The effect of processing temperature on texture evolution and variant selection during phase transformation in Ti-6A-4V

In the present study, the role of starting texture on texture evolution and variant selection during α→β →α transformation has been studied. Firstly, the samples were thermomechanically processed at different temperatures in order to generate significantly different α texture but similar recrystallized grain morphology in both cases. Subsequently, both materials were recrystallized and then heat-treated above the β transus followed by 1°C/min cooling rate to promote diffusional phase transformation starting from β grain boundary, EBSD texture analysis in both specimens showed that β heat treatment produced α texture components that were similar to the recrystallized α texture but with different intensities. The degree of variant selection was assessed by comparing the strength of the measured and predicted α texture from high temperature β texture assuming equal occurrence of all the possible 12 variants during β→ αtransformation. It was found that the material rolled at 950°C showed a greater tendency to variant selection than the material rolled at 800°C but the latter shows an overall stronger texture after (heat treatment. The findings are discussed in terms of β nucleation energies and combination of α texture components promoting the occurrence of β grain pairs with a common (110) pole.