Effect ofβ volume fraction on the dynamic grain growth during superplastic deformation of Ti3Al-based alloys

Abstract

The superplastic deformation behavior of 'FinAl based (~+/3) alloy was studied with respect to the volume fraction of ez2/fl. Three alloys containing 21, 50 and 77% in volume fractions of/3 exhibited large tensile elongations of over 500% at 970"C with a strain rate of 2.5 • 10 4 sec 1, The largest elongation was observed in the alloy with 21% of /3. As the volume fraction of ]3 phase increased, the flow stress and correspondingly, the strain-rate sensitivity values decreased. Due to the higher diffusivity of Ti in ,/3 phase than in ~h phase, the increase in ]3 volume fraction from 21% to 77% accelerated the dynamic grain growth, and degraded the superplasticity of the Ti3Al-based alloys. The strain-based grain growth behavior was quantitatively analyzed and incorporated into a constitutive equation. The calculated flow curves are in agreement with the experimental ones in the stable deformation region.

High Temperature Forming of Ti-6Al-4V Alloy Considering Microstructural Evolution

“…High-temperature forging and extrusion are widely applied in the aerospace industry. To produce complex shaped structural parts with defect free and homogeneous microstructure, it is essential not only to find optimum processing conditions at high temperature (mechanical aspects), but also to have clear understanding of microstructural evolution during the deformation (microstructural aspects) [1][2][3][4][5][6][7]. So far, many investigations have been carried out by use of finite element method (FEM) to predict the distribution of stress, strain and temperature of the deformed parts, but most of the works have ignored the effect of microstructural evolution during the deformation, which often misled the prediction revealing considerable deviation between experimental results and predicted ones.…”