High Efficient Thermomechanical Processing of a Beta-Stabilized Gamma-TiAl Alloy

Due to the strong demand for higher efficiencies, reduced CO₂ emissions and weight reduction in aircraft engines, the substitution of presently used materials by novel light-weight, high-temperature alloys like gamma-TiAl based alloys has started already. The requirement for balanced high mechanical properties of low pressure turbine blades in new generation aircraft engines favors a hot working strategy. Thermomechanical processing of gamma-TiAl based alloys is a complex and challenging task due to a small processing window. Isothermal forging, as state of the art process for this material group, results in high productions costs and lower productivity. Due to these facts Bohler Schmiedetechnik GmbH & Co KG has developed a higher efficient near conventional thermomechanical processing technology. Lower die temperature and processing at standard atmosphere as well as the use of standard hydraulic presses with higher ram speed results in a highly economical process. Subsequent heat treatment strategies can be used to tailor microstructure and therefore mechanical properties according to customer needs. The presentation summarizes our effort to establish a “near conventional” forging route for the fabrication of TiAl components for aerospace industry. The path from lab scale compression tests for material data generation via finite element modeling to industrial scale forging trials and mechanical properties evaluation is shown.