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P. Barriobero Vila:
"Effect of heat treatments on the microstructure of deformed Ti-6Al-4V";
Supervisor: F. Warchomicka; E308 - Institut für Werkstoffwissenschaft und Werkstofftechnologie, 2010; final examination: 12-24-2010.

Titanium alloys are widely used in aerospace applications due to their unique combination of low density and high strength. The Ti6Al4V alloy, which has the highest percentage of all applications, belongs to the group of α+β alloys. For α+β alloys as well as for β alloys, the mechanical properties which are relevant for particular applications are optimized for microstructural control. A prerequisite for property optimization is a profound knowledge of the microstructure-property relationships on one hand, and of the microstructure´s evolution as a result of processing on the other hand.
Annealing heat treatments below β transus temperature followed by different cooling rates are carried to hot deformed samples in α+β field. The experimental results show the influence of deformation temperature in the final microstructure after the annealing. A posterior effect of an ageing treatment is also studied after annealing presenting a strong interdependence of the resulting cooling rate on the final microstructure. In addition, a combination of isothermal heat treatments below β transus followed by controlled cooling rates were carried out to samples deformed in the α+β field with the intention to obtain recrystallized structures.
The microstructure is analyzed at different zones of the sample by quantitative analysis after annealing showing a lean influence of deformation parameters. Differential scanning calorimetry analysis with dilatometry and hardness tests are also used to investigate the correlation of the microstructure after the heat treatments with the deformation parameters.

http://publik.tuwien.ac.at/files/PubDat_215998.pdf