Effect of Annealing Temperature on Microstructure and Texture Evolution of TC18 Titanium Alloy

Abstract:

Sharp texture in large sizing integration of titanium alloy forgings, which were more easily formed by heterogeneity of stress field and temperature field during forging, is harmful for safety and reliability of products application. By use of EBSD techniques this paper observed the microstructure and texture of TC18 titanium bars at center layer and surface layer, and analyzed the evolution regularity of microstructure and texture after forging and annealing process under different temperature. Results show that after α+β region annealing, most β grains were recovered, some α grains recrystallized, and the grains size and texture of β phases were scarcely changed. When annealed near phase transformation temperature, large sized recovery β grains grew by grains size advantage; some α grains, particularly the lamellar α grains in β grain boundaries, grew by the combination of near oriented α grains; some special oriented α grains trended to transform, the transformed α grains would not create new β phase nuclei. After β region annealing, β phase texture were weakened obviously because β grains recrystallized and grew up without orientation preference.

Key words:TC18 titanium alloy; Microstructure; Texture; EBSD