Dynamic restoration and texture evolution of pure tantalum during warm deformation

Abstract

Microstructural evolution of pure tantalum during compression at temperatures and strain rates of 600–1100 °C/0.001–1 s−1 has been investigated. The results show that the restoration is mainly achieved by dynamic recovery at 600–800 °C/0.001 s−1 or 1100 °C/0.01–1 s−1, while continuous dynamic recrystallization (CDRX) has been obviously activated at a higher temperature and a lower strain rate of 1100 °C/0.001 s−1. The formation of both subgrains and recrystallized grains has been significantly promoted with temperature rising from 800 to 1100 °C at 0.001 s−1 or strain rate decreasing from 0.01 to 0.001 s−1 at 1100 °C, thus resulting in the obviously increased strain rate sensitivity (m). The deformed microstructures possess a mix of 〈111〉 and 〈100〉 textures. The <111> texture is strengthened when a large fraction of deformed grains develops at minor strains, lower temperatures and higher strain rates. The 〈100〉 texture shows an explosive growth via <100> subgrains bulging into regions with high-density low angle boundaries (LABs) in <111> grains when subgrain fraction has substantially increased after 60% height reduction at 1100 °C/0.001 s−1.