R. Martin, UDRI, Dayton, OH; S. Sathish, University of Dayton Research Institute, Dayton, OH, OH
The currently used high temperature turbine engine disks consist of two separate sections welded together. The inner section has a fine grain microstructure while the outer section has large grain sizes. The two microstructures are designed to mitigate different types of accumulated damage in the disk. The outer section is exposed to higher temperatures compared to the inner section and experience creep damage over time. To mitigate the failure due to creep damage the large grain microstructure is created. Recently new engine turbine disks have been developed with out the need for welding two separate sections. The new disks have been developed to have fine grain microstructure in the inner section and very large grain microstructure in the outer section. Instead of welding structure, the new disks have a continuously graded microstructure. The defects and damage developed during service for the currently used disks are fairly well known. In the case of new disk material, defects and the damage accumulation processes need to be investigated to develop appropriate NDE tools. In this direction, this paper presents the results of the measurement of elastic modulus, electrical conductivity and residual stress performed using traditional NDE techniques. Local variation of the properties across the microsructurally graded LSHR material were measured using different methods. The elastic modulus variations were measured using focused acoustic beam. The eddy current technique was used to measure the local electrical conductivity variations. The residual stress measurements were performed using a dedicated x-ray residual stress analyzer. The results of the three physical properties are presented and the local variations are discussed along with the microstructure variations.
Summary: NDE study on characterization of low solvus high refractory graded microstructure alloy
