Effects of Recrystallization on Microstructure and Texture Evolution of Cold-Rolled Ti-6Al-4V Alloy

Abstract

The effects of recrystallization during annealing process on microstructure and texture evolution of cold-rolled Ti-6Al-4V alloy plates were investigated. The plates after cold rolling with a thickness reduction of 5, 10, and 15% were annealed under different conditions of 750 °C for 1 h, 800 °C for 1 h, and 800 °C for 1.5 h, respectively. It was found out that the recrystallization temperature decreased with increasing rolling reduction due to higher storage energy, while the extension of annealing time caused grain growth. For the cold-rolled plate with a reduction of 10%, the resulting microstructure showed more equal-axis grains after annealing at 800 °C for 1 h, among different conditions. Moreover, the XRD results showed that the cold-rolled plate composed mainly of {0001} 〈10-10〉 basal texture, {10-11} 〈1-210〉 and {01-12} 〈10-10〉 pyramidal textures, and {01-10} 〈10-10〉 prismatic texture, and that the weak {10-11} 〈1-210〉 texture was transformed to components {01-12} 〈10-10〉 and {01-10} 〈10-10〉, which were expected to improve formability. Electron back-scattered diffraction results ascertained that two mechanisms, i.e., recrystallization sites of preferred orientations and favorable grain growth both played important roles in static recrystallization.