Study of thermomechanical conditions leading to abnormal grain growth in Ti6Al4V

Ti-6Al-4V is the most widely used α + β titanium alloy. The mechanical properties of this alloy are very sensitive to the microstructure depending on the details of the processing route used in the production of the structural parts. For some applications, Ti-6Al-4V is deformed in the α + β domain and then annealed above the β transus. Under certain conditions, large β grains are observed due to abnormal grain growth (AGG) and such microstructure should be avoided. The aim of this presentation is to study the conditions of AGG in Ti-6Al-4V during β annealing.

Various samples showing abnormal grain growth has been analyzed. It is shown that a sharp crystallographic texture can produce abnormal grain growth during β annealing. A pilot press has been used to produce such texture. A set of experiments permits to highlight the impact of temperature and of deformation on the occurrence of the AGG.