Influence of cold plastic deformation on phase transformations and mechanical properties in metastable beta-tit anium alloys.

Annealing heat treatment in hardened materials induces the occurrence of phenomena such as recovery, recrystallization and grain growth, resulting in microstructural changes and different properties of the material in levels previous to the deformation. This work evaluated the influence of cold work in the phase transformations and hence the mechanical properties in Ti-15Mo-3Al-0.2Si-3NB, a metastable beta-titanium alloys, and variations with Cr additions, Ti13Mo-3NB-3Al-0.2Si-1,6Cr and Ti-13Mo-3NB-3Al-0.2Si-3,2Cr when subjected to different deformation and heat treatments. These processes have been investigated by microstructural analysis, differential scanning calorimetry and Vickers microhardness measurements, which allowed the quantitative determination of the activation energy involved in the recrystallization of the material, the recrystallization temperatures, the evolution of the recrystallized fraction with temperature, dislocation density and the driving force associated with the recrystallization and grain growth kinetics.