Grain refinement of α/β phase Ti-6Al-4V alloy by thermomechanical treatment

This paper summarizes the experiment on grain refinement of two phase Ti-6Al-4V alloy by thermomechanical treatment (TMT) methods. The hot rolling was conducted on alloy with starting equiaxed-α, 20 micron grain size, at temperature range of 850-950๐C and reduction per pass of 16 and 64 % plus air cooling. It was found that the 950๐C deformation with 64 % reduction per pass produces the 8 micron refined equiaxed-α. Grain refinement at the temperature of α/β phase equilibrium below transus temperature with large reduction percentage is resulted by dynamic recrystallization (DRX). However, hot rolling with 16% reduction per pass produces very large flow α structure which can be refined by globularization during annealing. The annealed structure at 950๐C for 4 hours shows globularized-α which grain-aspect-ratio is 1.2. 1