Assessment of hot processing for gamma titanium aluminide compressor blades

Due to the high flow stresses of gamma titanium aluminides, for a long time the development of a wrought route at an industrial scale was considered impractical given the forging facilities available in industry today. The approach adopted in this study to overcome this problem was to develop an industrial forging route comprising two forming steps. The target component was a high pressure compressor (HPC) blade. The forging route described in this paper, which is now in development, will yield a refined, fully recrystallized microstructure. Using standard industrial facilities available today for Ni-based alloys will allow manufacturing costs and quality to remain comparable to those of today's products. The innovation comprises the development and demonstration of an industrial forging route for TiAl against the prevailing wisdom (too problematic) and further optimization to give a commercially viable process. This work has been successful because it combines a fundamental understanding of material behavior during forming, with a pragmatic approach to the limitations of commercial manufacturing routes. This paper deals with an assessment of hot processing for gamma titanium aluminide to manufacture compressor blades and represents a progress report on an effort under way at Rolls-Royce Deutschland.