and microstructure characterization of a near alpha titanium alloy TA32 sheet with a nominal composition of Ti-5.5Al-3.5Sn-3Zr-1Mo-0.5Nb-0.7Ta-0.3Si in vacuum environment were systematically investigated. The maximum superplastic elongation was obtained to be 702% at 940 ?C with a strain rate of 3.33 x 10-3 s-1. The superplastic deformation constitutive equation was established and the average apparent activation energy (Q) and strain rate sensitivity (m) were calculated to be 316.3 kJ/mol and 0.46, respectively. The spheroidizing process of alpha lath was accelerated by dynamic globularization (DG). Active dislocation motion was observed and developed an attractive interaction with Silicides ((TiZr)6Si3). Transformation of low angle grain boundaries (LAGBs,2? < 15?) to high angle boundaries (HAGBs, theta 15?) was promoted by dynamic recrystallization (DRX). Significant change in texture intensity of B-type and R-type texture was observed after superplastic deformation, which was attributed to grain rotation. Superplastic deformation of TA32 sheet was mainly controlled by grain boundary sliding (GBS) along with kinds of accommodation processes, including DG, DRX, dislocation motion, grain rotation and grain growth.Superscript/Subscript Available更多