High Temperature Material for turbine Structures
|Volvo Aero Aktiebolag
|Funding from Vinnova
|SEK 2 000 000
|July 2009 - December 2011
Purpose and goal
During fatigue in metallic materials cracks are initiated and grow with each load cycle until they reach critical length. Fatigue characterization of materials is usually carried out at 1 Hz; the result of which is then used for the design of aircraft components. At high temperatures (> 500 °C) cracks may however grow several order of magnitude faster if they at the same time are subjected to tensile stress during an extended period of time (dwell time) due to an interaction between grain boundary oxidation and the concentration of stress at the crack tip. Results from the initial phase of the cooperation project between Volvo Aero Corporation and Chalmers have convincingly demonstrated that this effect must be taken seriously. The knowledge already generated is of world class but more understanding is needed to enable us to develop material models which are useful in design work. In the anticipated continuation we are now ready to fully utilize the advanced instruments at our disposal and also the outcome of the Turbokraft project running in Linköping to reach this goal.
Expected results and effects
Actual results from previous project have already been recognized internationally indicating that our present approach is frutiful. This implies that we will be positioned as a convincing partner in the design for hot life of structural aircraft engien components.
Planned approach and implementation
The goal of this project that has already been running for two years at Applied Physics and at Materials Technology and Manufacturing at Chalmers in cooperation with Volvo Aero, is to reveal the mechanisms behind the crack growth which during the dwell time occurs in the grain boundaries. By this understanding it is possible to build realistic models of the hot fatigue life to be used in desing work. Testing will be carried out at Volvo Aero and at KIMAB but also in collaboration with Turbokraft at Linköpings universitet who is responsible for building the models.