Evolution of recrystallisation texture and microstructure in low alloyed titanium sheets

Abstract

The evolution of microstructure and crystallographic texture in low alloyed titanium sheets, initially deformed by 80% cold rolling, are investigated at different stages of the recrystallisation process. Optical and transmission electron microscopies, as well as X-ray diffraction and EBSD are used to provide information about recrystallisation mechanisms and kinetics. Orientation Density Function (ODF) differences are used to quantitatively compare recrystallised and deformed states. The main texture features of the deformed state evolve only slightly during the primary recrystallisation. The major changes in texture result from secondary recrystallisation or grain growth. Primary recrystallisation can be roughly separated into two stages. The first one is very fast and corresponds to the appearance of new grains in about 80% of the material volume. The second stage is more sluggish. It corresponds to the disappearance of the so-called “white grains”, which did not twin during deformation due to their stable orientation near { ϕ 1=0°, φ=45°, ϕ 2=0°}. Recovery is an important mechanism throughout the process and deformation heterogeneities must be taken into account for a good understanding of the recrystallisation in titanium.