MULTI-CAST TURBINE AIRFOILS AND METHOD FOR MAKING SAME

• US 20090269193A1
• Filed: 04/28/2008
• Published: 10/29/2009
• Est. Priority Date: 04/28/2008
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Original Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Inventors: PLANTE, Ghislain, LAROSE, Joel
• Granted Patent: US 8,267,663 B2
• Time in Patent Office: Days
• US Class Current: 415/200
• CPC Class Codes: B23K 20/1205 using translation movement
• CPC Class Codes: B23K 2101/001 Turbines
• CPC Class Codes: F01D 5/147 Construction, i.e. structural features, e.g. of weight-saving hollow blades F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18
• CPC Class Codes: F01D 5/28 Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
• CPC Class Codes: F05B 2230/239 Inertia or friction welding
• CPC Class Codes: F05D 2230/21 by casting
• CPC Class Codes: F05D 2300/607 Monocrystallinity

Abstract

A gas turbine engine airfoil is made from separate cast sections having different cast alloy structures. The cast alloy structures are selected on the basis of the local operating conditions of each section. Friction welding can be used to join the sections together.

Claims

1. A method of providing a multi-material turbine airfoil having a tip and a root spaced-apart along a spanwise direction of the airfoil, the method comprising:

a) identifying airfoil sections in the spanwise direction subject, in use, to different conditions;

b) selecting different cast alloy materials for the airfoil sections identified in a), the different cast alloy materials being selected in accordance with the conditions encountered by each of the identified airfoil;

c) casting the airfoil sections; and

d) friction welding the airfoil sections in an end-to-end relationship along the spanwise direction of the airfoil.

2. The method defined in claim 1, wherein the turbine airfoil has a platform, wherein a) comprises identifying a root fixing section, and wherein d) comprises joining the root fixing section to a remaining section of the turbine airfoil along a joining line extending chordwise through the airfoil above the platform.

3. The method defined in claim 1, wherein the turbine airfoil has a platform, wherein a) comprises identifying a root fixing section, and wherein d) comprises joining the root fixing section to a remaining section of the turbine airfoil along a joining line extending chordwise through the airfoil below the platform in a shank portion of the airfoil.

4. The method defined in claim 1, wherein a) comprises identifying a tip section, a midspan section and a root fixing section;

wherein b) comprises selecting three different cast alloy materials respectively suited for the conditions encountered by the tip section, the midspan section and the root fixing section; and

wherein d) comprises friction welding the tip section and the root fixing section to opposed ends of the midspan section.

5. The method defined in claim 4, wherein the turbine airfoil has a platform, and wherein the midspan section and the root fixing section are joined along a weld line located above the platform.

6. The method defined in claim 4, wherein the turbine airfoil has a platform, and wherein the midspan section and the root fixing section are joined along a weld line located below the platform.

7. The method defined in claim 1, comprising removing a damaged section of the airfoil;

selecting a cast alloy material suited for the local condition encountered by the damaged part;

using the selected cast alloy material, casting a new section corresponding to the damaged section, and friction welding the new section to a remaining portion of the gas turbine airfoil.

8. The method defined in claim 1, comprising considering a spanwise temperature distribution in the airfoil during engine operations, and taking into account the temperature distribution in the selection of material.

9. The method defined in claim 4, wherein the tip section comprises a first single crystal alloy, the midspan section comprises a second single crystal alloy, and the root fixing portion comprises a third single crystal alloy, a directionally-solidified alloy or a polycrystalline alloy.

10. A method of providing a multi-alloy turbine airfoil, comprising conceptually dividing the airfoil along a spanwise direction into sections subjected to different conditions during engine operation, individually selecting cast alloy materials suited for each of the sections, separately casting the sections with the cast alloy materials selected for each particular section, and friction welding the different sections together.

11. The method defined in claim 10, comprising dividing the airfoil in a tip section, a midspan section and a root fixing section;

selecting three different cast alloy materials respectively suited for the conditions encountered by the tip section, the midspan section and the root fixing section; and

friction welding the tip section and the root fixing section to opposed ends of the midspan section.

12. The method defined in claim 11, wherein the tip section is made of a first single crystal alloy, the midspan section is made of a second single crystal alloy, and the root fixing portion is made of a third single crystal alloy, a directionally-solidifed or an equiaxed alloy.

13. The method defined in claim 10, wherein the alloys used are nickel-based.

14. A method for making a multi-cast turbine airfoil, the method comprising:

casting a first airfoil section with a first alloy, casting a second airfoil section with a second alloy, the first and second alloys having different properties and being respectively selected as a function of the conditions encountered by the first and second airfoil sections, and friction welding the first airfoil section to the second airfoil section in a plane normal to a span direction of the turbine airfoil.

15. The method defined in claim 14, wherein the bonding plane extends from a leading edge to a trailing edge of the airfoil.

16. The method defined in claim 14, further comprising casting a third airfoil section with a third alloy, and friction welding said third airfoil section to said second airfoil section.

17. The method defined in claim 16, wherein said first, second and third airfoil sections respectively correspond to a tip portion, a midspan portion and a root portion of the turbine airfoil.

18. A method for making a multi-cast turbine airfoil, the method comprising:

determining a temperature profile to which the turbine airfoil is, in use, subjected;

determining at least two axial sections of the turbine airfoil subjected to different temperatures, a second one of the at least two axial sections being subjected to a higher temperature than a first section;

selecting a lower temperature alloy of the first section and a higher temperature alloy for the second section, using said lower and higher temperature alloys to respectively make said first and second sections, and welding the first and the second sections together.

19. A gas turbine engine airfoil comprising a tip portion having a first cast alloy structure joined at a first friction weld to an intermediate airfoil portion having a second cast alloy structure, and a fixing portion having a third cast alloy structure, the fixing portion being joined at a second friction weld to the intermediate airfoil portion, said first, second and third cast alloy structures having different properties respectively suited for the conditions prevailing at the tip portion, the intermediate portion and the fixing portion of the gas turbine engine airfoil.