M. H. Buescher, D. G. Terlinde, Otto Fuchs KG, Meinerzhagen, Germany; G. Wegmann, Airbus Deutschland GmbH, Bremen, Germany

Summary: A major challenge for future aircraft projects will be the implementation of high strength beta titanium forgings for structural applications against the background of weight reduction and overall performance improvement. Metastable beta titanium alloys provide the benefit of very high specific strength levels combined with a high fracture toughness and an excellent high cycle fatigue behaviour. Due to a relatively slow kinetics the alloy Ti 5553 can be solution treated by air cooling and therefore provides a better possibility of controlling internal stresses in contrast to the water quenching of the alloy Ti 10-2-3. Together with a considerable cost saving against Ti 10-2-3 the alloy Ti 5553 becomes an alternative for highly loaded parts like flap tracks and pylon or landing gear applications. The main objective of this research project is the optimisation of the thermo-mechanical processing (forging and heat treatment) of the alloy Ti 5553 to achieve the optimum combination of medium strength (Rp0,2 > 1000 MPa), fracture toughness and crack propagation resistance. Within the project in a first step the influence of different parameters like deformation degree, deformation temperature, solution treatment temperature and ageing temperature on the properties is investigated on different hand forgings. In a second step the mechanical characteristics of a die forging made of Ti 5553 are evaluated. The results will be presented and discussed.