Single crystal grain structure seals and method of forming
The present disclosure relates to advanced materials, particularly single crystal grain structures including the formation of single crystal grain structures. Single crystal grain structures offer improved mechanical properties when used with individual components. Improving mechanical properties is favorable for components that are used in applications with high temperature, pressure, and stress. In these applications, mechanical failure is extremely undesirable. Individual components, such as seals, can be designed with a single crystal grain structure in a preferred direction. By selecting a preferred direction, and orienting the single crystal grain structure accordingly, the single crystal grain structure can improve the component's mechanical properties. Single crystal grain structure seals and the method of forming the seals, therefore, offer various improvements to individual components, specifically when the components are designed for high temperature, pressure, and stress applications.
1. A seal comprising:
a leading edge;
a trailing edge; and
a seal body having a plurality of bends between the leading edge and the trailing edge, wherein the seal body has a cross-sectional shape having bends, and wherein the seal body is formed of a sheet of material having a single crystal grain structure, the single crystal grain structure oriented in a crystallographic direction following the bends of the cross-sectional shape of the seal body.
2. The seal of claim 1 , wherein the seal is a circumferential seal.
3. The seal of claim 1 , wherein the seal is a W-seal for a gas turbine engine.
4. The seal of claim 1 , wherein the cross-sectional shape of the seal includes at least one of a trough and a ridge between the trailing edge and leading edge.
5. The seal of claim 1 , wherein the single crystal grain structure includes facet orientation.
6. The seal of claim 1 , wherein the seal is formed of a precipitation hardened nickel based super alloy with more than 5% weight aluminum, or more than 50% by volume of the precipitates if aluminum is added in combination with elements such as titanium, tantalum or niobium to form the precipitates.
7. The seal of claim 1 , wherein the seal body is configured with a uniform thickness.
8. The seal of claim 1 , wherein maximum exposure temperature is within a range of 650° C. to 1100° C.
9. The seal of claim 1 , wherein the cross-sectional shape of the seal is configured to deflect in an axial direction of the seal.
10. A single crystalline seal, the single crystalline seal comprising:
a sheet of material having a first end;
a second end;
a cross-sectional shape, the cross-sectional shape being a two-dimensional shape having a plurality of bends and represented by a cross-section of the single crystalline seal, such that the cross-sectional shape is substantially the same at the first end, the second end, and a plurality of locations along the single crystalline seal between the first end and the second end; and
a single crystal grain structure direction, the single crystal grain structure direction directed along the bends of the cross-sectional shape, such that the single crystal grain structure direction is configured in the same direction as the bends of the cross-sectional shape.
11. The single crystalline seal of claim 10 , wherein the first end and the second end are connected, such that the single crystalline seal forms a circular shape from the first end to the second end.
12. The single crystalline seal of claim 10 , wherein the cross-sectional shape is a W-shape.
13. A method of forming a single crystal grain structure seal, the method comprising:
melting a crystalline material;
casting a single crystalline bar, the single crystalline bar being cast from the crystalline material and a seed, the seed having a desired crystalline orientation, such that the single crystalline bar is cast with the desired crystalline orientation;
rolling the single crystalline bar into a single crystalline sheet through warm working at a desired temperature; and
rolling the single crystalline sheet in an extrusion direction to create a cross-sectional shape having a plurality of bends,
wherein the cross-sectional shape has a single crystal grain structure direction, the single crystal grain structure direction directed along the cross-sectional shape, such that the single crystal grain structure direction is configured in the same direction as the cross-sectional shape.
14. The method of claim 13 , wherein the crystalline material is a precipitation hardened nickel based super alloy with more than 5% weight aluminum, or more than 50% by volume of the precipitates if aluminum is added in combination with elements such as titanium, tantalum or niobium to form the precipitates.
15. The method of claim 13 , wherein the cross-sectional shape is formed such that a cross-section of the cross-sectional shape is a W-shape.
16. The method of claim 13 , wherein the rolling process further includes at least one of a pre-heat treating process, intermediate annealing process, and post-heat treating process.
17. The method of claim 16 , wherein the rolling process is repeated more than one time to limit the reduction rate, in order to avoid overstressing the resulting single crystal grain structure.